Co-reporter:Ye Fu, Congcong Gong, Wencai Wang, Liqun Zhang, Evgenii Ivanov, and Yuri Lvov
ACS Applied Materials & Interfaces September 6, 2017 Volume 9(Issue 35) pp:30083-30083
Publication Date(Web):August 16, 2017
DOI:10.1021/acsami.7b09677
An antifouling ethylene-vinyl acetate copolymer (EVA) coating with halloysite clay nanotubes loaded with maleimide (TCPM) is prepared. Such antifoulant encapsulation allowed for extended release of TCPM and a long-lasting, efficient protection of the coated surface against marine microorganisms proliferation. Halloysite also induces the composite’s anisotropy due to parallel alignment of the nanotubes. The maleimide loaded halloysite incorporated into the polymer matrix allowed for 12-month release of the bacterial inhibitor preventing fouling; it is much longer than the 2–3 month protection when TCPM is directly admixed into EVA. The antifouling properties of the EVA-halloysite nanocomposites were tested by monitoring surface adhesion and proliferation of marine V. natriegens bacteria with SEM. As compared to the composite directly doped with TCPM-antifoulant, there were much less bacteria accumulated on the EVA-halloysite-TCPM coating after a 2-month exposure to seawater. Field tests at South China Sea marine station further confirmed the formulation efficiency. The doping of 28 wt % TCPM loaded halloysite drastically enhanced material antifouling property, which promises wide applications for protective marine coating.Keywords: halloysite; marine antifouling; nanotubes; sustained release; thermoplastic;
Co-reporter:Weiwei Lei, Thomas P. Russell, Lei Hu, Xinxin Zhou, He Qiao, Wencai Wang, Runguo Wang, and Liqun Zhang
ACS Sustainable Chemistry & Engineering June 5, 2017 Volume 5(Issue 6) pp:5214-5214
Publication Date(Web):May 4, 2017
DOI:10.1021/acssuschemeng.7b00574
A series of biobased elastomers, poly(di-n-alkyl itaconate-co-isoprene)s (PDAIIs), were prepared by using itaconic acid as a renewable starting material. It is revealed that pendent chain profoundly affected the structure and properties of PDAIIs. The molecular structures of the PDAIIs were analyzed by 1H NMR and FTIR. Dialkyl itaconate to isoprene reactivity ratios measured by Kelen–Tüdös method demonstrated that PDAIIs with short side chains tended to alternate copolymerized and the long side chain ones tented to gradient copolymerized. Glass transition temperature, dielectric properties, and thermal stability of the PDAIIs were studied and these properties were tunable by varying the side chain length. Tensile tests revealed that cross-linked PDAIIs are elastic with a high elongation at break. With renewable resources and the side chain adjustability, PDAII elastomers potentially have a positive economic and ecological impact.Keywords: Alkyl side chain; Biobased elastomers; Itaconic acid; Monoalcohol; Polymer structure design; Renewable;
Co-reporter:He Qiao, Wenji Xu, Mingyuan Chao, Jun Liu, Weiwei Lei, Xinxin Zhou, Runguo Wang, and Liqun Zhang
Industrial & Engineering Chemistry Research 2017 Volume 56(Issue 4) pp:
Publication Date(Web):January 6, 2017
DOI:10.1021/acs.iecr.6b03517
Epoxy group-functionalized biobased elastomer poly(dibutyl itaconate-ter-isoprene-ter-glycidyl methacrylate) (PDBIIG) was synthesized via redox emulsion polymerization using glycidyl methacrylate (GMA) as the epoxy group-included monomer. The silica/PDBIIG nanocomposite was prepared without adding silane coupling agents. The ring-opening reaction, which occurred between the hydroxyl groups on the silica surfaces and the epoxy groups of the PDBIIG chains during mixing and vulcanization, was confirmed via bound rubber tests and Fourier transform infrared spectroscopy. This reaction was facilitated through heat treatment at 150 °C effectively. The introduction of covalent bonds significantly improved the interfacial interaction and dispersion of silica, which was indicated by transmission electron microscopy and rubber process analyzer (RPA) results. With the same silica loading and compounding procedure, the inclusion of 3.7 wt % GMA increased the modulus at 100% strain by 150.0% and the modulus at 300% strain by 152.3%. For the dynamic mechanical properties, the nanocomposite with GMA exhibited higher wet skid resistance and lower rolling resistance than the nanocomposite without GMA.
Co-reporter:Zhijun Yang, Wenyi Kuang, Zhenghai Tang, Baochun GuoLiqun Zhang
ACS Applied Materials & Interfaces 2017 Volume 9(Issue 8) pp:
Publication Date(Web):February 7, 2017
DOI:10.1021/acsami.7b00690
Although carbon nanotubes (CNTs) have been produced in industrial scale, their poor dispersibility in organic solvents still imposes a huge challenge for their practical applications. In the present work, we propose a generic mechanochemical grafting strategy to prepare the organo-soluable CNTs, which is facile, efficient, and scalable. Significantly, the solvent spectrum of the CNTs suspension can be simply extended by changing the chemical composition of the grafted elastomer chains. The prospect of the organo-solubale CNTs is demonstrated by the free-standing buckypapers by direct filtration of the CNT colloids. Such buckypapers exhibit great potential as robust and ultraflexible conductors due to the combination of high toughness and stable conductivity under cyclic bending and twisting. Furthermore, this facile surface modification strategy of CNTs also enables remarkable improvement in mechanical properties of CNT-based rubber composites. We envision that the present work offers a facile yet efficient strategy for scalable production of organosoluable CNTs and other nanoparticles, which is of great scientific and technological interest.Keywords: buckypaper; carbon nanotube; flexible conductor; mechanical properties; organo-soluble;
Co-reporter:Xiaoran Hu, Hailan Kang, Yan Li, Yiting Geng, Runguo Wang, Liqun Zhang
Polymer 2017 Volume 108() pp:11-20
Publication Date(Web):13 January 2017
DOI:10.1016/j.polymer.2016.11.045
•Fully renewable TPVs consisting of synthesized biobased elastomer and PLA by in situ dynamic vulcanization are prepared.•The morphology study proves phase inversion occurred during the dynamic vulcanization process.•The TPVs own renewable origins, good processability and reprocessability, excellent degradability and biocompatibility.•The superior 3D-printed performances indicate the TPVs is ideal 3D-printing biomedical materials.3D-printing of polymers provides the opportunity to fabricate materials into customized sizes and shapes. The present study describes fully renewable thermoplastic vulcanizates (TPVs) consisting of synthesized biobased elastomer (PLBSI) and poly (lactic acid) (PLA) by in situ dynamic vulcanization for 3D-printed materials. The morphology study implied in situ dynamic vulcanization and phase inversion occurs and leads the PLBSI elastomer dispersed as microparticles in PLA matrix. Then, the morphological evolution mechanism was proposed and indicated the dispersed PLBSI elastomer microparticles are actually agglomerates of elastomer nanoparticles. The PLBSI/PLA TPVs perform good processability and reprocessability by rheological and recyclability tests. Besides, good in vitro degradability and cytotoxicity suggests PLBSI/PLA TPVs are promising sustainable biomaterials. The superior strength and elasticity confirmed by the tensile tests of 3D-printed samples, and firm microstructure and the reliable printed accuracy of 3D-printed samples investigated by SEM implied the PLBSI/PLA TPVs were ideal 3D-printing materials.
Co-reporter:Xinxin Zhou;Baochun Guo;Liqun Zhang;Guo-Hua Hu
Chemical Society Reviews 2017 vol. 46(Issue 20) pp:6301-6329
Publication Date(Web):2017/10/16
DOI:10.1039/C7CS00276A
Mimicking natural structures has been highly pursued in the fabrication of synthetic polymeric materials due to its potential in breaking the bottlenecks in mechanical properties and extending the applications of polymeric materials. Recently, it has been revealed that the energy dissipating mechanisms via sacrificial bonds are among the important factors which account for strong and tough attributes of natural materials. Great progress in synthesis of polymeric materials consisting of sacrificial bonds has been achieved. The present review aims at (1) summarizing progress in the mechanics and chemistry of sacrificial bond bearing polymers, (2) describing the mechanisms of sacrificial bonds in strengthening/toughening polymers based on studies by single-molecule force spectroscopy, chromophore incorporation and constitutive laws, (3) presenting synthesis methods for sacrificial bonding including dual-crosslink, dual/multiple-network, and sacrificial interfaces, (4) discussing the important advances in engineering sacrificial bonding into hydrogels, biomimetic structures and elastomers, and (5) suggesting future works on molecular simulation, viscoelasticity, construction of sacrificial interfaces and sacrificial bonds with high dissociative temperature. It is hoped that this review will provide guidance for further development of sacrificial bonding strategies in polymeric materials.
Co-reporter:Wenhui Wang;Guanyi Hou;Zijian Zheng;Lu Wang;Jun Liu;Youping Wu;Liqun Zhang;Alexey V. Lyulin
Physical Chemistry Chemical Physics 2017 vol. 19(Issue 24) pp:15808-15820
Publication Date(Web):2017/06/21
DOI:10.1039/C7CP01453H
Using short polymer chains and through molecular dynamics simulation, we designed a well-dispersed nanoparticle (NP) network, which was then incorporated with the polymer matrix. First, we examined the effects of the dual-end grafted chains flexibility and density on the spatial distribution of this particular polymer nanocomposites system. By changing the interaction strength between the matrix polymer chains and the dual-end grafted chains in the semi-interpenetrating network system (NP network), we analyzed the interpenetration state between the linear polymer matrix and the NP network via calculating the total interfacial interaction energy. Moreover, the uniaxial tensile stress–strain and orientation behavior influenced by the interaction strength between the matrix polymer and the grafted chains were investigated for both the semi-interpenetrating network system and the interpenetrating network system (NP network and matrix network). Furthermore, for the interpenetrating network system, we modulated the integrity of the NP network ranging from 0% to 100%, corresponding to the gradual transition of the dispersion morphology of the NPs from the aggregation state to the uniform dispersion state, to examine the effect of the NP network on the tensile mechanical behavior. In particular, by simulating the dynamic shear process in the semi-interpenetrating network system, the composites were found to exhibit a lower non-linear behavior (the famous Payne effect), a higher storage modulus, and a lower tangent loss at large strain amplitude with increasing NP network integrity. In general, our results could provide a new approach for the design of high-performance polymer nanocomposites by taking advantage of the semi-interpenetrating or interpenetrating network reinforcing structure.
Co-reporter:Meihong Liao;Pengbo Wan;Jiangru Wen;Min Gong;Xiaoxuan Wu;Yonggang Wang;Rui Shi;Liqun Zhang
Advanced Functional Materials 2017 Volume 27(Issue 48) pp:
Publication Date(Web):2017/12/01
DOI:10.1002/adfm.201703852
AbstractHealable, adhesive, wearable, and soft human-motion sensors for ultrasensitive human–machine interaction and healthcare monitoring are successfully assembled from conductive and human-friendly hybrid hydrogels with reliable self-healing capability and robust self-adhesiveness. The conductive, healable, and self-adhesive hybrid network hydrogels are prepared from the delicate conformal coating of conductive functionalized single-wall carbon nanotube (FSWCNT) networks by dynamic supramolecular cross-linking among FSWCNT, biocompatible polyvinyl alcohol, and polydopamine. They exhibit fast self-healing ability (within 2 s), high self-healing efficiency (99%), and robust adhesiveness, and can be assembled as healable, adhesive, and soft human-motion sensors with tunable conducting channels of pores for ions and framework for electrons for real time and accurate detection of both large-scale and tiny human activities (including bending and relaxing of fingers, walking, chewing, and pulse). Furthermore, the soft human-motion sensors can be enabled to wirelessly monitor the human activities by coupling to a wireless transmitter. Additionally, the in vitro cytotoxicity results suggest that the hydrogels show no cytotoxicity and can facilitate cell attachment and proliferation. Thus, the healable, adhesive, wearable, and soft human-motion sensors have promising potential in various wearable, wireless, and soft electronics for human–machine interfaces, human activity monitoring, personal healthcare diagnosis, and therapy.
Co-reporter:Shafiullah Khan, Wang Runguo, Kamran Tahir, Zhang Jichuan, Liqun Zhang
Journal of Photochemistry and Photobiology B: Biology 2017 Volume 170(Volume 170) pp:
Publication Date(Web):1 May 2017
DOI:10.1016/j.jphotobiol.2017.04.006
•Bio-syntheses of Au nanoparticles using Cotoneaster horizontalis extract on time scale (~ 5 min)•Spherical and well dispersed AuNPs with small size of 18 ± 2 nm•The catalytic activity of AuNPs was confirmed through 4-NP reduction to 4-Ap•The AuNPs was evaluated for antibacterial against P. aeruginosa.A simple, green method is described for the synthesis of Gold (Au) nanoparticles (NPs) using Cotoneaster horizontalis extract as a phyto-reducer and capping agent with superior photo inhibition activity against Pseudomonas aeruginosa. Different from the other methods used elevated temperatures for nanoparticles synthesis, the novelty of our method lies in its energy saving process and fast synthesis rates (~ 5 min for AuNPs), and its potential to tune the nanoparticles size and afterward their catalytic activity. The starch, fatty acid and reducing sugars present in the extract are mostly responsible for repaid reduction rate Au+ 3 ions to AuNPs. Strong Plasmon resonance (SPR) of AuNPs was observed at 560 nm, which indicates the formation of gold nanoparticles. Uv-visible spectroscopy, high resolution transmission electron microscope (HRTEM) and energy dispersion X-ray diffraction (XRD) were preformed to find out the formation of AuNPs. Proficient reduction of 4-nitrophenol (4-NP) into 4-aminophenol (4-AP) in the presence of AuNPs and NaBH4 was observed and was found to depend upon the nanoparticle size or the extract concentration. The AuNPs was also evaluated for antibacterial against P. aeruginosa. Before transferred it into antibacterial activity, it placed under visible light for 120 min. The same experiment was performed in dark as control medium. The photo irradiated AuNPs was observed to be more effective against P. aeruginosa. The result showed that diameter of zone of inhibition of visible light irradiated AuNPs against P. aeruginosa was 17 (± 0.5) and in dark was 8 (± 0.4) mm.Download high-res image (144KB)Download full-size image
Co-reporter:Xinxin Zhou, Qinan Zhang, Runguo Wang, Baochun Guo, Yuri Lvov, Guo-Hua Hu, Liqun Zhang
Composites Part A: Applied Science and Manufacturing 2017 Volume 102(Volume 102) pp:
Publication Date(Web):1 November 2017
DOI:10.1016/j.compositesa.2017.08.013
Poly(dibutyl itaconate-co-isoprene-co-methacrylic acid) (PDIM)/halloysite nanotubes (HNTs) nanocomposites with strong interfacial interaction were prepared by co-coagulation of PDIM latex and HNTs aqueous suspension, followed by mechanical kneading with rubber additives. The interfacial interaction, thermal properties, morphology, and mechanical properties of the nanocomposites were investigated. The hydrogen bonds were confirmed in the nanocomposites. Morphology investigation showed uniform and individual dispersion of HNTs in the PDIM matrix. With the incorporation of HNTs into the PDIM matrix, the tensile strength and the fracture energy were significantly improved without sacrificing the extensibility. The improved mechanical properties were correlated to the co-coagulation and the strong hydrogen bonds. Especially, the morphology investigation of tensile fracture surfaces revealed a mechanism for the improved mechanical performance, in which the stress was efficiently transferred from PDIM to HNTs via hydrogen bonds and then the dissociation of the hydrogen bonds dissipated energy to increase the fracture energy of the nanocomposites.
Co-reporter:Guanyi Hou;Wei Tao;Jun Liu;Yangyang Gao;Liqun Zhang;Ying Li
Physical Chemistry Chemical Physics 2017 vol. 19(Issue 47) pp:32024-32037
Publication Date(Web):2017/12/06
DOI:10.1039/C7CP06199D
The structure–property relationship of polymer nanocomposites (PNCs) has been extensively investigated, but less effort has been devoted to studying the effect of chain architectures. Herein, through coarse-grained molecular dynamics simulation, we build six different chain architectures namely linear, branch-2 (with two side chains), branch-4 (with four side chains), branch-10 (with ten side chains), star-4 (with four arms) and star-6 (with six arms), by fixing the molecular weight per chain. First, we examine the effect of the interfacial interaction between the polymer and nanoparticles (NPs) εnp on the dispersion of NPs, by calculating the radial distribution function between NPs, the second virial coefficient and the average number of neighbor fillers. We observe a non-monotonic change of the NP dispersion as a function of εnp for all PNCs with different chain architectures, indicating the optimal dispersion of NPs at moderate εnp. Meanwhile, we find that the star-6, branch-4 and linear chains promote the best dispersion of NPs at moderate εnp, compared to the other chain architectures. Then we investigate the strain hardening behavior and chain orientation of these PNCs under uniaxial tension. We find that the star-6 chains demonstrate relatively the most remarkable reinforced mechanical behavior of PNCs. Furthermore, we probe the effect of end-functionalization of polymer chains with different architectures on the dispersion of NPs, by comparing them to the case without any functionalization. We find that the introduction of the end-functionalization benefits mostly the high degree of chain branching for promoting the dispersion of NPs. Meanwhile, we observe that when the tensile strain is small, the branch-4 structure shows relatively improved mechanical properties, however, when the tensile strain is large, the star-6 and branch-10 structures display the best mechanical properties, and the end-functionalization evidently improves the mechanical properties of the PNCs. Our simulation results provide guidelines to tailor the dispersion of NPs and the mechanical properties of PNCs, by taking advantage of the chain architecture and its end-functionalization strategy.
Co-reporter:Dan Yang;Shuo Huang;Mengnan Ruan;Yibo Wu;Shuxin Li;Hao Wang;Jinyu Zhang;Haonan Ma;Wenli Guo;Liqun Zhang
Journal of Materials Chemistry C 2017 vol. 5(Issue 31) pp:7759-7767
Publication Date(Web):2017/08/10
DOI:10.1039/C7TC00978J
Designed core–shell structured titanium dioxide–poly(dopamine)-silver (TiO2–PDA-Ag) particles were prepared via self-polymerization of poly(dopamine) and electroless plating of nano-silver particles. The poly(dopamine) layer was used not only to improve the interfacial interaction between TiO2 and the nitrile-butadiene rubber (NBR) matrix but also as chemisorption sites for silver ions. Then the TiO2–PDA-Ag particles were introduced into the NBR matrix to prepare dielectric composites. The effect of the nano-Ag content on morphology, dielectric properties, and electrical properties of the composites was thoroughly investigated. It was found that the Coulomb-blockade effect of nano-Ag particles led to the composites with relatively low dielectric loss and relatively high electrical breakdown strength. This simple and effective approach provides a promising route to adjust the dielectric properties of dielectric composites via the Coulomb-blockade effect.
Co-reporter:Jie Liu;Jun Liu;Sheng Wang;Jing Huang;Siwu Wu;Zhenghai Tang;Baochun Guo;Liqun Zhang
Journal of Materials Chemistry A 2017 vol. 5(Issue 48) pp:25660-25671
Publication Date(Web):2017/12/12
DOI:10.1039/C7TA08255J
Rubbers are widely applied in tires, seals, biomedical materials and aerospace applications because of their unique high elasticity. However, combining high self-healing capability and excellent mechanical performance in a rubber remains a formidable challenge. In this work, inspired by the energy dissipation mechanism and the recoverability of sacrificial bonds, the authors describe a dual-dynamic network design of a high-performance elastomer in which weaker multiple hydrogen bonds and stronger Zn–triazole coordination have been engineered into an unvulcanized cis-1,4-polyisoprene (IR) matrix. Accordingly, the elastomer obtains high tensile strength (21 MPa) and toughness (60 MJ m−3). The facilitated chain orientation in such a dual-dynamic network is finely substantiated by the molecular dynamics simulation results. Significantly, this dual-dynamic network design enables a fully cut elastomer to be healed at mild temperature. Under healing at 80 °C for 24 h, the healed elastomer regains excellent mechanical properties (tensile strength of 15.5 MPa and fracture energy of 42.8 MJ m−3). We envision that this design concept can not only develop a new network construction method in rubbers instead of vulcanization, but also provide inspiration for preparing advanced elastomers with the combination of excellent mechanical performance and high self-healing capability.
Co-reporter:Ye Fu, Chun Yang, Yuri M. Lvov, Liqun Zhang, Wencai Wang
Chemical Engineering Journal 2017 Volume 328(Volume 328) pp:
Publication Date(Web):15 November 2017
DOI:10.1016/j.cej.2017.06.142
•A method to load antioxidant into carbon nanotubes for sustained release is proposed.•The sustained release of antioxidant from carbon nanotubes extends its action time.•The antioxidant amount in the rubber composite is enlarged without causing blooming.•The thermal-oxidative & ozone aging resistance of SBR/CNTs is improved.In this work, a novel strategy to avoid the blooming of antioxidants and improve the aging-resistance of styrene-butadiene rubber (SBR) was proposed by using carbon nanotubes (CNTs) loaded with antioxidant N-(1, 3-dimethyl) butyl-N′-phenyl-p-phenylenediamine (4020) as filler. The sustained release of antioxidant from carbon nanotubes extends its action time. The amount of antioxidant in the rubber composites allows for a concentration of 2.0 wt.% without causing blooming by encapsulating antioxidant into carbon nanotubes. The aging resistance of SBR/CNTs composites was studied by comparing the mechanical properties before and after thermal-oxidative and ozone aging. A fifteen-day thermal-oxidative aging test at 100 °C shows preservation of mechanical properties and a twenty-four-hour ozone aging test shows no cracks. Furthermore, due to the present of thermal and electrical conductive carbon nanotubes, the rubber composites emerge thermal conductivity of 0.303 W/m·K and electrical conductivity of 4.74 × 107 Ω·cm which can be extended for many potential applications, such as long service life tires and antistatic conveyer belts. This loading and sustained release approach can be extended to antimicrobial, antifouling, and other application.Download high-res image (140KB)Download full-size image
Co-reporter:Baochun Guo, Zhenghai Tang, Liqun Zhang
Progress in Polymer Science 2016 Volume 61() pp:29-66
Publication Date(Web):October 2016
DOI:10.1016/j.progpolymsci.2016.06.001
Functional elastomer nanocomposites have found numerous applications in diverse hi-tech areas. Transport phenomena, such as electrical conductivity, thermal conductivity and gas/liquid barrier properties, have been the major focus of functional elastomer nanocomposite research. Despite essential progress in these areas, a summary and discussion of state-of-the-art strategies for regulating the transport performances of nanocomposites based on the transportation mechanisms of electrons, phonons and mass are lacking. In the present review, a brief introduction of transport mechanisms in elastomer nanocomposites precedes a systematic summary of the important progress in elastomer nanocomposites with electrical/thermal conductivities and lowered mass permeabilities, with emphasis on the latest structural control strategies for tuning transport properties. Key applications of functional elastomer nanocomposites related to transport phenomena are also introduced. Overall, this review summarizes the state of the art in the design and performance enhancement of elastomer nanocomposites based on the relationships between their structures and transport properties, governed by the components/composition, interface/dispersion and fabrication.
Co-reporter:Dan Yang, Mengnan Ruan, Shuo Huang, Yibo Wu, Shuxin Li, Hao Wang, Yuwei Shang, Bingyao Li, Wenli Guo and Liqun Zhang
Journal of Materials Chemistry A 2016 vol. 4(Issue 33) pp:7724-7734
Publication Date(Web):01 Jul 2016
DOI:10.1039/C6TC01504B
In order to obtain a nitrile-butadiene rubber (NBR) dielectric elastomer composite with excellent electromechanical properties, a combination of bio-inspired poly(dopamine) (PDA) deposition and γ-methacryloxypropyl trimethoxy silane (KH570) grafting was proposed to functionalize the surface of titanium dioxide (TiO2) nanoparticles. Inspired by adhesive proteins in mussels, dopamine self-polymerization was used to deposit a thin adherent PDA film onto the surface of TiO2. KH570 that contains double bonds was then grafted through the reactions with hydroxyl and indole groups of the PDA surface. The chemical structure and composition of the TiO2 surface were characterized by XPS, FTIR, and HR-TEM. Because of the introduction of PDA grafted with the KH570 layer, the NBR composites filled with modified TiO2 displayed better filler dispersion, higher dielectric constant, lower elastic modulus, and higher electric breakdown field compared with composites filled with pristine TiO2 particles. Finally, a large actuated strain of about 16% at 60 kV mm−1 without any pre-strains was shown by the composite of NBR filled with 20 phr modified TiO2 particles, which is 53% larger than that of NBR without a filler. The process was fast, simple, efficient, nontoxic, and controllable, which can provide a new universal method for modification of dielectric fillers to improve the dielectric properties and electromechanical properties of dielectric elastomers.
Co-reporter:Rui Shi, Jiajia Xue, Hanbin Wang, Renxian Wang, Min Gong, Dafu Chen, Liqun Zhang and Wei Tian
Journal of Materials Chemistry A 2016 vol. 4(Issue 2) pp:348-348
Publication Date(Web):10 Dec 2015
DOI:10.1039/C5TB90174J
Correction for ‘Fabrication and evaluation of a homogeneous electrospun PCL–gelatin hybrid membrane as an anti-adhesion barrier for craniectomy’ by Rui Shi et al., J. Mater. Chem. B, 2015, 3, 4063–4073.
Co-reporter:Weiwei Lei, Xinxin Zhou, Thomas P. Russell, Kuo-chih Hua, Xiaoping Yang, He Qiao, Wencai Wang, Fanzhu Li, Runguo Wang and Liqun Zhang
Journal of Materials Chemistry A 2016 vol. 4(Issue 34) pp:13058-13062
Publication Date(Web):04 Aug 2016
DOI:10.1039/C6TA05001H
Globally, we are faced with a massive growth in the number of urban vehicles. This growth comes at the cost of enormous fuel consumption, CO2 emissions and air pollution, commonly seen as a haze. With a strategy to fabricate low roll-resistance green tire elastomers from large-scale, bio-based chemicals, specifically itaconic acid, mono-alcohols and conjugated dienes, each of these problems can be reduced. By combining a molecular structural design with non-petroleum based silica and an in situ process to tune the viscoelastic properties of the elastomer composites, we have successfully manufactured silica/poly(di-n-butyl itaconate-co-butadiene) nanocomposite-based green tires that have very low roll-resistance, excellent wet skid resistance and good wear resistance, promote fuel efficiency and reduce our dependence on petrochemical resources. The results shown here open an important avenue for the synthetic rubber and automobile industry to ameliorate a major problem facing many cities worldwide, and also provide an effective route for resource sustainability.
Co-reporter:Shuquan Sun, Dong Wang, Thomas P. Russell, and Liqun Zhang
ACS Macro Letters 2016 Volume 5(Issue 7) pp:839
Publication Date(Web):June 28, 2016
DOI:10.1021/acsmacrolett.6b00278
Mapping the structure evolution and mechanical properties of elastic polymers or biomaterials during bulk deformation has been difficult, yet this information has long been thought to be key for understanding the structure–mechanical property relationship necessary to guide the design of new materials. Here we use a nanomechanical mapping to assess the structural evolution and mechanical properties of a deformed isoprene rubber (IR) to elucidate a self-reinforcement mechanism in this material. A hierarchical nanofibrillar structure, ranging from several to a hundred nanometers in size, comprised of fibers oriented parallel to the stretching direction was found. The nanofibers, connected by oriented amorphous tie chains, form a network structure that is responsible for significantly enhanced stress, a key factor giving rise to the self-reinforcement of IR and, more than likely, most elastomers that undergo strained-induced crystallization.
Co-reporter:Zhao Wang, Xing Zhang, Liqun Zhang, Tianwei Tan, and Hao Fong
ACS Sustainable Chemistry & Engineering 2016 Volume 4(Issue 5) pp:2762
Publication Date(Web):March 27, 2016
DOI:10.1021/acssuschemeng.6b00275
The objective of this study was to explore an environment-friendly route to synthesize nonisocyanate based poly(ester urethanes) of poly(1,10-bis(hydroxyethyloxycarbonylamino) decane-co-dicarboxylic acid) (PBDA) from renewable materials/resources. In specific, 1,10-bis(hydroxyethyloxycarbonylamino)decane (BHD) was first synthesized from ethylene carbonate and decamethylene diamine via the melt ring-opening reaction. Subsequently, the PBDAs with tunable properties were synthesized from BHD and five dicarboxylic acids (including three biobased ones of oxalic acid, sebacic acid, and itaconic acid) via the melt polycondensation reaction. The structural, physical, and mechanical properties of PBDAs were characterized by FTIR, NMR, XRD, GPC, TGA, and mechanical testing machine; additionally, the environmental stability was evaluated upon measuring the water absorption amount in deionized water and the degradation percentage in phosphate buffer saline. The results indicated that the PBDAs possessed reasonably good properties and thus could potentially be used for engineering applications; moreover, because their macromolecular chains/backbones contained ester and urethane groups (which would usually result in excellent cytocompatibility), it was envisioned that these PBDAs might also be suitable for some biological and/or biomedical applications.Keywords: Biobased polymers; Environment-friendly synthesis; Green chemistry; Nonisocyanate based poly(ester urethanes); Sustainable materials
Co-reporter:Runguo Wang, Jichuan Zhang, Hailan Kang, Liqun Zhang
Composites Science and Technology 2016 Volume 133() pp:136-156
Publication Date(Web):14 September 2016
DOI:10.1016/j.compscitech.2016.07.019
Bio-based polymer products derived from renewable agricultural and biomass feedstock have become increasingly important as these sustainable and eco-efficient products bring a significant reduction in greenhouse gas emissions and saving of fossil energy in comparison with conventional pertrochemical-based materials. A series of bio-based elastomers from large-scale produced and petroleum independent monomers such as succinic acid, sebacic acid, itaconic acid, 1,3-propanediol, 1,4-butanediol, soybean oil, glycerol, citric acid, etc have been developed by authors. Same as conventional elastomers, bio-based elastomers possess low glass transition temperature, high elasticity and low strength, and this implies that they must be reinforced by nano-fillers. However, they also possess particular and novel properties due to their characteristic macromolecular structures and aggregation structure. For example, the existence of abundant ester groups, terminal carboxyl groups, and terminal hydroxyl groups in bio-based polyester elastomers endow polar fillers like silica disperse homogeneous in the elastomer matrix without surface modification. Even though, for incorporation of easily agglomerated fillers like graphene and layered silicates, elaborately dispersion and interfacial tailoring technique is necessary. Combined with specific structures and relevant effective composite technology, bio-based elastomer composites exhibit versatile potential applications in tire tread, PLA toughener, thermoplastic vulcanizates, and dielectric elastomer, etc.
Co-reporter:Zhijun Yang, Jun Liu, Ruijuan Liao, Ganwei Yang, Xiaohui Wu, Zhenghai Tang, Baochun Guo, Liqun Zhang, Yong Ma, Qiuhai Nie, Feng Wang
Composites Science and Technology 2016 Volume 132() pp:68-75
Publication Date(Web):23 August 2016
DOI:10.1016/j.compscitech.2016.06.015
The energy loss of tires during service is closely related to the hysteresis of tire tread, which is governed by the dispersion and interface of the elastomer nanocomposites. However, traditional undeformable spherical fillers have approached a bottleneck in regulating the viscoelasticity and lowering the hysteresis loss. Herein, the designed covalent interface in the graphene/elastomer nanocomposite maximizes the reinforcement of the nanomaterial as well as minimizes the dynamic energy loss. The reinforced interfacial interaction, an ultralow percolation threshold of tensile strength and high reinforcement synergistically benefit these nano-organized rubber nanocomposites. The energy losses under dynamic loading are largely suppressed in this material, due to the reduced nano-scale frictions. The developed graphene/elastomer nanocomposites are applied to typical dynamic rubber product - auto tires, and the tests indicate that these tires possess energy efficiency close to the highest “A-grade”, which gave great economic and environmental improvements. The critical role of interface structure in the performance of the elastomer nanocomposites was revealed and new design strategy for low dynamic energy losses in rubber products was suggested.
Co-reporter:Yangyang Gao, Dapeng Cao, Youping Wu, Jun Liu and Liqun Zhang
Soft Matter 2016 vol. 12(Issue 12) pp:3074-3083
Publication Date(Web):09 Feb 2016
DOI:10.1039/C5SM02803E
By adopting coarse-grained molecular dynamics simulation, we investigate the effects of end-functionalization and shear flow on the destruction and recovery of a nanorod conductive network in a functionalized polymer matrix. We find that the end-functionalization of polymeric chains can enhance the electrical conductivity of nanorod filled polymer nanocomposites, indicated by the decrease of the percolation threshold. However, there exists an optimal end-functionalization extent to reach the maximum electrical conductivity. In the case of steady shear flow, both homogeneous conductive probability and directional conductive probability perpendicular to the shear direction decrease with the shear rate, while the directional conductive probability parallel to the shear direction increases. Importantly, we develop a semi-empirical equation to describe the change of the homogeneous conductive probability as a function of the shear rate. Meanwhile, we obtain an empirical formula describing the relationship between the anisotropy of the conductive probability and the orientation of the nanorods. In addition, the conductivity stability increases with increasing nanorod volume fraction. During the recovery process of the nanorod conductive network, it can be fitted well by the model combining classical percolation theory and a time-dependent nanorod aggregation kinetic equation. The fitted recovery rate is similar for different nanorod volume fractions. In summary, this work provides some rational rules for fabricating polymer nanocomposites with excellent performance of electrical conductivity.
Co-reporter:Yonglai Lu, Jun Liu, Guanyi Hou, Jun Ma, Wencai Wang, Fei Wei, Liqun Zhang
Composites Science and Technology 2016 Volume 137() pp:94-101
Publication Date(Web):12 December 2016
DOI:10.1016/j.compscitech.2016.10.020
Carbon nanotubes (CNTs) attract considerable scientific and engineering interest because of their excellent mechanical, electrical and thermal properties. Today, when manufacturers use CNTs, purification, chemical modifications and dispersion techniques are usually applied rendering them cost-effective in large-scale applications. Our research shows that multi-wall CNTs bundles (MWCNTBs) with the same alignment, orientation and high surface defects for each CNT can be directly incorporated into the elastomer matrix through melt compounding. A uniform dispersion of CNTs and strong interfacial interactions between elastomers and CNTs due to the silane-coupling agent can be simultaneously produced. The resulting elastomer/MWCNTBs nanocomposites demonstrate excellent mechanical properties, high thermal conductivity and low volume resistivity. Note that this nanocomposite is achieved using common compounding equipment that is easy to industrialize. Through further scale-up, we confirmed that this elastomer/MWCNTBs nanocomposite has the most optimized comprehensive performance with practical applications for fuel-savings and engineering tires. These advantages include fuel efficiency, anti-static electricity and long-time fatigue resistance. In light of the large number of tires used worldwide, this work is promising for future large-scale industrial applications of CNTs.
Co-reporter:Xiaoran Hu, Yan Li, Manqiang Li, Hailan Kang, and Liqun Zhang
Industrial & Engineering Chemistry Research 2016 Volume 55(Issue 34) pp:9195
Publication Date(Web):August 12, 2016
DOI:10.1021/acs.iecr.6b02159
Composites of poly(lactic acid) (PLA) and a series of renewable and biobased copolyesters (PLBSIs) were manufactured by melt blending to toughen PLA. Benefiting from reasonable macromolecular design, the introduction of lactic acid in PLBSIs not only increases the compatibility with PLA but also helps PLBSIs turn from crystalline plastic to amorphous elastomer. The increasing compatibility was proved by the decreasing particle size of PLBSIs in PLA, and the better toughening effect of elastomer than that of plastic was characterized by the thermal tensile test. Thus, the supertoughened PLA composites were obtained and exhibited maximum elongation at break of 324% and impact strength of 35.7 kJ/m2, 50 and 15 times higher than neat PLA, respectively. Excellent performance in 3D-printed tensile tests implies the toughened PLA was ideal 3D-printing ink. The supertoughened PLA will eliminate the brittleness of PLA for wide application and possess great potential for industrial and engineering fields.
Co-reporter:Zhao Wang, Yunhu Peng, Liqun Zhang, Yong Zhao, Roman Vyzhimov, Tianwei Tan, and Hao Fong
Industrial & Engineering Chemistry Research 2016 Volume 55(Issue 10) pp:2784-2789
Publication Date(Web):February 25, 2016
DOI:10.1021/acs.iecr.5b04527
The objective of this study was to explore palm oil (PMO) as a green/renewable plasticizer for ethylene propylene diene monomer (EPDM) rubber; for comparison, the commonly used plasticizer of petroleum-based paraffin oil (PO) was also investigated. The plasticization effects of PMO and PO on EPDM rubber compounds were systematically studied; in specific, the Mooney viscosity, processing properties, and cross-linking characteristics of EPDM rubber compounds with different loading amounts of plasticizer (i.e., PMO or PO) were characterized, and the mechanical properties and thermal stability of cross-linked EPDM rubber compounds were also evaluated. The results indicated that the performance/effect of PMO on processing and mechanical properties of EPDM rubber was similar/comparable to that of PO, whereas PMO is renewable with lower cost. Therefore, PMO would be a cost-effective green plasticizer that could replace PO for EPDM rubber.
Co-reporter:Sihang Gao;Runguo Wang;Bowen Fang;Hailan Kang;Lixin Mao;Liqun Zhang
Journal of Applied Polymer Science 2016 Volume 133( Issue 1) pp:
Publication Date(Web):
DOI:10.1002/app.42855
ABSTRACT
A series of poly(succinic acid/sebacic acid/itaconic acid/butanediol/propanediol) bio-based and non-crystalline engineering elastomers (BEE) were obtained by changing the molar ratio of succinic acid (SA) to sebacic acid (SeA) from 5:5 (BEE-5) to 8:2 (BEE-8). We prepared bio-based engineering elastomer composites (BEE/CB) by mixing BEE with carbon black N330. The low-temperature and oil resistance properties of the BEE/CB composites were investigated in terms of low-temperature brittleness, coefficient of cold resistance under compression, oil resistance test at different temperatures, and tensile properties. The results showed that the low-temperature brittleness temperature of the BEE/CB composites ranged from −50 to −60°C and the coefficient of cold resistance under compression was 0.18 high at −60°C for BEE-7/CB and 0.23 high at −40°C for BEE-8/CB. The oil resistance properties of BEE-7/CB were higher than those of nitrile-butadiene rubber N240S (NBR N240S), and the oil resistance properties of BEE-8/CB were even as high as those of nitrile-butadiene rubber N220S (NBR N220S). © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 132, 42855.
Co-reporter:Miaomiao He;Tao Wei;Liqun Zhang;Qingxiu Jia
Polymer Engineering & Science 2016 Volume 56( Issue 7) pp:829-836
Publication Date(Web):
DOI:10.1002/pen.24311
We studied the crystallization behaviors of bio-based BDIS polyamides synthesized from the following biomass monomers: 1,4-butanediamine (BD), 1,10-decanediamine (DD), itaconic acid (IA), and sebacic acid (SA). Isothermal crystallization, melting behavior, and nonisothermal crystallization of BDIS polyamides were investigated by differential scanning calorimetry (DSC). The Avrami equation was used to describe the isothermal crystallization of BDIS polyamides. The modified Avrami equation, the Ozawa equation, the modified Ozawa equation, and an equation combining the Avrami and Ozawa equations were used to describe the nonisothermal crystallization. The equilibrium melting point temperature of BDIS polyamide was determined to be 163.0°C. The Avrami exponent n was found to be in the range of 2.21–2.79 for isothermal crystallization and 4.10–5.52 for nonisothermal crystallization. POLYM. ENG. SCI., 56:829–836, 2016. © 2016 Society of Plastics Engineers
Co-reporter:Lu Wang, Zijian Zheng, Theodoros Davris, Fanzhu Li, Jun Liu, Youping Wu, Liqun Zhang, and Alexey V. Lyulin
Langmuir 2016 Volume 32(Issue 33) pp:8473-8483
Publication Date(Web):July 26, 2016
DOI:10.1021/acs.langmuir.6b01049
In this work we perform molecular-dynamics simulations, both on the coarse-grained and the chemistry-specific levels, to study the influence of morphology on the mechanical properties of polymer nanocomposites (PNCs) filled with uniform spherical nanoparticles (which means without chemical modification) and patchy spherical nanoparticles (with discrete, attractive interaction sites at prescribed locations on the particle surface). Through the coarse-grained model, the nonlinear decrease of the elastic modulus (G′) and the maximum of the viscous modulus (G″) around the shear strain of 10% is clearly reproduced. By turning to the polybutadiene model, we examine the effect of the shear amplitude and the interaction strength among uniform NPs on the aggregation kinetics. Interestingly, the change of the G′ as a function of the aggregation time exhibited a maximum value at intermediate time attributed to the formation of a polymer-bridged filler network in the case of strong interaction between NPs. By imposing a dynamic periodic shear, we probe the change of the G′ as a function of the strain amplitude while varying the interaction strength between uniform NPs and its weight fraction. A continuous filler network is developed at a moderate shear amplitude, which is critically related to the interaction strength between NPs and the weight fraction of the fillers. In addition, we study the self-assembly of the patchy NPs, which form the typical chain-like and sheet-like structures. For the first time, the effect of these self-assembled structures on the viscoelastic and stress–strain behavior of PNCs is compared. In general, in the coarse-grained model we focus on the size effect of the rough NPs on the Payne effect, while some other parameters such as the dynamic shear flow, the interaction strength between NPs, the weight fraction, and the chemically heterogeneous surface of the NPs are explored for the chemistry-specific model.
Co-reporter:Zhenghai Tang, Jing Huang, Baochun Guo, Liqun Zhang, and Fang Liu
Macromolecules 2016 Volume 49(Issue 5) pp:1781-1789
Publication Date(Web):February 17, 2016
DOI:10.1021/acs.macromol.5b02756
Reinforcing rubbers and expanding their application galleries are two important issues in material science and engineering. In this work, we demonstrate a bioinspired design of high-performance and macroscopically responsive diene-rubber by engineering sacrificial metal–ligand motifs into a chemically cross-linked architecture network. The metal–ligand bonds are formed through the coordination reaction between the pyridine groups in butadiene–styrene–vinylpyridine rubber (VPR) and metal ions. Under external load, the metal–ligand bonds serve as sacrificial bonds that preferentially rupture prior to the covalent network, which dissipates energy and facilitates rubber chain orientation. Based on the function mechanisms, the modulus, tensile strength, and toughness of the samples are simultaneously improved without sacrificing the extensibility, and these properties can be conveniently tuned by varying the structure parameters of the covalently cross-linked network and metal–ligand bonds. Moreover, the dissociation/re-formation of metal–ligand bonds upon heating/cooling can endow VPR with thermally triggered adaptive recovery for shape memory application.
Co-reporter:Haibo Yang, Fanzhu Li, Tung W. Chan, Li Liu, Liqun Zhang
Composites Part B: Engineering 2016 Volume 92() pp:160-166
Publication Date(Web):1 May 2016
DOI:10.1016/j.compositesb.2015.10.020
Based on the micromechanical theory, the effect of the shapes of nanofillers on the viscoelasticity of rubber nanocomposites was evaluated by the finite element analysis. The shapes of nanofillers we discussed included sphere, cylinder, tube, plate, ring, and spring. Two types of interphase – “bonding interphase” and “frictional interphase” – which represented the strong interphase and the weak interphase respectively were assumed to discuss the effect of interphase on the viscoelasticity of rubber nanocomposites. The dissipation and loss factors were calculated and discussed. The predicted results show that the shapes of nanofillers have great effect on the viscoelasticity of rubber nanocomposite. Including the spring nanofillers in the rubber matrix can greatly decrease the loss factor of the nanocomposite when the interphase is a “bonding interphase,” while including the ring nanofillers in the rubber matrix can greatly increase the loss factor of the nanocomposite when the interphase is a “frictional interphase.”
Co-reporter:Yan Gui, Junchi Zheng, Xin Ye, Dongli Han, Meimei Xi, Liqun Zhang
Composites Part B: Engineering 2016 Volume 85() pp:130-139
Publication Date(Web):February 2016
DOI:10.1016/j.compositesb.2015.07.001
With the help of a new coupling agent Si747, silica water slurry and styrene–butadiene rubber (SBR) latex were successfully co-coagulated by the latex compounding method, even silica/SBR masterbatches with silica loading as high as 200 phr could be prepared by such method. Compared to the traditional dry blending method, the latex compounding method had lower energy consumption during mixing and better silica dispersion in rubber matrix. Meanwhile, the effect of the amount of silica in the SBR latex on the properties of silica/SBR composites was investigated, and the results showed that the larger the amount of silica in the rubber matrix, the stronger the filler network. The performance of these composites was good and the dispersion of silica was relatively homogeneous. Furthermore, the masterbatches with high silica loading were mixed with emulsion polymerized styrene–butadiene rubber (ESBR) or solution polymerized styrene–butadiene rubber (SSBR). The silica dispersed better in ESBR than in SSBR.
Co-reporter:Xiuying Zhao, Kaijing Niu, Yong Xu, Zheng Peng, Li Jia, David Hui, Liqun Zhang
Composites Part B: Engineering 2016 Volume 107() pp:106-112
Publication Date(Web):15 December 2016
DOI:10.1016/j.compositesb.2016.09.073
Epoxidized natural rubber (ENR) was used as a compatibilizer to prepare ternary composites with natural rubber (NR) and nitrile butadiene rubber (NBR). The morphological, structural, and mechanical properties of the NR/NBR/ENR ternary composites were systematically investigated by using SEM, AFM, TEM, DSC, DMTA, and tensile testing. The NR matrix was the continuous phase, and NBR was the dispersed phase with a size of several micrometers. ENR reduced the aggregation of the NBR phase and improved the compatibility between NR and NBR. According to the rule of “like dissolves like”, with increasing polarity, ENR migrated from the NR matrix and was dispersed into the NBR phase or gathered at the interface between NR and NBR. Compared with pure NR, the ternary composites had a higher tan δ at 0 °C and lower tan δ at 60 °C, related to the wet grip and rolling resistance of tread materials, respectively. The results also indicated that the prepared NR/NBR/ENR ternary composites exhibited improved tensile strength and tear strength because of the strain-induced crystallization of NR. Therefore, the NR/NBR/ENR ternary composites are promising high-performance tire tread materials.
Co-reporter:Xiaoran Hu, Xiaolin Shen, Mengfei Huang, Chaohao Liu, Yiting Geng, Runguo Wang, Riwei Xu, He Qiao, Liqun Zhang
Polymer 2016 Volume 84() pp:343-354
Publication Date(Web):10 February 2016
DOI:10.1016/j.polymer.2016.01.007
•Based on microbial production of 2,3-butanediol in our laboratory, we synthesized linear and crosslinkable bio-elastomers.•The introduction of 2,3-butanediol can highly suppress the crystallization of bio-elastomers and makes them fully amorphous.•These bio-elastomers can be effectively reinforced by nanosilica and their degradation rate can be adjusted by crosslinking.•Good performances of bio-elastomers make them environment-friendly and potential candidates for engineering applications.Highly purified 2,3-butanediol (2,3-BDO) was obtained from glycerol by using metabolically engineered Escherichia coli through biosynthetic pathways. The bio-elastomers with high strength and elasticity was then prepared from the synthetic 2,3-butanediol and several commercially renewable monomers as promising materials for engineering applications. The molecular weights, chemical structures, and thermal transitions of the bio-elastomers were confirmed by GPC, NMR, FTIR, TGA, DSC and WAXD. Importantly, the introduction of 2,3-BDO can limit and even prevent the crystallization of these bio-elastomers, which makes them amorphous and ensure their high elasticity. Furthermore, the bio-elastomers were highly reinforced with nanosilica which can meet the requirements for the majority of rubber products. Results of in vitro degradation tests prove these bio-elastomers can adjust the degradation rate of their composites by crosslinking. Cell adhesion and proliferation were adopted to evaluate the potential biocompatibility of SiO2/PBPSSI composites and the results indicated that all the SiO2/PBPSSI composites were essentially noncytotoxic. In general, the petroleum-independent monomers, relatively simple synthesis and adjustable degradation rate could greatly reduce environmental impact and the fine mechanical properties and excellent biocompatibility make these novel synthetic bio-elastomers sustainable materials for engineering applications.
Co-reporter:Shafiullah Khan, Zhao Wang, Runguo Wang, Liqun Zhang
Materials Science and Engineering: C 2016 Volume 67() pp:554-560
Publication Date(Web):1 October 2016
DOI:10.1016/j.msec.2016.05.071
•A monomer was designed and synthesized from limonene via Thiol-ene-Click Reactions.•Bio-based elastomers were first synthesized from the difunctional monomer and diacid.•The synthesized elastomers could be cross-linked with dicumyl peroxide (DCP).The additions of 2-mercaptoethanol to (S)-(−)-limonene via click reaction is described as an adaptable and efficient way to obtain alcohol functionalized renewable monomer for the synthesis of new cross-linkable bio-based elastomers. Thiol first reacted with the limonene endocyclic double bond and then reacted with the exocyclics double bond to form the difunctional monomer. The structure of the monomer was determined by using FTIR, 1H NMR and mass spectrometry. Thermal Gravimetric Analysis (TGA) and Differential Scanning Calorimetrys (DSC) characterization exposed that this monomer could be used to synthesize elastomers with excellent and adaptable thermal properties. The molecular weight of the synthesized elastomer could reach 186 kDaa via melting polycondensation route and the structure–properties relationship was deliberated. Finally, these elastomers were mixed with dicumyl peroxide (DCP) to form cross-linked elastomers with certain mechanical property, and the gel contents of the elastomers were confirmed by using Soxhlet extraction method.
Co-reporter:Xuhui Zhang, Zhenghai Tang, Baochun Guo, and Liqun Zhang
ACS Applied Materials & Interfaces 2016 Volume 8(Issue 47) pp:
Publication Date(Web):November 9, 2016
DOI:10.1021/acsami.6b10881
It poses a huge challenge to expand the application gallery of rubbers into advanced smart materials and achieve the reinforcement simultaneously. In the present work, inspired by the metal–ligand complexations of mussel byssus, ferric ion was introduced into an oxygen-abundant rubber network to create additional metal–oxygen coordination cross-links. Such complexation has been revealed to be highly efficient in enhancing the strength and toughness of the rubbers. Significantly, such complexation also enables the functionalization of the rubber into highly damping or excellent multishape memory materials. We envision that the present work offers an efficient yet facile way of creating advanced elastomers based on industrially available diene-based rubber.Keywords: biomimetic; damping; metal−oxygen coordination; toughness; triple-shape memory polymer;
Co-reporter:Fanzhu Li, Jun Liu, Haibo Yang, Yonglai Lu, Liqun Zhang
Polymer 2016 Volume 101() pp:199-207
Publication Date(Web):28 September 2016
DOI:10.1016/j.polymer.2016.08.065
•Heat build-up analysis for rubber compounds was performed.•Thermo-mechanical coupling approach and nonlinear viscoelastic theory were used.•Creep effect on heat build-up for rubber compounds was firstly considered.•Dynamic property softening effect on heat build-up was firstly considered.•A highly sophisticated equipment was used to verify calculated temperature results.Based on nonlinear viscoelastic theory and coupled thermo-mechanical approach, heat build-up analysis of a rubber specimen under cyclic loading was performed through finite element analysis. The determination of the rubber material properties attracted particular attention. The thermo-mechanical coupling approach can be divided into three major parts: deformation, dissipation, and thermal modules. In the deformation module, uniaxial, planar, and equibiaxial tensile tests were used to determine the hyperelastic constitutive equation. In the dissipation module, an analytical method for calculating the energy dissipation rate was established. The dynamic properties were updated as a function of the strain and temperature based on the modified Kraus model. Creep effect and dynamic property softening effect on the viscoelastic properties were firstly considered. In the thermal module, the dependence of thermal parameters on temperature was established. A highly sophisticated equipment which can measure the temperature rise curves both on the surface and at the heart of the rubber specimen was used to verify the calculated results. The comparison between numerical results and experimental data shows that the proposed analysis method provides a satisfactory way to predict heat build-up for rubber compounds.
Co-reporter:Yangyang Gao, Dapeng Cao, Youping Wu, Jun Liu, Liqun Zhang
Polymer 2016 Volume 101() pp:395-405
Publication Date(Web):28 September 2016
DOI:10.1016/j.polymer.2016.08.103
•Relationship among anisotropy of conductive probability, electrostatic force and interaction.•Relationship among percolation threshold, electrostatic force and interaction.•Evolution process of conductivity network structure with or without electric field.Facilitating the electric field to fabricate high performance polymer nanocomposites (PNCs) is always a great and promising strategy. In this work, the effect of the electric field on the conductive property of the PNCs is investigated by adopting coarse-grained molecular dynamics simulation. The translational and rotational diffusion of the nanorod gradually decreases with the increase of the nanorod aspect ratio; however, it is nearly independent of the nanorod volume fraction. Under the electric field, it exhibits a limited decrease, but more anisotropy of the translational diffusion of the nanorod. Meanwhile, the nanorods can not experience the random rotation, which is attributed to the electrostatic force. In addition, on one hand, the electrostatic force exerting on the nanorods induces the nanorod orientation, leading to the decrease of the homogeneous conductive probability; however, the electrostatic interaction induces the connection of the nanorod, resulting in the increase of the homogeneous conductive probability. Additionally, the directional conductive probability parallel to the electric field direction increases; however, the directional conductive probability perpendicular to the electric field direction shows a continuous decrease. Considering these two effects, the decrease or the increase of the homogeneous conductivity probability depends on the competition between the electrostatic force and the electrostatic interaction. The relationship among the anisotropy of the conductive probability, the nanorod volume fraction, the electrostatic force and the electrostatic interaction can be described quantitatively by an empirical formula. Another empirical formula is adopted to quantitatively describe the relationship among the percolation threshold, the electrostatic force and the electrostatic interaction. Meanwhile, the evolution process of the conductivity network structure is studied with or without the electric field. In summary, this work quantitatively describes the effect of the electric field on the conductive property of the PNCs, which can provide some useful guidances to design and fabricate PNCs with excellent conductivity properties by taking advantage of the external electric field.
Co-reporter:Jun Liu, Zijian Zheng, Fanzhu Li, Weiwei Lei, Yangyang Gao, Youping Wu, Liqun Zhang, Zhong Lin Wang
Nano Energy 2016 Volume 28() pp:87-96
Publication Date(Web):October 2016
DOI:10.1016/j.nanoen.2016.08.002
•The end-linking elastomer network exhibits excellent dynamic mechanical properties.•The DHL is reduced for ~50% compared to silica nanoparticles filled elastomer.•Our approach provides a versatile framework to fabricate the fuel-saving tires.Achieving energy sustainability has imposed a great challenge to improve fuel efficient vehicles. Tires, to overcome the rolling resistance, are responsible for a rather large fraction of energy consumed by vehicles, and a 10% reduction in the rolling resistance corresponds to a 2% decline in the fuel consumption, which, for instance, would save 1–2 billion gallon of fuel per year consumed by the entire passenger vehicle fleet in the United States. From the materials’ perspective, the key bottleneck to lower the rolling resistance of tires lies in designing a novel kind of advanced elastomeric polymer nanocomposites tailored for tire tread, with remarkably low dynamic hysteresis loss (DHL). Here we show that, a nanoparticle chemically end-linking elastomer network, with nanoparticles (NPs) acting as netpoints to chemically connect the dual end-groups of each polymer chain to form a network, exhibits excellent static and dynamic mechanical properties of super-low DHL. The DHL is reduced for ~50% compared to silica NPs filled elastomer that is conventionally used for tire tread. By taking advantage of a library of other nanomaterials such as functionalized carbon nanotube and graphene, our approach provides a versatile framework to fabricate the fuel-saving tires, opening up valuable opportunities for large-scale industrial applications of these nanomaterials in the tire industry.In this work we show that, a nanoparticle chemically end-linking elastomer network, with nanoparticles (NPs) acting as netpoints to chemically connect the dual end-groups of each polymer chain to form a network, exhibits excellent super-low dynamic hysteresis, opening an avenue for fabricating fuel-saving tires towards environmental protection.
Co-reporter:Weiwei Lei;He Qiao;Xinxin Zhou;Wencai Wang;Liqun Zhang
Science China Chemistry 2016 Volume 59( Issue 11) pp:1376-1383
Publication Date(Web):2016 November
DOI:10.1007/s11426-016-0200-4
Bio-based elastomer poly(diethyl itaconate-co-isoprene) (PDEII) was designed and synthesized by redox-initiated emulsion polymerization from diethyl itaconate and isoprene with mass ratio of 20:80, 40:60, 60:40 and 80:20. The number-average molecular weights of PDEII exceeded 140000 with relatively high yields. The physical properties of PDEII, such as glass transition temperatures and thermostability, were comparable with conventional synthetic elastomers and can be readily tuned by varying the ratio of diethyl itaconate to isoprene. The interaction between silica and PDEII macromolecules was effectively enhanced with the increase of diethyl itaconate content by endowing high polarity. The oil-resistance relevant properties of silica/ PDEII80 (80% diethyl itaconate, 20% isoprene) such as retention of tensile strength, retention of elongation at break and change in volume even surpass those of silica/NBR 240S after soaked in ASTM 3# oil at different temperatures.
Co-reporter:Rui Shi, Jiajia Xue, Hanbin Wang, Renxian Wang, Min Gong, Dafu Chen, Liqun Zhang and Wei Tian
Journal of Materials Chemistry A 2015 vol. 3(Issue 19) pp:4063-4073
Publication Date(Web):17 Apr 2015
DOI:10.1039/C5TB00261C
Adhesion formation between dura mater and the overlying temporalis muscle following decompressive craniectomy can make subsequent cranioplasty difficult and adds to the risks of the procedure. In this work, we developed an electrospun PCL–gelatin hybrid membrane to be planted at decompressive craniectomy for preventing adhesion formation and facilitating subsequent cranioplasty. We prepared poly(ε-caprolactone)-gelatin (PG) nanofiber membranes with different PCL–gelatin ratios. The architectural features, mechanical properties, cell barrier functions, in vivo degradability, biocompatibility and anti-adhesion function were investigated. All membranes were found to have high tensile strength, and the strength of the membranes improved with the PCL content increased. All the PG membranes presented good biocompatibility and cell isolation performances while an increase in the gelatin content resulted in an enhancement of cell adhesion and proliferation. Subcutaneous implantation in rabbits for 6 months demonstrated that all the membranes showed good biocompatibility and adjustable biodegradation behaviour. In rabbit cranial defects model, no adhesions were observed, either between the PG membranes and the dura, or between the membranes and the temporal muscle after 1 month implantation. PG membranes' anti-adhesive properties and biodegradable characteristics make it useful as a dural onlay for craniotomy in which a second surgery is planned.
Co-reporter:Dan Yang, Fengxing Ge, Ming Tian, Nanying Ning, Liqun Zhang, Changming Zhao, Kohzo Ito, Toshio Nishi, Huaming Wang and Yunguang Luan
Journal of Materials Chemistry A 2015 vol. 3(Issue 18) pp:9468-9479
Publication Date(Web):24 Mar 2015
DOI:10.1039/C5TA01182E
Dielectric elastomers are referred to as artificial muscles because of their excellent properties. However, the need for high operating voltage limits their practical application. A reduction of the operating voltage can be achieved with novel elastomers offering intrinsically high electromechanical sensitivity. In this work, slide-ring materials with a necklace-like molecular structure are prepared as dielectric elastomer materials. These slide-ring materials are found to exhibit high dielectric constants, low elastic moduli, and high electromechanical sensitivity due to their special structural characteristics. Barium titanate particles modified by γ-methacryloxypropyl trimethoxy silane (KH570) are incorporated into the slide-ring materials to further improve the actuated performance of the slide-ring materials. A high actuated strain (26%) at a relatively low electric field (12 kV mm−1) is obtained on the circular membrane actuator without any pre-strains, much more excellent than those of other dielectric elastomers reported in the literature. In addition, an obviously larger displacement is achieved by the slide-ring composite than that of commercial dielectric elastomer VHB 4910 on a cone-type actuator at the same electric field. These results demonstrate that our research might help to establish a new synthetic route to high performance dielectric elastomers.
Co-reporter:Ye Fu, Detao Zhao, Pengjun Yao, Wencai Wang, Liqun Zhang, and Yuri Lvov
ACS Applied Materials & Interfaces 2015 Volume 7(Issue 15) pp:8156
Publication Date(Web):April 8, 2015
DOI:10.1021/acsami.5b00993
A novel aging-resistant styrene–butadiene rubber (SBR) composite is prepared using the antioxidant N-isopropyl-N′-phenyl-p-phenylenediamine (4010NA) loaded inside of halloysite clay nanotubes and used as filler. Loading the antioxidant inside of halloysite allows for its sustained release for nine months in the rubber matrix. By utilizing modified halloysite, the antioxidant concentration in this rubber nanoformulation is tripled without causing “blooming” defects. Furthermore, the halloysite is silanized to enhance its miscibility with rubber. The aging resistance of SBR–halloysite composites is studied by comparing the mechanical properties before and after thermal-oxidative aging. A seven-day test at 90 °C shows preservation of mechanical properties, and no 4010NA blooming is observed, even after one month. Styrene–butadiene rubber with 27 wt % halloysite loaded with 4010NA shows marked increase in aging resistance and promising future of halloysite as a functional rubber filler.Keywords: Aging resistant; elastomer; halloysite; nanotubes; sustained release;
Co-reporter:He Qiao, Runguo Wang, Hui Yao, Xinxin Zhou, Weiwei Lei, Xiaoran Hu and Liqun Zhang
Polymer Chemistry 2015 vol. 6(Issue 34) pp:6140-6151
Publication Date(Web):07 Jul 2015
DOI:10.1039/C5PY00720H
Bio-based poly(dibutyl itaconate-ter-isoprene-ter-4-vinylpyridine) (PDBIIVP) elastomers with different 4-vinylpyridine (4-VP) contents were synthesized by redox emulsion polymerization for the purpose of designing and preparing green graphene oxide (GO)/PDBIIVP nanocomposites with strong interfacial interaction. The ionic bonding interfaces in the nanocomposites were the result of electrostatic attraction between the in situ protonated pyridine groups of PDBIIVP and the electronegative GO sheets with hydrochloric acid during latex co-coagulation and were confirmed by X-ray photoelectron spectroscopy. The inclusion of a small amount of 4-VP (less than 7 wt%) improved the dispersion of GO, the interfacial interaction between PDBIIVP and GO, and the performance of the GO/PDBIIVP nanocomposite markedly. The reinforcement effects of GO on the mechanical and gas barrier properties of PDBIIVP increased continuously with increasing 4-VP content. Additionally, GO/PDBIIVP nanocomposites with a fixed 4-VP content and different GO loadings were prepared and characterized. As the GO loading increased, the performance of the nanocomposites improved greatly. For the GO/PDBIIVP with 7.0 wt% of 4-VP and 4 phr of GO, the tensile strength increased by 700%, the volume loss of abrasion decreased by 53%, and the gas permeability decreased by 63% compared with those of the neat PDBIIVP. The remarkable improvements are attributed to the strong ionic bonding interfaces between the pyridine-included bio-based elastomer and GO. We believe that this work of new polymer construction with the functional group targeting the interfacial interaction with GO should be an important strategy for developing GO-based polymer nanocomposites with high performance.
Co-reporter:Xiaoran Hu, Hailan Kang, Yan Li, Manqiang Li, Runguo Wang, Riwei Xu, He Qiao and Liqun Zhang
Polymer Chemistry 2015 vol. 6(Issue 47) pp:8112-8123
Publication Date(Web):10 Sep 2015
DOI:10.1039/C5PY01332A
Novel poly(lactate/butanediol/sebacate/itaconate) (PLBSI) copolyesters with sustainability and biocompatibility were synthesized by using direct melting polycondensation. The molecular weights, chemical structures, and compositions of the copolyesters were confirmed by GPC, NMR, and FTIR. By controlling the content of lactic acid, the copolyesters were transformed from rigid plastics to flexible elastomers. The PLBSI elastomers were highly reinforced with nanosilica which can meet the tensile strength requirements for the majority of rubber products. More importantly, the PLBSI elastomers can be used as PLA tougheners owing to the similar lactate structures of PLA and PLBSI. The toughened PLA can be applied as excellent three-dimensional printing ink. Besides, the crosslinked PLBSI plastics were demonstrated to be promising shape memory polymers with excellent shape fixity and recovery rate. The renewable monomers, relatively simple polymerization, and versatile performance make our PLBSI copolyesters promising for various medical and engineering applications.
Co-reporter:Yangyang Gao, Dapeng Cao, Jun Liu, Jianxiang Shen, Youping Wu and Liqun Zhang
Physical Chemistry Chemical Physics 2015 vol. 17(Issue 35) pp:22959-22968
Publication Date(Web):28 Jul 2015
DOI:10.1039/C5CP01953B
We adopted molecular dynamics simulation to study the conductive property of nanorod-filled polymer nanocomposites by focusing on the effects of the interfacial interaction, aspect ratio of the fillers, external shear field, filler–filler interaction and temperature. The variation of the percolation threshold is anti N-type with increasing interfacial interaction. It decreases with an increase in the aspect ratio. At an intermediate filler–filler interaction, a minimum percolation threshold appears. The percolation threshold decreases to a plateau with temperature. At low interfacial interaction, the effect of an external shear field on the homogeneous probability is negligible; however, the directional probability increases with shear rate. Moreover, the difference in conductivity probabilities is reduced for different interfacial interactions under shear. Under shear, the decrease or increase of conductivity probability depends on the initial dispersion state. However, the steady-state conductivity is independent of the initial state for different interfacial interactions. In particular, the evolution of the conductivity network structure under shear is investigated. In short, this study may provide rational tuning methods to obtain nanorod-filled polymer nanocomposites with high conductivity.
Co-reporter:Jianxiang Shen, Jun Liu, Haidong Li, Yangyang Gao, Xiaolin Li, Youping Wu and Liqun Zhang
Physical Chemistry Chemical Physics 2015 vol. 17(Issue 11) pp:7196-7207
Publication Date(Web):10 Feb 2015
DOI:10.1039/C4CP05520A
Through coarse-grained molecular dynamics simulations, we have studied the effects of grafting density (Σ) and grafted chain length (Lg) on the structural, mechanical and visco-elastic properties of end-grafted nanoparticles (NPs) filled polymer nanocomposites (PNCs). It is found that increasing the grafting density and grafted chain length both enhance the brush/matrix interface thickness and improve the dispersion of NPs, but there seems to exist an optimum grafting density, above which the end-grafted NPs tend to aggregate. The uniaxial stress–strain behavior of PNCs is also examined, showing that the tensile stress is more enhanced by increasing Lg compared to increasing Σ. The tensile modulus as a function of the strain is fitted following our previous work (Soft Matter, 2014, 10, 5099), exhibiting a gradually reduced non-linearity with the increase of Σ and Lg. Meanwhile, by imposing a sinusoidal external shear strain, for the first time we probe the effects of Σ and Lg on the visco-elastic properties such as the storage modulus G′, loss modulus G′′ and loss factor tanδ of end-grafted NPs filled PNCs. It is shown that the non-linear relation of G′ and G′′ as a function of shear strain amplitude decreases with the increase of Σ and Lg, which is consistent with experimental observations. We infer that the increased mechanical and reduced non-linear visco-elastic properties are correlated with the enhanced brush/matrix interface and therefore better dispersion of NPs and stronger physical cross-linking. This work may provide some rational means to tune the mechanical and visco-elastic properties of end-grafted NPs filled polymer nanocomposites.
Co-reporter:Dan Yang, Shuo Huang, Yibo Wu, Mengnan Ruan, Shuxin Li, Yuwei Shang, Xiuguo Cui, Jiaxin Zhou, Wenli Guo and Liqun Zhang
RSC Advances 2015 vol. 5(Issue 124) pp:102157-102166
Publication Date(Web):13 Nov 2015
DOI:10.1039/C5RA18394D
Dielectric elastomers (DEs), which are capable of displaying considerable stress and strain in response to an applied electric field, have shown the closest similarity in performance to natural muscles. However, the high operating voltage of DEs limits their practical application. A reduction of the operating voltage can be achieved through increasing the dielectric constant and/or decreasing the elastic modulus. Here, an all-organic non-percolative dielectric composite with enhanced electromechanical actuating performance was prepared by introducing polyaniline (PANI) and epoxidized soybean oil (ESO) into a nitrile-butadiene rubber (NBR) matrix. A small amount of PANI was used to increase the dielectric constant through adding electron movement which is similar to dipole polarization, while ESO was used to decrease the elastic modulus of the composite through weakening intermolecular interactions in NBR and molecular interaction between NBR and PANI. Finally, an actuated strain of 2.5% was obtained at 4.5 V μm−1 by 4 phr PANI/NBR composite filled with 50 phr ESO, a 700% improvement in actuated strain compared with the actuated strain (0.31%) of pure NBR at 4.5 V μm−1 without any pre-strains. In comparison with other dielectric composites filled with conductive filler, the ESO/PANI/NBR composite also displays a relative advantage under conditions of no pre-strain and low electric field.
Co-reporter:Weiwei Lei, Runguo Wang, Dan Yang, Guanyi Hou, Xinxin Zhou, He Qiao, Wencai Wang, Ming Tian and Liqun Zhang
RSC Advances 2015 vol. 5(Issue 59) pp:47429-47438
Publication Date(Web):21 May 2015
DOI:10.1039/C5RA06576C
A new dielectric elastomer with large actuated strain driven by low electric field was synthesized from di-n-butyl itaconate and isoprene through free radical redox emulsion polymerization. The effect of the copolymerized proportion of poly(di-n-butyl itaconate-co-isoprene) (PDBII) and the dosage of crosslinking agent on the elastic modulus, dielectric properties, and actuated strain of the elastomer were investigated, and a potential dielectric elastomer candidate containing 70 wt% di-n-butyl itaconate was obtained. The permittivity of the PDBII crosslinked by 3.0 phr of dicumyl peroxide was 5.68 at 103 Hz, which was higher than that of commercial acrylic and silicone dielectric elastomers. Without any prestrain, an actuated strain of 20% was obtained at an electric field of 30 kV mm−1. In order to further increase the actuated strain, barium titanate (BaTiO3), a high-dielectric-constant ceramic powder, was utilized to fill the PDBII to form a BaTiO3/PDBII composite. The dielectric constant of the composite increased with increasing content of BaTiO3, and the elastic modulus of the composite was lower than that of the unfilled PDBII, leading to a larger dielectric actuated strain of the composite.
Co-reporter:Hailan Kang, Xiaoran Hu, Manqiang Li, Liqun Zhang, Youping Wu, Nanying Ning and Ming Tian
RSC Advances 2015 vol. 5(Issue 30) pp:23498-23507
Publication Date(Web):26 Feb 2015
DOI:10.1039/C4RA17024E
Owing to the sustainability and environmental friendliness of biobased polymers, we adopted synthesized biobased polyester elastomer (BPE) and polylactide (PLA) as the two components to produce a new biobased thermoplastic vulcanizate (TPV) by an in situ dynamical crosslinking and mixing method. The effect of blending ratio on the dynamic crosslinking and micromorphology of TPV was investigated by mixing torque measurements, degree of crosslinking measurements, TEM, DSC, and rheological properties. A large amount of crosslinked BPE particles were dispersed in the PLA continuous phase, with the particle sizes ranging from 1 to 4 μm, indicating the occurrence of phase inversion during the dynamical crosslinking and mixing process. The tensile strength and elongation at break of the biobased TPVs ranged from 11.4 MPa to 17.8 MPa and 154% to 184%, respectively. Reprocessing did not significantly reduce the mechanical properties, as an indication that biobased TPVs, like thermoplastics, have good reprocessability. In vitro cytotoxicity tests showed that our TPVs were nontoxic, at least towards mouse fibroblasts. Thus, these novel biobased TPVs with excellent mechanical properties and low cytotoxicity are reported for the first time in the flied of thermoplastic elastomers for engineering and biomedical applications.
Co-reporter:Min He, Jiajia Xue, Huan Geng, Hao Gu, Dafu Chen, Rui Shi, Liqun Zhang
Applied Surface Science 2015 Volume 335() pp:121-129
Publication Date(Web):30 April 2015
DOI:10.1016/j.apsusc.2015.02.037
Highlights
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Core/sheath PCL/gelatin nanofiber membrane loaded with metronidazole in a wide range of drug loading (5–35 wt.%) were successfully fabricated in good quality.
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The encapsulation of gelatin can effectively alleviate the initial burst release of drugs.
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The membrane can inhibit the growth of bacteria as the drug content reaches 10% (w/w), and the bacterial inhibition ability can effectively last at least 4 weeks.
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The encapsulation of gelatin can overcome the disadvantage of PCL's hydrophobicity, which can effectively promote the adhesion and proliferation of cells.
Co-reporter:Zhenghai Tang, Jing Huang, Xiaohui Wu, Baochun Guo, Liqun Zhang, and Fang Liu
Industrial & Engineering Chemistry Research 2015 Volume 54(Issue 43) pp:10747-10756
Publication Date(Web):October 8, 2015
DOI:10.1021/acs.iecr.5b03146
In silica-filled rubber composites, the silanization modification of silica plays a vital role in enhancing the compatibility between silica and a rubber matrix and hence the properties of the composites. In the present study, with the goal of promoting silanization reactivity and extent, we utilize a phosphonium ionic liquid (PIL) as a novel catalyst for the silanization reaction between silica and bis(3-triethoxysilylpropyl)-tetrasulfide (TESPT), a commonly used silane in the tire industry, in the styrene–butadiene rubber (SBR) matrix. Dynamic rheological measurement, bound rubber measurement, freezing point depression, and heat capacity increment together show that the addition of a small amount of PIL into a TESPT-modified SBR/silica composite gives rise to significant improvement in the interfacial adhesion between silica and the rubber matrix, which is on account of the promoted silanization extent of silica with the catalyst of PIL. Consequently, the resulting composite prepared at room temperature with fewer parts of TESPT exhibits superior overall performance in comparison with the composites prepared by adding excessive TESPT and compounding at an elevated temperature. In particular, the energy loss during rolling of the rubber wheel is drastically decreased as a result of the improved interfacial silanization, which shows great potential in energy-saving green tires.
Co-reporter:Huimei Zhang;Ming Lu;Qiuyu Lu;Bo He;Liqun Zhang;Yakang Liu
Journal of Applied Polymer Science 2015 Volume 132( Issue 18) pp:
Publication Date(Web):
DOI:10.1002/app.41914
ABSTRACT
Cross-linked α-methylstyrene and acrylonitrile (MStAN) copolymer particles in a latex form were synthesized by free radical emulsion polymerization. The particles showed a narrow size distribution and an average diameter of 65 nm. The amount of the vinyl groups at the surface of the (MStAN) copolymer particles resulted from varied amount of the initiator (APS) and the cross-linking agent (DVB) was detected by iodine titration method. When filled into ethylene propylene rubber (EPR), the MStAN nano-particles exhibited excellent reinforcing capabilities, and with the increase of the vinyl groups at the surface of MStAN particles, the tensile stress of MStAN/EPR increased. Results demonstrated that the vinyl groups at the surface of the (MStAN) copolymer particles provided certain chemical interactions between the filler particles and the macromolecular chains of rubber matrix. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41914.
Co-reporter:Jiajia Xue, Yuzhao Niu, Min Gong, Rui Shi, Dafu Chen, Liqun Zhang, and Yuri Lvov
ACS Nano 2015 Volume 9(Issue 2) pp:1600
Publication Date(Web):January 13, 2015
DOI:10.1021/nn506255e
Guided tissue regeneration/guided bone regeneration membranes with sustained drug delivery were developed by electrospinning drug-loaded halloysite clay nanotubes doped into poly(caprolactone)/gelatin microfibers. Use of 20 wt % nanotube content in fiber membranes allowed for 25 wt % metronidazole drug loading in the membrane. Nanotubes with a diameter of 50 nm and a length of 600 nm were aligned within the 400 nm diameter electrospun fibers, resulting in membranes with doubling of tensile strength along the collector rotating direction. The halloysite-doped membranes acted as barriers against cell ingrows and have good biocompatibility. The metronidazole-loaded halloysite nanotubes incorporated in the microfibers allowed for extended release of the drugs over 20 days, compared to 4 days when directly admixed into the microfibers. The sustained release of metronidazole from the membranes prevented the colonization of anaerobic Fusobacteria, while eukaryotic cells could still adhere to and proliferate on the drug-loaded composite membranes. This indicates the potential of halloysite clay nanotubes as drug containers that can be incorporated into electrospun membranes for clinical applications.Keywords: anti-infection; clay nanotubes; electrospinning; guided tissue regeneration; sustained drug delivery;
Co-reporter:He Qiao, Runguo Wang, Hui Yao, Xiaohui Wu, Weiwei Lei, Xinxin Zhou, Xiaoran Hu, Liqun Zhang
Polymer 2015 Volume 79() pp:1-11
Publication Date(Web):19 November 2015
DOI:10.1016/j.polymer.2015.10.011
•Ionic bonding interfaces were introduced to the composite through interface tailoring.•The dispersion of layered silicate was improved as pyridine group content increases.•Pyridine group has profound effect on the interfacial interaction.•The performance of the bio-based elastomer was improved significantly.Green nanocomposites consisting of bio-based poly(dibutyl itaconate-ter-isoprene-ter-4-vinylpyridine) (PDBIIVP) elastomers with different 4-vinylpyridine (4-VP) contents and natural layered silicate montmorillonite (MMT) were prepared by a green latex co-coagulation method. The effects of the pyridine groups on the interfacial interaction, morphology, and performance of the nanocomposites were investigated. Ionic bonding interfaces, which were confirmed by X-ray photoelectron spectroscopy, were introduced to the nanocomposites through the electrostatic attraction between the protonated pyridine groups of the modified elastomers and the electronegative MMT during the co-coagulation of PDBIIVP latex and MMT aqueous suspension with hydrochloric acid. The dispersion of MMT and the interfacial interaction between PDBIIVP and MMT were improved remarkably, as demonstrated by X-ray diffraction, transmission electron microscopy, rubber process analyzer (RPA) results and swelling tests. The mechanical and gas barrier properties of PDBIIVP improved markedly with increasing 4-VP content. For the PDBIIVP with 7.0 wt% 4-VP, the addition of 10 phr of MMT increased the tensile strength by 730% and reduced the gas permeability by 71%.
Co-reporter:Haibo Yang, Fanzhu Li, Tung W. Chan, Li Liu, Liqun Zhang
Composites Part B: Engineering 2015 Volume 74() pp:171-177
Publication Date(Web):1 June 2015
DOI:10.1016/j.compositesb.2015.01.020
Background/PurposeRubber nanocomposites have been widely used in many engineering fields due to their unique properties such as high elasticity and viscoelasticity. Much attention has been paid to the viscoelasticity of rubbers because it directly relates to the performance of the rubber products.MethodsBased on the micromechanical theory, the finite element method is used to analyze the effect of elastic modulus and volume content of spring-shape nanofillers on the dynamic viscosity of composites.ResultsThe simulation results show that there is an optimal elastic modulus of spring-shape nanofillers to make the loss factor a minimum. There is a threshold value of spring-shape nanofiller content for the dissipation energy density of composite.ConclusionThe elastic modulus of spring-shape nanofillers has a large effect on the loss factor of composites. The selection of elastic modulus of spring-shape nanofillers is critical for applications of composites. The efficiency of spring-shape nanofillers in reducing the dynamic viscosity of composites is so high that volume content of spring-shape nanofillers as low as 0.1% can greatly reduce the loss factor of composites with bonding interface.
Co-reporter:Xinxin Zhou;Runguo Wang;Weiwei Lei;He Qiao;Haoling Ji
Science China Chemistry 2015 Volume 58( Issue 10) pp:1561-1569
Publication Date(Web):2015 October
DOI:10.1007/s11426-015-5332-y
Poly(dibutyl itaconate-co-isoprene-co-methacrylic acid) (PDIM) elastomer was designed and synthesized by redox emulsion polymerization under mild conditions. PDIM has high molecular weight, relatively high yield, and low glass transition temperature (Tg). The structure of PDIM was determined by FTIR and NMR, and the carboxyl content was obtained by titration in a non-proton solvent. Tensile strength and elongation at break increased with increasing carboxyl content. In addition, the interaction between PDIM and silica was elucidated by rubber process analyzer (RPA) and TEM, and the results showed that the silica-PDIM interaction was strong, but the silica-silica interaction was weak.
Co-reporter:Xue Li;Hai-lan Kang;Jian-xiang Shen
Chinese Journal of Polymer Science 2015 Volume 33( Issue 3) pp:433-443
Publication Date(Web):2015 March
DOI:10.1007/s10118-015-1596-0
The “sliding graft copolymer” (SGC), in which many linear poly-ɛ-caprolactone (PCL) side chains are bound to cyclodextrin rings of a polyrotaxane (PR), was prepared and employed to toughen diglycidyl ether of bisphenol A (DGEBA) based epoxy resin. The aim of the work is to understand the effect of SGC on the miscibility, morphology, thermal behavior, curing reaction and mechanical performance of the cured systems. From differential scanning calorimetry (DSC) analysis and dynamic mechanical thermal analysis (DMTA) of DGEBA/SGC thermosetting blends, it is found that DGEBA and SGC are miscible in the amorphous state. Fourier transform infrared spectroscopy (FTIR) suggested that the miscibility between SGC and DGEBA is due to the existence of intermolecular specific interactions (viz. hydrogen bonding). The impact strength is improved by 4 times for DGEBA/SGC (80/20) blends compared with that of the unmodified system. The increase in toughness of SGC-modified thermosets can be explained by the effect of intermolecular specific interactions of SGC with DGEBA, which is beneficial to induce the plastic deformation of matrix. This is the first report on utilizing this novel supramolecular polymer to toughen rigid epoxy matrix.
Co-reporter:Jiajia Xue, Min He, Yuanzhe Liang, Aileen Crawford, Phil Coates, Dafu Chen, Rui Shi and Liqun Zhang
Journal of Materials Chemistry A 2014 vol. 2(Issue 39) pp:6867-6877
Publication Date(Web):05 Sep 2014
DOI:10.1039/C4TB00737A
Infection is the major reason for GTR/GBR membrane failure in clinical applications. In this work, we developed GTR/GBR membranes with localized drug delivery function to prevent infection. Hierarchical membranes containing micro- and nano-fibers were fabricated. The effects of the incorporation of gelatin and loading content of metronidazole (MNA) (0, 5, 10, 20, 30, and 40 wt% polymer) on the properties of the electrospun membranes were investigated. The interaction between PCL and MNA was identified by molecular dynamics simulation. MNA was released in a controlled manner, and the antibacterial activity of the released MNA remained. The incorporation of gelatin and MNA improved the hydrophilicity, biocompatibility, and in vitro biodegradation rate of PCL nanofibers. The electrospun membranes allowed cells to adhere to and proliferate on them and showed excellent barrier function. The membrane loaded with 30% MNA had the best comprehensive properties. Subcutaneous implantation results demonstrated that MNA-loaded membranes evoked a less severe inflammatory response than pure PCL nanofibers. These results demonstrated the potential of MNA-loaded membranes as GTR/GBR membranes with antibacterial and anti-inflammatory functions for biomedical applications.
Co-reporter:Hailan Kang, Manqiang Li, Zhenghai Tang, Jiajia Xue, Xiaoran Hu, Liqun Zhang and Baochun Guo
Journal of Materials Chemistry A 2014 vol. 2(Issue 45) pp:7877-7886
Publication Date(Web):17 Oct 2014
DOI:10.1039/C4TB01304B
Novel biobased isosorbide-containing copolyesters (PBISI copolyesters) with both biocompatibility and sustainability were synthesized by using commercially available biobased diols and diacids. Due to the presence of itaconate in copolyesters, it can be readily crosslinked by peroxide into a crystallizable network. The structure and thermal properties of PBISI copolyesters were determined by 1H NMR, FTIR, DSC, and WAXD. The chain composition, melting point and crystallinity of the PBISI copolyesters can be tuned continuously by changing the content of isosorbide. The crosslinked copolyester is demonstrated to be a promising shape memory polymer (SMP) with excellent shape memory properties including shape fixity and shape recovery rate close to 100%. The switching temperatures of PBISI-based SMPs can be tuned between 26 °C and 54 °C by altering the composition of PBISI copolyesters and curing extent. Cell adhesion and proliferation were adopted to evaluate the potential biocompatibility of PBISI-based SMPs, and the results indicated that all the PBISI-based SMPs were essentially noncytotoxic, making them suitable for fabricating biomedical devices.
Co-reporter:Chao Zha, Wencai Wang, Yonglai Lu, and Liqun Zhang
ACS Applied Materials & Interfaces 2014 Volume 6(Issue 21) pp:18769
Publication Date(Web):October 17, 2014
DOI:10.1021/am504426j
Strong interfacial interaction and nanodispersion are necessary for polymer nanocomposites with expectations on mechanical performance. In this work, montmorillonite (MMT) was first structurally modified by acid treatment to produce more silanol groups on the layer surface. This was followed by chemical modification of γ-methacryloxy propyl trimethoxysilane molecule (KH570) through covalent grafting with the silanol groups. 29Si and 27Al magic angle spinning (MAS) NMR results revealed the microstructural changes of MMT after acid treatment and confirmed the increase of silanol groups on acid-treated MMT surfaces. Thermogravimetric analysis indicated an increase in the grafted amount of organosilane on the MMT surface. X-ray diffraction (XRD) showed that the functionalization process changed the highly ordered stacking structure of the MMT mineral into a highly disordered structure, indicating successful grafting of organosilane to the interlayer surface of the crystalline sheets. The styrene–butadiene rubber (SBR)/MMT nanocomposites were further prepared by co-coagulating with SBR latex and grafted-MMT aqueous suspension. During vulcanization, a covalent interface between modified MMT and rubber was established through peroxide-radical-initiated reactions, and layer aggregation was effectively prevented. The SBR/MMT nanocomposites had highly and uniformly dispersed MMT layers, and the covalent interfacial interaction was finally achieved and exhibited high performance.Keywords: acid treatment; latex compounding method; montmorillonite; rubber; silane
Co-reporter:Hailan Kang, Kanghua Zuo, Zhao Wang, Liqun Zhang, Li Liu, Baochun Guo
Composites Science and Technology 2014 Volume 92() pp:1-8
Publication Date(Web):24 February 2014
DOI:10.1016/j.compscitech.2013.12.004
Graphene oxide/carboxylated acrylonitrile butadiene rubber (GO/XNBR) nanocomposites with high mechanical and gas barrier properties were fabricated by using a simple and environment-friendly latex co-coagulation method. The oxygen-containing groups attached to the surface of GO generate strong interactions with the XNBR chains through hydrogen bonding (H-bonding), as confirmed by Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimeter (DSC) results. The morphology of the nanocomposites was characterized by high resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD), which show highly exfoliated and uniform dispersion of GO sheets in the matrix. The tensile strength and tear strength of the nanocomposite with 1.9 vol% of GO increased by 357% and 117%, respectively, over those of the matrix. The gas permeability of the nanocomposite is significantly lower than that of the matrix. The high mechanical properties and low gas permeability of the nanocomposite are correlated to the homogeneous dispersion of the GO sheets and strong interfacial interactions, which facilitate the load transfer from XNBR to the GO sheets.
Co-reporter:Yangyang Gao, Jun Liu, Jianxiang Shen, Dapeng Cao and Liqun Zhang
Physical Chemistry Chemical Physics 2014 vol. 16(Issue 34) pp:18483-18492
Publication Date(Web):21 Jul 2014
DOI:10.1039/C4CP02431A
Through coarse-grained molecular dynamics simulation, we aim to uncover the rupture mechanism of polymer–nanorod nanocomposites by characterizing the structural and dynamic changes during the tension process. We find that the strain at failure is corresponding to the coalescence of a single void into larger voids, namely the change of the free volume. And the minimum of the Van der Walls (VDWL) energy reflects the maximum mobility of polymer chains and the largest number of voids of polymer nanocomposites. After the failure, the stress gradually decreases with the strain, accompanied by the contract of the highly orientated polymer bundles. In particular, we observe that the nucleation of voids prefers to occur from where the ends of polymer chains are located. We systematically study the effects of the interfacial interaction, temperature, the length and volume fraction of nanorods, chain length, bulk cross-linking density and interfacial chemical bonds on the rupture behavior, such as the stress at failure, the tensile modulus and the rupture energy. The rupture resistance ability increases with the increase of the interfacial interaction, rod length, and bulk cross-linking density. With an increase in the interfacial interaction, it induces the rupture transition from mode A (no bundles) to B (bundles). The transition point of the stress at failure as a function of the temperature roughly corresponds to the glass transition temperature. At longer chain length, a non-zero stress plateau occurs. And excessive chemical bonds between polymers and nanorods are harmful to the rupture property. We find that an optimal volume fraction of nanorods exists for the stress–strain behavior, which can be rationalized by the formation of the strongest polymer–nanorod network, leading to the slowest mobility of nanorods.
Co-reporter:Jun Liu, Jianxiang Shen, Yangyang Gao, Huanhuan Zhou, Youping Wu and Liqun Zhang
Soft Matter 2014 vol. 10(Issue 44) pp:8971-8984
Publication Date(Web):22 Sep 2014
DOI:10.1039/C4SM02005G
To systematically study the effect of functionalized chain groups on polymer nanocomposites, we perform our simulation work in the following two ways. In the case of dilute loading of nanoparticles (NPs) with different geometries (spherical, sheet-like, rod-like NPs), we adopt coarse-grained molecular dynamics simulation to study the structural, dynamic and mechanical properties of polymer nanocomposites influenced by the terminal groups of linear polymer chains. We observe that the terminal groups have more probability to be adsorbed onto the surface of NPs with decreasing temperature, chain molecular weight and increasing chain stiffness. For all NPs with different geometries, more terminal groups segregate into the surface of NPs with increase in the interaction energy εf–n between the terminal groups and the NPs. We also notice that the attractive interaction between the terminal groups and the sheet-like NPs induces the appearance of a gradient of translational dynamics of polymer chains, and the relaxation at the chain length scale is evidently different for various adsorbed layers, whereas the segmental relaxation only becomes slightly slower nearby the sheet-like NPs. For both pure and filled systems with spherical NPs, it is found that the stress–strain curves and bond orientations are significantly enhanced with increase in the interaction strength between the terminal groups as well as terminal groups and NPs. In the case of concentrated loading of NPs, we construct the atomistic models of C60, CNT and graphene to accurately account for the “many body effect.” We explore the influence of the functionalization position along the chain backbone on the dispersion kinetics, realizing that the end-functionalization is more effective. The end-groups effect on the chain configuration, chain packing and graphene equilibrium dispersibility is examined. The translational and rotational (segmental and terminal relaxation) dynamics influenced by the interactions between the end groups and graphene are probed by tuning εf–n and the volume fraction of graphene ϕ. Moreover, the shift in the glass transition temperature influenced by εf–n and ϕ is quantitatively estimated by fitting the temperature dependence of the relaxation time using the Vogel–Fulcher–Tammann (VFT) equation. This work is hoped to provide a deep understanding of the polymer nanocomposites with functionalized polymer chains.
Co-reporter:Jianxiang Shen, Jun Liu, Yangyang Gao, Xiaolin Li and Liqun Zhang
Soft Matter 2014 vol. 10(Issue 28) pp:5099-5113
Publication Date(Web):08 May 2014
DOI:10.1039/C4SM00233D
By setting up a coarse-grained model of polymer nanocomposites, we monitored the change in the elastic modulus as a function of the strain, derived from the stress–strain behavior by determining uniaxial tension and simple shear of two typical spatial distribution states (aggregation and dispersion) of nanoparticles (NPs). In both these cases, we observed that the elastic modulus decreases non-linearly with the increase of strain and reaches a low plateau at larger strains. This phenomenon is similar to the so-called “Payne effect” for elastomer nanocomposites. Particularly, the modulus of the aggregation case is more sensitive to the imposed strain. By examining the structural parameters, such as the number of neighboring NPs, coordination number of NPs, root-mean-squared average force exerted on the NPs, local strain, chain conformations (bridge, dangle, loop, interface bead and connection bead), and the total interaction energy of NP–polymer and NP–NP, we inferred that the underlying mechanism of the aggregation case is the disintegration of the NP network or clusters formed through direct contact; however, for the dispersion case, the non-linear behavior is attributed to the destruction of the NP network or clusters formed through the bridging of adsorbed polymer segments among the NPs. The former physical network is influenced by NP–NP interaction and NP volume fraction, while the latter is influenced by NP–polymer interaction and NP volume fraction. Lastly, we found that for the dispersion case, further increasing the inter-particle distance or grafting NPs with polymer chains can effectively reduce the non-linear behavior due to the decrease of the physical network density. In general, this simulation work, for the first time, establishes the correlation between the micro-structural evolution and the strain-induced non-linear behavior of polymer nanocomposites, and sheds some light on how to reduce the “Payne effect”.
Co-reporter:Rui Shi, Jiajia Xue, Min He, Dafu Chen, Liqun Zhang, Wei Tian
Polymer Degradation and Stability 2014 Volume 109() pp:293-306
Publication Date(Web):November 2014
DOI:10.1016/j.polymdegradstab.2014.07.017
Nanofiber membranes composed of polycaprolactone (PCL), PCL/metronidazole (MNA), PCL/gelatin/MNA, and PCL/gelatin/MNA/acetic acid (HAC), named P0, P30, PG30, and PGH30, respectively, were fabricated by electrospinning for application in guided tissue/bone regeneration (GTR/GBR) therapies. The architectural features, mechanical properties, hydrophilicity, drug-encapsulation efficiency, drug-release pattern, antimicrobial properties, cell barrier functions, in vitro/vivo degradability and biocompatibility were investigated. All membranes were found to have high tensile strength, which is required for GTR applications. Strong interactions among PCL, gelatin, and MNA resulted in high drug loading efficiency, which was further improved by the incorporation of gelatin and HAC. MNA incorporation gave the membranes good antimicrobial property, while reducing host versus graft reaction, improving the hydrophilicity and accelerating the degradation. Gelatin incorporation considerably improved cytocompatibility, while accelerating the degradation dramatically. Very low quantities (0.1% v/v with respect to polymer solution) of HAC effectively prevented the phase separation of PCL and gelatin, resulting in homogeneous nanofiber, which facilitates stable physical properties. The drug-release profiles of all drug-loading membranes were consistent with the inflammation cycle characteristics. High drug loading and trace amounts of HAC did not cause any adverse reactions, as evidenced by subcutaneous implantation. Both P0 and P30 maintained their cell barrier function in vivo for as long as 24 weeks; PGH30, for 8 weeks; and PG30, for less than 8 weeks. These findings enabled a comprehensive understanding of the influence of different compositions on the structure and performance of the membranes, thereby supporting the design of membranes with superior overall performance for GTR/GBR application.
Co-reporter:Yang Meng, Junfeng Chu, Jiajia Xue, Chaohao Liu, Zhen Wang and Liqun Zhang
RSC Advances 2014 vol. 4(Issue 59) pp:31249-31260
Publication Date(Web):02 Jul 2014
DOI:10.1039/C4RA02293A
Although polysiloxane elastomers have many merits, their fast crystallization at low temperature is problematic in some fields. In this study, a novel non-crystallizable, low-Tg epoxidized polysiloxane (ESR) with functional epoxy groups in side chains was designed and synthesized though two steps: (i) the preparation of poly(methylvinylsiloxane) (SR) by anionic ring-opening copolymerization of 2,4,6,8-tetramethyl-2,4,6,8-tetravinyl cyclotetrasiloxane and octamethylcyclotetrasiloxane, and (ii) the subsequent epoxidation of the SR. Reaction kinetic studies demonstrated that the epoxidation of SR was a second-order reaction and more than 90% of the double bonds were converted into epoxy groups during the epoxidation. Despite a slight increase in the Tg of ESRs as the content of epoxy groups increased, the low-temperature performances of ESRs were greatly improved because of the inhibition of the crystallization of polysiloxane chains. Surprisingly, the ESRs also showed higher thermal degradation temperatures than the traditional poly(dimethylsiloxane) did. The excellent low-temperature performance and high degradation temperatures endowed the ESR with great potential as an elastic material in the aerospace industry where materials have to undergo very high and low temperature.
Co-reporter:Jinwei Shi, Hua Zou, Linlin Ding, Xiaolin Li, Kuan Jiang, Tung Chen, Xiaodan Zhang, Liqun Zhang, Dongyun Ren
Polymer Degradation and Stability 2014 Volume 99() pp:166-175
Publication Date(Web):January 2014
DOI:10.1016/j.polymdegradstab.2013.11.010
Liquid reclaimed rubber (LRR) was produced from ground tire rubber (GTR) in a continuous operation by using a co-rotating twin-screw extruder. The effects of reclaiming recipe, screw configuration combination, barrel temperature, and screw speed on the degree of reclamation were investigated. Through the adjustment of these conditions, an LRR with a sol fraction of 73.5% was obtained. Characterizations of the LRR by gel-permeation chromatography (GPC), differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), and re-vulcanized ability tests showed that the LRR had unique properties – low viscosity, good compatibility with natural rubber (NR), and re-vulcanized ability. Because of these properties of LRR, it was used as reactive polymeric plasticizer in NR to replace the conventional oils such as the environmental aromatic oil (EAO) used in this study. The plasticizing effect, acetone extraction, mechanical properties, and thermostability of the LRR/NR compounds were investigated and compared with those of EAO/NR compounds. The results show that the plasticizing efficiency of LRR is somehow lower than that of EAO. In addition, the LRR-plasticized NR has higher tensile strength, modulus at 100% and 300% elongation, hardness, extraction resistance, and thermostability than EAO-plasticized NR.
Co-reporter:Jinwei Shi;Kuan Jiang;Hua Zou;Linlin Ding;Xiaodan Zhang;Xiaolin Li;Liqun Zhang;Dongyun Ren
Journal of Applied Polymer Science 2014 Volume 131( Issue 11) pp:
Publication Date(Web):
DOI:10.1002/app.40298
ABSTRACT
In this study, the reclamation of sulfur (S)-cured isoprene rubber (IR) was investigated independently after the impregnation process of the reclaiming reagent diphenyl disulfide (DD) into the crosslinked IR matrix with supercritical carbon dioxide (scCO2) as the transmission medium. According to the mass uptake of DD into IR and scanning electron microscopy–energy-dispersive X-ray spectrometry measurements, DD was highly impregnated and homogeneously dispersed in the network under 12 MPa at 80°C for 11 h in scCO2. During the impregnation process, almost no reclaiming reaction occurred. Then, through three different reclaiming methods, a mechanochemical method, a chemical method with oxygen, and a chemical method without oxygen, the influences of the shear force, reclaiming atmosphere, reaction time, and amounts of reclaiming reagent on the reclamation with crosslinked IR with pre-impregnated DD were independently investigated and compared with those of the reaction without pre-impregnated DD. The sol fraction of the reclaimed rubber and molecular weight of the sol were measured. The results show that the reclaiming speed greatly depended on the amount of reclaiming reagent and that the reclaiming reaction was dramatically accelerated when the reclaiming reagents were pre-impregnated into the crosslinked IR under the same processing conditions. This indicated that the impregnation time of the reclaiming reagent into the crosslinked network constituted a large proportion of the reclaiming time. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40298.
Co-reporter:Yangyang Gao;Jun Liu;Liqun Zhang;Dapeng Cao
Macromolecular Theory and Simulations 2014 Volume 23( Issue 1) pp:36-48
Publication Date(Web):
DOI:10.1002/mats.201300127
The interfacial polymer-nanosheet behavior is investigated to fully understand the interfacial interaction mechanism. The emphasis is placed on the discussion whether a “polymer glassy layer” in the proximity of the nanosheet exists or not. Results indicate that a “polymer glassy layer” actually exists near the nanosheet surface for strongly attractive interfacial interaction. Moreover, the glass transition temperatures at different interfacial interactions are explored, and a gradient of polymer chain dynamics near the nanosheet surface is observed. In short, this work provides a valuable reference for understanding polymer-nanosheet interfacial behavior.
Co-reporter:Lei Jiang;Hailan Kang;Zhao Wang;Liqun Zhang;Lixin Mao;Yiqing Wang
Journal of Applied Polymer Science 2014 Volume 131( Issue 18) pp:
Publication Date(Web):
DOI:10.1002/app.40756
ABSTRACT
A novel hydroxyl-terminated bio-based engineering elastomer (BEE) was synthesized from four bio-based monomers by adding excess diol. Then the BEE was chain extended in Haake torque rheometer with 4,4-diphenyl methane diisocyanate (MDI) as chain extender. The molar ratio of NCO/OH, reaction temperature and reaction time of the chain-extension reaction were studied, and the optimum condition was determined by the gel permeation chromatography (GPC), soxhlet extraction, and fourier transform infrared spectroscopy (FTIR) results. After chain extension, (i) the number-average molecular weight of BEE became about 3.5 times of the original BEE, (ii) the thermal stability was improved and the crystallization rate was lower, (iii) and the mechanical properties were significantly improved with nano-SiO2 as reinforcing filler. The chain-extended BEE would have potential wide applications in engineering field. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40756.
Co-reporter:Bowen Fang;Hailan Kang;Runguo Wang;Zhao Wang;Wencai Wang;Liqun Zhang
Journal of Applied Polymer Science 2014 Volume 131( Issue 19) pp:
Publication Date(Web):
DOI:10.1002/app.40862
ABSTRACT
Bio-based elastomers used in industry have attracted much attention. We prepared bio-based engineering polyester elastomer (BEE) nanocomposites by mixing bio-based engineering polyester elastomers with carbon (CB). The CB/BEE nanocomposites were exposed to an artificial weathering environment for different time periods. Both its aging behavior changes and aging mechanism were investigated in this article. The tensile strength retention rates were each above 90% after aging at 100°C and 125°C for 72 h. CB/BEE nanocomposites exhibited good anti-aging properties. Furthermore, the chemical changes were detected by Fourier transform infrared spectroscopy and differential scanning calorimetry. The crosslink density changes during aging of BEE were determined as well. A plausible aging mechanism of BEE was proposed. It can be concluded that the thermal oxidation process gives priority to further crosslinking in the initial period of aging. As the aging time increases, chain scission becomes the dominant element in the subsequent thermal oxidation process. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40862.
Co-reporter:Yang Meng;Junfeng Chu;Chaohao Liu;Zheng Wei;Liqun Zhang
Journal of Applied Polymer Science 2014 Volume 131( Issue 21) pp:
Publication Date(Web):
DOI:10.1002/app.40983
ABSTRACT
A series of poly(methylvinylsiloxane) elastomer (VMQ) composites with improved oil resistance were prepared by introducing uniform polar polymer phases into VMQ matrix through the in situ reaction of reactive polar monomers—hydroxyethyl methacrylate (HEMA) and hydroxypropyl methacrylate (HPMA)—during peroxide curing. Differential scanning calorimetry and Fourier transform infrared measurements demonstrated that HEMA and HPMA had high reactivity and most of the monomers participated in the in situ reaction during peroxide curing. Transmission electron microscopic images showed that the uniform nanophases with the diameters in the range of 20–50 nm formed in the VMQ vulcanizates. The generated nanophases could interact with silica to form a strong filler network in the VMQ matrix, resulting in a significant increase of the modulus at low elongation of the VMQ vulcanizates. With increasing the content of polar monomers, the tensile strength decreased slightly, the elongation at break, the hardness and the 100% modulus increased, but the 300% modulus decreased significantly due to the decrease of the crosslink density. The incorporation of HEMA or HPMA into VMQ matrix could significantly improve the oil resistance of polysiloxane elastomer, and the oil resistance of the composites containing HEMA was a little better than that of the composites containing HPMA. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40983.
Co-reporter:Chen Zhang;Xiujuan Jiang;Zhiyang Zhao;Lixin Mao;Liqun Zhang;Phil Coates
Journal of Applied Polymer Science 2014 Volume 131( Issue 22) pp:
Publication Date(Web):
DOI:10.1002/app.41049
For medical applications, 4,4′-dicyclohexyl methane diisocyanate (HMDI)-based poly(carbonate urethane)s were synthesized from HMDI and 1,4-butanediol as hard segments and poly(carbonate diol) (number-average molecular weight = 2000 g/mol) as soft segments. The effects of wide-range γ irradiation on the samples were examined through a series of analytical techniques. Scanning electron microscopy revealed that γ irradiation etched and roughened the surfaces of the irradiated samples. The gel content and crosslinking density measurements confirmed that crosslinking occurred along with degradation at all of the investigated irradiation doses and the degree of both crosslinking and degradation increased with increasing irradiation dose. Fourier transform infrared spectroscopy demonstrated that chain scission in the γ-irradiated samples occurred at the carbonate and urethane bonds. The decreasing molecular weight and tensile strength indicated that the degradation increased with the γ-irradiation dose. Differential scanning calorimetry and dynamic mechanical thermal analysis indicated that γ irradiation had no significant effect on the phase-separation structures. There was a slight reduction in the contact angle. An evaluation of the cytotoxicity demonstrated the nontoxicity of the nonirradiated and irradiated polyurethanes. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 41049.
Co-reporter:Zhao Wang, Tao Wei, Xiao Xue, Miaomiao He, Jiajia Xue, Meng Song, Sizhu Wu, Hailan Kang, Liqun Zhang, Qingxiu Jia
Polymer 2014 Volume 55(Issue 19) pp:4846-4856
Publication Date(Web):15 September 2014
DOI:10.1016/j.polymer.2014.07.034
•We synthesized a class of fully bio-based BDIS polyamide from large-scale biomass feedstocks.•Some BDIS possess both excellent mechanical property and good processability.•The tensile strength of the BDIS (IA-50%) fiber is comparable with that of commercial PA6 fiber.•Some BDIS polyamide could become elastic after absorbing water.•The BDIS (IA-50%, 80%) are transparent amorphous and tough polyamides.A class of bio-based aliphatic polyamides (BDIS) was synthesized by melting copolycondensation from four biomass monomers: originated (SA), itaconic acid (IA), 1, 10-decanediamine (DD), and 1, 4-butanediamine (BD). IA was introduced into the system in order to adjust the chemical structure and the aggregation structures of the BDIS polyamide. Thus, some new polyamides with tunable properties were obtained, such as semi-crystalline polyamide with relatively low melting point, glassy polyamide with excellent toughness, and even rubbery polyamide after hydration. Some of the BDIS can be well melting spinned into fibers with comparable strength as polyamide-6. The BDIS with 100% itaconic acid can even be dissolved in ethanol, which makes it possibly be used by coating and dipping methods. In vitro cytotoxicity tests showed that these polyamides are nontoxic towards mouse fibroblasts and have great potential in biomedical applications.
Co-reporter:Yangyang Gao, Jun Liu, Jianxiang Shen, Liqun Zhang, Dapeng Cao
Polymer 2014 Volume 55(Issue 5) pp:1273-1281
Publication Date(Web):10 March 2014
DOI:10.1016/j.polymer.2014.01.042
Nowadays, achieving a uniform dispersion of rod-like molecules (like carbon nanotube) in a polymer matrix is still a complicated and unsettled issue in polymer physics and chemical physics. It is very significant to fully understand the effects of deterministic factors on dispersion and aggregation processes of nanorods in the polymer matrix. Here, we adopt a coarse-grained molecular dynamics simulation to investigate the nanorod- filled polymer nanocomposites. It is found that the characteristic relaxation time of the end-to-end vector correlation exhibits an Arrhenius-like temperature-dependent behavior and both the rotational and translational diffusion coefficients have a linear relationship with temperature. By tuning the polymer–nanorod interaction in a wide range, we obtain the spatial organization of nanorods and the best dispersion state at the intermediate interfacial interaction. Meanwhile, we observe that grafting polymer chains on the nanorod surface could promote the dispersion. Moreover, a lower or higher temperature than glassy transition temperature can prevent the nanorod aggregation. The aggregation of nanorods can be significantly accelerated by nanorod–nanorod attraction, while inhibited by cross-linking of polymer chains and external shear fields. In short, by tailoring the deterministic factors above, we can effectively control the dispersion or even spatial organization of one-dimensional nanorods in polymer nanocomposites.
Co-reporter:Shafiullah Khan, Zhao Wang, Runguo Wang, Liqun Zhang
Phytochemistry Letters 2014 10() pp: 204-208
Publication Date(Web):
DOI:10.1016/j.phytol.2014.09.007
Co-reporter:Jiajia Xue, Min He, Hao Liu, Yuzhao Niu, Aileen Crawford, Phil D. Coates, Dafu Chen, Rui Shi, Liqun Zhang
Biomaterials 2014 35(34) pp: 9395-9405
Publication Date(Web):
DOI:10.1016/j.biomaterials.2014.07.060
Co-reporter:Jun Liu;Yong-Lai Lu;Ming Tian;Fen Li;Jianxiang Shen;Yangyang Gao;Liqun Zhang
Advanced Functional Materials 2013 Volume 23( Issue 9) pp:1156-1163
Publication Date(Web):
DOI:10.1002/adfm.201201438
Abstract
Among all carbon nanostructured materials, helical nanosprings or nanocoils have attracted particular interest as a result of their special mechanical behavior. Here, carbon nanosprings are used to adjust the viscoelasticity and reduce the resulting hysteresis loss (HL) of elastomeric polymer materials. Two types of nanospring-filled elastomer composites are constructed as follows: system I is obtained by directly blending polymer chains with nanosprings; system II is composed of the self-assembly of a tri-block structure such as chain-nanospring-chain. Coarse-grained molecular dynamics simulations show that the incorporation of nanosprings can improve the mechanical strength of the elastomer matrix through nanoreinforcement and considerably decrease the hysteresis loss. This finding is significant for reducing fuel consumption and improving fuel efficiency in the automobile tire industry. Furthermore, it is revealed that the spring constant of nanosprings and the interfacial chemical coupling between chains and nanosprings both play crucial roles in adjusting the viscoelasticity of elastomers. It is inferred that elastomer/carbon nanostructured materials with good flexibility and reversible mechanical response (carbon nanosprings, nanocoils, nanorings, and thin graphene sheets) have both excellent mechanical and low HL properties; this may open a new avenue for fabrication of high performance automobile tires and facilitate the large-scale industrial application of these materials.
Co-reporter:Dan Yang, Ming Tian, Dongdong Li, Wencai Wang, Fengxing Ge and Liqun Zhang
Journal of Materials Chemistry A 2013 vol. 1(Issue 39) pp:12276-12284
Publication Date(Web):08 Aug 2013
DOI:10.1039/C3TA12090B
To obtain a dielectric elastomer with excellent dielectric properties and actuated strain, we used bio-inspired dopamine to functionalize the surface of barium titanate (BT) particles. X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) were used to confirm that a poly(dopamine) (PDA) layer of ca. 3.0 nm had been successfully deposited on the surface of the barium titanate particles. With the introduction of the PDA layer, the compatibility between the barium titanate filler and the elastomer matrix (hydrogenated nitrile-butadiene rubber) was significantly improved, which also resulted in the composites displaying better filler dispersion, higher dielectric constant, lower dielectric loss, and higher electric breakdown field compared with composites filled with pristine BT particles. Furthermore, the composites filled with PDA-coated BT (BT–PDA) exhibited higher electromechanical sensitivity (β) than the composites filled with pristine BT, leading to increased actuated strains. Nevertheless, the β of composites filled with pristine BT decreased with increasing content of filler, resulting in decreased actuated strains. Finally, a large actuated strain of 20% without any prestrain was achieved by the composite filled with BT–PDA, which is 54% larger than the largest actuated strain of the polymer without functionalized filler. Moreover, the dopamine functionalization method is simple, efficient, nontoxic, and easy to control, and can be used as a general strategy for improving the dielectric constant, breakdown strength, and actuated strain of dielectric elastomers.
Co-reporter:Wencai Wang, Runyuan Li, Ming Tian, Li Liu, Hua Zou, Xiuying Zhao, and Liqun Zhang
ACS Applied Materials & Interfaces 2013 Volume 5(Issue 6) pp:2062
Publication Date(Web):March 6, 2013
DOI:10.1021/am302956h
A facile method was developed to fabricate highly electrically conductive aramid fibers. The immobilization of silver nanoparticles on the surface of polymetaphenylene isophthamide (PMIA) fibers was carried out by the functionalization of the PMIA fibers with poly(dopamine), followed by electroless silver plating. The poly(dopamine) (PDA) layer was deposited on the PMIA surface by simply dipping the PMIA substrate into an alkaline dopamine solution. The silver ions can be chemically bound to the catechol and indole functional groups in PDA. The silver ions were reduced into silver nanoparticles by using glucose as the reducing agent, resulting in a distinct silver layer on the PMIA surface. The obtained silver deposit was homogeneous and compact. The chemical composition of the modified PMIA fibers was studied by X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray spectroscopy (EDS), and the crystalline structure of the silver-coated PMIA fibers was characterized by powder X-ray diffraction (XRD). The topography of the modified PMIA fibers was investigated by scanning electron microscopy (SEM). The four-point probe resistivity meter was used to study the electrical resistivity of the silver-coated PMIA fibers, the results indicated that the electrical resistivity could be as low as 0.61 mΩ·cm, with a controllable silver content, and a satisfactory stability by ultrasonic treatment.Keywords: dopamine; electrical resistivity; electroless plating; poly(metaphenylene isophthamide); silver; surface;
Co-reporter:Zhenghai Tang, Hailan Kang, Qiuyan Wei, Baochun Guo, Liqun Zhang, Demin Jia
Carbon 2013 Volume 64() pp:487-498
Publication Date(Web):November 2013
DOI:10.1016/j.carbon.2013.07.103
Graphene oxide was directly reduced into graphene in N-methyl-pyrrolidone with the assisted-dispersion of vapor grown carbon nanofibers (VGCF), resulting in a homogeneous dispersion of VGCF–graphene hybrid filler (VGCF–G). In the hybrid filler, VGCF served as effective stabilizers for graphene by adsorbing VGCF onto graphene through π–π interaction. Subsequently, the as-prepared VGCF–G was incorporated into a bio-based polyester (BE) to prepare BE/VGCF–G composites by solution blending. In the composites, graphene was complete exfoliated with the assisted-dispersion of VGCF. Simultaneously, graphene acted as “compatibilizer” to improve the dispersion of VGCF and enhance the interfacial adhesions. As a consequence, the binary combination of VGCF and graphene showed remarkable synergistic effects in improving the electrical conductivity and mechanical properties of the BE/VGCF–G composites. For example, at the filler content of 4.8 vol%, the electrical conductivity of BE/VGCF–G composite is about 4 orders of magnitude higher than BE/VGCF composite containing VGCF alone, and the ultimate stress and modulus of BE/VGCF–G composite is 58% and 45% higher than those for BE/VGCF composite. Furthermore, multi-stimuli responsive shape memory performances (electro-activated and infrared-triggered) of the composites were investigated. BE/VGCF–G composites showed a combination of higher shape memory recovery, stronger recovery stress and faster response, compared with BE/VGCF composites.
Co-reporter:Dan Yang, Ming Tian, Wencai Wang, Dongdong Li, Runyuan Li, Haoliang Liu, Liqun Zhang
Electrochimica Acta 2013 Volume 87() pp:9-17
Publication Date(Web):1 January 2013
DOI:10.1016/j.electacta.2012.08.122
Novel silica/poly(dopamine)/silver (from inner to outer) (denoted as SiO2/PDA/Ag) conductive micro-particles were first synthesized by biomimetic poly(dopamine) coating. These micro-particles were then coated with a poly(dopamine) layer to form core/shell-structured particles, with silica/poly(dopamine)/silver core and poly(dopamine) shell (denoted as SiO2/PDA/Ag/PDA). This multilayer core/shell micro-particles were confirmed by scanning electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and transmission electron microscope. Polymer composites were then prepared by mechanical blending of poly(dimethyl siloxane) and the core/shell-structured particles. It was found that the silver layer and the poly(dopamine) shell had good adhesion with substrate and they kept intact even under violent shearing stress during mechanical mixing. The effect of the thickness of outermost poly(dopamine) shell as well as the loading amount of this filler on the dielectric and electrical properties of the composites was further studied. The results showed that the dielectric constant, dielectric loss, and conductivity of the composites decreased with increasing shell thickness (10–53 nm) at the same loading level. And the maximal dielectric constant of composites was achieved in the composites filled with SiO2/PDA/Ag/PDA (with 10–15 nm PDA shell) particles, which was much larger than that of the composite filled with SiO2/PDA/Ag particles without insulative PDA shell. At the same time, the composites can change from conductor into insulator by controlling the shell thickness of core/shell-structured conductive particles. This simple and controllable biomimetic method may be applied to construct many other conductive filler in order to realize controllable dielectric and electrical performance of polymer composites.Graphical abstractHighlights► Conductive core/shell-structured particles were synthesized by biomimetic method. ► These particles with silica/poly(dopamine)/silver core and poly(dopamine) shell. ► Dielectric composites were prepared with resulted particles and silicone elastomer. ► The dielectric properties of the composites can be controlled by shell thickness. ► This biomimetic method is simple, nontoxic, efficient and easy to control.
Co-reporter:Zhenghai Tang, Daqin Sun, Dan Yang, Baochun Guo, Liqun Zhang, Demin Jia
Composites Science and Technology 2013 Volume 75() pp:15-21
Publication Date(Web):11 February 2013
DOI:10.1016/j.compscitech.2012.11.019
Bio-based polyester (BE) was synthesized through polycondensation using the plant-derived resources as the starting materials. Vapor grown carbon nanofiber (VGCF) was then incorporated into BE to prepare BE/VGCF composites by simple melting blending. The uniform dispersion of VGCF and fairly strong interfacial adhesion between BE and VGCF led to a significant improvement in the mechanical properties of the composites. Besides, the incorporation of VGCF successfully converted the insulating BE into electrically conductive composites with a percolation threshold of 2.5 vol.%. The composites showed excellent electroactive shape memory properties, which reached a shape recovery ratio of 97% within 90 s with a direct current voltage of 20 V. The combination of the significantly improved mechanical properties and excellent electroactive shape memory performance of BE/VGCF composites opens up the new opportunity for the electroactive actuator materials in a sustainable manner.
Co-reporter:Shao-Jian He, Yi-Qing Wang, Mei-Mei Xi, Jun Lin, Yang Xue, Li-Qun Zhang
Polymer Degradation and Stability 2013 Volume 98(Issue 9) pp:1773-1779
Publication Date(Web):September 2013
DOI:10.1016/j.polymdegradstab.2013.05.012
In order to minimize the oxidative degradation of SBR at high temperature, the nano-dispersed clay layers were introduced by using the SBR/clay (100/80) nanocompound to prepare SBR/clay/carbon black (CB) nanocomposites, then the effects of nano-clay on the properties of SBR nanocomposites are investigated. The clay layers and CB are uniformly dispersed in the SBR matrix at nano-scale. The mechanical properties of the SBR/clay/CB nanocomposites mostly decrease with the increase of clay loading, however, with the increase of clay loading, the change rate of the mechanical properties of the nanocomposites decreases and the aging coefficient of the nanocomposites rises, and the length and depth of the cracks of the aged nanocomposites after bending decrease, which means that the clay layers can provide the nanocomposites excellent thermal aging resistance and heat resistance. The experiment of aging with air and without air proved the importance of oxygen during rubber aging process. The FTIR spectra show the generation of oxygen-containing group on the external surface of the nanocomposites during aging. The DSC results indicate the differences between the internal layer and the external layer of the aged nanocomposites.
Co-reporter:Yangyang Gao, Jun Liu, Jianxiang Shen, Dapeng Cao and Liqun Zhang
RSC Advances 2013 vol. 3(Issue 44) pp:21655-21665
Publication Date(Web):09 Sep 2013
DOI:10.1039/C3RA43863E
The layered polymer nanocomposites have attracted great interest from scientists due to their unique properties. However, the formation mechanism of these nanocomposites in the intercalation process is not fully understood yet. In this work, we simulate the intercalation processing of polymer chains into two layered sheets. By systematically tuning the polymer–sheet interaction, temperature, chain length, organic surfactant modification and interlayer distance, we found that the intermediate polymer–sheet interaction, low polymer molecular weight and large interlayer distance would enhance the intercalation kinetics. However, the presence of surfactants promotes the intercalation process of chains into layered sheets only when the interaction between polymer and surfactants is strong enough. In the intercalation process, the polymer chain first elongates and then contracts. To uncover the mechanism of aggregation and formation of layered sheets–polymer network, we examine the formation of bridge chains between layered sheets. Generally, the polymer chain does not adsorb totally on one single layer, but crosses over from one layer to another. Moreover, the number of bridge chains monotonically decreases with the increase of the polymer–sheet interaction and interlayer distance, but increases with the polymer chain length. It is expected that the structural and dynamic behavior of polymer chains intercalated into the layered sheets could deepen our understanding of polymer nanocomposites filled with layered sheets.
Co-reporter:Huimin Zhang;Chaoming Shi;Miaomiao He;Qingxiu Jia;Liqun Zhang
Journal of Applied Polymer Science 2013 Volume 130( Issue 6) pp:4449-4456
Publication Date(Web):
DOI:10.1002/app.39542
ABSTRACT
Polyamide 6 (PA6) gels were prepared by the dissolution of PA6 powder in formic acid with CaCl2 as a complexing agent. The concentration of the polymer was 16% w/v. PA6 fibers were obtained through gel-spinning, drawing, decomplexation, and heat-setting processes. The structure and properties of the fibers at different stages were characterized with differential scanning calorimetry, thermogravimetric analysis, X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy. The experiment results indicate that the melting transition of the as-spun fibers obtained by the extrusion of the PA6/CaCl2/HCOOH solution into a coagulation bath through a die disappeared. A porous structure existed in the as-spun fibers, which led to poor mechanical properties. Compared with the as-spun fibers, the melting and glass-transition temperatures of the decomplexed and drawn fibers retained their original values from PA6, the degree of crystallinity increased, the porous structure disappeared, and the mechanical properties were improved. The maximum modulus and tensile strength obtained from the drawn fibers in this study were 32.3 GPa and 530.5 MPa, respectively, at the maximum draw ratio of 10. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 4449–4456, 2013
Co-reporter:Zhao Wang;Yue Han;Xing Zhang;Zhaohui Huang;Liqun Zhang
Journal of Applied Polymer Science 2013 Volume 130( Issue 6) pp:4457-4463
Publication Date(Web):
DOI:10.1002/app.39589
ABSTRACT
Ethylene propylene diene monomer (EPDM) compounds were prepared with different amounts of transgenic soybean oil (TSO), a renewable and reactive plasticizer. For comparison, similar compounds were prepared with petroleum-based paraffin oil (PO), one of the most common plasticizers for EPDM. The plasticization effects of TSO and of PO were studied by Mooney viscometry, capillary rheometry, differential scanning calorimetry (DSC), and rubber processing analysis (RPA). The results showed that TSO has better plasticization effect than PO on EPDM. In addition, the curing characteristics of the EPDM compounds were studied. TSO was found to react with the curing agent dicumyl peroxide (DCP) during the curing process. Excessive amounts of TSO led to low crosslinking density, which was improved by adjusting the added amount of DCP. The mechanical properties, extraction resistance, and thermal stability of the EPDM vulcanizates plasticized with different amounts of TSO and PO were compared to determine the optimum amount of TSO to replace PO. At the same amount and no more than 15 phr of plasticizer, the TSO-plasticized EPDM vulcanizate has higher tensile and tear strength, elongation at break, extraction resistance, and thermal stability, but lower Shore A hardness than the PO-plasticized EPDM vulcanizate. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 4457–4463, 2013
Co-reporter:Kuan Jiang;Jinwei Shi;Youyong Ge;Rui Zou;Pengjun Yao;Xiaolin Li ;Liqun Zhang
Journal of Applied Polymer Science 2013 Volume 127( Issue 4) pp:2397-2406
Publication Date(Web):
DOI:10.1002/app.37542
Abstract
Sulfur-cured butyl rubber was devulcanized completely in supercritical CO2 by using diphenyl disulfide (DD) as a devulcanizing reagent. The optimum devulcanizing conditions were studied and the sol fraction of the reclaimed rubber obtained was up to 98.5%. The possible devulcanizing mechanism was investigated. Then, the sol component of reclaimed rubber was characterized by gel permeation chromatography, 1H-NMR, and differential scanning calorimetry, and the reclaimed rubber was characterized by TGA. Because of the substitution of a large portion of allylic hydrogen by sulfurated functional groups during vulcanization, the signal of the olefinic proton shift. As a result of the numerous decreases in the active crosslinking sites and the remaining DD, reclaimed rubber could not be cured by sulfur. At last, the blends of virgin butyl rubber and different contents of reclaimed rubber were revulcanized and their mechanical properties investigated. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Co-reporter:Runguo Wang;Hui Yao;Weiwei Lei;Xinxin Zhou;Liqun Zhang;Kuo-chih Hua;Joseph Kulig
Journal of Applied Polymer Science 2013 Volume 129( Issue 3) pp:1546-1554
Publication Date(Web):
DOI:10.1002/app.38865
Abstract
A novel poly(diisoamyl itaconate-co-isoprene) (PDII) bioelastomer was prepared by redox emulsion polymerization based on itaconic acid, isoamyl alcohol, and isoprene. Carbon black (CB), silica, and silica with coupling agent (bis(3-(triethoxysilyl)-propyl)tetrasulfide [TESPT]-silica) were used as fillers to reinforce the novel elastomer. The difference in morphology, interfacial interaction, thermal properties, and mechanical properties of PDII composites filled with different fillers was studied. The homogeneous dispersion of silica and CB in the PDII matrix was confirmed by scanning electron microscopy and transmission electron microscopy. Silica had homogenous dispersion possibly because of the formation of hydrogen bonds between the silica silanols and the PDII macromolecular chains. PDII/silica and PDII/TESTP-silica have lower crosslink density and crosslinking rate than PDII/CB owing to the adsorption of accelerators by the silanols in the silica surfaces. PDII/silica had comparable tensile strength but higher elongation at break than PDII/CB. The tensile strength of PDII/TESPT-silica was higher than PDII/CB and PDII/silica. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Co-reporter:Jinwei Shi;Kuan Jiang;Dongyun Ren;Hua Zou;Yao Wang;Xuejian Lv;Liqun Zhang
Journal of Applied Polymer Science 2013 Volume 129( Issue 3) pp:999-1007
Publication Date(Web):
DOI:10.1002/app.38727
Abstract
Four different reclaiming methods involving important reclaiming factors such as temperature, shear force, and atmosphere were used to reclaim ground tire rubber. The structure and performance of the reclaimed rubber were investigated. The reclaimed samples were all found to be mixtures of three parts: the sol part, a loosely crosslinked gel part, and low molecular substances. For a reclaimed product to have both good processability and mechanical properties, the ideal structure should be that the sol fraction and its molecular weight (Mn) are as high as possible. However, the high sol fraction and high Mn cannot be reached at the same time because of the nonselective scission of the main chain and crosslink bonds. Thus, for a reclaimed rubber to have high quality, the presence of some amount of gel fraction is essential. Our preliminary results showed that the recommended reclaiming method would be a process under oxygen-free atmosphere, without severe shear force, and at relative low temperature. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Co-reporter:Fan Ren;Xiaojiao Zhang;Zheng Wei;Junfeng Chen;Dawei Dong;Xiaolin Li;Liqun Zhang
Journal of Applied Polymer Science 2013 Volume 129( Issue 4) pp:2261-2272
Publication Date(Web):
DOI:10.1002/app.38960
Abstract
The flame-retardant properties of asphalt for some building applications are very important. This article is mainly focused on the influence of particle size and content of magnesium hydroxide (MH) on the flame-retardant properties of asphalt. The limit oxygen index and cone calorimeter results indicate that as the MH content and mesh number increase, the flame-retardant properties of MH-filled flame-retardant asphalt show a rising trend. But the role of particle size in smoke suppression is not obvious. Several tests confirm that the dispersion of the MH have some influence on the flame-retarding effect of asphalt. The 3000 mesh MH for the preparation of flame-retardant asphalt shows optimal performance. The experimental data show that the softening point of flame-retardant asphalt increases, but the ductility and penetration decrease with increasing MH content. MH affects the asphalt viscosity, but not affects the adhesion of the asphalt to gravel. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Co-reporter:Yannan Quan;Ming Lu;Ming Tian;Shouke Yan;Zhongzhen Yu;Liqun Zhang
Journal of Applied Polymer Science 2013 Volume 130( Issue 1) pp:680-686
Publication Date(Web):
DOI:10.1002/app.39210
Abstract
Expanded graphite (EG) is prepared by microwave irradiation to expandable graphite. A stable aqueous suspension of EG is obtained through dispersing EG into deionized water in the presence of surfactant under ultrasonication. Nanocomposites are prepared by compounding EG aqueous suspension with alkyl acrylate elastomer latex. It is showed that, by the latex compounding method (LCM), EG platelets are finely dispersed in the elastomer matrix. The nanocomposites exhibit remarkable improvements in mechanical properties, wear resistance, and gas barrier property. The prepared compound also shows certain electrical conductivity, but soon loses it after milled on a miller. Meanwhile, a dramatic change in EG network is observed corresponding to the loss of electrical conductivity. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Co-reporter:Yannan Quan;Yiqing Wang;Youping Wu;Ming Lu;Chao Zha;Xiaohui Wu;Liqun Zhang
Journal of Applied Polymer Science 2013 Volume 130( Issue 1) pp:113-119
Publication Date(Web):
DOI:10.1002/app.39119
Abstract
A highly dispersed montmorillonite (MMT)/styrene-butadiene rubber (SBR) nanocomposite is prepared by combining the latex compounding method and spray-drying process. The MMT layers exhibit a nearly exfoliated structure in the spray-dried powder. But when subjected to strains higher than 40%, the sprayed powdered nanocomposite goes through an irreversible transformation of the MMT network, showing a dramatic decrease in the storage modulus. XRD, SEM, and high resolution transmission electron microscopy results confirm the structure transformation of the MMT/SBR nanocomposite during processing. With intensive shearing during milling, the MMT layers are oriented, and further aggregations are observed in the vulcanizate. The processing procedures greatly alter the structures of the MMT/SBR nanocomposite. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Co-reporter:Hailan Kang, Bo Qiao, Runguo Wang, Zhao Wang, Liqun Zhang, Jun Ma, Phil Coates
Polymer 2013 Volume 54(Issue 9) pp:2450-2458
Publication Date(Web):19 April 2013
DOI:10.1016/j.polymer.2013.02.053
Biodegradable, biocompatible polylactide (PLA) synthesized from renewable resources has attracted extensive interests over the past decades and holds great potential to replace many petroleum-derived plastics. With no loss of biodegradability and biocompatibility, we highly toughened PLA using a novel bioelastomer (BE)–synthesized from biomass diols and diacids. Although PLA and BE are immiscible, BE particles of ∼1 μm in diameter are uniformly dispersed in the matrix, and this indicates some compatibility between PLA and BE. BE significantly increased the cold crystallization ability of PLA, which was valuable for practical processing and performance. SEM micrographs of fracture surface showed a brittle-to-ductile transition owing to addition of BE. At 11.5 vol%, notched Izod impact strength improved from 2.4 to 10.3 kJ/m2, 330% increment; the increase is superior to previous toughening effect by using petroleum-based tougheners.
Co-reporter:Yang Meng, Zheng Wei, Ling Liu, Li Liu, Liqun Zhang, Toshio Nishi, Kohzo Ito
Polymer 2013 Volume 54(Issue 12) pp:3055-3064
Publication Date(Web):24 May 2013
DOI:10.1016/j.polymer.2013.03.061
In this work, two different polyhedral oligomeric silsesquioxanes (POSS)—octaisobutyl-POSS (OIBS) and allylisobutyl-POSS (AIBS)—were incorporated into poly(methylvinylsiloxane) (VMQ) by melt mixing and then the corresponding blends were chemically crosslinked by peroxide. NMR analysis revealed that AIBS molecules containing double bonds were successfully grafted onto VMQ macromolecular chains during the crosslinking of VMQ. Morphology and thermal stability studies by various methods discovered that the in-situ formation of chemical linking between POSS molecules and VMQ chains could significantly improve the dispersion of POSS particles and the thermal stability of VMQ. For the VMQ with 5 wt% POSS, AIBS exhibited nano-dispersion in VMQ matrix and improved the thermal stability of VMQ, but inert OIBS molecules aggregated extensively to form crystals and adversely affected the thermal stability, although AIBS and OIBS have similar solubility parameters and thermal stabilities. Further studies on the thermal stability of VMQ with different contents of AIBS showed that the thermal stability first increased with increasing content of AIBS but then began to decrease as the content of AIBS exceeded 7.5 wt%. X-ray diffraction and extraction experiments showed that extensive ungrafted AIBS molecules and their aggregates started to appear in the VMQ matrix as the content of AIBS exceeded 7.5 wt%. The study revealed that the grafted POSS hindered the thermal degradation of silicone rubber to cyclic oligomers but the ungrafted POSS favored the thermal degradation.
Co-reporter:Fen Li, Yonglai Lu, Li Liu, Liqun Zhang, Jiabin Dai, Jun Ma
Polymer 2013 Volume 54(Issue 8) pp:2158-2165
Publication Date(Web):3 April 2013
DOI:10.1016/j.polymer.2013.02.019
Although carbon nanotubes have been extensively studied since 1991, it is not clear the relations between the tubes' length and their composites' functional and mechanical performance. We in this study employed ball milling to reduce the length of multi-walled carbon nanotubes (MWNTs) from a few microns to hundreds of nm through milling for different time slots. The milled tubes demonstrated a 12.0% increase in surface area. When dispersed in an elastomer matrix, MWNTs showed two types of morphology: separately dispersed and clustered. The cluster size reduced with the ball-milling time. The ball milling obviously increased the composite fracture strain, while mild increase in tensile strength was observed. When MWNT/elastomer composites were compared with carbon black (CB) composites, both showed similar strength, but the former demonstrated markedly higher strength at low strain—a highly desired property for elastomers. The MWNT composites show a strong filler–filler interaction with an unobvious Payne effect. Although the ball milling slightly reduced the electrical and thermal conductivity of the MWCNT composites, they demonstrated much higher conductivity than the CB composites. The ball-milling reduced up to 18.2% of the composite internal heat rise.
Co-reporter:Zheng Wei, Shaojian He, Xin Liu, Jing Qiao, Jun Lin, Liqun Zhang
Polymer 2013 Volume 54(Issue 3) pp:1243-1250
Publication Date(Web):5 February 2013
DOI:10.1016/j.polymer.2012.12.060
For the past decade, much effort has been dedicated to non-fluorinated polymeric membranes as alternatives for commercial Nafion in the field of direct methanol fuel cells (DMFCs). However, most of researches have used solvents that are environmentally unfriendly during the membranes preparation. This work reported a novel solvent-free route to prepare non-fluorinated proton exchange membranes (PEMs) via the in situ reaction and grafting of sodium 4-styrene sulfonate (NaSS) to hydrogenated nitrile butadiene rubber (HNBR) during peroxide curing. Membrane morphology was characterized by TEM and SEM-EDX experiments. The effect of NaSS loading and unsaturation level of HNBR on the membrane properties were studied. The obtained membranes exhibited proton conductivity on the order of 0.01 S/cm and selectivity (the ratio of proton conductivity to methanol permeability) higher than that of Nafion, and could be potentially used for the application in DMFCs.
Co-reporter:Quanyong Liu, Lei Jiang, Rui Shi, Liqun Zhang
Progress in Polymer Science 2012 Volume 37(Issue 5) pp:715-765
Publication Date(Web):May 2012
DOI:10.1016/j.progpolymsci.2011.11.001
Degradable bioelastomers are novel polymer biomaterials mainly applied in soft tissue engineering and drug delivery. Synthetic degradable bioelastomers present four remarkable features: three-dimensional crosslinking network structure similar to that of natural elastins, high flexibility and elasticity capable of providing mechanical stimuli for tissue engineering constructs, matched mechanical properties especially with soft body tissues, and broad biodegradability that can be adjusted directly by crosslink density. In this review, degradable bioelastomers are divided into chemically and physically crosslinked bioelastomers. In view of the influence of crosslinking structures on the properties of bioelastomers, chemically crosslinked bioelastomers are further classified into thermo-cured and photo-cured bioelastomers, and physically crosslinked bioelastomers correspond to thermoplastic bioelastomers. In this contribution, after a discussion on the definition of and design strategies for degradable bioelastomers is delivered, the recent advances in the synthesis, properties (especially the in vitro degradation), and potential biomedical applications of these materials are described. Simultaneously, some insights on degradable bioelastomers have also been illuminated. Degradable bioelastomers are sure to play an increasingly significant role in the future developments of polymer biomaterials.
Co-reporter:Zhenghai Tang, Xiaohui Wu, Baochun Guo, Liqun Zhang and Demin Jia
Journal of Materials Chemistry A 2012 vol. 22(Issue 15) pp:7492-7501
Publication Date(Web):
DOI:10.1039/C2JM00084A
Co-reporter:Wenshan Guo, Hailan Kang, Yongwen Chen, Baochun Guo, and Liqun Zhang
ACS Applied Materials & Interfaces 2012 Volume 4(Issue 8) pp:4006
Publication Date(Web):July 20, 2012
DOI:10.1021/am300828u
Boehmite (BM) nanoplatelets were adopted to compound with fully biobased poly(propylene sebacate) (PPSe) to form the shape memory composites. The PPSe/BM composites kept excellent shape memory properties as previously reported PPSe. Compared to neat PPSe, the composites possess much higher mechanical properties above the melting point and faster biodegradation rate, which was demonstrated via tensile test at elevated temperature and in vitro degradation experiments in phosphate buffer saline (PBS), respectively. The obviously improved mechanical properties at elevated temperature are attributed to the uniform dispersion of the reinforcing boehmite nanoplatelets, which was facilitated by the interfacial interaction between BM and PPSe as revealed by FTIR, XPS, and XRD results. The faster degradation is correlated to accelerated hydrolysis by basic boehmite with surface aluminols. The potential biocompatibility, as substantiated by the outstanding cell viability and cell attachment, together with the realization of transformation temperature close to body temperature makes the PPSe/BM composites suitable for the biomedical applications, such as stents, in human body.Keywords: biobased polyester; boehmite; degradability; shape memory polymer;
Co-reporter:Wencai Wang, Wenjian Cheng, Ming Tian, Hua Zou, Le Li, Liqun Zhang
Electrochimica Acta 2012 Volume 79() pp:37-45
Publication Date(Web):30 September 2012
DOI:10.1016/j.electacta.2012.06.063
A biomimetic method for the preparation of highly conductive silver-plated polyethylene terephthalate (PET) fiber was demonstrated. First, the PET fibers were functionalized with a bio-inspired polydopamine (PDA) coating, simply by being dispersed in a dopamine solution under mild stirring at room temperature. Electroless plating of silver was then carried out on the surface of the PET-PDA fiber. An aqueous solution of silver nitrate and glucose was used as silver precursor and reducing reagent, respectively. The overall procedure is fast, simple, efficient, nontoxic, as well as controllable. The PDA layer on the PET surface was characterized by X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) spectroscopy, and contact angle measurement. The crystalline structure of the modified PET fiber was studied by X-ray diffraction (XRD). The morphology of the PET-PDA and the PET-Ag fiber was observed by scanning electron microscopy (SEM). SEM results showed that the silver layer coated on PET-PDA was continuous, uniform, and compact. The as-prepared PET-Ag fibers have good electrical conductivity, with surface resistivity as low as 0.4 mΩ cm. The binding force between the silver layer and PET-PDA fiber was strong enough that the silver layer remained compact and continuous after the PET-PDA/Ag fiber was rinsed under ultrasound for 4 h.Graphical abstractHighlights► PET/Ag fibers were prepared via a biomimetic surface functionalization method. ► The method is fast, simple, efficient, nontoxic, as well as controllable. ► The silver layer coated on PET-PDA fibers was continuous, uniform, and compact. ► The as-prepared PET-Ag fibers possess good electrical conductivity. ► The binding force between the silver layer and PET-PDA fiber was strong.
Co-reporter:Chunfang Zeng, Zhenghai Tang, Baochun Guo and Liqun Zhang
Physical Chemistry Chemical Physics 2012 vol. 14(Issue 28) pp:9838-9845
Publication Date(Web):23 May 2012
DOI:10.1039/C2CP40517B
For the purpose of preparing liquefied graphene oxide (GO), a process consisting of sulfonation with sodium sulfanilic acid and ionization with bulky amine-terminated Jeffamine® was designed and performed. The obtained hybrid fluid is actually a supramolecular ionic liquid (SIL) with sulfonated GO as the central anions and the terminal ammonium groups of Jeffamine® as the surrounding cations. The successful grafting of the GO sheets with Jeffamine® via an ionic structure was verified and the morphology of the SIL was characterized. The SIL based on GO (GO-SIL) exhibits excellent solubility and amphiphilicity. The rheological measurements confirm the essential viscoelasticity and the liquid-like behavior of GO-SIL. The present GO based SIL suggests promising applications in the fabrication of various GO or graphene based composite materials. In addition, the new functionalization method may guide the future work on acquiring derivatives with tunable properties by simply changing the bulky canopy.
Co-reporter:Ming Lu;Yiqing Wang;Youping Wu;Yannan Quan;Xiaohui Wu;Liqun Zhang;Baochun Guo
Macromolecular Materials and Engineering 2012 Volume 297( Issue 1) pp:20-25
Publication Date(Web):
DOI:10.1002/mame.201100136
Co-reporter:Ming Lu;Yiqing Wang;Youping Wu;Yannan Quan;Xiaohui Wu;Liqun Zhang;Baochun Guo
Macromolecular Materials and Engineering 2012 Volume 297( Issue 1) pp:
Publication Date(Web):
DOI:10.1002/mame.201290001
Co-reporter:Wencai Wang;Fengdan Jiang;Yi Jiang;Yonglai Lu;Liqun Zhang
Journal of Applied Polymer Science 2012 Volume 126( Issue 3) pp:789-795
Publication Date(Web):
DOI:10.1002/app.36936
Abstract
A spray drying approach has been used to prepare polyurethane/multiwalled carbon nanotube (PU/MWCNT) composites. By using this method, the MWCNTs can be dispersed homogeneously in the PU matrix in an attempt to improve the mechanical properties of the nanocomposites. The morphology of the resulting PU/MWCNT composites was investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). SEM and TEM observations illustrate that the MWCNTs are dispersed finely and uniformly in the PU matrix. X-ray diffraction results indicate that the microphase separation structure of the PU is slightly affected by the presence of the MWCNTs. The mechanical properties such as tensile strength, tensile modulus, elongation at break, and hardness of the nanocomposites were studied. The electrical and the thermal conductivity of the nanocomposites were also evaluated. The results show that both the electrical and the thermal conductivity increase with the increase of MWCNT loading. In addition, the percolation threshold value of the PU composites is significantly reduced to about 5 wt % because of the high aspect ratio of carbon nanotubes and exclusive effect of latex particles of PU emulsion in dispersion. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Co-reporter:Dan Yang, Ming Tian, Hailan Kang, Yingchao Dong, Haoliang Liu, Yingchun Yu, Liqun Zhang
Materials Letters 2012 Volume 76() pp:229-232
Publication Date(Web):1 June 2012
DOI:10.1016/j.matlet.2012.02.084
A new polyester dielectric elastomer aiming at large actuated strains driven by low electric fields was synthesized from five monomers through melt polycondensation. The polyester dielectric elastomer displays not only high dielectric constant but also low glass transition temperature. The effect of crosslink density on the elastic modulus, dielectric properties, and actuated strain of this elastomer was investigated. The sample with the lowest crosslink density showed high actuated strain (11.9%) at low electric field strength (just 15.6 kV/mm) without any prestrain. Moreover, this elastomer presented good cell compatibility. This research might help to establish a new route for electroactive polymers.Graphical abstractHighlights► A new polyester dielectric elastomer was synthesized. ► This dielectric elastomer exhibited excellent electromechanical properties. ► This dielectric elastomer showed good cell compatibility.
Co-reporter:Yan Wu;Rui Shi;Dafu Chen;Liqun Zhang;Wei Tian
Journal of Applied Polymer Science 2012 Volume 123( Issue 3) pp:1612-1620
Publication Date(Web):
DOI:10.1002/app.34556
Abstract
Modified nano-fumed silica (mn-silica)/poly(glycerol-sebacate-citrate), in which mn-silica loadings varied from 0 to 20 phr, were prepared by in situ polymerization and surface modification. The influence of mn-silica loadings on the structure and properties of the composites was studied. Scanning electron microscope (SEM) and transmission electron microscope (TEM) photos showed that the mn-silica dispersed well as nano-scale network in the matrix, and exhibited good interfacial bonding with the matrix. The mn-silica filled composites exhibited excellent comprehensive properties relative to the unfilled elastomers. Specially, the tensile strength improved from 0.9 MPa to 5.3 MPa. Results of the in vitro degradation test suggested that mn-silica loading could adjust the degradation rate of the composites in simulated body fluid solution. The MTT colorimetry with L929 cells substantiated that the introduction of mn-silica weakened the cytotoxicity of elastomers and made the composites accepted as qualified biomedical materials. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Co-reporter:Xiu-Ying Zhao;Ya-Jun Cao;Hua Zou;Jing Li
Journal of Applied Polymer Science 2012 Volume 123( Issue 6) pp:3696-3702
Publication Date(Web):
DOI:10.1002/app.35043
Abstract
Crosslinked nitrile-butadiene rubber (NBR)/hindered phenol composites were successfully prepared by mixing tetrakis [methylene-3-(3-5-ditert-butyl-4-hydroxy phenyl) propionyloxy] methane (AO-60) into NBR with 35% acrylonitrile mass fraction. The structural and mechanical properties of the NBR/AO-60 composites were systematically investigated by using differential scanning calorimeter, XRD, Fourier transform infrared, scanning electronic microscope, dynamic mechanical analyzer, and tensile testing. The results indicated that the AO-60 changed from crystalline form into amorphous form, and most of the AO-60 molecules could be uniformly dispersed in the NBR matrix. The glass transition temperature (Tg) of NBR/AO-60 composites increased gradually with increasing content of AO-60. The increase in Tg could be attributed to the formation of a strong hydrogen bonding network between the AO-60 molecules and the NBR matrix. Unlike the pure NBR, the NBR/AO-60 rubber composites had only one transition with a high loss factor. With increasing content of AO-60, the loss peak shifted to the high temperature region, the loss factor increased from 1.45 to 1.91, and the area under the tan δ versus temperature curve (TA) also showed a significant increase. All these results were ascribed to the good compatibility and strong intermolecular interactions between NBR and AO-60. Furthermore, all NBR/AO-60 composites exhibited higher glass transition temperatures and tensile strength than NBR, and they had other desirable mechanical properties. They have excellent prospects in damping material applications. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Co-reporter:Zheng Wei;Yonglai Lu;Shouke Yan;Yang Meng;Liqun Zhang
Journal of Applied Polymer Science 2012 Volume 124( Issue 1) pp:288-295
Publication Date(Web):
DOI:10.1002/app.34615
Abstract
The influence of the curing temperature on micro-nano structure transform of hydrogenated nitrile-butadiene rubber (HNBR) reinforced by zinc dimethacrylate (ZDMA) through in situ polymerization was studied by means of Scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, and X-ray diffraction. The results showed that both the amount and diameter of the poly-ZDMA aggregates increased and the graft ratio of poly-ZDMA decreased with the increase of curing temperature. Meanwhile, with the increase of curing temperature, the maximum torque of the curing curve, the crosslinking density (especially for the ionic crosslinking density), and the mechanical properties of HNBR/ZDMA composite decreased significantly. We put forward a possible mechanism that can well explain the phenomenon observed in this work. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Co-reporter:Xin Ye;Miao Tian
Journal of Applied Polymer Science 2012 Volume 124( Issue 2) pp:927-934
Publication Date(Web):
DOI:10.1002/app.35024
Abstract
Hydrogenated nitrile rubber (HNBR)/silica nanocomposites were prepared by in-situ modification dispersion technology, and the silane coupling agent γ-methacryloxypropyl trimethoxy silane (KH570) was chosen to promote the interfacial strength between silica particles and HNBR matrix and further improve the dispersion of silica particles. Rubber Process Analyzer (RPA2000) was used to test the Payne effect of HNBR/silica compounds, from which some interesting phenomena were found: the Payne effect became stronger after KH570 was added to HNBR/silica compound at room temperature, which was a contrary result compared to SBR/silica system. However, after stored for a month at room temperature, the Payne effect weakened, which was contrary to the traditional phenomenon of storage hardening of filled rubber. All these results are related to filler–filler interaction and filler–rubber interaction. The modulus at small strain amplitude of HNBR/silica compound with KH570 gradually decreased with the increase of times of circulatory strain sweep but that of compound without KH570 had almost no change, which was explained by Fourier Transform Infrared (FTIR) results that the reaction between silica and KH570 almost completed at the test condition: 80°C and about 1 h. The effects of silane amount, heat-treated temperature and time on the Payne effect of compounds and the mechanical properties of vulcanizates were also investigated. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Co-reporter:Ming Tian;Jibin Han;Hanguang Wu;Hongchi Tian;Qingyan She;Wenquan Chen;Liqun Zhang
Journal of Applied Polymer Science 2012 Volume 124( Issue 3) pp:1999-2006
Publication Date(Web):
DOI:10.1002/app.35222
Abstract
In this study, the morphologies of three types of acrylonitrile–butadiene rubber (NBR)/polypropylene (PP) thermoplastic vulcanizates (TPVs) (with an NBR/PP blend ratio of 70/30) were compared. The TPVs were (1) an ultrafine fully vulcanized acrylonitrile–butadiene rubber (UFNBR)/PP TPV made by the mechanical blending of UFNBR with PP, (2) a dynamically vulcanized NBR/PP TPV without the compatibilization of maleic anhydride grafted polypropylene (MP) and amine-terminated butadiene–acrylonitrile copolymer (ATBN), and (3) a dynamically vulcanized NBR/PP TPVs with the compatibilization of MP and ATBN. The influence of the compatibility therein on the size of the dispersed vulcanized NBR particles and the crystallization behavior of the PP in the TPVs and the resultant properties are also discussed. As indicated by Fourier transform infrared spectroscopy, scanning electron microscopy, differential scanning calorimetry, polarizing microscopy, dynamic mechanical thermal analysis, and rheological and mechanical testing, the compatibility was significantly improved by the reactive compatibilization of MP and ATBN, which led to a uniform and fine morphology. The compatibilization increased the crystallization rate and reduced the size of the spherulites of PP. On the other hand, it was found that the dispersed vulcanized NBR particles lowered the degree of crystallinity. The better the compatibility of the blend was, the lower the degree of crystallinity and the storage modulus were, but the higher the loss factor and the processing viscosity were. All TPVs showed almost the same oil resistance, but the TPV prepared with reactive compatibilization had the best mechanical properties. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Co-reporter:Qing-Xiu Jia;Zu-Jiang Xiong;Chao-Ming Shi;Xiao-Ning Wang
Journal of Applied Polymer Science 2012 Volume 124( Issue 6) pp:5165-5171
Publication Date(Web):
DOI:10.1002/app.33763
Abstract
Polyamide 6 (PA6) fibers were prepared by CaCl2 complexation and the gel spinning technique. PA6 was partially complexed with CaCl2 for the purpose of suppressing interchain amide group hydrogen bonding. The fibers were characterized with scanning electron microscopy, X-ray diffraction (XRD), differential scanning calorimetry (DSC), and Fourier transform infrared (FTIR) spectroscopy. In the gel spinning process, a mixed tetrachloroethane and chloroform solution was chosen as the coagulation bath after a comparison of different types of solutions. From our investigation of the morphology, structure, and mechanical properties of gel-spun and hot-drawn fibers, it was indicated that the modulus and tensile strength increased with increasing draw ratio, the orientation of the fibers was improved, and the cross section of the PA6 gel fibers became more smooth and tight. The results from the XRD, DSC, and FTIR tests indicated that calcium metal cations complexed with the carbonyl oxygen atoms of PA6. The maximum modulus and tensile strength values obtained in this study were 28.8 GPa and 413 MPa, respectively, at a draw ratio of 8. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Co-reporter:Zheng Wei;Yonglai Lu;Yang Meng;Liqun Zhang
Journal of Applied Polymer Science 2012 Volume 124( Issue 6) pp:4564-4571
Publication Date(Web):
DOI:10.1002/app.35486
Abstract
In this study, the wear (Akron and DIN) and the cutting and chipping (C&C) behaviors of hydrogenated nitrile butadiene rubber (HNBR) reinforced by carbon black (N115) and in-situ prepared zinc dimethacrylate (ZDMA) were investigated. It was validated that ZDMA was more effective than N115 to enhance the wear and C&C resistance of HNBR composites. The Akron wear resistance of the HNBR/N115 composites increased with the content of ZDMA, and the Schallamach ridges observed on the abraded surfaces became less and less clear. With increasing content of ZDMA, the failure mode of the DIN abraded surface underwent the transition from craters to Schallamach ridges, and finally to scratches. The HNBR/N115 composite reinforced by 10 phr ZDMA had the best DIN wear resistance when Schallamach ridges were the dominant failure mode. The use of 30 phr ZDMA can dramatically enhance the C&C resistance of the HNBR/N115 composites. The C&C resistance was suggested to be related to both the variation of the morphology of the C&C ridges and the direction of crack propagation as a function of the content of ZDMA. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Co-reporter:Tao Wei;Lijuan Lei;Hailan Kang;Bo Qiao;Zhao Wang;Liqun Zhang;Phil Coates;Kuo-Chih Hua;Joseph Kulig
Advanced Engineering Materials 2012 Volume 14( Issue 1-2) pp:112-118
Publication Date(Web):
DOI:10.1002/adem.201100162
Abstract
Biomass feedstock is a viable alternative to finite fossil fuel resources to provide many of the same—plus others that petrochemicals cannot—chemical building blocks required to fabricate durable and high-performance materials. We demonstrate here for the first time a new generation of synthesized elastomers, namely bio-based engineering elastomers (BEE). These are of particular significance because they are synthesized from monomers derived from biomass, by routes which are suitable for large scale production, and they exhibit thermo-mechanical properties at least equivalent to current commercial petrochemical-derived elastomers. Bio-based monomers in large scale production, such as sebacic acid, itaconic acid, succinate acid, 1,3-propanediol, and 1,4 butanediol are chosen to generate the first synthetic BEE matrix through melting polycondensation—a comparatively simple reaction scheme offering good control and the potential for low cost, large-scale production. A novel linear BEE, an almost non-crystalline copolyester elastomer with low glass transition temperature (Tg) containing double bonds is designed and synthesized using multiple monomers (to help suppress crystallization). Silica nanoparticles are then introduced into the BEE matrix to achieve significant strengthening and improved environmental stability. Chemical crosslinks formed by peroxide and the pendant double bonds in the copolyester macromolecules endow the BEE with both the necessary high elasticity and required environmental stability. The BEE nanocomposites obtained exhibit excellent thermomechanical properties, such as an ultimate tensile strength of 20 MPa.
Co-reporter:Tao Wei;Lijuan Lei;Hailan Kang;Bo Qiao;Zhao Wang;Liqun Zhang;Phil Coates;Kuo-Chih Hua;Joseph Kulig
Advanced Engineering Materials 2012 Volume 14( Issue 1-2) pp:
Publication Date(Web):
DOI:10.1002/adem.201290006
Co-reporter:Zhao Wang, Xing Zhang, Runguo Wang, Hailan Kang, Bo Qiao, Jun Ma, Liqun Zhang, and Hao Wang
Macromolecules 2012 Volume 45(Issue 22) pp:9010-9019
Publication Date(Web):November 5, 2012
DOI:10.1021/ma301938a
A new series of soybean-oil-based elastomers poly(epoxidized soybean oil-co-decamethylene diamine) (PESD) was synthesized by ring-opening polymerization from epoxidized soybean oil (ESO) and decamethylene diamine (DDA) in different molar ratios. The effect of the molar ratio on the structure and properties of PESD was identified by various methods. According to the results of Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (1H NMR) and thermogravimetry (TGA), the glycerol center of ESO was broken by ammonolysis as expected in the process of polymerization, which resulted in un-cross-linked elastomers with low glass transition temperatures (Tg) ranging from −30 to −17 °C. PESD-3 (molar ratio of DDA to ESO is 2:1) was found to have the highest molecular weight and was most suitable for further processing. Then, PESD-3 was successfully cross-linked through succinic anhydride by a general rubber processing method to obtain a cross-linked bioelastomer. The mechanism of chain growth, ammonolysis of ester group, and cross-linking of PESD-3 was studied. The tensile strength of cross-linked PESD could be flexibly adjusted from 0.8 to 8.5 MPa by using different amounts of succinic anhydride without reinforcing fillers. The final bioelastomer possesses good damping property, low water absorption, and low degradation rate in phosphate buffer solution. These properties indicate potential engineering applications.
Co-reporter:Ming Lu, Bo He, Liansheng Wang, Wen Ge, Qiuyu Lu, Yakang Liu, Liqun Zhang
Composites Part B: Engineering 2012 Volume 43(Issue 1) pp:50-56
Publication Date(Web):January 2012
DOI:10.1016/j.compositesb.2011.04.030
Latex-formed core–shell nanoparticles composed of cross-linked polystyrene (PS) core and polyisoprene (PI) shell were successfully synthesized by means of a two-stage emulsion polymerization. The PS core possessed a Z-average diameter of 50.3 nm, and the PS–PI particles took a spherical shape with a Z-average size of 50–70 nm in diameter. Shell thickness was controlled by varying isoprene loading. Necessary interphase interactions between the core and shell domains were also achieved by grafting and swelling polymerization. Latex compounding method was employed to prepare the filled elastomer compounds. As expected, the PS–PI core–shell nanoparticles exhibited excellent reinforcement to elastomeric matrix, enhancing the tensile strength of the styrene–butadiene rubber by approximately 400%. The lower density, better interfacial interactions, and latex compounding process would benefit the PS–PI nanoparticles reinforced elastomer nanocomposites in energy saving.
Co-reporter:Zheng Wei, Yonglai Lu, Yang Meng, Liqun Zhang
Polymer 2012 Volume 53(Issue 6) pp:1409-1417
Publication Date(Web):9 March 2012
DOI:10.1016/j.polymer.2012.01.056
In this work, we chose the HNBR/ZDMA composite as a system reinforced by the metal salt of unsaturated carboxylic acids (MSUCA) and systematically studied the evolution of the in-situ polymerization of ZDMA particles during peroxide curing. Differential scanning caborimetry, Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, transmission electron microscopy and polarization microscopy were used in this study. The microstructure of the remaining micron-sized dispersions in the cured HNBR/ZDMA was verified for the first time, and a new mechanism for in-situ polymerization of ZDMA, i.e., the solid bulk polymerization initialized onto the surface of ZDMA particles, was put forward. Moreover, we discussed how the micron-sized dispersions generated by the solid bulk polymerization of undiffused ZDMA particles affected the crosslink structures and mechanical properties of the vulcanizate.
Co-reporter:Zhenghai Tang, Yanda Lei, Baochun Guo, Liqun Zhang, Demin Jia
Polymer 2012 Volume 53(Issue 2) pp:673-680
Publication Date(Web):24 January 2012
DOI:10.1016/j.polymer.2011.11.056
Individually dispersed graphene colloid is prepared using cationic dye rhodamine B (RhB) as a non-covalent modifier. Characterizations by UV–vis, photoluminescence and Raman, the graphene-RhB interactions are shown to be cation-π and π-π. Subsequently, the obtained graphene is incorporated into polyvinyl alcohol (PVA) to fabricate PVA/graphene composites by simple solution casting. On addition of 1.0 wt% graphene, the tensile strength and tensile modulus are increased by 178% and 139%, respectively. Interestingly, the strain of the composites is greatly maintained, which is related to the uniqueness interfacial structure and morphology of the composites. This work provides a promising methodology to fabricate high performance graphene-based composites with superior strength and ductility by simultaneously combining the reinforcement of graphene sheets and the uniqueness interfacial structure.
Co-reporter:Zhenghai Tang, Hailan Kang, Zuoli Shen, Baochun Guo, Liqun Zhang, and Demin Jia
Macromolecules 2012 Volume 45(Issue 8) pp:3444-3451
Publication Date(Web):April 13, 2012
DOI:10.1021/ma300450t
Many reported polymer/graphene composites, even some with excellent graphene dispersion, do not possess impressive conductivity, which may be due to the failure in forming interconnected conductive paths. In this work, a kind of bio-based polyester (BE) is synthesized by polycondensation between plant-derived diols and diacids. It is then grafted onto graphene oxide (GO) via the easterification between hydroxyls of BE and carboxyls of GO. Subsequently, the grafted GO is subjected to reduce by vitamin C. Because of the presence of terminal hydroxyl group in both ends of the BE chains and multiple carboxyl groups on GO, the grafts form specific spatial interconnection structure in BE matrix. The resulting BE/graphene composites possess impressive low threshold percolation of electrical conductivity, in combination of high thermal conductivity.
Co-reporter:Runguo Wang, Jun Ma, Xinxin Zhou, Zhao Wang, Hailan Kang, Liqun Zhang, Kuo-chih Hua, and Joseph Kulig
Macromolecules 2012 Volume 45(Issue 17) pp:6830-6839
Publication Date(Web):August 21, 2012
DOI:10.1021/ma301183k
A novel cross-linkable, high molecular weight poly(diisoamyl itaconate-co-isoprene) (PDII) elastomer was prepared by emulsion polymerization based on itaconic acid, isoamyl alcohol, and isoprene. Both persulfate and redox initiators were used for the copolymerization of diisoamyl itaconate and isoprene at different monomer ratios. Redox-initiated PDII has much higher molecular weight but relatively lower yield than the persulfate-initiated one. PDII with a number-average molecular weight of 352 000 and a glass transition temperature of −39.5 °C was obtained when the mass ratio of diisoamyl itaconate to isoprene was 80/20. Diisoamyl itaconate and isoprene reactivity ratios were determined by two conventional linear methods: the Fineman–Ross method and the Kelen–Tüdös method. Molecular dynamics simulation and FTIR were used to study the interaction between silica and PDII macromolecules, and the result showed that hydrogen bonds were formed between silica silanols and PDII macromolecules. Silica-reinforced PDII exhibited good mechanical performance, such as ultimate tensile strength above 11 MPa and elongation at break above 400%.
Co-reporter:Zhenghai Tang, Chunfang Zeng, Yanda Lei, Baochun Guo, Liqun Zhang and Demin Jia
Journal of Materials Chemistry A 2011 vol. 21(Issue 43) pp:17111-17118
Publication Date(Web):07 Sep 2011
DOI:10.1039/C1JM13239C
Individually dispersed graphene colloid is prepared using common and industrially available fluorescent whitening agents (FWAs) as stabilizers. Characterizations by UV-vis, fluorescence and Raman spectra demonstrate that FWAs are successfully anchored onto graphene sheets by π–π interaction. The results from AFM indicate the individual dispersion of graphene sheets in water. FWAs are demonstrated as highly efficient in suspending graphene with high concentration(6.2 mg ml−1). Subsequently, the obtained graphene sheet is incorporated into a chitosan (CS) matrix by solution casting to fabricate CS/graphene composites. Morphological observations substantiate the homogeneous dispersion of graphene in the CS matrix and the strong interfacial adhesion between them. The significant improvements in tensile strength and toughness of the composite films are concurrently observed.
Co-reporter:Jun Liu, Sizhu Wu, Liqun Zhang, Wenchuan Wang and Dapeng Cao
Physical Chemistry Chemical Physics 2011 vol. 13(Issue 2) pp:518-529
Publication Date(Web):05 Nov 2010
DOI:10.1039/C0CP00297F
By employing an idealized model of a polymer network and filler, we have investigated the stress-strain behavior by tuning the filler loading and polymer–filler interaction in a broad range. The simulated results indicate that there actually exists an optimal filler volume fraction (between 23% and 32%) for elastomer reinforcement with attractive polymer–filler interaction. To realize this reinforcement, the rubber–filler interaction should be slightly stronger than the rubber–rubber interaction, while excessive chemical couplings are harmful to mechanical properties. Meanwhile, our simulated results qualitatively reproduce the experimental data of Bokobza. By introducing enough chemical coupling between the rubber and the filler, an upturn in the modulus at large deformation is observed in the Mooney-Rivlin plot, attributed to the limited chain extensibility at large deformation. Particularly, the filler dispersion state in the polymer networks is also characterized in detail. It is the first demonstration via simulation that the reinforcement mechanism stems from the nanoparticle-induced chain alignment and orientation, as well as the limited extensibility of chain bridges formed between neighboring nanoparticles at large deformation. The former is influenced by the filler amount, filler size and filler–rubber interaction, and the latter becomes more obvious by strengthening the physical and chemical interactions between the rubber and the filler. Remarkably, the reason for no obvious reinforcing effect in filled glassy or semi-crystalline matrices is also demonstrated. It is expected that this preliminary study of nanoparticle-induced mechanical reinforcement will provide a solid basis for further insightful investigation of polymer reinforcement.
Co-reporter:Zhen-Hua Wang;Yong-Lai Lu;Jun Liu;Zhi-Min Dang;Weimin Wang
Polymers for Advanced Technologies 2011 Volume 22( Issue 12) pp:2302-2310
Publication Date(Web):
DOI:10.1002/pat.1761
Abstract
In this paper, nanoalumina (Al2O3) highly filled ethylene propylene diene monomer (EPDM) composites are prepared, and the mechanical (static and dynamic) properties and thermal conductivity are investigated systemically through various characterization methods. Furthermore, influences of in situ modification (mixing operation assisted by silane at high temperature for a certain time) with the silane-coupling agent bis-(3-triethoxy silylpropyl)-tetrasulfide (Si69) and stearic acid (SA) pretreatment on the nano-Al2O3 filled composites are as well investigated. The results indicate that nano-Al2O3 particles can not only perform well in reinforcing EPDM, but also improve the thermal conductivity significantly. Assisted by in situ modification with Si69, the mechanical properties (especially dynamic mechanical properties) of the nano-Al2O3 filled composites are improved obviously, without influencing the thermal conductivity. By comparing to the traditional reinforcing fillers, such as carbon black (grade N330) and silica, in situ modified nano-Al2O3 filled composites exhibit excellent performance in mechanical (static and dynamic) properties as well as better thermal conductivity, especially lower compression heat build-up and better fatigue resistance. In general, our work indicates that nano-Al2O3, as the novel thermal conductive reinforcing filler, is suitable to prepare rubber products serving in dynamic conditions, with the longer expected service life. Copyright © 2010 John Wiley & Sons, Ltd.
Co-reporter:Zhenhua Wang;Yonglai Lu;Jun Liu;Zhimin Dang;Liqun Zhang;Weimin Wang
Journal of Applied Polymer Science 2011 Volume 119( Issue 2) pp:1144-1155
Publication Date(Web):
DOI:10.1002/app.32736
Abstract
In this article, nano-zinc oxide (ZnO) filled ethylene propylene diene monomer (EPDM) composites are prepared, and the mechanical (static and dynamic) properties and thermal conductivity are investigated respectively, which are further compared with the traditional reinforcing fillers, such as carbon black and nano-silica. Furthermore, influence of in-situ modification (mixing operation assisted by silane at high temperature for a certain time) with the silane-coupling agent Bis-(3-thiethoxy silylpropyl)-tetrasufide (Si69) on the nano-ZnO filled composites is as well investigated. The results indicate that this novel reinforcing filler nano-ZnO can not only perform well in reinforcing EPDM but can also improve the thermal conductivity significantly. In-situ modification with Si69 can enhance the interfacial interaction between nano-ZnO particles and rubber matrix remarkably, and therefore contribute to the better dispersion of filler. As a result, the mechanical properties and the dynamic heat build-up of the nano-ZnO filled composites are improved obviously by in-situ modification, without influencing the thermal conductivity. In comparison with traditioanl reinforcing fillers, in-situ modified nano-ZnO filled composites exhibit the excellent performance in both mechanical (static and dynamic) properties and better thermal conductivity. In general, our work indicates that nano-ZnO, as the novel thermal conductive reinforcing filler, is suitable to prepare elastomer products serving in dynamic conditions, with the longer expected service life. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Co-reporter:Xiuying Zhao;Daling Xiao;Sizhu Wu;Yiping Feng;Liqun Zhang;Weimin Wang
Journal of Applied Polymer Science 2011 Volume 120( Issue 2) pp:906-913
Publication Date(Web):
DOI:10.1002/app.33198
Abstract
By employing the melt blending method, selective hindered amines were oriented to disperse in the hard phase of thermoplastic polyurethane (TPU). The microstructure and performance of organic hybrids consisting of TPU and poly-[(1-hydroxyethyl -2,2,6,6- tetramethyl- 4-hydroxyl piperidine)]-glycolsuccinate (GW-622) and poly-{[6-(1,1,3,3-tetramethylbutyl) -imino]-[1,3,5-triazine-2,4- dimethyl] [2-(2,2,6,6- tetramethyl piperidinyl)- imino]-cyclohexane-[4-(2,2,6,6-tetramethyl piperidinyl)-imino]} (GW-944) were investigated by dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), scanning electric microscopy (SEM), and tensile measurement. The neat TPU matrix displayed only one glass transition peak in the DMA curve, whereas the TPU/GW-622 hybrids exhibited two overlapping loss peaks, and the TPU/GW-944 hybrids demonstrated two separated relaxation peaks. The second excited relaxation peak of the hybrids was attributed to the oriented distribution of hindered amine in TPU and strong intermolecular interactions between the hindered amine and the hard segments of TPU. The complex and interesting evolution in structure and properties of the hybrids with hindered amine incorporation was interpreted. The loss peak areas (TA) of the hybrids increased greatly, and the high temperature damping properties was expected to improve. This kind of novel hybrid presented a promising future as high performance damping material. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Co-reporter:Ming Lu;Jianjun Zhou;Liansheng Wang;Wei Zhao;Yonglai Lu;Liqun Zhang;Yakang Liu
Journal of Applied Polymer Science 2011 Volume 120( Issue 4) pp:2459-2467
Publication Date(Web):
DOI:10.1002/app.33460
Abstract
Crosslinked α-methylstyrene and acrylonitrile (MStAN) copolymer particles in a latex form were synthesized by free radical emulsion polymerization. The particles took a spherical shape with an average size of 53.1 nm in a narrow distribution. When filled into styrene-butadiene rubber (SBR), nitrile-butadiene rubber (NBR), and natural rubber (NR), the MStAN nano-particles exhibited excellent reinforcing capabilities and the best in NBR. By the employment of heat treatment, mechanical properties of the MStAN-filled SBR composites had got remarkable further improvements. But mechanical properties, together with the morphology, of the MStAN-filled NBR composites, varied little after heat treatment, which, however, divulged the naturally good compatibility between the MStAN particles and the NBR matrix. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Co-reporter:Ming Tian, Qinghua Hu, Haiyan Wu, Lifeng Zhang, Hao Fong, Liqun Zhang
Materials Letters 2011 Volume 65(19–20) pp:3076-3079
Publication Date(Web):October 2011
DOI:10.1016/j.matlet.2011.06.089
Herein we report that fibers of polybutadiene rubber (BR) with high morphological stability were made through combination of electrospinning and in-situ photo-crosslinking. This study revealed that (1) the formation of electrospun BR fibers was correlated with the overlap/entanglement of BR macromolecules in the spinning solutions; for the formation of uniform fibers without beads and/or beaded fibers, the concentration of spinning solution had to be higher than the “critical chain entanglement concentration (Ce)”; and (2) the in-situ photo-crosslinking was an effective method to considerably improve the morphological stability of electrospun BR fibers; upon prolonged storage under ambient condition or even upon immersion in tetrahydrofuran (a good solvent for BR), the crosslinked BR fibers well retained their morphology. It is envisioned that electrospun rubber fibers could be utilized for the development of innovative composites with substantially improved toughness and/or impact strength.Highlights► Fibers of polybutadiene rubber (BR) with high morphological stability are prepared. ► The fibers are prepared through combination of electrospinning and in-situ photo-crosslinking. ► Formation of electrospun BR fibers is correlated with overlap/entanglement of BR macromolecules in spinning solutions. ► In-situ photo-crosslinking is an effective method to considerably improve the morphological stability of electrospun BR fibers.
Co-reporter:Ming Tian, Shi Yin, Hua Zou, Lili Su, Liqun Zhang
Composites Part B: Engineering 2011 Volume 42(Issue 7) pp:1937-1944
Publication Date(Web):October 2011
DOI:10.1016/j.compositesb.2011.05.040
Ethylene propylene diene monomer rubber composites reinforced with micro- and nano-sized short fibers were made by mechanically blending of silanized fibrillar silicate (FS) nanofibers and polyamide 66 (PA-66) microfibers. A synergistic reinforcement on static and dynamic mechanical properties was revealed. When FS nanofibers and PA-66 microfibers were used together in an appropriate volume ratio, static and dynamic mechanical properties (such as tensile stress, mechanical anisotropy, compression modulus, dynamic storage modulus and tensile fatigue property) of the resulting composites were substantially improved. The co-reinforcement mechanism of nano- and micro-sized fibers was discussed in terms of composite fracture morphology. The synergetic reinforcement effect on the dynamic fatigue properties is attributed to the result of competitive factors including stress transfer, crack initiation and propagation, and matrix reinforcement, whereas the synergetic reinforcement effect on the static tensile properties is achieved due to the strong interfacial adhesion between FS nanofibers and rubber.
Co-reporter:Jun Liu, Yangyang Gao, Dapeng Cao, Liqun Zhang, and Zhanhu Guo
Langmuir 2011 Volume 27(Issue 12) pp:7926-7933
Publication Date(Web):May 19, 2011
DOI:10.1021/la201073m
It is a great challenge to fully understand the microscopic dispersion and aggregation of nanoparticles (NPs) in polymer nanocomposites (PNCs) through experimental techniques. Here, coarse-grained molecular dynamics is adopted to study the dispersion and aggregation mechanisms of spherical NPs in polymer melts. By tuning the polymer–filler interaction in a wide range at both low and high filler loadings, we qualitatively sketch the phase behavior of the PNCs and structural spatial organization of the fillers mediated by the polymers, which emphasize that a homogeneous filler dispersion exists just at the intermediate interfacial interaction, in contrast with traditional viewpoints. The conclusion is in good agreement with the theoretically predicted results from Schweizer et al. Besides, to mimick the experimental coarsening process of NPs in polymer matrixes (ACS Nano2008, 2, 1305), by grafting polymer chains on the filler surface, we obtain a good filler dispersion with a large interparticle distance. Considering the PNC system without the presence of chemical bonding between the NPs and the grafted polymer chains, the resulting good dispersion state is further used to investigate the effects of the temperature, polymer–filler interaction, and filler size on the filler aggregation process. It is found that the coarsening or aggregation process of the NPs is sensitive to the temperature, and the aggregation extent reaches the minimum in the case of moderate polymer–filler interaction, because in this case a good dispersion is obtained. That is to say, once the filler achieves a good dispersion in a polymer matrix, the properties of the PNCs will be improved significantly, because the coarsening process of the NPs will be delayed and the aging of the PNCs will be slowed.
Co-reporter:Jianxiang Shen, Jun Liu, Yangyang Gao, Dapeng Cao, and Liqun Zhang
Langmuir 2011 Volume 27(Issue 24) pp:15213-15222
Publication Date(Web):October 31, 2011
DOI:10.1021/la203182u
By focusing on the grafted nanoparticles (NPs) embedded in polymer melts, a detailed coarse-grained molecular dynamics simulation is adopted to investigate the effects of the grafting density, the length of the matrix and grafted chains on the dispersion of the NPs. We have employed visualization snapshots, radial distribution functions (RDFs), the interaction energy between NPs, the number of neighbor NPs, and the conformation of the brush chains to clearly analyze the dispersion state of the grafted NPs. Our simulated results generally indicate that the dispersion of the NPs is controlled by both the excluded volume of the grafted NPs and the interface between the brushes and the matrix. It is found that increasing grafting density or grafted chain length leads to better dispersion, owing to larger excluded volume; however, increasing the length of the matrix chains leads to aggregation of NPs, attributed to both a progressive loss of the interface between the brushes and the matrix and the overlap between brushes of different NPs, intrinsically driven by entropy. Meanwhile, it is found that there exists an optimum grafting density (σc) for the dispersion of the NPs, which roughly obeys the following mathematical relation: σc is proportional to NmK/NgL, where K, L > 0 and Nm and Ng represent the length of the matrix and grafted chain length, respectively. Considering the practical situation that the grafted brushes and the matrix polymer are mostly not chemically identical, we also studied the effect of the compatibility between the brushes and the matrix polymer by taking into account the attraction between the grafted chains and the matrix chains. In general, our comprehensive simulation results are believed to guide the design and preparation of high-performance polymer nanocomposites with good or even tailored dispersion of NPs.
Co-reporter:Baochun Guo, Yongwen Chen, Yanda Lei, Liqun Zhang, Wen You Zhou, A. Bakr M. Rabie, and Jianqing Zhao
Biomacromolecules 2011 Volume 12(Issue 4) pp:
Publication Date(Web):March 7, 2011
DOI:10.1021/bm2000378
From the point of better biocompatibility and sustainability, biobased shape memory polymers (SMPs) are highly desired. We used 1,3-propanediol, sebacic acid, and itaconic acid, which have been industrially produced via fermentation or extraction with large quantities as the main raw materials for the synthesis of biobased poly(propylene sebacate). Diethylene glycol was used to tailor the flexibility of the polyester. The resulted polyesters were found to be promising SMPs with excellent shape recovery and fixity (near 100% and independent of thermomechanical cycles). The switching temperature and recovery speed of the SMPs are tunable by controlling the composition of the polyesters and their curing extent. The continuously changed switching temperature ranging from 12 to 54 °C was realized. Such temperature range is typical for biomedical applications in the human body. The molecular and crystalline structures were explored to correlate to the shape memory behavior. The combination of potential biocompatibility and biodegradability of the biobased SMPs makes them suitable for fabricating biomedical devices.
Co-reporter:Ying-jie Tan;Yu-rong Liang 梁玉蓉;Guo-sheng Hu
Chinese Journal of Polymer Science 2011 Volume 29( Issue 2) pp:225-231
Publication Date(Web):2011 March
DOI:10.1007/s10118-011-1029-7
A new approach was developed to prepare high-performance isobutylene-isoprene rubber/swollen organoclay nanocomposites by shear mixing. Compared with traditional melt compounding method, better dispersion of nanoclay layers in rubber matrix was verified through transmission electron microscopy (TEM) and X-ray diffraction (XRD). The nanocomposites also exhibit significantly improved mechanical properties and gas barrier property. As a mechanism, the molecules of organic swelling agent play a vital role in accelerating the diffusion and intercalation of the matrix molecules.
Co-reporter:Zhenhua Wang, Jun Liu, Sizhu Wu, Wenchuan Wang and Liqun Zhang
Physical Chemistry Chemical Physics 2010 vol. 12(Issue 12) pp:3014-3030
Publication Date(Web):09 Feb 2010
DOI:10.1039/B919789C
Nano-strengthening by employing nanoparticles is necessary for high-efficiency strengthening of elastomers, which has already been validated by numerous researches and industrial applications, but the underlying mechanism is still an open challenge. In this work, we mainly focus our attention on studying the variation of the tensile strength of nanofilled elastomers by gradually increasing the filler content, within a low loading range. Interestingly, the percolation phenomenon is observed in the relationship between the tensile strength and the filler loading, which shares some similarities with the percolation phenomenon occurring in rubber toughened plastics. That is, as the loading of nanofillers (carbon black, zinc oxide) increases, the tensile strength of rubber nanocomposites (SBR, EPDM) increases slowly at first, then increases abruptly and finally levels off. Meanwhile, the bigger the particle size, the higher the filler content at the percolation point, and the lower the corresponding tensile strength of rubber nanocomposites. The concept of a critical particle–particle distance (CPD) is proposed to explain the observed percolation phenomenon. It is suggested that rubber strengthening through nanoparticles is attributed to the formation of stretched straight polymer chains between neighbor particles, induced by the slippage of adsorbed polymer chains on the filler surface during tension. Meanwhile, the factors to govern this CPD and the critical minimum particle size (CMPS) figured out in this work are both discussed and analyzed in detail. Within the framework of this percolation phenomenon, this paper also clearly answers two important and intriguing issues: (1) why is it necessary and essential to strengthen elastomers through nanofillers; (2) why does it need enough loading of nanofillers to effectively strengthen elastomers. Moreover, on the basis of the percolation phenomenon, we give out some guidance for reinforcement design of rubbery materials: the interfacial interactions between rubber and fillers cannot be complete chemical bonding, and partial physical absorption of macromolecular chains on the filler surface is necessary, otherwise the formation of stretched straight chains would be seriously hindered. There should exist such an optimum crosslinking density for a certain filler reinforced rubber system, and as well an optimum filler loading for rubber strengthening. Additionally, the different percolation behaviors of Young’s modulus, the tensile strength and the electrical conductivity are compared and analyzed in our work. Lastly, molecular simulation indicates that it is not possible to strengthen glassy or hard polymer matrices by incorporating spherical nanoparticles. In general, by providing substantial experimental data and detailed analyses, this work is believed to promote the fundamental understanding of rubber reinforcement, as well provide better guidance for the design of high-performance and multi-functional rubber nanocomposites.
Co-reporter:Rui Shi;Aichen Zhu;Dafu Chen;Xiujuan Jiang;Xiaochuan Xu;Liqun Zhang;Wei Tian
Journal of Applied Polymer Science 2010 Volume 115( Issue 1) pp:346-357
Publication Date(Web):
DOI:10.1002/app.31136
Abstract
A series of starch/PVA (SP) films with the thickness of 0.05–0.1 mm were cast by solvent method. The swelling and degradation behaviors in simulated blood fluid (SBF) and simulated saliva fluid (SSF) within 30 days were investigated. In vitro biocompatibility was also evaluated. Research purpose of this work was to supply basic data for SP films' potential application in guide tissue regeneration (GTR) technology. It took 10–20 min for different samples to reach to their maximum water absorption and 30 min to lever off. The weight loss of all samples decreased rapidly in the first day in both of SBF or SSF, and then it changed slightly in SSF but decreased step by step in SBF. The mechanical properties of the wet SP films were satisfied with the requirement of GTR membrane. No matter in SBF or SSF, although the mechanical properties decreased rapidly in the first day, they changed slightly after that. Cytotoxicity and L929 fibroblasts attachment test proved that the SP film possesses excellent cell affinity. Hemolysis ratios of all samples were less than 5%. All results demonstrated that SP film is a promising candidate in GTR treatment. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Co-reporter:Daling Xiao;Xiuying Zhao;Yiping Feng;Ping Xiang;Liqun Zhang;Weimin Wang
Journal of Applied Polymer Science 2010 Volume 116( Issue 4) pp:2143-2150
Publication Date(Web):
DOI:10.1002/app.31828
Abstract
The organic hybrids of thermoplastic polyurethane (TPU)/hindered phenol (AO-80) were prepared through melt blending, which was followed by hot and cold pressing procedure. The microstructure and dynamic mechanical properties of the hybrids were systematically investigated through SEM, DSC, XRD, FTIR, DMA and a tensile tester. The experimental results indicated that AO-80 was completely dissolved in the matrix. The glass transition of the soft segments of TPU was found to shift to higher temperature with the amount of AO-80 increasing, whereas the glass transition of the hard segments exhibited nearly no evident change, indicating that AO-80 was selectively located in the soft region of TPU and the formation of the strong intermolecular interactions (hydrogen bonding) between AO-80 and the soft region of TPU. With the increase of AO-80 in the hybrids, the tanδ peak gradually shifted to higher temperatures and the maximal tanδ value increased from 0.4 to 1.6. Meanwhile, the glass transition temperature ranges broadened and the TA value increased greatly with the more content of AO-80. Because of the decrease of the hard segments amount in the hybrids, the tensile stress of these hybrids decreased, but still maintained at a high level. The hybrids were expected to have potential applications as high performance damping materials combined with good mechanical properties. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Co-reporter:Xiaoping Zhang, Shipeng Wen, Shui Hu, Qi Chen, Hao Fong, Liqun Zhang and Li Liu
The Journal of Physical Chemistry C 2010 Volume 114(Issue 9) pp:3898-3903
Publication Date(Web):February 12, 2010
DOI:10.1021/jp9119843
Herein, we report that an innovative type of 1D nanomaterials, electrospun composite nanofibers (diameters ∼175 ± 25 nm) containing a complex of Eu(TTA)3phen in a matrix of polyvinylpyrrolidone (PVP), was prepared and characterized, and their luminescent properties were evaluated. The study revealed that, when the content of Eu(TTA)3phen was low (i.e., less than 23 wt %), the Eu(TTA)3phen was predominantly distributed in the composite nanofibers as molecular clusters and/or nanoscaled particles with sizes smaller than 10 nm; this substantially enhanced intermolecular interactions between individual Eu(TTA)3phen molecules and the neighboring chain segments of PVP. The Judd−Ofelt theory was used to study the effect of the dispersion of Eu(TTA)3phen on the local chemical environment of Eu3+ ions. The composite nanofibers demonstrated a significant improvement of luminescent efficiency compared with neat Eu(TTA)3phen.
Co-reporter:Quanyong Liu, Junyue Wu, Tianwei Tan, Liqun Zhang, Dafu Chen, Wei Tian
Polymer Degradation and Stability 2009 Volume 94(Issue 9) pp:1427-1435
Publication Date(Web):September 2009
DOI:10.1016/j.polymdegradstab.2009.05.023
Multi-walled carbon nanotube (MWCNT)/poly(glycerol–sebacate–citrate) (PGSC) elastomer composite were prepared and their morphologies, compositions, glass transition temperatures, mechanical properties, water absorption, biodegradation and cytotoxicity were investigated. Results showed that the chemical structures of PGSC elastomers were hardly influenced by the MWCNT loadings, and physical adsorption was thought as the main interaction between the MWCNTs and PGSC matrixes. When the MWCNT loading was 3 wt%, MWCNTs displayed a homogenous dispersion in the matrixes, and the composite's strength and modulus respectively reached 4.4 MPa and 9.2 MPa, increasing by 62.96% and 33.33% than that of pure PGSC matrixes. The degradation rates of the composites tended to decrease with the increase of MWCNT loadings in simulated body fluid (SBF) solution. The composites presented no cytotoxicity especially when the MWCNT loadings were above 1 wt%. We expect the composites can be used as degradable bio-coatings and tissue engineering scaffolds in future.
Co-reporter:Lijuan Lei, Li Li, Liqun Zhang, Dafu Chen, Wei Tian
Polymer Degradation and Stability 2009 Volume 94(Issue 9) pp:1494-1502
Publication Date(Web):September 2009
DOI:10.1016/j.polymdegradstab.2009.04.034
Novel nano-hydroxyapatite (n-HAp)/poly((1,2-propanediol-sebacate)-citrate) (PPSC) composites, with varying the amount of n-HAp (5–20 wt%), for potential use in the soft tissue engineering were developed in the present work. The structure of composites was characterized by FT-IR and 13C NMR, the micromorphology of n-HAp and the dispersion property of n-HAp in n-HAp/PPSC composites were characterized by SEM and TEM. The experimental results showed that no obvious chemical bonds generated between n-HAp and PPSC matrix. Homogeneous distribution of nanoparticles in the polymer matrix was validated. DSC and DMA indicated that the Tg of the composites decreased with increasing the n-HAp content, as the chemical cross-linking density of the composites decreased. The mechanical properties of the composites were prominently improved, when the amount of n-HAp increased up to 20 wt%, the modulus of the composites increased 11.4 times, and the tensile strength of the composites increased 8.2 times. The hydrophilicity, water absorption, and degradation rate of composites can be tuned through varying the concentration of n-HAp. In vitro cytotoxicity was evaluated by the MTT assay with the L929 cell. The cell relative growth rates of the composites with the amount of n-HAp more than 10 wt% exceeded 75% after 7 days of incubation.
Co-reporter:Xiu-Ying Zhao;Yong-Lai Lu;Da-Ling Xiao;Si-Zhu Wu
Macromolecular Materials and Engineering 2009 Volume 294( Issue 5) pp:345-351
Publication Date(Web):
DOI:10.1002/mame.200800375
Co-reporter:Yu-Rong Liang;Wei-Liang Cao;Xiao-Bin Zhang;Ying-Jie Tan;Shao-Jian He
Journal of Applied Polymer Science 2009 Volume 112( Issue 5) pp:3087-3094
Publication Date(Web):
DOI:10.1002/app.29575
Abstract
Nanocomposites were prepared with different grades of nitrile–butadiene rubber (NBR) [with nitrile (CN) contents of 26, 35, and 42%] with organoclay (OC) by a melt-compounding process. The rubber/clay nanocomposites were examined by transmission electron microscopy (TEM) and X-ray diffraction (XRD). An increase in the polarity of NBR affected the XRD results significantly. The dispersion level of the nanofiller in the nanocomposites was determined by a function of the polarity of the rubber, the structure of the clay, and their mutual interaction. The intercalated structure and unintercalated structure coexisted in the lower polar of NBR. In addition, a relatively uniformly dispersed state corresponded to a more intercalated structure, which existed in the higher polar of NBR matrix. Furthermore, high-pressure vulcanization changed the extent of intercalation. The mechanical properties and gas barrier properties were studied for all of the compositions. As a result, an improvement in the mechanical properties was observed along with the higher polarity of NBR. This improvement was attributed to a strong interaction of hydrogen bonding between the CN of NBR and the OH of the clay. Changes in the gas barrier properties, together with changes in the polarity of the rubbers, were explained with the help of the XRD and TEM results. The higher the CN content of the rubber was, the more easily the OC approached to the nanoscale, and the higher the gas barrier properties were. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Co-reporter:Jun Liu, Dapeng Cao, Liqun Zhang and Wenchuan Wang
Macromolecules 2009 Volume 42(Issue 7) pp:2831-2842
Publication Date(Web):March 9, 2009
DOI:10.1021/ma802744e
We systematically investigated the structural and dynamic properties of nanofilled elastomer on the basis of the idealized model of elastomer and nanoparticle. The simulated results indicate that the introduced nanoparticles induce more efficient chain packing. Meanwhile, a mobility gradient of polymer chains is found to exist approaching the nanoparticles. For the dynamic properties, we find for the first time that both the time−concentration and time−temperature superposition principles (TCSP and TTSP) are applicable at the chain length scale, while both break down at the segmental length scale for the filled system. However, the TTSP still holds at the segmental length scale for the pure system. Furthermore, the time−temperature−concentration superposition principle (TTCSP) applies well for the terminal relaxation of polymer nanocomposites. This scaling behavior has the underlying implication that the rheological properties (i.e., steady-state shear viscosity) of polymer nanocomposites possess thermorheological simplicity. In addition, interestingly, the characteristic relaxation time as a function of filler concentration exhibits an Arrhenius temperature dependence, if the concentration variation is regarded as an inverse of temperature variation. We suggest the introduced nanoparticles exert the similar effect to the thermodynamic variables (e.g., pressure and temperature) on the polymer dynamics. Lastly the stress relaxation of the model system is also examined. The decay of the bond orientation of polymer chains during the relaxation process is studied by changing the draw ratio, the filler loadings and the affinity between the nanoparticle and polymer. In order to equivalently investigate the stress relxation, we propose a new approach named conformational relaxation. It is observed that the conformational relaxation can be approximately fitted well by an exponential function for the pure and filled systems, similar to the stress relaxation. The TTSP is also applicable for the conformational relaxation of the pure system, while breaks down for that of the filled system. The relaxation time extracted by fitting the conformational relaxation curves with an exponential function at different temperatures, exhibits an Arrhenius relationship with the temperature for the pure and filled systems. Moreover, contrary to the isotropic dynamics during the creep process of the polymer from the simulated results of de Pablo, our simulated result shows an anistropic polymer dynamics with an accelerated relxation in the predeformed direction during the stress relaxation process.
Co-reporter:Qing-Xiu Jia, You-Ping Wu, Yi-Qing Wang, Ming Lu, Li-Qun Zhang
Composites Science and Technology 2008 Volume 68(3–4) pp:1050-1056
Publication Date(Web):March 2008
DOI:10.1016/j.compscitech.2007.07.006
Taking advantages of latex compounding method, clay was nano-dispersed into rubber matrix and 3-aminopropyltriethoxysilane (named KH550) was simultaneously intercalated into clay galleries during co-coagulating procedure. Then bis(triethoxysilylpropyl)tetrasulfide (named Si69) was incorporated into above KH550-modified nanocompounds by mechanical blending. The structure and properties of the nanocomposites were investigated by X-ray diffraction (XRD), Fourier transform infrared spectrum (FTIR), transmission electron microscopy (TEM), scanning electron microscope (SEM), dynamic mechanical thermal analyzer (DMTA) and mechanical testing. The results showed that a chemical bridge between organically modified clay and rubber matrix through Si69 was built during vulcanization, and the interfacial strength of the cured nanocomposites was remarkably improved. Thus a high performance styrene–butadiene rubber/clay nanocomposite was gained by such a two-step method, which illustrated eight times higher modulus at 300% strain and seven times higher tensile strength compared with cured pure rubber.
Co-reporter:Rui Shi, Jingliang Bi, Zizheng Zhang, Aichen Zhu, Dafu Chen, Xinhua Zhou, Liqun Zhang, Wei Tian
Carbohydrate Polymers 2008 Volume 74(Issue 4) pp:763-770
Publication Date(Web):21 November 2008
DOI:10.1016/j.carbpol.2008.04.045
A series of starch/polyvinyl alcohol (PVA) films, denoted SP films, with varying concentrations (5–30 wt%) of citric acid (CA) were solvent cast at 140 °C. The effects of CA on the chemical structure, thermal properties, swelling degree, mechanical properties, crystallinity, and cytotoxicity were investigated. Fourier-transform infrared (FT-IR) spectroscopy showed that an esterification took place between CA and starch (or PVA) during molding at 140 °C. This esterification and the multi-carboxyl structure of CA resulted in a chemical cross-linking of the blended system. Furthermore, the esterification occurred more easily between starch and CA as opposed to between the PVA and CA. The residual-free CA acted as a plasticizer for the starch and PVA. As compared to the hydroxyl groups on glycerol, the carboxyl groups on CA were capable of forming stronger hydrogen bonds between CA and other components, and this cross-linking and strong hydrogen bonding enhanced the thermal stability of the SP films. Consequently, the water absorbance decreased from 33% to 20% as the CA percentage increased from 5 to 30 wt%. When 5 wt% CA was added, the tensile strength of the sample increased from 39 to 48 MPa, but when even more CA was added (from 5 to 30 wt%), the tensile strength decreased from 48 to 42 MPa and the elongation at break increased from 102% to 208%. This was caused by the plasticizing effect of the residual-free CA in the blend. The cell relative growth rates of samples with varying CA concentrations exceeded 80% after 7 days of incubation, and this demonstrated that there was no significant toxicity on the cells’ growth when the CA content was less than 20 wt%.
Co-reporter:Yurong Liang, Weiliang Cao, Zhao Li, Yiqing Wang, Youping Wu, Liqun Zhang
Polymer Testing 2008 Volume 27(Issue 3) pp:270-276
Publication Date(Web):May 2008
DOI:10.1016/j.polymertesting.2007.11.003
A new strategy for preparation of isobutylene–isoprene rubber (IIR)/clay nanocomposites is reported based on two steps, i.e., preparation of swollen orgnomontmorillonite, followed by shear mixing on a two-roll mill with IIR. The dispersion of clay was investigated by transmission electron microscopy (TEM) and X-ray diffraction (XRD). TEM images demonstrate that both exfoliated and intercalated nanoclay layers co-exist in these nanocomposites. XRD patterns reveal that the basal spacing of clay increases from 4.2 nm for swollen organic modified silicates to 6.2 nm for those dispersed in nanocompounds, and the dispersion structure is extremely disordered and close to an exfoliated structure. The experimental results show that the mechanical and gas barrier properties of nanocomposites increased with increasing amount of clay. The properties of nanocomposites prepared by the new method, such as shore A hardness, tensile strength, air-tightness and so on, were superior to those of nanocomposites by the solution intercalation and the traditional melt intercalation methods with non-swollen organic clay. The IIR/clay nanocomposites which were prepared by the novel method could be used in rubber products which require a high barrier to gas, such as tire inner-tube and inner-liner.
Co-reporter:Youping Wu;Honghai Huang;Wei Zhao;Huifeng Zhang;Yiqing Wang ;Liqun Zhang
Journal of Applied Polymer Science 2008 Volume 107( Issue 5) pp:3318-3324
Publication Date(Web):
DOI:10.1002/app.24892
Abstract
The effect of dispersion of clay in rubber on the mechanical properties and flame retardance of rubber/montmorillonite (MMT) nanocomposites and rubber/MMT microcomposites were investigated in the present article, and the results were compared with the performance of silica reinforced rubber composites. Cone calorimeter test and limiting oxygen index test were employed to evaluate the flame retardance. From the results, it could be seen that the rubber/MMT nanocomposites always possessed the best flame retardance, such as lower peak heat release rate and higher fire performance index value. In addition, the rubber/MMT nanocomposites also showed better mechanical properties than the pure rubber and the other composites, especially in tear strength. With the rubber/silica composites, as expected, the silica could appropriately endow the rubber with flame retardance. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Co-reporter:You-Ping Wu;Qing-Song Zhao;Su-He Zhao
Journal of Applied Polymer Science 2008 Volume 108( Issue 1) pp:112-118
Publication Date(Web):
DOI:10.1002/app.26843
Abstract
The influence of in situ modification of silica with bis-(3-(triethoxysilyl)-propyl)-tetrasulfide (TESPT) on filler network in silica filled solution SBR compound was investigated. In situ modification greatly increased the bound rubber content. TEM observation of silica gel showed that bridging and interlocking of absorbed chains on the surface of silica particles formed the filler network. Rubber processing analyzer (RPA) was used to characterize the filler network and interaction between silica and rubber by strain and temperature sweeps. In situ modification improved the dispersion of silica, and in the meantime, the chemical bonds were formed between silica and rubber, which conferred the stability of silica dispersion during the processing. Compared to the compound without in situ modification, the compound with in situ modification of silica exhibited higher tan δ at low strains and lower tan δ at high strains, which can be explained in terms of filler network in the compounds. After in situ modification, DMTA results showed silica-filled SSBR vulcanizate exhibited higher tan δ in the temperature range of −30 to 10°C, and RPA results showed that it had lower tan δ at 60°C when the strain was more than 3%. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Co-reporter:Ping Xiang;Xiu-Ying Zhao;Da-Ling Xiao;Yong-Lai Lu
Journal of Applied Polymer Science 2008 Volume 109( Issue 1) pp:106-114
Publication Date(Web):
DOI:10.1002/app.27337
Abstract
In this article, a new nitrile–butadiene rubber (NBR) crosslinked composites containing poly(viny chloride) (PVC) and hindered phenol (AO-80 and AO-60) was successfully prepared by melt-blending procedure. Microstruture and dynamic mechanical properties of the composites were investigated using SEM, DSC, XRD, and DMTA. Most of hindered phenol was dissolved in the NBR/PVC matrix and formed a much fine dispersion. The results of DSC and DMTA showed that strong intermolecular interaction was formed between the hindered phenol and NBR/PVC matrix. The NBR/PVC/AO-80 crosslinked composites showed only one transition with higher glass transition temperature and higher tan δ value than the neat matrix, whereas for the NBR/PVC/AO-60 crosslinked composites, a new transition appeared above the glass transition temperature of matrix, which was associated with the intermolecular interaction between AO-60 and PVC component of the matrix. Both AO-80 and AO-60 in the crosslinked composites existed in amorphous form. Furthermore, the chemical crosslinking of composites resulted in better properties of the materials, e.g., considerable tensile strength and applied elastic reversion. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Co-reporter:Hongyuan Cheng;Ming Tian ;Liqun Zhang
Journal of Applied Polymer Science 2008 Volume 109( Issue 5) pp:2795-2801
Publication Date(Web):
DOI:10.1002/app.27564
Abstract
The aim of this study was to improve the toughness of recycled poly(ethylene terephthalate) (PET)/glass fiber (GF) blends through the addition of ethylene–butyl acrylate–glycidyl methacrylate copolymer (EBAGMA) and maleic anhydride grafted polyethylene–octene (POE-g-MAH) individually. The morphology and mechanical properties of the ternary blend were also examined in this study. EBAGMA was more effective in toughening recycled PET/GF blends than POE-g-MAH; this resulted from its better compatibility with PET and stronger fiber/matrix bonding, as indicated by scanning electron microscopy images. The PET/GF/EBAGMA ternary blend had improved impact strength and well-balanced mechanical properties at a loading of 8 wt % EBAGMA. The addition of POE-g-MAH weakened the fiber/matrix bonding due to more POE-g-MAH coated on the GF, which led to weakened impact strength, tensile strength, and flexural modulus. According to dynamic rheometer testing, the use of both EBAGMA and POE-g-MAH remarkably increased the melt storage modulus and dynamic viscosity. Differential scanning calorimetry analysis showed that the addition of EBAGMA lowered the crystallization rate of the PET/GF blend, whereas POE-g-MAH increased it. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Co-reporter:Ming Tian;Lijun Cheng;Liqun Zhang
Journal of Applied Polymer Science 2008 Volume 110( Issue 1) pp:262-269
Publication Date(Web):
DOI:10.1002/app.28675
Abstract
Four representative rubber matrices with varying molecular polarity, such as SBR, NBR, EPDM, and CNBR, were reinforced by mechanical blending with γ-(methacryloxy)proxyltrimethoxy silane (KH570) silanized natural fibrillar silicate (FS)/unmodified FS when dicumyl peroxide was used as a curing agent. The effects of the loading amount of silane coupling agent KH570 and the type of rubber matrix on the dispersion of FS as well as the FS-rubber interfacial bonding were investigated. The mechanical properties of various rubber composites filled with unmodified FS and silanized FS individually were compared. As indicated by SEM and TEM, unmodified FS showed better dispersion in polar CNBR than in nonpolar SBR, whereas the improvement of the dispersion is more for SBR after the silanization of FS, constructing a stronger filler network. Compared with unmodified FS/rubber composites, silanized FS/rubber composites exhibited a higher interphase crosslinking network as well as a lower loss factor, indicating the improvement of the FS-rubber interfacial bonding. The more the loading amount of KH570 was, the more the FS-SBR bonding was improved. Similarly, the improvement of the FS-rubber bonding was more evident in nonpolar SBR and EPDM after FS was silanized, causing the more increase in mechanical properties, relative to polar NBR and CNBR. In strong molecular polar rubber such as CNBR and NBR, the strong interfacial bonding was achieved even if FS was not silanized with KH570, so that the composites filled with unmodified FS also possessed good mechanical properties. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Co-reporter:Yong-Lai Lu;Zhao Li;Li-Xin Mao;Yao Li;You-Ping Wu;Yu-Rong Liang
Journal of Applied Polymer Science 2008 Volume 110( Issue 2) pp:1034-1042
Publication Date(Web):
DOI:10.1002/app.28690
Abstract
In this work, the influence of curing temperature on microstructures of isobutylene–isoprene rubber/clay nanocomposites (IIRCNs) prepared by melt compounding was characterized using wide-angle X-ray diffraction and TEM. The gas barrier and tensile properties of IIRCN cured under different temperature were examined. The results reveal that high pressure, curing reactions, and reactions of amine intercalants with curing agents together play important roles on determining the final microstructures of cured IIRCNs. Changing curing temperature would dramatically alter intercalated structure, dispersion homogeneity, filler–rubber interaction strength, and crosslinking density of obtained IIRCN, resulting in great difference in final properties. Finally, some suggestions for the preparation of successful RCNs were proposed. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Co-reporter:Jian Yang, Ming Tian, Qing-Xiu Jia, Jun-Hong Shi, Li-Qun Zhang, Szu-Hui Lim, Zhong-Zhen Yu, Yiu-Wing Mai
Acta Materialia 2007 Volume 55(Issue 18) pp:6372-6382
Publication Date(Web):October 2007
DOI:10.1016/j.actamat.2007.07.043
Abstract
The facile latex approach has been adopted to finely incorporate graphite nanosheets into elastomeric polymer matrix to obtain high-performance elastomeric nanocomposites with improved mechanical properties and functional properties. Scanning electron microscopy, transmission electron microscopy and X-ray diffraction experiments show that the nanostructures of the final nanocomposites exhibit a high degree of exfoliation and intercalation of graphite in the nitrile-butadiene rubber (NBR) matrix. Mechanical and dynamic-mechanical tests demonstrate that the NBR/graphite nanocomposites possess greatly increased elastic modulus and tensile strength, and desirably strong interfaces. The unexpected self-crosslinking of elastomer/graphite nanocomposites was discovered and then verified by oscillating disc rheometry and equilibrium swelling experiments. After critically examining various polymer types by X-ray photoelectron spectroscopy, electron spin resonance and Fourier transform infrared spectroscopy, a radical initiation mechanism was proposed to explain the self-crosslinking reaction. These NBR/graphite nanocomposites possess significantly improved wear resistance and gas barrier properties, and superior electrical/thermal conductivity. Such versatile functional properties make NBR nanocomposites a promising new class of advanced materials.
Co-reporter:Yong-Lai Lu, Zhao Li, Zhong-Zhen Yu, Ming Tian, Li-Qun Zhang, Yiu-Wing Mai
Composites Science and Technology 2007 Volume 67(Issue 14) pp:2903-2913
Publication Date(Web):November 2007
DOI:10.1016/j.compscitech.2007.05.018
A series of highly filled rubber/clay nanocomposites (RCNs) based on ethylene-propylene diene rubber (EPDM), styrene butadiene rubber (SBR) and epichlorohydrin rubber (ECO) were prepared by melt blending with traditional rubber processing technique. Wide-angle X-ray diffraction (WAXD) characterization shows that the highly filled RCNs (up to ∼60 wt%) have intercalated silicate structures. TEM observations reveal that the dispersion homogeneity of clay layers improves with increasing content of organically modified clay (OMC). It was shown by dynamic mechanical thermal analysis (DMTA) for the first time that the melt-like thermal transition of alkyl chains of the surfactant of OMC still occurs in the intercalated OMC. Addition of large amount OMC to rubber greatly improves the modulus of material. Highly filled RCNs also possess outstanding gas barrier properties when compared to neat rubbers.
Co-reporter:Li Liu, Wan Zhang, Xiaolin Li, X.-F. Wu, C. Yang, Y.-D. Liu, L. He, Yong-Lai Lu, Ri-Wei Xu, Xiu-Juan Zhang, Li-Qun Zhang, Ri-Guang Jin
Composites Science and Technology 2007 Volume 67(Issue 10) pp:2199-2207
Publication Date(Web):August 2007
DOI:10.1016/j.compscitech.2005.07.001
In the present study, we examined the luminescent properties of uncured and cured samarium tris-(2-thenoyltrifluoroacetone)-1,10-phenanthroline/nitrile rubber composites (Sm(TTA)3phen/NBR, i.e. Sm-complex/NBR). The formula of Sm-complex was determined by infrared spectroscopy (IR) and elementary analysis. The composites were investigated and characterized by photoluminescent (PL) spectroscopy, scanning electron microscopy (SEM) and X-rays diffraction (XRD). The characteristic emission fluorescent intensities of the Sm3+ in both uncured and cured composites increase with the increase of Sm-complex content. For the nitrile rubber composites with the same content of Sm(TTA)3phen, the uncured composites are found to have lower luminescent intensity than that of cured composites. To explain this result, we propose that the cross-linking network structure can help to stabilize the coordination environment of the Sm3+ ion and improve the energy transfer efficiency from the outside energy to the central Sm3+ ion. In our study, the rare earth organic complexes were dispersed homogeneously into the NBR matrix. The fluorescent intensity of the composites was high and no fluorescent quenching had been observed until the complexes concentration was up to 14.3%.
Co-reporter:Lijuan Lei, Tao Ding, Rui Shi, Quanyong Liu, Liqun Zhang, Dafu Chen, Wei Tian
Polymer Degradation and Stability 2007 Volume 92(Issue 3) pp:389-396
Publication Date(Web):March 2007
DOI:10.1016/j.polymdegradstab.2006.12.004
Degradable bioelastomers represent a useful class of biomaterials. In this paper, a novel biodegradable network of elastomeric polyesters, poly((1,2-propanediol-sebacate)-citrate) (PPSC), was synthesized by condensation of 1,2-propanediol, sebacic acid and citric acid without any catalyst. An oligomeric diol of 1,2-propanediol-sebacate was first synthesized by carrying out a controlled condensation reaction between 1,2-propanediol and sebacic acid, and then a pre-polymer was synthesized by condensation of the diol and citric acid, whereat the pre-polymer was post-polymerized and simultaneously crosslinked in mold at 120 °C. A series of PPSC polymers were prepared at different post-polymerization times and different monomers' ratio. Tg confirms that PPSC is totally amorphous at 37 °C. The mechanical properties of PPSC testified that the new polymers are typical elastomers with low hardness and large elongation. The different post-polymerization times and monomers' ratio had strong influence on the degradation rates and mechanical performances. The material was expected to be useful for drug controlled delivery, tissue engineering scaffold and other biomedical applications.
Co-reporter:Quanyong Liu;Ming Tian;Tao Ding;Rui Shi;Yuxing Feng;Liqun Zhang;Dafu Chen;Wei Tian
Journal of Applied Polymer Science 2007 Volume 103(Issue 3) pp:1412-1419
Publication Date(Web):8 NOV 2006
DOI:10.1002/app.24394
A thermoplastic poly(glycerol sebacate) elastomer (TMPGS), prepared by a two-step method for the first time, is characterized in the present work. First, non-crosslinked poly(glycerol sebacate) (PGS) prepolymers at the 1 : 1 molar ratio of glycerol to sebacic acid were synthesized through a condensation reaction. Second, TMPGSs were achieved through prepolymers that continued to react after the addition of more sebacic acid at a total molar ratio of 2 : 2.5 (glycerol/sebacic acid). The swelling experiments demonstrated that its crosslinking density was low and that it was composed of sol and gel. Compared with our previous results, the content of sol decreased but still reached >60%. Differential scanning calorimetry (DSC) studies demonstrated that TMPGS was crystallizable and had a glass transition temperature below −20°C, but at close to 37°C, its state altered and became almost amorphous. It was explained that both the semi-interpenetrated polymer networks composed of sol and gel and the crystal regions imparted thermoplasticity to the elastomer. Finally, the in vitro degradation tests illuminated the degradation characteristic of TMPGS in 37°C phosphate buffered saline solution (pH = 7.4). © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1412–1419, 2007
Co-reporter:Ming Tian;Quanyong Liu;Liqun Zhang;Wei Tian;Dafu Chen;Rui Shi;Quanyong Liu;Ming Tian;Rui Shi;Liqun Zhang;Dafu Chen;Wei Tian
Journal of Applied Polymer Science 2007 Volume 104(Issue 2) pp:1131-1137
Publication Date(Web):26 JAN 2007
DOI:10.1002/app.25606
Thermoplastic poly(glycerol sebacate) (TMPGS) elastomers originating from three prepolymers with different molecular weights were prepared first, and then the structure and properties were studied. Specifically, by swelling tests, gel permeation chromatography, X-ray diffraction, and differential scanning calorimetry, the crosslinking densities, sol contents and compositions, crystallization, and thermal performances of three TMPGSs were examined. Finally, the degradability in a 37°C phosphate-buffered saline solution (pH = 7.4) was also illuminated. The three TMPGSs had similar chemical structures, but the different molecular weights of the prepolymers influenced their final compositions and properties to a great extent. Furthermore, both hydrogen bonding and plasticization action in the elastomers played important roles in balancing the overall properties of the TMPGS elastomers. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1131–1137, 2007
Co-reporter:Quanyong Liu;Tao Ding;Yanming Han;Rui Shi;Wei Tian;Dafu Chen;Liqun Zhang
Journal of Applied Polymer Science 2007 Volume 103(Issue 1) pp:574-586
Publication Date(Web):23 OCT 2006
DOI:10.1002/app.25193
In this study, a soft and thermoplastic starch with an improved ageing-resistant property was prepared by melt blending method for a biodegradable biomaterial. The glycerol content varies from 30 to 60 wt %. The aging temperature and humidity of the glycerol-plasticized thermoplastic starch (GTPS) was 37°C and 50 ± 5 RH %, respectively. The retrogradation was characterized by X-ray diffraction (XRD), dynamic mechanical thermal analysis (DMTA), Fourier transform infrared (FTIR), and the stress-strain mechanical properties. The XRD results suggest that high content of glycerol promotes the formation of single helix structure of V-type, but inhibits double helix structure of B-type. Changing of the tan δ, storage modules (E′), and the glass transition temperatures as a function of glycerol content and ageing time was detected by DMTA. FTIR result shows that the shifting speed of the peak of hydroxyl group stretching fell as the glycerol content increased. The glycerol content has no obvious effect on the mechanical properties when it is high enough. Results from all characterizations demonstrate that the ageing speed is closely relative to the plasticizers content. The higher content of glycerol possesses an obviously inhibitory effect on the ageing. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 574–586, 2007
Co-reporter:Ya Wang;Yi-Qing Wang;Hui-Feng Zhang
Macromolecular Rapid Communications 2006 Volume 27(Issue 14) pp:1162-1167
Publication Date(Web):20 JUL 2006
DOI:10.1002/marc.200600106
Summary: Based on the fact that rubber can be chemically modified by sulfur, and sulfur can diffuse into rubber driven by a concentration gradient and chemical reaction, a new approach for the preparation of a polymer with a gradient from rubbery to glassy phase has been developed using the sulfur-vulcanization reaction of rubber. The gradient polymer obtained exhibits a wide transition range spanning over 100 °C with a peak half-width of 69 °C. The mechanism of forming the gradient structure is also discussed.
Co-reporter:Rui Shi, Tao Ding, Quanyong Liu, Yanming Han, Liqun Zhang, Dafu Chen, Wei Tian
Polymer Degradation and Stability 2006 Volume 91(Issue 12) pp:3289-3300
Publication Date(Web):December 2006
DOI:10.1016/j.polymdegradstab.2006.06.007
Degradation in vitro is of importance in implanted biological industry. This research investigated the swelling and degradation behaviours of glycerol plasticized thermoplastic starch (GTPS) in simulated body fluid (SBF) and simulated saliva fluid (SSF), respectively. The weight loss, swelling degree and linear extensibility as a function of time were measured. Changes in the morphology (SEM), chemical structure (FT-IR), crystal property (XRD) and thermogravimetic property (TG) during degradation were also investigated. Results show that the degradation in SSF was much quicker than that in SBF. About 1 h was needed for the swelling equilibrium in SBF, which was a little quicker than that in SSF. In alkaline solution the swelling speed and the swelling degree were larger than those in neutral and acidic solutions. The degradation in SBF was typical bulk degradation. In SSF the surface and bulk degradation took place synchronously, but the surface degradation played an important role in the first 2 h. Results from FT-IR and XRD suggest that the glycosidic linkages in starch chains were broken and the crystal structure in GTPS was destructed during degradation. Cytotoxicity test was used to investigate the effects of the short-term extracted dilutions and long-term degradation products on the cells, which illustrates that the degradation products not only had non-toxicity but also accelerated the cells' growth.
Co-reporter:Ming Tian, Yonglai Lu, Wenli Liang, Lijun Cheng and Liqun Zhang
Polymer Journal 2006 38(11) pp:1105-1113
Publication Date(Web):October 4, 2006
DOI:10.1295/polymj.PJ2005231
Palygorskite (AT) mineral was selected as a nano-fiber precursor due to its unique structure characteristics and surface chemical property, to construct a novel nano-fiber/rubber nanocomposites by using a simple and cost-efficient preparation method. Upon shear force during traditional mechanical mixing, the numerous nano-fibers contained in palygorskite micro-powder were released into rubber matrix resulted from weak stacking force between nano-fibers and high shear stress associated with high viscosity of rubber matrix. Meanwhile these nano-fibers were orientated along the shear direction the same as micro-short fiber. In situ modification using silane coupling agent can improve the dispersion of AT and strengthen the interfacial bonding between AT and rubber. The result from dynamic mechanical thermal analysis shows that the incorporation of palygorskite into rubber matrix markedly lowers the loss factor of rubber in glassy transition region and increases storage modulus of rubber. These nanocomposites exhibit stress-strain characteristics that are similar to that of micro-short fiber reinforced rubber, evident anisotropy in mechanical properties, good processing properties, as well as low cost and easily practiced by industry.
Co-reporter:Ming Tian, Yuan-Wang Tang, Yong-Lai Lu, Jinliang Qiao, Tie Li and Li-Qun Zhang
Polymer Journal 2006 38(1) pp:50-56
Publication Date(Web):
DOI:10.1295/polymj.38.50
Novel ultra-fine full-vulcanized powdered rubber/ethylene-propylene-diene terpolymer (UFPR/EPDM) blends were firstly prepared by compounding ultra-fine full-vulcanized SBR or NBR particles into EPDM matrix. The morphology and mechanical properties of these novel elastomer blends were investigated. Some unexpected and interesting phenomena were observed. A promising method to prepare elastomer blends with excellent performances was proposed.
Co-reporter:Honghai Huang;Wenli Liang;Li Liu;Liqun Zhang;Ming Tian;Honghai Huang;Ming Tian;Li Liu;Wenli Liang;Liqun Zhang
Journal of Applied Polymer Science 2006 Volume 100(Issue 6) pp:4461-4469
Publication Date(Web):8 MAR 2006
DOI:10.1002/app.22677
Four kinds of magnesium hydroxide (Mg(OH)2) with different particle sizes are chosen and mixed with ethylene vinyl acetate copolymer (EVA) to investigate the effect of particle size on the flame retardancy of composites, which is evaluated by limiting oxygen index (LOI) testing, horizontal fire testing, and cone calorimeter. When Mg(OH)2 filling level changes from 35 to 70 wt %, the composites filled with nano-Mg(OH)2 do not always possess the best flame retardancy, and among the composites filled with micro-Mg(OH)2, the composites filled with 800 mesh Mg(OH)2 show the best flame retardancy; however, the composites filled with 1250 mesh presents the worst one. So the effect of particle size on the flame retardancy of micro-Mg(OH)2-filled EVA is not linear as expected. All the differences are thought to result from both particle size effect and distributive dispersion level of Mg(OH)2. To prepare the composites with better mechanical properties and flame retardancy, authors suggested that Mg(OH)2 of smaller size should be chosen as flame retardant, and good dispersion of Mg(OH)2 particles also should be assured. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4461–4469, 2006
Co-reporter:Ming Tian;Lijun Cheng;Wenli Liang;Liqun Zhang
Macromolecular Materials and Engineering 2005 Volume 290(Issue 7) pp:681-687
Publication Date(Web):30 JUN 2005
DOI:10.1002/mame.200400400
Summary: Fibrillar silicate (FS)/rubber nanocomposites were successfully prepared by directly mixing modified FS with rubber matrix. It is found that FS could be separated into nano-fibrils with diameters less than 100 nm by the shear forces during mixing. The stress-strain characteristics of these composites are similar to those for short micro-fiber/rubber composites (SFRC). Nevertheless, these FS/rubber composites have some outstanding advantages over the conventional SFRC, even though the reinforcing effect of FS is restricted due to its small shape aspect ratio. More importantly, the differences in mechanical properties of the composites in the two different directions show that SBR/FS and NBR/FS composites both exhibit obvious anisotropy, which strongly depends on the preparation process, FS concentration, and rubber matrix. These factors were thoroughly investigated in this paper, and it can be concluded that the anisotropy of the composites was due to the orientation of nano-fibrils.
Co-reporter:He Qiao, Mingyuan Chao, David Hui, Jun Liu, Junchi Zheng, Weiwei Lei, Xinxin Zhou, Runguo Wang, Liqun Zhang
Composites Part B: Engineering (1 April 2017) Volume 114() pp:
Publication Date(Web):1 April 2017
DOI:10.1016/j.compositesb.2017.02.021
Epoxy group-functionalized styrene-butadiene rubbers (G-ESBRs) with different epoxy group contents were synthesized through emulsion polymerization using glycidyl methacrylate (GMA) as the epoxy group-included monomer, and the silica/G-ESBR nanocomposites without silane coupling agents were prepared. The covalent bonding interfaces, resulting from a ring-opening reaction between the hydroxyl groups on the silica surfaces and the epoxy groups of G-ESBR, were formed during the preparation of the silica/G-ESBR nanocomposites. By increasing the epoxy group content, the number of covalent bonds at the interface increases, contributing to an improvement of the interfacial interaction between the G-ESBR and silica and the dispersion of silica, which were verified and analyzed in detail by bound rubber measurement, transmission electron microscopy (TEM) and rubber process analyzer (RPA). The silica/G-ESBR nanocomposites with improved dispersion of silica and interfacial interaction showed decreased rolling resistance and increased wet skid resistance. The mechanical properties of the nanocomposites were greatly improved with increasing epoxy group contents. The highest tensile strength reached 29.4 MPa at a GMA content of 4.8 wt%, a 55.6% increase compared with that of the nanocomposite without epoxy group.
Co-reporter:Wenhui Wang, Guanyi Hou, Zijian Zheng, Lu Wang, Jun Liu, Youping Wu, Liqun Zhang and Alexey V. Lyulin
Physical Chemistry Chemical Physics 2017 - vol. 19(Issue 24) pp:NaN15820-15820
Publication Date(Web):2017/05/17
DOI:10.1039/C7CP01453H
Using short polymer chains and through molecular dynamics simulation, we designed a well-dispersed nanoparticle (NP) network, which was then incorporated with the polymer matrix. First, we examined the effects of the dual-end grafted chains flexibility and density on the spatial distribution of this particular polymer nanocomposites system. By changing the interaction strength between the matrix polymer chains and the dual-end grafted chains in the semi-interpenetrating network system (NP network), we analyzed the interpenetration state between the linear polymer matrix and the NP network via calculating the total interfacial interaction energy. Moreover, the uniaxial tensile stress–strain and orientation behavior influenced by the interaction strength between the matrix polymer and the grafted chains were investigated for both the semi-interpenetrating network system and the interpenetrating network system (NP network and matrix network). Furthermore, for the interpenetrating network system, we modulated the integrity of the NP network ranging from 0% to 100%, corresponding to the gradual transition of the dispersion morphology of the NPs from the aggregation state to the uniform dispersion state, to examine the effect of the NP network on the tensile mechanical behavior. In particular, by simulating the dynamic shear process in the semi-interpenetrating network system, the composites were found to exhibit a lower non-linear behavior (the famous Payne effect), a higher storage modulus, and a lower tangent loss at large strain amplitude with increasing NP network integrity. In general, our results could provide a new approach for the design of high-performance polymer nanocomposites by taking advantage of the semi-interpenetrating or interpenetrating network reinforcing structure.
Co-reporter:Weiwei Lei, Xinxin Zhou, Thomas P. Russell, Kuo-chih Hua, Xiaoping Yang, He Qiao, Wencai Wang, Fanzhu Li, Runguo Wang and Liqun Zhang
Journal of Materials Chemistry A 2016 - vol. 4(Issue 34) pp:NaN13062-13062
Publication Date(Web):2016/08/04
DOI:10.1039/C6TA05001H
Globally, we are faced with a massive growth in the number of urban vehicles. This growth comes at the cost of enormous fuel consumption, CO2 emissions and air pollution, commonly seen as a haze. With a strategy to fabricate low roll-resistance green tire elastomers from large-scale, bio-based chemicals, specifically itaconic acid, mono-alcohols and conjugated dienes, each of these problems can be reduced. By combining a molecular structural design with non-petroleum based silica and an in situ process to tune the viscoelastic properties of the elastomer composites, we have successfully manufactured silica/poly(di-n-butyl itaconate-co-butadiene) nanocomposite-based green tires that have very low roll-resistance, excellent wet skid resistance and good wear resistance, promote fuel efficiency and reduce our dependence on petrochemical resources. The results shown here open an important avenue for the synthetic rubber and automobile industry to ameliorate a major problem facing many cities worldwide, and also provide an effective route for resource sustainability.
Co-reporter:Rui Shi, Jiajia Xue, Hanbin Wang, Renxian Wang, Min Gong, Dafu Chen, Liqun Zhang and Wei Tian
Journal of Materials Chemistry A 2016 - vol. 4(Issue 2) pp:NaN348-348
Publication Date(Web):2015/12/10
DOI:10.1039/C5TB90174J
Correction for ‘Fabrication and evaluation of a homogeneous electrospun PCL–gelatin hybrid membrane as an anti-adhesion barrier for craniectomy’ by Rui Shi et al., J. Mater. Chem. B, 2015, 3, 4063–4073.
Co-reporter:Dan Yang, Ming Tian, Dongdong Li, Wencai Wang, Fengxing Ge and Liqun Zhang
Journal of Materials Chemistry A 2013 - vol. 1(Issue 39) pp:NaN12284-12284
Publication Date(Web):2013/08/08
DOI:10.1039/C3TA12090B
To obtain a dielectric elastomer with excellent dielectric properties and actuated strain, we used bio-inspired dopamine to functionalize the surface of barium titanate (BT) particles. X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) were used to confirm that a poly(dopamine) (PDA) layer of ca. 3.0 nm had been successfully deposited on the surface of the barium titanate particles. With the introduction of the PDA layer, the compatibility between the barium titanate filler and the elastomer matrix (hydrogenated nitrile-butadiene rubber) was significantly improved, which also resulted in the composites displaying better filler dispersion, higher dielectric constant, lower dielectric loss, and higher electric breakdown field compared with composites filled with pristine BT particles. Furthermore, the composites filled with PDA-coated BT (BT–PDA) exhibited higher electromechanical sensitivity (β) than the composites filled with pristine BT, leading to increased actuated strains. Nevertheless, the β of composites filled with pristine BT decreased with increasing content of filler, resulting in decreased actuated strains. Finally, a large actuated strain of 20% without any prestrain was achieved by the composite filled with BT–PDA, which is 54% larger than the largest actuated strain of the polymer without functionalized filler. Moreover, the dopamine functionalization method is simple, efficient, nontoxic, and easy to control, and can be used as a general strategy for improving the dielectric constant, breakdown strength, and actuated strain of dielectric elastomers.
Co-reporter:Jun Liu, Sizhu Wu, Liqun Zhang, Wenchuan Wang and Dapeng Cao
Physical Chemistry Chemical Physics 2011 - vol. 13(Issue 2) pp:NaN529-529
Publication Date(Web):2010/11/05
DOI:10.1039/C0CP00297F
By employing an idealized model of a polymer network and filler, we have investigated the stress-strain behavior by tuning the filler loading and polymer–filler interaction in a broad range. The simulated results indicate that there actually exists an optimal filler volume fraction (between 23% and 32%) for elastomer reinforcement with attractive polymer–filler interaction. To realize this reinforcement, the rubber–filler interaction should be slightly stronger than the rubber–rubber interaction, while excessive chemical couplings are harmful to mechanical properties. Meanwhile, our simulated results qualitatively reproduce the experimental data of Bokobza. By introducing enough chemical coupling between the rubber and the filler, an upturn in the modulus at large deformation is observed in the Mooney-Rivlin plot, attributed to the limited chain extensibility at large deformation. Particularly, the filler dispersion state in the polymer networks is also characterized in detail. It is the first demonstration via simulation that the reinforcement mechanism stems from the nanoparticle-induced chain alignment and orientation, as well as the limited extensibility of chain bridges formed between neighboring nanoparticles at large deformation. The former is influenced by the filler amount, filler size and filler–rubber interaction, and the latter becomes more obvious by strengthening the physical and chemical interactions between the rubber and the filler. Remarkably, the reason for no obvious reinforcing effect in filled glassy or semi-crystalline matrices is also demonstrated. It is expected that this preliminary study of nanoparticle-induced mechanical reinforcement will provide a solid basis for further insightful investigation of polymer reinforcement.
Co-reporter:Zhenhua Wang, Jun Liu, Sizhu Wu, Wenchuan Wang and Liqun Zhang
Physical Chemistry Chemical Physics 2010 - vol. 12(Issue 12) pp:NaN3030-3030
Publication Date(Web):2010/02/09
DOI:10.1039/B919789C
Nano-strengthening by employing nanoparticles is necessary for high-efficiency strengthening of elastomers, which has already been validated by numerous researches and industrial applications, but the underlying mechanism is still an open challenge. In this work, we mainly focus our attention on studying the variation of the tensile strength of nanofilled elastomers by gradually increasing the filler content, within a low loading range. Interestingly, the percolation phenomenon is observed in the relationship between the tensile strength and the filler loading, which shares some similarities with the percolation phenomenon occurring in rubber toughened plastics. That is, as the loading of nanofillers (carbon black, zinc oxide) increases, the tensile strength of rubber nanocomposites (SBR, EPDM) increases slowly at first, then increases abruptly and finally levels off. Meanwhile, the bigger the particle size, the higher the filler content at the percolation point, and the lower the corresponding tensile strength of rubber nanocomposites. The concept of a critical particle–particle distance (CPD) is proposed to explain the observed percolation phenomenon. It is suggested that rubber strengthening through nanoparticles is attributed to the formation of stretched straight polymer chains between neighbor particles, induced by the slippage of adsorbed polymer chains on the filler surface during tension. Meanwhile, the factors to govern this CPD and the critical minimum particle size (CMPS) figured out in this work are both discussed and analyzed in detail. Within the framework of this percolation phenomenon, this paper also clearly answers two important and intriguing issues: (1) why is it necessary and essential to strengthen elastomers through nanofillers; (2) why does it need enough loading of nanofillers to effectively strengthen elastomers. Moreover, on the basis of the percolation phenomenon, we give out some guidance for reinforcement design of rubbery materials: the interfacial interactions between rubber and fillers cannot be complete chemical bonding, and partial physical absorption of macromolecular chains on the filler surface is necessary, otherwise the formation of stretched straight chains would be seriously hindered. There should exist such an optimum crosslinking density for a certain filler reinforced rubber system, and as well an optimum filler loading for rubber strengthening. Additionally, the different percolation behaviors of Young’s modulus, the tensile strength and the electrical conductivity are compared and analyzed in our work. Lastly, molecular simulation indicates that it is not possible to strengthen glassy or hard polymer matrices by incorporating spherical nanoparticles. In general, by providing substantial experimental data and detailed analyses, this work is believed to promote the fundamental understanding of rubber reinforcement, as well provide better guidance for the design of high-performance and multi-functional rubber nanocomposites.
Co-reporter:Chunfang Zeng, Zhenghai Tang, Baochun Guo and Liqun Zhang
Physical Chemistry Chemical Physics 2012 - vol. 14(Issue 28) pp:NaN9845-9845
Publication Date(Web):2012/05/23
DOI:10.1039/C2CP40517B
For the purpose of preparing liquefied graphene oxide (GO), a process consisting of sulfonation with sodium sulfanilic acid and ionization with bulky amine-terminated Jeffamine® was designed and performed. The obtained hybrid fluid is actually a supramolecular ionic liquid (SIL) with sulfonated GO as the central anions and the terminal ammonium groups of Jeffamine® as the surrounding cations. The successful grafting of the GO sheets with Jeffamine® via an ionic structure was verified and the morphology of the SIL was characterized. The SIL based on GO (GO-SIL) exhibits excellent solubility and amphiphilicity. The rheological measurements confirm the essential viscoelasticity and the liquid-like behavior of GO-SIL. The present GO based SIL suggests promising applications in the fabrication of various GO or graphene based composite materials. In addition, the new functionalization method may guide the future work on acquiring derivatives with tunable properties by simply changing the bulky canopy.
Co-reporter:Yangyang Gao, Jun Liu, Jianxiang Shen, Dapeng Cao and Liqun Zhang
Physical Chemistry Chemical Physics 2014 - vol. 16(Issue 34) pp:NaN18492-18492
Publication Date(Web):2014/07/21
DOI:10.1039/C4CP02431A
Through coarse-grained molecular dynamics simulation, we aim to uncover the rupture mechanism of polymer–nanorod nanocomposites by characterizing the structural and dynamic changes during the tension process. We find that the strain at failure is corresponding to the coalescence of a single void into larger voids, namely the change of the free volume. And the minimum of the Van der Walls (VDWL) energy reflects the maximum mobility of polymer chains and the largest number of voids of polymer nanocomposites. After the failure, the stress gradually decreases with the strain, accompanied by the contract of the highly orientated polymer bundles. In particular, we observe that the nucleation of voids prefers to occur from where the ends of polymer chains are located. We systematically study the effects of the interfacial interaction, temperature, the length and volume fraction of nanorods, chain length, bulk cross-linking density and interfacial chemical bonds on the rupture behavior, such as the stress at failure, the tensile modulus and the rupture energy. The rupture resistance ability increases with the increase of the interfacial interaction, rod length, and bulk cross-linking density. With an increase in the interfacial interaction, it induces the rupture transition from mode A (no bundles) to B (bundles). The transition point of the stress at failure as a function of the temperature roughly corresponds to the glass transition temperature. At longer chain length, a non-zero stress plateau occurs. And excessive chemical bonds between polymers and nanorods are harmful to the rupture property. We find that an optimal volume fraction of nanorods exists for the stress–strain behavior, which can be rationalized by the formation of the strongest polymer–nanorod network, leading to the slowest mobility of nanorods.
Co-reporter:Yangyang Gao, Dapeng Cao, Jun Liu, Jianxiang Shen, Youping Wu and Liqun Zhang
Physical Chemistry Chemical Physics 2015 - vol. 17(Issue 35) pp:NaN22968-22968
Publication Date(Web):2015/07/28
DOI:10.1039/C5CP01953B
We adopted molecular dynamics simulation to study the conductive property of nanorod-filled polymer nanocomposites by focusing on the effects of the interfacial interaction, aspect ratio of the fillers, external shear field, filler–filler interaction and temperature. The variation of the percolation threshold is anti N-type with increasing interfacial interaction. It decreases with an increase in the aspect ratio. At an intermediate filler–filler interaction, a minimum percolation threshold appears. The percolation threshold decreases to a plateau with temperature. At low interfacial interaction, the effect of an external shear field on the homogeneous probability is negligible; however, the directional probability increases with shear rate. Moreover, the difference in conductivity probabilities is reduced for different interfacial interactions under shear. Under shear, the decrease or increase of conductivity probability depends on the initial dispersion state. However, the steady-state conductivity is independent of the initial state for different interfacial interactions. In particular, the evolution of the conductivity network structure under shear is investigated. In short, this study may provide rational tuning methods to obtain nanorod-filled polymer nanocomposites with high conductivity.
Co-reporter:Jianxiang Shen, Jun Liu, Haidong Li, Yangyang Gao, Xiaolin Li, Youping Wu and Liqun Zhang
Physical Chemistry Chemical Physics 2015 - vol. 17(Issue 11) pp:NaN7207-7207
Publication Date(Web):2015/02/10
DOI:10.1039/C4CP05520A
Through coarse-grained molecular dynamics simulations, we have studied the effects of grafting density (Σ) and grafted chain length (Lg) on the structural, mechanical and visco-elastic properties of end-grafted nanoparticles (NPs) filled polymer nanocomposites (PNCs). It is found that increasing the grafting density and grafted chain length both enhance the brush/matrix interface thickness and improve the dispersion of NPs, but there seems to exist an optimum grafting density, above which the end-grafted NPs tend to aggregate. The uniaxial stress–strain behavior of PNCs is also examined, showing that the tensile stress is more enhanced by increasing Lg compared to increasing Σ. The tensile modulus as a function of the strain is fitted following our previous work (Soft Matter, 2014, 10, 5099), exhibiting a gradually reduced non-linearity with the increase of Σ and Lg. Meanwhile, by imposing a sinusoidal external shear strain, for the first time we probe the effects of Σ and Lg on the visco-elastic properties such as the storage modulus G′, loss modulus G′′ and loss factor tanδ of end-grafted NPs filled PNCs. It is shown that the non-linear relation of G′ and G′′ as a function of shear strain amplitude decreases with the increase of Σ and Lg, which is consistent with experimental observations. We infer that the increased mechanical and reduced non-linear visco-elastic properties are correlated with the enhanced brush/matrix interface and therefore better dispersion of NPs and stronger physical cross-linking. This work may provide some rational means to tune the mechanical and visco-elastic properties of end-grafted NPs filled polymer nanocomposites.
Co-reporter:Zhenghai Tang, Chunfang Zeng, Yanda Lei, Baochun Guo, Liqun Zhang and Demin Jia
Journal of Materials Chemistry A 2011 - vol. 21(Issue 43) pp:NaN17118-17118
Publication Date(Web):2011/09/07
DOI:10.1039/C1JM13239C
Individually dispersed graphene colloid is prepared using common and industrially available fluorescent whitening agents (FWAs) as stabilizers. Characterizations by UV-vis, fluorescence and Raman spectra demonstrate that FWAs are successfully anchored onto graphene sheets by π–π interaction. The results from AFM indicate the individual dispersion of graphene sheets in water. FWAs are demonstrated as highly efficient in suspending graphene with high concentration(6.2 mg ml−1). Subsequently, the obtained graphene sheet is incorporated into a chitosan (CS) matrix by solution casting to fabricate CS/graphene composites. Morphological observations substantiate the homogeneous dispersion of graphene in the CS matrix and the strong interfacial adhesion between them. The significant improvements in tensile strength and toughness of the composite films are concurrently observed.
Co-reporter:Zhenghai Tang, Xiaohui Wu, Baochun Guo, Liqun Zhang and Demin Jia
Journal of Materials Chemistry A 2012 - vol. 22(Issue 15) pp:
Publication Date(Web):
DOI:10.1039/C2JM00084A
Co-reporter:Dan Yang, Mengnan Ruan, Shuo Huang, Yibo Wu, Shuxin Li, Hao Wang, Yuwei Shang, Bingyao Li, Wenli Guo and Liqun Zhang
Journal of Materials Chemistry A 2016 - vol. 4(Issue 33) pp:NaN7734-7734
Publication Date(Web):2016/07/01
DOI:10.1039/C6TC01504B
In order to obtain a nitrile-butadiene rubber (NBR) dielectric elastomer composite with excellent electromechanical properties, a combination of bio-inspired poly(dopamine) (PDA) deposition and γ-methacryloxypropyl trimethoxy silane (KH570) grafting was proposed to functionalize the surface of titanium dioxide (TiO2) nanoparticles. Inspired by adhesive proteins in mussels, dopamine self-polymerization was used to deposit a thin adherent PDA film onto the surface of TiO2. KH570 that contains double bonds was then grafted through the reactions with hydroxyl and indole groups of the PDA surface. The chemical structure and composition of the TiO2 surface were characterized by XPS, FTIR, and HR-TEM. Because of the introduction of PDA grafted with the KH570 layer, the NBR composites filled with modified TiO2 displayed better filler dispersion, higher dielectric constant, lower elastic modulus, and higher electric breakdown field compared with composites filled with pristine TiO2 particles. Finally, a large actuated strain of about 16% at 60 kV mm−1 without any pre-strains was shown by the composite of NBR filled with 20 phr modified TiO2 particles, which is 53% larger than that of NBR without a filler. The process was fast, simple, efficient, nontoxic, and controllable, which can provide a new universal method for modification of dielectric fillers to improve the dielectric properties and electromechanical properties of dielectric elastomers.
Co-reporter:Hailan Kang, Manqiang Li, Zhenghai Tang, Jiajia Xue, Xiaoran Hu, Liqun Zhang and Baochun Guo
Journal of Materials Chemistry A 2014 - vol. 2(Issue 45) pp:NaN7886-7886
Publication Date(Web):2014/10/17
DOI:10.1039/C4TB01304B
Novel biobased isosorbide-containing copolyesters (PBISI copolyesters) with both biocompatibility and sustainability were synthesized by using commercially available biobased diols and diacids. Due to the presence of itaconate in copolyesters, it can be readily crosslinked by peroxide into a crystallizable network. The structure and thermal properties of PBISI copolyesters were determined by 1H NMR, FTIR, DSC, and WAXD. The chain composition, melting point and crystallinity of the PBISI copolyesters can be tuned continuously by changing the content of isosorbide. The crosslinked copolyester is demonstrated to be a promising shape memory polymer (SMP) with excellent shape memory properties including shape fixity and shape recovery rate close to 100%. The switching temperatures of PBISI-based SMPs can be tuned between 26 °C and 54 °C by altering the composition of PBISI copolyesters and curing extent. Cell adhesion and proliferation were adopted to evaluate the potential biocompatibility of PBISI-based SMPs, and the results indicated that all the PBISI-based SMPs were essentially noncytotoxic, making them suitable for fabricating biomedical devices.
Co-reporter:Jiajia Xue, Min He, Yuanzhe Liang, Aileen Crawford, Phil Coates, Dafu Chen, Rui Shi and Liqun Zhang
Journal of Materials Chemistry A 2014 - vol. 2(Issue 39) pp:NaN6877-6877
Publication Date(Web):2014/09/05
DOI:10.1039/C4TB00737A
Infection is the major reason for GTR/GBR membrane failure in clinical applications. In this work, we developed GTR/GBR membranes with localized drug delivery function to prevent infection. Hierarchical membranes containing micro- and nano-fibers were fabricated. The effects of the incorporation of gelatin and loading content of metronidazole (MNA) (0, 5, 10, 20, 30, and 40 wt% polymer) on the properties of the electrospun membranes were investigated. The interaction between PCL and MNA was identified by molecular dynamics simulation. MNA was released in a controlled manner, and the antibacterial activity of the released MNA remained. The incorporation of gelatin and MNA improved the hydrophilicity, biocompatibility, and in vitro biodegradation rate of PCL nanofibers. The electrospun membranes allowed cells to adhere to and proliferate on them and showed excellent barrier function. The membrane loaded with 30% MNA had the best comprehensive properties. Subcutaneous implantation results demonstrated that MNA-loaded membranes evoked a less severe inflammatory response than pure PCL nanofibers. These results demonstrated the potential of MNA-loaded membranes as GTR/GBR membranes with antibacterial and anti-inflammatory functions for biomedical applications.
Co-reporter:Rui Shi, Jiajia Xue, Hanbin Wang, Renxian Wang, Min Gong, Dafu Chen, Liqun Zhang and Wei Tian
Journal of Materials Chemistry A 2015 - vol. 3(Issue 19) pp:NaN4073-4073
Publication Date(Web):2015/04/17
DOI:10.1039/C5TB00261C
Adhesion formation between dura mater and the overlying temporalis muscle following decompressive craniectomy can make subsequent cranioplasty difficult and adds to the risks of the procedure. In this work, we developed an electrospun PCL–gelatin hybrid membrane to be planted at decompressive craniectomy for preventing adhesion formation and facilitating subsequent cranioplasty. We prepared poly(ε-caprolactone)-gelatin (PG) nanofiber membranes with different PCL–gelatin ratios. The architectural features, mechanical properties, cell barrier functions, in vivo degradability, biocompatibility and anti-adhesion function were investigated. All membranes were found to have high tensile strength, and the strength of the membranes improved with the PCL content increased. All the PG membranes presented good biocompatibility and cell isolation performances while an increase in the gelatin content resulted in an enhancement of cell adhesion and proliferation. Subcutaneous implantation in rabbits for 6 months demonstrated that all the membranes showed good biocompatibility and adjustable biodegradation behaviour. In rabbit cranial defects model, no adhesions were observed, either between the PG membranes and the dura, or between the membranes and the temporal muscle after 1 month implantation. PG membranes' anti-adhesive properties and biodegradable characteristics make it useful as a dural onlay for craniotomy in which a second surgery is planned.
Co-reporter:Dan Yang, Fengxing Ge, Ming Tian, Nanying Ning, Liqun Zhang, Changming Zhao, Kohzo Ito, Toshio Nishi, Huaming Wang and Yunguang Luan
Journal of Materials Chemistry A 2015 - vol. 3(Issue 18) pp:NaN9479-9479
Publication Date(Web):2015/03/24
DOI:10.1039/C5TA01182E
Dielectric elastomers are referred to as artificial muscles because of their excellent properties. However, the need for high operating voltage limits their practical application. A reduction of the operating voltage can be achieved with novel elastomers offering intrinsically high electromechanical sensitivity. In this work, slide-ring materials with a necklace-like molecular structure are prepared as dielectric elastomer materials. These slide-ring materials are found to exhibit high dielectric constants, low elastic moduli, and high electromechanical sensitivity due to their special structural characteristics. Barium titanate particles modified by γ-methacryloxypropyl trimethoxy silane (KH570) are incorporated into the slide-ring materials to further improve the actuated performance of the slide-ring materials. A high actuated strain (26%) at a relatively low electric field (12 kV mm−1) is obtained on the circular membrane actuator without any pre-strains, much more excellent than those of other dielectric elastomers reported in the literature. In addition, an obviously larger displacement is achieved by the slide-ring composite than that of commercial dielectric elastomer VHB 4910 on a cone-type actuator at the same electric field. These results demonstrate that our research might help to establish a new synthetic route to high performance dielectric elastomers.
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![(1S,3R,6S,8R,11S,13R,16S,18R,21S,23R,26S,28R,31S,33R)-5,10,15,20,25,30,35-heptakis(hydroxymethyl)-2,4,7,9,12,14,17,19,22,24,27,29,32,34-tetradecaoxaoctacyclo[31.2.2.2~3,6~.2~8,11~.2~13,16~.2~18,21~.2~23,26~.2~28,31~]nonatetracontane-36,37,38,39,40,41,42,4](/data/chemimg/1332100/79647-56-6.png)
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