Co-reporter:Yihu Song, Qiang Zheng
Polymer 2017 Volume 130(Volume 130) pp:
Publication Date(Web):9 November 2017
DOI:10.1016/j.polymer.2017.09.070
•Linear rheology of silica filled poly(2-vinylpyridine) is dependent on sizes of both the polymer and filler.•Linear rheological responses of the nanocomposite and its filler phase follow time-concentration superpositioning principle.•The filler phase is viscoelastic rather than elastic and exhibits a very broad spectrum of relaxation time.Nanoparticles reinforcement of polymers has been of great interest to researchers for the better part of a century. However, researchers are in confusion in describing the role of filler network. Herein we report a framework to solve both reinforcement and dissipation of nanocomposites with respect to strain amplification effect of dynamically retarded bulk polymer phase and jamming of nanoparticles in the filler phase, disclosing a new mechanism differing from previously established ones. We show how the viscoelastic filler phase impacts on the terminal flow of the matrix. Our finding, which counters the conventional understandings of nanoparticles reinforcement, provides a unique description of linear rheology of nanocomposites comprised by fillers of different sizes and polymers of different molecular weights.Linear rheology of silica filled poly(2-vinylpyridine) is dependent on sizes of both the polymer and filler, which is involved in the interplay between the dynamically retarded bulk polymer phase and the viscoelastic filler phase.Download high-res image (159KB)Download full-size image
Co-reporter:Yihu Song, Lingbin Zeng, Aizhi Guan, Qiang Zheng
Polymer 2017 Volume 121(Volume 121) pp:
Publication Date(Web):14 July 2017
DOI:10.1016/j.polymer.2017.06.020
•Reinforcement and dissipation of polymer nanocomposites melts follow a unique time-concentration superpositioning principle.•Unified hydrodynamic-to-non-hydrodynamic regime transition are revealed for the nanocomposites and their filler phase.•Temperature influences the strain amplification effect introduced by the filler to the dynamically retarded bulk phase.Nanoparticle reinforcement at low and moderately high loadings has been assigned to the hydrodynamic and networking effects, respectively while the conclusions are ambiguous without specifying the “frequency”-dependent polymer dynamics. Herein a unique time-concentration superpositioning (TCS) principle is disclosed for accounting for the hydrodynamic-to-jamming regime transition associated with the apparent liquid-to-solid transition of multi-walled carbon nanotubes (MWCNTs) filled polystyrene (PS) melt. This principle is applicable to both reinforcement and dissipation of the composites at different temperatures. It is also testified for the pure filler effect introduced by MWCNTs to the dynamically retarded bulk phase. The new findings may shed light on the creation of rheological models that include the polymer dynamics beyond the conventional studies under the guidance of hydrodynamic and jamming theories.Both reinforcement and dissipation of multi-wall carbon nanotubes filled polystyrene melts at various frequencies and filler concentrations follow a unique time-concentration superpositioning principle, which discloses a hydrodynamic-to-jamming regime transition and sheds a light on solution of the conflicts of the hydrodynamic and filler networking effects in nanocomposites.Download high-res image (175KB)Download full-size image
Co-reporter:Yihu Song, Jing Bu, Min Zuo, Yang Gao, Wenjing Zhang, Qiang Zheng
Polymer 2017 Volume 127(Volume 127) pp:
Publication Date(Web):3 October 2017
DOI:10.1016/j.polymer.2017.08.038
•Core-shell (CS) nanoparticles with crosslinked PMMA shell were fabricated.•The remarkable depression of Tg induced by SiO2 and CS was both observed at low loadings.•The formation of RAF layer around SiO2 leaded to the adjacent molecular packing frustration.•The “lubrication” effect of nonwetting interface around CS caused the segmental acceleration.Core-shell (CS) nanocomposite particles with 53.4 wt% cross-linked poly (methyl methacrylate) (PMMA) shell of 11.6 nm in thickness were fabricated via miniemulsion polymerization of methyl methacrylate in the presence of modified nanosilica. The influence of nanosilica and CS nanoparticles on glass transition and segmental dynamics of PMMA in the nanocomposites prepared via solution casting was compared. The remarkable depression (≥10 °C) of glass transition temperature (Tg) induced by the incorporation of SiO2 and CS was both observed at low loadings. Here, different mechanisms were responsible for the effect of SiO2 and CS on the segmental acceleration of PMMA matrix. The formation of rigid amorphous fraction (RAF) layer around SiO2 with the thickness of 16.4 nm led to the adjacent molecular packing frustration, while the “lubrication” effect of nonwetting interface between the grafted crosslinked chains and matrix chains resulted in the segmental acceleration and the reduction of dynamic fragility.The formation ofRAF layer around SiO2 leaded to the adjacent molecular packing frustration, while the “lubrication” effect of nonwetting interface around CS caused the segmental acceleration.Download high-res image (129KB)Download full-size image
Co-reporter:Yihu Song, Aizhi Guan, Lingbin Zeng, Qiang Zheng
Composites Science and Technology 2017 Volume 151(Volume 151) pp:
Publication Date(Web):20 October 2017
DOI:10.1016/j.compscitech.2017.08.014
The filler reinforcement effect has been extensively investigated for the better part of a century while most of the conclusions are ambiguous without specifying the “frequency”-dependent polymer dynamics. Herein a recently proposed time-concentration superpositioning principle, disclosing a unique hydrodynamic-to-non-hydrodynamic transition with respect to filler loading and frequency, is examined in the linear rheology of multi-walled carbon nanotubes, carbon black and silica filled high-density polyethylene composites. The results suggest that the filler topology and filler-polymer interaction strongly influence the strain amplification effect, the dynamics retardation in the bulk phase and the critical filler concentration defining the hydrodynamic-to-non-hydrodynamic transition of the composites. The new findings may open a way for quantitative assessment of the roles played by the polymer, the filler and their interfacial interactions to the composites' rheology.
Co-reporter:Yihu Song, Lingbin Zeng, Qiang Zheng
Composites Science and Technology 2017 Volume 147(Volume 147) pp:
Publication Date(Web):28 July 2017
DOI:10.1016/j.compscitech.2017.05.003
Nanoparticle reinforcement beyond the hydrodynamics regime has been predominantly assigned to filler networking effect. Herein a unique hydrodynamics-to-nonhydrodynamics transition has been disclosed by creating master curves of relative dynamic modulus as a function of scaled frequency. Such conclusion is drawn for polystyrene filled with four different carbon fillers, i.e., carbon black, fullerene, multi-walled carbon nanotubes and graphite nanoplatelets. Additional rheological contribution of the filler phase beyond the hydrodynamics regime disclosed is sensitive to the filler type. The study may provide guidance for fundamental researches on the simultaneous reinforcement and dissipation of composites varying with filler topology.
Co-reporter:Jianliang Xiao, Jifei Zhang, Weiyang Lv, Yihu Song, Qiang Zheng
Carbon 2017 Volume 123(Volume 123) pp:
Publication Date(Web):1 October 2017
DOI:10.1016/j.carbon.2017.07.049
Comprehensive treatment of multifarious contaminations in waterbody demands multifunctional adsorbents with easy reusability, high efficiency, and broad-spectrum adsorption performance. Herein hydrothermally reduced graphene oxide/poly (vinyl alcohol) (TRGO/PVA) aerogels fulfilling these requirements were developed via a facile and green in situ hydrothermal reduction followed by direct sol-aerogel transformation strategy. The interfacial interaction between TRGO sheets and PVA macromolecules as proved by various methods could effectively prevent TRGO from aggregation, which improves mechanical and adsorption performances and assures reusability of aerogels. The aerogels demonstrate an attractive broad-spectrum universality in adsorbing diverse cationic, anionic and nonionic dyes, surpassing most adsorbents that could only remove either positively or negatively charged dyes. The aerogels demonstrate a promising synergetic effect for adsorption two oppositely charged dyes, exhibiting the highest total adsorption amount (>900 mg/g) among known absorbents for removing mixed dyes. Besides, the aerogels after hydrophobic modification are able to effectively adsorb common oils and organic solvents spilling on water. Furthermore, the aerogels are compressible, dimension stable and solvent resistive and can be easily regenerated, bringing a great superiority in the comprehensive treatment of multiple contaminations in waterbody.Download high-res image (459KB)Download full-size image
Co-reporter:Yi-hu Song 宋义虎;Ling-bin Zeng;Qiang Zheng
Chinese Journal of Polymer Science 2017 Volume 35( Issue 11) pp:1436-1446
Publication Date(Web):31 August 2017
DOI:10.1007/s10118-017-1987-5
The performance of reinforced rubber compounds depends on the filler composition while the reinforcement and dissipation mechanisms still remain unclear. Herein linear and nonlinear dynamic rheological responses of carbon black/silica hybrid filler filling nature rubber compounds are investigated. The rheological contributions of dynamically retarded bulk phase and filler network are revealed to be crucial at high and low frequencies, respectively, and the bulk phase is shown to be of vital importance for the occurrence of nonlinear Payne effect at mediate frequencies. A framework for simultaneously solving reinforcement and dissipation varying with filler composition and content is suggested, providing a new perspective in understanding the filling effect for manufacturing high-performance rubber materials.
Co-reporter:Ruiquan Yang, Yihu Song, Qiang Zheng
Polymer 2017 Volume 116(Volume 116) pp:
Publication Date(Web):5 May 2017
DOI:10.1016/j.polymer.2017.04.003
•Strain amplification effect is responsible for reinforcement of rubbery compounds.•Molecular disentanglement is mainly responsible for Payne effect.•Payne effect of low-filling compounds occurs at iso-stress condition.•Interparticle friction is the main reason of G″ overshoot.Filling significantly reinforces rubbers and introduces rheological nonlinearity, which is usually ascribed to filler networking and destructuring effects while conceptual conflicts still exist. Herein nonlinear rheology of compounds of fumed silica filled emulsion-polymerized styrene butadiene rubber is investigated with respect to silica type (hydrophilic and hydrophobic) and loading. The results revealed that, at low silica loadings, the reinforcement is involved in strain amplification effect and the rheological nonlinearity is initiated by a critical microscopic strain of bulk rubber matrix or a critical stress of the compounds. At high silica loadings when silica tends to develop an agglomerated structure, the reinforcement efficiency and the critical stress for onset of nonlinearity are reduced notably. Instead, an overshoot of loss modulus occurs accompanying with onset of nonlinearity involved in additional dissipation of mechanical energy possibly arising from friction among silica particles in their agglomerates.Payne effect of low-filled ESBR/FS compounds has an iso-stress character, which originates from stress-induced disentanglement of ESBR chains and well explains the reinforcement in linearity region. The breakdown of agglomerates in high-filled compounds decreases critical stress of Payne effect as a result of rigidity and fragility of the agglomerates and yields an overshoot of loss modulus as a result of interparticle friction.Download high-res image (167KB)Download full-size image
Co-reporter:Jianliang Xiao;Weiyang Lv;Zhou Xie
Journal of Materials Science 2017 Volume 52( Issue 10) pp:5807-5821
Publication Date(Web):20 January 2017
DOI:10.1007/s10853-017-0818-y
It is a challenge to develop broad-spectrum, high-efficiency, easy-recyclable adsorbents for the removal of water contaminants. Herein, l-cysteine-reduced graphene oxide/poly(vinyl alcohol) (CRG/PVA) ultralight aerogels with good mechanical strength and reusability are prepared via a direct sol–aerogel transition strategy by freeze drying. At optimized composition, the aerogel shows high adsorption efficiency toward both cationic and anionic dyes, overcoming the defect of many traditional adsorbents that usually can only remove one type of organic dyes. The adsorption is proved to involve in π–π interaction between CRG and dyes, endowing the aerogel with universality in adsorbing a wide range of conjugated dyes. Moreover, a remarkable synergetic effect is observed for removal of two oppositely charged dyes from aqueous system, yielding exceptionally high total adsorption capacities surpassing all known adsorbents examined for removing binary dyes. Thus, the CRG/PVA aerogel demonstrates great potential for usage as reusable, high-efficiency, and broad-spectrum adsorbent in water treatment.
Co-reporter:Yihu Song, Qiang Zheng
Progress in Materials Science 2016 Volume 84() pp:1-58
Publication Date(Web):December 2016
DOI:10.1016/j.pmatsci.2016.09.002
With substantial progresses in reinforcement mechanism of nanoparticle filled polymers (NPFPs) beyond the hydrodynamic limit, now is the time to reconsider this topic characterized by emergence of a universal solid-like rheology at nanoparticle contents above a critical value in relation to the heterogeneously retarded polymer dynamics and structured filler network. A comprehensive survey is presented herein to report the cluster-cluster aggregation model, and jamming, percolation and soft colloidal dynamics theories and their applications in NPFPs in relation to nanoparticle reinforcement of polymers beyond hydrodynamics. Methods for separating the filler contribution to the reinforcement within the frame work of two-phase models are highlighted and three main kinds of theoretical models (cluster-cluster aggregation model, jamming theory, and rigidity percolation theory) are discussed for addressing the conflicts of concepts in experiments. Many years research practice shows that there is still lack of a credible relation describing the reinforcement with respect to the network structure (nanoparticle dispersity) mediated by microscopic interaction and sample preparation. Furthermore, viscoelasticity of the filler phase is discussed according to two-phase models and beyond. Finally several open challenges are remarked.
Co-reporter:Jianliang Xiao, Weiyang Lv, Zhou Xie, Yeqiang Tan, Yihu Song and Qiang Zheng
Journal of Materials Chemistry A 2016 vol. 4(Issue 31) pp:12126-12135
Publication Date(Web):07 Jul 2016
DOI:10.1039/C6TA04119A
π–π interactions between graphene and organic dyes with a conjugate aromatic structure play a key role in the field of high-efficiency, broad-spectrum adsorbents for the removal of water contaminants. L-Cysteine reduced graphene oxide (RGO-Cys) has a good conjugate structure and dispersity in aqueous solution, endowing it with great adsorption efficiency towards anionic, nonionic and cationic dyes with a conjugate aromatic structure mainly via π–π interactions, as proved by the Raman spectrum and special adsorption experiments. The maximum adsorption capability for anionic indigo carmine (IC) and cationic neutral red (NR) is as high as 1005.7 mg g−1 and 1301.8 mg g−1, respectively, the former being the highest among those reported for adsorbents known to date. The total adsorption amount in mixed dye solutions is even higher (>3500 mg g−1), the highest total capability for simultaneous adsorption of anionic and cationic dyes in their solution mixtures. The π–π stacking adsorption mechanism ensures RGO-Cys to be used as a broad-spectrum adsorbent with high efficiency for many kinds of dye contaminants in water while the remnant carboxyl groups on graphene nanosheets facilitate effective adsorption towards Cu2+ with a capability as high as 139.2 mg g−1, opening up many possibilities for the use of graphene in water cleaning including disinfection, decontamination, and desalination.
Co-reporter:Yunxiang Zhang, Min Zuo, Ting Liu, Yihu Song, Qiang Zheng
Composites Science and Technology 2016 Volume 123() pp:39-48
Publication Date(Web):8 February 2016
DOI:10.1016/j.compscitech.2015.11.031
•Novel core–shell TiO2-g-PMMA nanoparticles with crosslinked PMMA shell were prepared via seeded emulsion polymerization.•The TiO2-g-PMMA nanoparticles demonstrated excellent dispersion stability in the composites subjected to melt annealing.•The TiO2-g-PMMA nanoparticles scarcely affected molecular dynamics of the PVDF/PMMA (70/30) blend.•The TiO2-g-PMMA nanoparticles provided a general and effective strategy to fabricate composites with morphology stability.Titania (TiO2) or poly (methyl methacrylate) (PMMA)-grafted titania (TiO2-g-PMMA) were incorporated into miscible poly (vinylidene fluoride) (PVDF)/PMMA (70/30 by weight) blend by melt mixing. TiO2 particles exhibited aggregation in the composites as displayed by scanning electron microscopy observations and the storage modulus (G′) plateau in the low frequency (ω) region. This is accompanied with the restriction of molecular mobility and the elevation of glass transition temperature (Tg). Conversely, TiO2-g-PMMA nanoparticles with well-defined cross-linked PMMA shells of 5 nm in thickness are well-distributed in the matrix, without the influence on Tg and the appearance of low-ω plateau. The dispersion of TiO2 is not stable during the thermal annealing of the composite in the melt while the TiO2-g-PMMA nanoparticles demonstrate excellent dispersion stability. Broadband dielectric spectroscopies indicate that TiO2 influenced the molecular relaxations of αa and αc, while the effect of TiO2-g-PMMA was negligible. Furthermore, the core–shell structured TiO2-g-PMMA nanoparticles produced considerable smaller interfacial polarization than TiO2 in the composites.
Co-reporter:Jianliang Xiao, Yeqiang Tan, Yihu Song and Qiang Zheng
RSC Advances 2016 vol. 6(Issue 47) pp:41392-41403
Publication Date(Web):13 Apr 2016
DOI:10.1039/C6RA05255J
Modulating the processability, structure and properties simultaneously remains a challenge for the preparation of high-performance electrospun nanofibers. The influence of incorporating graphene oxide (GO) and chemically reduced graphene oxide (RGO) nanosheets on the rheological behaviors of polyamide 6 (PA 6) solutions was systematically investigated. A small amount (0.5 wt%) of GO could dramatically increase the steady viscosity of PA 6 solution at 0.001 s−1 (η0.001) by a factor of four, while the same content of RGO resulted in a threefold decrease. Based on the modulation of viscosity of the PA 6 spinning solutions by GO and RGO nanosheets, GO/PA 6 and RGO/PA 6 nanofibers with various structures and properties were successfully prepared via electrospinning. The addition of 1 wt% GO and RGO nanosheets improved PA 6 fibrous uniformity and fineness, and the spinnable concentration (SC) range of PA 6 was effectively broadened. The difference in interfacial interaction between nanosheets and the PA 6 matrix led to different crystallization behaviors of the electrospun PA 6 nanofibers. The formation of γ-form crystals was promoted by GO but inhibited by RGO, which offers a convenient strategy to modulate the mechanical properties of PA 6 nanofibers. In addition, the thermal stability and adsorption capacity of PA 6 nanofibers was enhanced by adding GO or RGO.
Co-reporter:Shunchang Gan, Zi Liang Wu, Huilong Xu, Yihu Song, and Qiang Zheng
Macromolecules 2016 Volume 49(Issue 4) pp:1454-1463
Publication Date(Web):February 2, 2016
DOI:10.1021/acs.macromol.5b02701
Carbon black filled natural rubber (CB/NR) is a paradigm of nanocomposite materials with high performances. However, the mechanism for the nonlinear Payne effect is still not fully clear. CB gel (CBG) network embedded in the entanglement rubber matrix is supposed to be crucial for the reinforcement and viscoelastic nonlinearity. In this paper, we report for the first time the preparation of bulk CBGs by extracting the highly filled compounds in toluene and the systematic study of their viscoelastic behaviors. The CBG obtained from highly filled compounds with CB loadings from 40 to 70 phr has almost identical microstructure and composition, containing 40 wt % inextractable rubber fractions, among which ∼12 wt % is glassy. Dynamic rheological studies show that the Payne effect of the CBG network is frequency-independent and highly resilient, exhibiting an unjamming characteristic. On the other hand, the Payne effect of highly filled compounds is determined by the coupling between the breakdown of CBG network and the frequency-dependent chain disentanglement of extractable rubber fractions. This work provides new insights into the Payne effect of CB filled NR and should merit designing other rubbery nanocomposites with high performances and functions.
Co-reporter:Tao Ye;Qiang Zheng
Colloid and Polymer Science 2016 Volume 294( Issue 2) pp:389-397
Publication Date(Web):2016 February
DOI:10.1007/s00396-015-3790-6
Sulfobetaine 3-[N,N-dimethyl-N-(2-methacryloxylethyl)ammonio]-propane sulfonate (DMAPS) was used to copolymerize with acrylamide (AM) to prepare salt-sensitive copolymers. According to salt-in effects at the same chloride anion investigated using turbidimetric titration method, dissolution of the copolymer is related to cations, following the order of Al3+ > Mg2+ > Ca2+ > Na+ ~ K+ > Li+. It was found that the electrostatic shielding effect rather than the acid-base interaction was the major reason for the salt-in effect. The salt expansion effect, monitored by intrinsic viscosity under given ionic strengths (I), exhibited an efficiency sequence of cations differing from the salt-in effect. Both single molecule and intermolecular aggregation were found in even dilute solution. Expansion of single molecules and aggregates and breakdown and reformation of aggregates by hydrophobic interaction can be seen as I increases. These conformation changes were used to explain the rheological behavior of copolymer in dilute, semi-dilute, and concentrated solutions (or suspensions).
Co-reporter:Li-na Zhang;Yi-hu Song 宋义虎;Qiang Zheng 郑强
Chinese Journal of Polymer Science 2016 Volume 34( Issue 4) pp:483-490
Publication Date(Web):2016 April
DOI:10.1007/s10118-016-1775-7
Poly(methyl methacrylate) (PMMA) based ionomers with different lanthanum (La(III)) contents (PMMA-XLa) synthesized by free radical solution polymerization were applied to poly(vinyl chloride) (PVC) resins as a kind of multifunctional aids, and their performances were evaluated by measuring the static stability time, initial discoloration, transparency, fusion behavior and tensile strength of the modified PVC. The ionomers with proper lanthanum (La(III)) contents show a better thermal stability efficiency in comparison with traditional stabilizer lanthanum stearate. Meantime, they can accelerate PVC plasticization more efficiently than PMMA. The rigid PVC products stabilized with the ionomers present good transparency and enhanced tensile strength.
Co-reporter:Yunxiang Zhang, Min Zuo, Yihu Song, Xueping Yan, Qiang Zheng
Composites Science and Technology 2015 Volume 106() pp:39-46
Publication Date(Web):16 January 2015
DOI:10.1016/j.compscitech.2014.10.024
The molecular relaxations in melt-extruded poly(vinylidene fluoride) (PVDF)/poly(methyl methacrylate) (PMMA) blends with less than 40 wt% PMMA were investigated using dynamic rheological measurement and broadband dielectric spectroscopy. According to dynamic rheology, the total chain entanglement density of the blend melts increased with adding PMMA, and the dissimilar chains were more likely to entangle with each other than similar ones. Furthermore, PMMA facilitated the relaxation process. The dielectric temperature spectra revealed strong structural heterogeneity in the semicrystalline blends whose αa and αc relaxations were accelerated by increasing PMMA content. The αa and αc relaxations were shown to follow the Vogel–Fulcher–Tamman and Arrhenius equations, which allows assigning their molecular origins clearly to amorphous PVDF interphase and the amorphous portions within the crystalline PVDF phase, respectively. However, there exist structural heterogeneities in amorphous PVDF/PMMA mixture phase associated to intermolecular entanglement between dissimilar chains, giving rise to one or two αm relaxations in the dielectric temperature spectra depending on the PMMA content.
Co-reporter:Yiting Xu, Qiang Zheng and Yihu Song
Physical Chemistry Chemical Physics 2015 vol. 17(Issue 30) pp:19815-19819
Publication Date(Web):19 Jun 2015
DOI:10.1039/C5CP02463C
Novel nanoparticle ionic liquids (NILs) are prepared by grafting modified nanoparticles with long-chain ionic liquids (ILs). The NIL behaves like a liquid at ambient temperature. We studied the rheological behavior of the IL and NIL over the range of 10–55 °C and found an extraordinary difference between the IL and NIL: a small content of nanosilica (7%) moderately improves the crystallinity by 7% of the poly(ethylene glycol) (PEG) segment in the IL, and it improves the dynamic moduli significantly (by 5 times at room temperature). It retards the decay temperature (by 10 °C) of the dynamic moduli during heating as well. The thermal rheological hysteresis observed during heating–cooling temperature sweeps is ascribed to the melting–recrystallization of the PEG segments. Meanwhile, the IL and NIL express accelerated crystallization behavior in comparison with the oligomeric anion. For the first time, we find that ILs and NILs are able to form nanoparticle-containing spherulites at room temperature after long time aging.
Co-reporter:Tao Ye;Qiang Zheng
Colloid and Polymer Science 2015 Volume 293( Issue 3) pp:797-807
Publication Date(Web):2015 March
DOI:10.1007/s00396-014-3467-6
Sulfobetaine 3-[N,N-dimethyl-N-(2-methacryloxylethyl)ammonio]-propane sulfonate (DMAPS) was used to copolymerize with acrylamide (AM) to prepare salt-sensitive copolymers. The optimal reaction conditions, such as initiator concentration, temperature, and reaction time, to achieve the largest weight averaged molecular weight (Mw) and the lowest polydispersity index (PDI) were studied. The reactivity ratios of AM and DMAPS (r1, r2) were calculated to be (0.45, 0.84) by the Fineman-Ross method, and (0.47, 0.91) by the Kelen-Tüdös method. The Q-e values of DMAPS were calculated to be (0.30, −0.38). DMAPS was found to be more easily to add into the copolymer than AM to form random copolymers with a slight alternating tendency. Solution rheology and molecular size of the copolymers as a function of Mw were studied in 1 M NaCl solution, a near θ-solution, by rotational rheometer and light scattering methods, respectively. Undisturbed dimension of the copolymers was evaluated according to Stockmayer-Fixman relation.
Co-reporter:Ying-jie Xu;Yi-hu Song 宋义虎;Qiang Zheng
Chinese Journal of Polymer Science 2015 Volume 33( Issue 5) pp:697-708
Publication Date(Web):2015 May
DOI:10.1007/s10118-015-1619-x
The effects of nanosilica (SiO2) on crystallization and thermal aging behaviors of polyethylene terephthalate (PET) have been studied using differential scanning calorimetry (DSC) and polarized optical microscopy (POM), viscometry, tensile testing and scanning electron microscopy (SEM). For non-isothermal and isothermal crystallizations, the crystallization rate of PET increases considerably with increasing content of SiO2 providing a large number of nucleation sites, but the relative crystallinity of the nanocomposites has little differences with that of neat PET. According to POM observation, the nucleation of PET becomes faster and the nucleation density increases significantly with increasing SiO2 content. For PET and its nanocomposites thermally aged at 190 °C, the results of intrinsic viscosity, carboxyl content and tensile test show that the degradation rate of PET is reduced with the addition of a small content of SiO2, but the degradation rate increases with further addition of SiO2, owing to the dual effect of SiO2 on PET degradation.
Co-reporter:Zhong Zheng, Yihu Song, Ruiquan Yang, and Qiang Zheng
Langmuir 2015 Volume 31(Issue 50) pp:13478-13487
Publication Date(Web):November 30, 2015
DOI:10.1021/acs.langmuir.5b03899
Immobilized polymer fractions have been claimed to be of vital importance for sol–gel transitions generally observed in nanoparticle dispersions but remain a matter of debate regarding mechanism and difficulty for prediction. Here we investigate the immobilized layer structures of trifunctionality polyether polyol (PPG) near the surfaces of hydrophilic and hydrophobic fumed silica (FS) nanoparticles to reveal the role of surface chemistry on the molecular dynamics and sol–gel transitions of the dispersions. Using modulated differential scanning calorimetry, we measure the specific heat capacity during glass transition and the enthalpy during cold-crystallization. Comparing with hydrophobic FS that forms a fully immobilized (glassy) layer, we find that hydrophilic FS immobilizes more PPG, forming a partially immobilized outer layer being unable to crystallize next to the inner glassy layer. By correlating the thickness of the glassy layer with half of the minimum spacing between nanoparticles, we directly evidence the percolation of this layer along the nearest neighbor nanoparticles responsible for the sol–gel transition. Using effective volume fraction including the glassy layer, we successfully construct master curves of relative viscosity of both hydrophilic and hydrophobic FS dispersions, pointing to a common sol–gel transition mechanism mediated by the surface chemistry.
Co-reporter:Zhong Zheng, Yihu Song, Huilong Xu, and Qiang Zheng
Macromolecules 2015 Volume 48(Issue 24) pp:9015-9023
Publication Date(Web):December 3, 2015
DOI:10.1021/acs.macromol.5b02004
Immobilized polymer layers surrounding nanoparticles are proposed to be of essentially vital importance for the reinforcement of nanofiller to polymer matrices, but there is still a need to clarify its contribution to diverse rheological performance like colloidal stability and gelation. In this study, we find for the first time that introducing a trace amount of secondary/tertiary amine efficiently thickens the immobilized glassy layer in hydrophilic fumed silica (FS) filled polypropylene glycol (PPG) from 1.5 to 4.5 nm, which simultaneously promotes gelation of the liquid-like dispersion even containing extremely low contents of FS (<2 vol %). By coordinately using modulated differential scanning calorimetry and rheology methods, we find strong evidence that (1) the amine-promoted gelation is due to thickening and easy-percolation of the inner glassy layer converted from an outer uncrystallizable layer, and (2) the dispersion rheology could be well normalized within the framework of a two-phase model incorporating effective volume fraction of nanoparticles plus the glassy layers. We also highlight the importance of the surface chemistry of FS for adjusting the polymer immobilization and dispersion rheology.
Co-reporter:Yihu Song, Chunfeng Xu and Qiang Zheng
Soft Matter 2014 vol. 10(Issue 15) pp:2685-2692
Publication Date(Web):15 Jan 2014
DOI:10.1039/C3SM52856A
We report a facile kinetic strategy in combination with styrene–butadiene–styrene (SBS) copolymer compatibilizers for preparing carbon black (CB) filled immiscible polypropylene (PP)/polystyrene (PS) (1/1) blends with finely tuned morphologies and show the important role of location and migration of CB nanoparticles in determining the electrical conductivity and rheological behaviour of the composites. A novel method of mixing a SBS/CB (5/3) masterbatch with the polymers allowed producing composites with CB aggregates dispersed partially in the unfavorable PP phase and partially in the PP side of the interface to exhibit diverse phase connectivity and electrical conductivity depending on the compounding sequences. A cocontinuous morphology with CB enrichment along the interface was formed in the composite prepared by mixing the SBS/CB masterbatch with the premixed PP/PS blend, giving rise to a highest electrical conductivity and dynamic moduli at low frequencies. On the other hand, mixing the masterbatch with one and then with another polymer yielded droplet (PS)-in-matrix (filled PP) composites. The composites underwent phase coalescence and CB redistribution accompanied by marked dynamic electrical conduction and modulus percolations as a function of time during thermal annealing at 180 °C. The composites with the initial droplet-in-matrix morphology progressed anomalously into the cocontinuous morphology, reflecting a common mechanism being fairly nonspecific for understanding the processing of filled multicomponent composites with tailored performances of general concern.
Co-reporter:Xiaohu Zhang;Hongmei Yang;Qiang Zheng
Polymer Engineering & Science 2014 Volume 54( Issue 12) pp:2848-2858
Publication Date(Web):
DOI:10.1002/pen.23843
High density polyethylene (HDPE)/ethylene-vinyl acetate copolymer (EVA) blends with selective crosslinking the EVA phase were prepared and the crystallization, rheological, and mechanical behaviors were studied. Selective crosslinking of EVA component could greatly improve both tensile and impact strengths of the HDPE-rich blends and influence melting enthalpy at different annealing temperature in successive self-nucleation and annealing procedure. Dynamic mechanical analysis reveals that glass transition temperatures of both the HDPE and EVA components are lowered upon blending and are raised upon crosslinking. The uncrosslinked HDPE/EVA blends are unstable in the melt and show increment in storage modulus (G′) and decay in loss tangent (tanδ) with annealing time associated with phase coarsening. However, morphology of selectively crosslinked blends in the melt state is highly unstable, characterized by a fast migration of uncrosslinked HDPE component out of the crosslinked EVA phase to the surface resulting in a rapid decay in G′ and an increment in tanδ at the early stage of annealing. POLYM. ENG. SCI., 54:2848–2858, 2014. © 2014 Society of Plastics Engineers
Co-reporter:Tao Ye;Qiang Zheng
Colloid and Polymer Science 2014 Volume 292( Issue 9) pp:2185-2195
Publication Date(Web):2014/09/01
DOI:10.1007/s00396-014-3246-4
The copolymer of acrylamide and 3-[N-(2-methacryloxylethyl)-N,N-dimethylammonio]-propane sulfonate (PAM-MDMPS) was prepared via free radical copolymerization. Solubility of the copolymers was studied by turbidimetric titration method under different conditions. It was found for the first time that the critical salt concentration to dissolve the copolymer showed a plateau over one order of magnitude up to the critical overlap concentration. Rheological behavior and chain conformation of the copolymers in 1 M NaCl solution were also studied. The concentration regions according to scaling theory were found the same as neutral polymers in good solvent. The specific viscosities could be normalized by the overlap parameter. According to the Huggins relation, the copolymers adopted a more compact conformation in 1 M NaCl with increasing MDMPS content due to the hydrophobic association of the betaine unit in the macromolecular backbone, which was stabilized by the strongly hydrated dipolar pendant chains.
Co-reporter:Xiang Wang;Miao Du 杜淼;Yi-hu Song 宋义虎;Qiang Zheng
Chinese Journal of Polymer Science 2014 Volume 32( Issue 10) pp:1381-1389
Publication Date(Web):2014 October
DOI:10.1007/s10118-014-1524-8
Loach skin mucin was isolated from loach skin mucus and found to be similar to mammalian mucins in many aspects, i.e., low amino acid residue content, high molecular weight, presence of hydrophobic blocks and gel-forming characteristics in water. However, loach skin mucin can form a weak gel in water at a much lower concentration (3 mg/mL) than mammalian mucins, indicating its good hydrophilicity. Loach skin mucin can also form a stable adsorption layer on gold surface in aqueous environment, owing to the existence of hydrophobic blocks within mucin. The nature of high hydrophilicity and interfacial behavior give loach skin mucin potential as excellent material for use in solid-water interfaces for antifouling and lubrication, and should be crucial to the versatile functions of loach skin mucus.
Co-reporter:Yeqiang Tan, Lijun Fang, Jianliang Xiao, Yihu Song and Qiang Zheng
Polymer Chemistry 2013 vol. 4(Issue 10) pp:2939-2944
Publication Date(Web):25 Mar 2013
DOI:10.1039/C3PY00164D
A facile and general method to covalently functionalize graphene oxide (GO) with copolymers, using poly(styrene-co-methylmethacrylate) (P(St-co-MMA)) as an example, via miniemulsion polymerization is described in this study. After in situ reduction, insulating GO is converted to conductive reduced-graphene oxide (RGO). P(St-co-MMA) grafted RGO as conducting filler was incorporated into immiscible polystyrene (PS)/poly(methyl methacrylate) (PMMA) blend to prepare conductive polymer composites (CPCs). The lowest percolation threshold (0.02 vol%) among all the reported values for graphene-filled CPCs was achieved due to the controllable preferential distribution of the modified RGO at the interfacial region between PS and PMMA phases, attributed to P(St-co-MMA) grafted on the surface of RGO behaving as compatibilizers to improve interfacial interactions with both the two phases. Moreover, P(St-co-MMA) grafting modified RGO could obviously enhance the compatibility reflected by a significant reduction of the size of dispersed phase, for an example, by nearly one order of magnitude for PS/PMMA (4/1 in volume) blends.
Co-reporter:Yunxiang Zhang;Yingjie Xu;Qiang Zheng
Journal of Applied Polymer Science 2013 Volume 130( Issue 3) pp:2143-2151
Publication Date(Web):
DOI:10.1002/app.39405
ABSTRACT
A novel rigid poly(vinyl chloride) (PVC)/acrylonitrile–styrene–acrylate (ASA) copolymer blend with good ultraviolet (UV) irradiation resistance and toughness was reported. ASA with good weatherability and toughness was mixed with PVC by conical twin-screw extruder to improve the UV irradiation resistance and toughness of PVC. The blends were characterized using Fourier-transform infrared spectra, dynamic mechanical analysis, and scanning electron microscope. Notch Charpy impact test was used to characterize the UV radiation induced changes in toughness. The results showed that ASA was able to toughen PVC with simultaneously improving heat resistance, thermal stabilization, and protecting PVC from irradiation photochemical degradation. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2143–2151, 2013
Co-reporter:Chunfeng Xu;Yeqiang Tan;Qiang Zheng
Polymer International 2013 Volume 62( Issue 2) pp:238-245
Publication Date(Web):
DOI:10.1002/pi.4289
Abstract
The influences of styrene–butadiene–styrene (SBS) copolymer compatibilizer and compounding process on the electrical conduction and thermal stabilities of carbon black (CB)-filled immiscible polypropylene (PP)/polystyrene (PS) (1/1) blends were investigated. The immiscible CB/PP/PS composite with CB homogeneously located in the PS phase exhibited the highest resistivity and the fastest variation amplitudes of electrical resistivity (ρ) and rheological parameters upon annealing. An optimal content of 5 vol% SBS could significantly lower ρ of the composites by partially trapping CB particles in the PP/PS interfacial region and by reducing the phase size. The compatibilizer markedly slowed down the variation amplitudes of ρ and rheological parameters and the phase coalescence of the composites submitted to thermal annealing. The (SBS/CB)/PP/PS composite with CB located at the PP/PS interface and in the PP phase prepared by blending a (SBS/CB) masterbatch with PP and PS exhibited lower ρ and better thermal stability in comparison with the CB/SBS/PP/PS composite with CB mainly within the PS phase and partially at the PP/PS interface prepared by direct blending. Spreading and wetting coefficients were used to explain the CB distribution and the phase morphology of the composites. © 2012 Society of Chemical Industry
Co-reporter:Shao-min Sun;Yi-hu Song 宋义虎;Qiang Zheng
Chinese Journal of Polymer Science 2013 Volume 31( Issue 5) pp:809-814
Publication Date(Web):2013 May
DOI:10.1007/s10118-013-1271-2
Rheological properties of wheat gliadins in 50% (V/V) aqueous propanol were carried out as a function of gliadin concentration c and temperature. The solutions at 20 g L−1 to 200 g L−1 behave as Newtonian fluids with an flow activation energy of 23.5–27.3 kJ mol−1. Intrinsic viscosity [η] and Huggins constant kH are determined according to Huggins plot at c ≤ 120 g L−1. The results reveal that gliadins are not spherical shaped and the molecular size tends to increase with temperature due to improved solvation.
Co-reporter:Yun-xiang Zhang;Yi-hu Song 宋义虎;Qiang Zheng
Chinese Journal of Polymer Science 2013 Volume 31( Issue 2) pp:325-332
Publication Date(Web):2013 February
DOI:10.1007/s10118-013-1219-6
Nano-sized rod-like titanium dioxide (TiO2) filled rigid poly(vinyl chloride) (PVC) nanocomposites were prepared by using injection-molding method. Vicat, Charpy impact and tensile tests as well as thermogravimetric and dynamic mechanical analyses were used to characterize the structure and properties of the nanocomposites. The results showed that nano-TiO2 could improve Vicat softening temperature and also improve thermal stability of PVC during the stages of dehydrochlorination and formation of carbonaceous conjugated polyene sequences, which can be ascribed to restriction of the nanoparticles on the segmental relaxation as being evidenced by raises in glass transition and β-relaxation temperatures of PVC upon filling TiO2. Addition of TiO2 nanoparticles less than 40 phr (parts per hundreds of resin) could significantly improve impact strength of the composites while the TiO2 agglomeration at high contents leads to a reduction in impact toughness.
Co-reporter:Ye-qiang Tan;Yi-hu Song 宋义虎;Qiang Zheng 郑强
Chinese Journal of Polymer Science 2013 Volume 31( Issue 3) pp:399-406
Publication Date(Web):2013 March
DOI:10.1007/s10118-013-1234-7
Colloidal suspensions of glutaraldehyde (GA) crosslinked or grafted graphene oxide (GO) sheets were fabricated by simply tailoring the feed sequence. The different structures were confirmed by Fourier transform infrared spectra and X-ray diffraction. As demonstration of the utilities, the different colloidal suspensions were used to prepare free-standing papers by flow-directed filtration and poly(vinyl alcohol) (PVA)-based nanocomposite films by casting. Free-standing papers from GA crosslinked GO sheets exhibited better mechanical properties than unmodified GO paper, while nanocomposite films from GA grafted GO exhibit higher tensile strength and Young’s modulus.
Co-reporter:Yeqiang Tan, Yihu Song and Qiang Zheng
Nanoscale 2012 vol. 4(Issue 22) pp:6997-7005
Publication Date(Web):13 Sep 2012
DOI:10.1039/C2NR32160B
Rheology of graphene oxide (GO) and chemically reduced graphene oxide (RGO) nanosheets suspended in poly(vinyl alcohol) (PVA) solution were investigated by altering nanosheet loading and reduction time of RGO in a wide range. A small amount (0.5 wt%) of GO and RGO in the dilute regime of filler resulted in a threefold increase and a fourfold decrease in steady viscosity at 0.01 s−1, respectively; increasing GO and RGO loadings in the semi-dilute regime of filler caused steady viscosity to increase to different degrees. Meanwhile, the steady viscosity of the suspension decreased gradually by more than one order of magnitude with increasing reduction time of RGO. By characterizing the microstructure in suspensions, the style and relative density of H-bonding between PVA chains and nanosheets were confirmed to account for the suspension rheology. Modulation of viscosity in a wide range via simply control of the loading and reduction time of RGO was hydrogen bonding-driven, which was successfully applied to electrospinning to prepare nanocomposite nanofibers. The addition of 1 wt% GO and RGO with respect to the polymer mass significantly improved PVA fibrous uniformity and fineness, and the spinnable concentration range of PVA was greatly broadened from (8.5–11.3 wt%) to (5–18 wt%). Meanwhile, the thermal stability of the nanofibers was also enhanced by GO or RGO addition.
Co-reporter:Xiaohu Zhang;Hongmei Yang;Qiang Zheng
Journal of Applied Polymer Science 2012 Volume 126( Issue 3) pp:939-946
Publication Date(Web):
DOI:10.1002/app.36978
Abstract
Influence of commercial phenol antioxidants Irganox 300, 1010, 1035, and 1076 on peroxide-cure reaction of low-density polyethylene (LDPE) was evaluated through isothermal dynamic rheological and nonisothermal differential scanning calorimetry (DSC) testing. The results indicated that phenol antioxidants could reduce storage modulus of LDPE completely crosslinked at 175°C while they have a neglectable effect on gel fracture and activity energy of crosslinking reaction. On the other hand, time sweep dynamic rheological test revealed the antioxidants 1035 and 1076 with low molecular weight and low melting point could significantly depress scorch of crosslinkable LDPE at 135°C. The isothermal time sweep dynamic rheology test method was more sensitive than nonisothermal DSC test for characterizing the influence of phenol antioxidants on crosslinking kinetics of peroxide-cure reaction of LDPE. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Co-reporter:Xianze Yin;Yeqiang Tan;Yuyin Chen;Qiang Zheng
Polymer International 2012 Volume 61( Issue 9) pp:1439-1446
Publication Date(Web):
DOI:10.1002/pi.4230
Abstract
Shell-crosslinked core–shell nanoparticles (SCCSNs) were prepared via miniemulsion polymerization of styrene in the presence of silane-modified inorganic silica. The polystyrene (PS) shell of 58.6% in weight fraction was crosslinked using divinylbenzene. SCCSNs were spherical with a diameter distribution from 32 to 98 nm determined by dynamic light scattering. Dynamic rheology of SCCSNs suspended in PS/toluene solution was compared with that of suspensions of naked silica. The critical strain for onset of rheological nonlinearity was independent of SCCSN concentration above a concentration threshold, which differs from the silica suspensions. Linear dynamic rheological investigation revealed that SCCSN suspensions with a PS volume fraction of 20% were fluid-like at low particle concentrations while suspensions containing 4.2 vol% SCCSNs formed a gel-like structure. On the contrary, the silica suspensions with 20.0 vol% PS underwent a fluid-to-solid-like transition with increasing silica concentration. Reasons for the different rheological behaviors of the naked silica and SCCSN suspensions are discussed. Copyright © 2012 Society of Chemical Industry
Co-reporter:Xiaohu Zhang;Hongmei Yang;Qiang Zheng
Journal of Applied Polymer Science 2012 Volume 126( Issue 6) pp:1885-1894
Publication Date(Web):
DOI:10.1002/app.36754
Abstract
The secondary antioxidants Irganox 168 and 242 and dilaurylthiodipropionate (didodecyl-3,3′-thiodipropionate) (DLTP) were chosen to be combined with the primary phenol antioxidants Irganox 300, 1010, 1035, and 1076, and the effects of the binary combined systems of antioxidants on the peroxide curing reaction and the long-term stability of crosslinked low-density polyethylene (XLPE) were studied through isothermal dynamic rheological and mechanical testing. The results show that the primary phenol antioxidants with lower melting points had better resistance to scorching and exhibited good synergistic effects with the secondary antioxidants. Irganox 168 had little resistance to scorching, whereas Irganox DLTP had moderate resistance, and Irganox 242 had the greatest resistance. Irganox 168 and DLTP guaranteed the mechanical properties well, whereas Irganox 242 reduced the tensile strength obviously. Irganox 300 and 1035 combined with secondary antioxidants performed poorly in long-term thermal aging test, whereas Irganox 1076 in combination with secondary antioxidants displayed a moderate effect of aging resistance, and Irganox 1010 showed the best effect. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2012
Co-reporter:Xiaohu Zhang, Hongmei Yang, Yihu Song, Qiang Zheng
Polymer 2012 Volume 53(Issue 14) pp:3035-3042
Publication Date(Web):21 June 2012
DOI:10.1016/j.polymer.2012.05.004
Dicumy peroxide (DCP) modification of low density polyethylene (LDPE) below gel point (GP) produces modified LDPE (mLDPE) with wide molecular weight distributions while the random crosslinking beyond GP yields crosslinked LDPE (XLPE). Molecular weight distributions of mLDPE below GP and the sol-fractions of XLPE above GP were investigated. The sol-fractions in XLPE were extracted to prepare XLPE gels of different crosslinking densities. Both XLPE and the gels were subjected to shear action for studying dynamic rheology and relaxation modulus in the linearity region for revealing the role of entanglements and dangling chains to viscoelasticity of the randomly crosslinked network. The results revealed that the sol-fractions with molecular weight much higher than entanglement molecular weight contributed to equilibrium modulus in addition to the gel network, which lowered the DCP dosage for appearance of critical gel behavior of XLPE in comparison with the XLPE gel. However, rheological method yielded critical DCP dosages for appearance of apparent gel behaviors far beyond the chemical GP from the extraction experiment. The sol-fraction residing in the network gave rise to additional contribution to relaxation modulus of XLPE, shortening network relaxation time and improving equilibrium modulus.
Co-reporter:Xiao-nan Zhu;Yi-hu Song 宋义虎;Qiang Zheng 郑强
Chinese Journal of Polymer Science 2012 Volume 30( Issue 2) pp:316-327
Publication Date(Web):2012 March
DOI:10.1007/s10118-012-1125-3
A series of acrylate processing aid (ACR)-based ionomers with different lanthanide (La(III)) ion and acid contents were synthesized, and the interaction between ionomer and zinc stearate (ZnSt2) was investigated immediately after thermally annealing the ionomer/ZnSt2 (3/1 in weight) mixtures at 180°C. The results revealed that the ion groups in ionomer have a strong interaction with ZnSt2. The annealed mixtures contained hot alcohol extractable and unextractable ZnSt2. The melting of ZnSt2 and the thermal behavior of the ionomer in the annealed mixtures were seriously influenced by the contents of La(III) and acid in the ionomers. The ionomer containing 0.25 mmol/g acid and 0.37 mmol/g La(III) has a detectable cluster phase. Annealing its ZnSt2 mixture could break down the cluster phase and lower glass transition temperature of the ionomer matrix. However, washing away the extractable ZnSt2 led to the reappearance of the cluster transition temperature and return of the glass transition temperature of matrix to the original position.
Co-reporter:Xian-ze Yin;Ye-qiang Tan;Yi-hu Song 宋义虎
Chinese Journal of Polymer Science 2012 Volume 30( Issue 1) pp:26-35
Publication Date(Web):2012 January
DOI:10.1007/s10118-012-1099-1
Polystyrene coated silica (SiO2@PS) core-shell composite particles with averaged diameter of about 290 nm were prepared by in situ emulsion polymerization of styrene on the surface of γ-methacryloxypropyltrimethoxysilane grafted SiO2 nanoparticles of 20–50 nm in diameter. Rheological behavior and dispersion stability of SiO2@PS suspension in 10 wt% PS solution were compared with suspensions of untreated SiO2 and silane modified SiO2 nanoparticles. Suspensions of the untreated and the silane modified SiO2 exhibited obvious shear thinning. The SiO2@PS suspension exhibits shear viscosity considerably smaller than suspensions of untreated and silane modified SiO2 at low shear rates. Transmission electron microscopy showed that the composite particles can uniformly and stably disperse in PS solution compared to other suspensions, implying that the PS shell can effectively enhance the particle compatibility with PS macromolecules in solution.
Co-reporter:Yihu Song;Qing Cao;Qiang Zheng
Colloid and Polymer Science 2012 Volume 290( Issue 17) pp:1837-1842
Publication Date(Web):2012 November
DOI:10.1007/s00396-012-2804-x
Annealing-induced viscoelastic and electric conduction variations were traced by simultaneous measurement of resistance and dynamic modulus to carbon black (CB)-filled high-density polyethylene, polystyrene, and polypropylene at elevated temperatures. The resistance decay during annealing the melts is closely related to terminal relaxation of polymer chains and the temperature-mediated interfacial tension between CB and the matrix. On the other hand, a time–temperature–concentration superposition principle was disclosed to evolution of dynamic modulus for the filled melts at different temperatures and CB volume fractions. Annealing the filled melts causes a liquid-to-solid-like transition and the differences in kinetic constant for evolution of dynamic modulus among the three systems at the same condition are involved in interfacial tension.
Co-reporter:Xianze Yin, Yeqiang Tan, Yang Gao, Yihu Song, Qiang Zheng
Polymer 2012 Volume 53(Issue 18) pp:3968-3974
Publication Date(Web):17 August 2012
DOI:10.1016/j.polymer.2012.07.035
Shell-crosslinked core–shell nanoparticles (SCCSN) of 63–104 nm in diameter and containing 79.1 wt% crosslinked polystyrene (PS) shell of 16.5–37.0 nm in thickness were prepared by miniemulsion polymerization of styrene in the presence of silane modified nanosilica. The PS shell was crosslinked using divinyl benzene in order to anchor the shell on the nanoparticle surface, to segregate the silica core from the matrix and to avoid entanglement between the shell PS and the matrix macromolecules in SCCSN filled PS composites. Steady and dynamic rheologies of SCCSN filled PS were compared with bare silica filled PS. The SCCSN filled PS composites exhibited exceedingly good rheological stability than silica filled ones during annealing. Both bare silica and SCCSN introduced a non-terminal dynamic rheology while they did not introduce additional mechanism responsible for origination of nonlinear steady flow except for macromolecular disentanglement of the PS matrix. The reinforcement of SCCSN to PS was related to the silica core even though the crosslinked shell could effectively eliminate filler aggregation as the case of silica filled PS.Graphical abstract
Co-reporter:Yang Gao, Yihu Song, Qiang Zheng
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2012 Volume 411() pp:40-49
Publication Date(Web):5 October 2012
DOI:10.1016/j.colsurfa.2012.06.043
Core–shell nanocomposite particles with a diameter of 200 nm and containing 22 wt.% polystyrene (PS) and 78 wt.% titania were fabricated via miniemulsion polymerization of styrene in the presence of modified nanotitania powder. The PS shell of nanocomposite particles had a crosslinked structure. The effects of reaction temperature, emulsifier concentration, and costabilizer on morphology, size and size distribution were investigated. By adjusting these parameters, it was able to control the size and morphology of the nanocomposite particles. The nanocomposite particles had a fine dispersibility and compatibility with PS solution. Steady rheology of the core–shell nanocomposite particles suspended PS solution revealed a slight viscosity reduction deviating from Stokes–Einstein prediction at 0.6 wt.% particle loading and a slight viscosity increase to the level of pure PS solution at 2.0 wt.% particle loading, which was significantly different from the nanotitania suspensions.Graphical abstractHighlights► MPS modification improves the dispersibility of nanotitania in organic medium significantly. ► Core–shell nanocomposite particles of controllable size are prepared. ► Nanocomposite particles of 200 nm in diameter contain 22 wt.% cross linked PS shell. ► Nanocomposite particle suspensions deviate from Stokes–Einstein prediction.
Co-reporter:Jing Guan, Yihu Song, Yu Lin, Xianze Yin, Min Zuo, Yuhua Zhao, Xiaole Tao, and Qiang Zheng
Industrial & Engineering Chemistry Research 2011 Volume 50(Issue 11) pp:6517-6527
Publication Date(Web):April 17, 2011
DOI:10.1021/ie101995j
Non-isocyanate polyurethane (NIPU) is a novel kind of polyurethane prepared by reaction of cyclo-carbonates and amines without use of toxic isocyanates. NIPU has attracted increasing attention because of its improvements in porosity, water absorption, and thermal and chemical resistance over conventional polyurethanes. Their potential technological applications include chemical-resistant coating, sealants, foam, etc. In this paper, on the basis of a comprehensive survey of the currently available literature on NIPU, we summarize recent progress in NIPU, and mainly discuss the syntheses of cyclo-carbonates oligomers, the reaction mechanism, and the preparation and application of different kinds of NIPU.
Co-reporter:Yeqiang Tan;Qing Cao;Qiang Zheng
Polymer International 2011 Volume 60( Issue 5) pp:823-832
Publication Date(Web):
DOI:10.1002/pi.3026
Abstract
The electrical and rheological behaviors of carbon black (CB)-filled immiscible polypropylene (PP)/polystyrene (PS) blends were investigated. The compounding sequence influences the phase morphology of the ternary CB/PP/PS composites and the distribution of CB aggregates. Simultaneous measurements of resistance and dynamic modulus were carried out to monitor the phase coalescence of the ternary composites and CB migration and agglomeration in the PS phase during annealing at temperatures above the melting point of PP. The variation of resistivity is mainly attributed to CB agglomeration in the PS phase and the interfacial region, while the variation of dynamic modulus is regarded as the superimposition of the phase coalescence and CB agglomeration in the PS phase. The ternary composites with the majority of CB particles distributed in the interfacial region show the lowest conductive percolation threshold and the most stable resistivity–temperature performance during heating–cooling cycles. Copyright © 2011 Society of Chemical Industry
Co-reporter:Xiaonan Zhu;Shaohui Chen;Peihua Du;Qiang Zheng
Polymer International 2011 Volume 60( Issue 9) pp:1355-1361
Publication Date(Web):
DOI:10.1002/pi.3088
Abstract
An acrylate processing aid (ACR)-based ionomer containing lanthanide (La(III)) ion was synthesized and the influences of the ionomer on thermal stability, fusion time, transparency and tensile properties of rigid poly(vinyl chloride) (PVC) were investigated. Results revealed that the ionomer with a suitable La(III) content behaved as a good stabilizer as well as processing aid to the rigid PVC product. The ionomer could accelerate fusion of PVC much more quickly than ACR because of the strong interaction between La(III) carboxylate and PVC. Moreover, it exhibited a stabilizing efficiency comparable to lanthanum and calcium stearates (LaSt3 and CaSt2). The composite stabilizer of ionomer/zinc stearate (ZnSt2) exhibited an ability to improve initial discoloration better than LaSt3/ZnSt2 and CaSt2/ZnSt2 because the ionomer could form a complex with ZnSt2 much more slowly than LaSt3 and CaSt2. The compounds stabilized using ionomer/ZnSt2 exhibited a transparency comparable to those stabilized using organotin or liquid barium/zinc stabilizers, which was much better than those stabilized using LaSt3/ZnSt2 and CaSt2/ZnSt2. Copyright © 2011 Society of Chemical Industry
Co-reporter:Yihu Song, Qiang Zheng
Polymer 2011 Volume 52(Issue 3) pp:593-596
Publication Date(Web):3 February 2011
DOI:10.1016/j.polymer.2010.12.047
A two phase model proposed for accounting for linear viscoelasticity of polymer nanocomposite melts [14] is applied to rubbers filled with nanoclay and conventional fillers (carbon black and silica) to probe mechanisms of the fluid- and the solid-like behaviors beyond the terminal flow region. This model shows strong applicability in linear rheology beyond terminal region for a variation of filled rubbers. Characteristic moduli of the “filler phase” from different filled rubbers could collapse onto a master curve, which reveals a jamming transition with increasing filler concentration across the percolation threshold. The strain amplification effect and reduced characteristic moduli of the “filler phase” are discussed within the framework of the cluster–cluster aggregation model.
Co-reporter:Yanyan Yang;Qiang Zheng
Journal of Food Science and Technology 2011 Volume 48( Issue 4) pp:489-493
Publication Date(Web):2011 August
DOI:10.1007/s13197-011-0255-x
Hydrated starch-gluten reconstituted doughs were prepared and dynamic rheological tests of the reconstituted doughs were performed using dynamic strain and dynamic frequency sweep modes. Influence of starch/gluten ratio on rheological behaviors of the reconstituted doughs was investigated. The results showed that the reconstituted doughs exhibited nonlinear rheological behavior with increasing strain. The mechanical spectra revealed predominantly elastic characteristics in frequency range from 10−1 rad s−1 to 102 rad s−1. Cole-Cole functions were applied to fit the mechanical spectra to reveal the influence of starch/gluten ratio on Plateau modulus and longest relaxation time of the dough network. The time-temperature superposition principle was applicable to a narrow temperature range of 25°C ~40°C while it failed at 50°C due to swelling and gelatinization of the starch.
Co-reporter:Yihu Song, Qiang Zheng
Polymer 2011 Volume 52(Issue 26) pp:6173-6179
Publication Date(Web):13 December 2011
DOI:10.1016/j.polymer.2011.11.010
The linear dynamic rheology for a series of filled polymer melts is investigated to take account for the respective contributions of the bulky polymer phase away from the filler inclusions and the “filler phase” composed of filler particles coated with polymer layer. Time-concentration superposition principles are introduced to the linear viscoelasticities of both the bulky polymer phase and the “filler phase”. The result highlights the importance of the polymer dynamics to both the “filler phase” and the composite melt. Polymer mediated filler jamming towards glass formation is revealed for the “filler phase”, which accounts for origin of the fluid-to-solid transition upon filling.
Co-reporter:Pei-hua Du;Jie Yu;Peng-fei Lin;Yi-hu Song 宋义虎
Chinese Journal of Polymer Science 2011 Volume 29( Issue 6) pp:
Publication Date(Web):2011 November
DOI:10.1007/s10118-011-1090-2
Hard poly(vinyl chloride) (PVC)/acrylonitrile-butadiene-styrene (ABS) blends were prepared using injectionmolding and influence of crosshead speed on mechanical properties was examined. Based on morphology parameters obtained from transmission electron microscopy photography and the material parameters from true stress-strain curves of neat PVC and ABS, yield stresses of the blends at different crosshead speeds were simulated employing a two-dimensional nine-particle model based on the finite element analysis (FEA). The FEA results were compared with the experimental yielding stress and the good agreement validated the simulation approach. The FEA approach allowed establishing a yielding criterion related to local yielding of the interstitial matrix between ABS particles.
Co-reporter:Shao-min Sun;Li Zhao;Yi-hu Song 宋义虎;Qiang Zheng 郑强
Chinese Journal of Polymer Science 2011 Volume 29( Issue 4) pp:483-489
Publication Date(Web):2011 July
DOI:10.1007/s10118-011-1052-8
Modulated-temperature differential scanning calorimetric and dynamic mechanical analyses and dielectric spectroscopy were used to investigate the glass transition of hydrated wheat gliadin powders with moisture absorption ranged from 2.30 db% to 18.21 db%. Glass transition temperature (Tg) of dry wheat gliadin was estimated according to the Gordon-Taylor equation. Structural heterogeneity at high degrees of hydration was revealed in dielectric temperature and frequency spectra. The activation energies (Ea) of the two relaxations were calculated from Arrhenius equation.
Co-reporter:Yan-yan Yang;Kai-zhou Zhang;Yi-hu Song 宋义虎
Chinese Journal of Polymer Science 2011 Volume 29( Issue 1) pp:87-92
Publication Date(Web):2011 January
DOI:10.1007/s10118-010-9185-8
Environment friendly thermosetting composites were prepared by blending wheat gluten (WG) and rice protein (RP) at different weight ratios with glycerol as plasticizer followed by compression molding the mixture at 120°C to crosslink the proteins. Reducing agent of sodium bisulfate and sodium sulfite and crosslinking agent formaldehyde were used to adjust the properties of the composites. Morphology, moisture absorption and tensile properties were evaluated. The results showed that formaldehyde could increase tensile strength of the composites without significant influence on Young’s modulus and elongation at break. On the other hand, reducing agents could improve tensile strength and extensibility simultaneously, which was much marked at WG/RP ratios from 7/3 to 3/7.
Co-reporter:Qing Cao, Yihu Song, Yeqiang Tan, Qiang Zheng
Carbon 2010 Volume 48(Issue 15) pp:4268-4275
Publication Date(Web):December 2010
DOI:10.1016/j.carbon.2010.07.036
Aggregation of carbon black (CB) aggregates in polystyrene melt was traced by simultaneous measurement of resistance (R) and dynamic storage modulus (G′) as a function of annealing time. There existed a dynamic resistance percolation in the time evolution of R while G′ increased gradually during the whole experimental time scale. Dynamic resistance and modulus percolation models were used to model the time-dependent R and G′, respectively. Furthermore, the time evolution of G′ was explained with a combination of the kinetic cluster–cluster aggregation model and the first order kinetics aggregation model. It was found that the aggregation of CB aggregates in the molten polystyrene has a close relation with the terminal relaxation of polystyrene molecules. The results indicated that the interfacial tension between polystyrene molecules and CB plays a crucial role in driving CB to aggregate.
Co-reporter:Yinyong Li, Xiaolei Guo, Pengfei Lin, Congcheng Fan, Yihu Song
Carbohydrate Polymers 2010 Volume 81(Issue 2) pp:484-490
Publication Date(Web):11 June 2010
DOI:10.1016/j.carbpol.2010.03.005
This work was aimed to prepare wheat gliadin/chitosan (CS) blend films and to evaluate influence of CS content on properties of the films. Morphology observation using scanning electron microscope (SEM) revealed a phase-separated structure and a phase reversion with respect to CS content in the blend films. Dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC) and Fourier transformation infrared (FTIR) spectrum measurements were conducted to assess the glass transition and microstructure of the films. Also studied were the mechanical properties and water barrier properties of the films. Results showed that gliadin/CS ratio had a significant effect on the functional performance of the films.
Co-reporter:Yihu Song, Qiang Zheng
Polymer 2010 Volume 51(Issue 14) pp:3262-3268
Publication Date(Web):24 June 2010
DOI:10.1016/j.polymer.2010.05.018
The linear dynamic rheology of polymer melts filled with nano-sized fillers is investigated in relation to a proposed two phase model. A common principle is disclosed for nanofilled polymers exhibiting either fluid- or solid-like behaviors with increasing filler volume fraction. The bulky polymer phase far away from the filler inclusions in the nanocomposites behaves the same as in the unfilled case while its contribution to the composite modulus is enlarged due to strain amplification effect. The filler forms aggregates together with polymer chains absorbed on the filler surface, which is termed as the “filler phase” in the proposed model. The dynamics of the “filler phase” slow down with increasing filler concentration. The applicability of the proposed two phase model is discussed in relation to the well-known structural inhomogeneity of nanofilled polymers as well as the strain amplification and the filler clustering effects.
Co-reporter:Yihu Song;Jie Tu;Qiang Zheng
Journal of Polymers and the Environment 2010 Volume 18( Issue 3) pp:260-265
Publication Date(Web):2010 September
DOI:10.1007/s10924-010-0247-3
Environmentally friendly green composites were prepared by blending Wheat gluten (WG) as matrix, dialdehyde starch (DAS) as filler and glycerol as plasticizer followed by compression molding of the mixture at 110 °C. The properties of the WG/DAS composite are compared with those of the WG/native wheat starch (NWS) composites. While tensile strength and strain at break decrease with increasing NWS content in the WG/NWS composites, a small content of DAS could improve tensile strength and strain at break simultaneously in the WG/DAS composites. The WG/DAS composites exhibit reduced moisture absorption in comparison with the WG/NEW composites. Formation of chemical bonding between DAS and WG is beneficial for the dispersion of DAS in the WG matrix and WG/DAS composites exhibit improved mechanical properties and reduced moisture absorption over the WG/NWS composites.
Co-reporter:Yihu Song, Lingfang Li and Qiang Zheng
Journal of Agricultural and Food Chemistry 2009 Volume 57(Issue 6) pp:2295-2301
Publication Date(Web):March 2, 2009
DOI:10.1021/jf802961b
The present study was to examine influence of epichlorohydrin (ECH) modification on structure and properties of glycerol-plasticized wheat gliadin films casting from ethanol/water (70/30 v/v) solution. The modified films were characterized using proton nuclear magnetic resonance (1H NMR), Fourier transformation infrared (FTIR) spectra, dynamic mechanical analysis (DMA), and scanning electron microscopy (SEM). Water resistance (moisture absorption MA, water vapor permeability WVP, and weight loss in water WLW), tensile mechanical properties (Young’s modulus E, tensile strength σb, and elongation at break εb), and thermal decomposition behavior were evaluated in relation to ECH content. Experimental results revealed that ECH modification gave rise to marked reduction in WLW and significant improvements in E and σb, which were accompanied by slight variations in MA, WVP, and thermal decomposition temperature. The improvements of E and σb were related to the formation of a partially cross-linked protein network even though the modification led to reductions in percentages of the hydrogen bonded NH groups and the β-sheet structure.
Co-reporter:Yi Hu Song, Ling Fang Li, Qiang Zheng
Chinese Chemical Letters 2009 Volume 20(Issue 5) pp:623-626
Publication Date(Web):May 2009
DOI:10.1016/j.cclet.2009.01.022
Influence of non-gelling methylcellulose (MC) on gelation behavior of wheat gliadins in 13 wt% alkaline propanol/water (50:50, v/v) solution was investigated using dynamic rheological time sweep test. Increasing MC concentration (CMC) up to CMC = 1 wt% caused a significant reduction in gelation time (tgel) of the solution and an increase in loss tangent (tan δ) value of the resultant gel at T < 30 °C.
Co-reporter:Min Zuo, Zheng Zheng Lai, Yi Hu Song, Qiang Zheng
Chinese Chemical Letters 2008 Volume 19(Issue 8) pp:992-995
Publication Date(Web):August 2008
DOI:10.1016/j.cclet.2008.05.028
Environment friendly thermosetting composites were prepared by blending wheat gluten (WG) as matrix, calcium carbonate (CaCO3) as filler and glycerol as plasticizer followed by compression molding the mixture at 120 °C to crosslink the WG matrix. Morphology observation showed that the CaCO3 particles were finely dispersed in matrix. Incorporation of CaCO3 up to 10 wt% into the composites caused Young's modulus and tensile strength to increase markedly. On the other hand, the moisture absorption and elongation at break decreased slightly.
Co-reporter:Yihu Song;Qiang Zheng
Journal of Applied Polymer Science 2008 Volume 110( Issue 5) pp:3009-3013
Publication Date(Web):
DOI:10.1002/app.26959
Abstract
The electric self-heating and conduction behaviors of a high-density polyethylene/acetylene carbon black composite crosslinked with electron-beam irradiation are studied with respect to the electric field and ambient temperature. On the basis of scaling arguments, the critical fields and current densities for the onsets of self-heating and global electrical breakdown are discussed with respect to the intrinsic resistivity at a given ambient temperature as well as the irradiation dosage. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Co-reporter:Yi-hu SONG, Qiang ZHENG, Cheng LIU
Chemical Research in Chinese Universities 2008 Volume 24(Issue 5) pp:644-647
Publication Date(Web):September 2008
DOI:10.1016/S1005-9040(08)60135-X
Abstract
Environmentally friendly biocomposites were prepared by blending wheat gluten(WG) as a matrix, hydroxyethyl cellulose(HEC) as a filler, and glycerol as a plasticizer, followed by thermo-molding of the mixture at 120 °C for crosslinking the matrix. Moisture absorption, tensile properties, dynamic mechanical analysis, and dynamic rheology were evaluated in relation to the glycerol content. Tensile strength and modulus drop dramatically with increasing glycerol content, which is accompanied by significant depression in the glass transition temperature and improvement in the extensibility of the biocomposites.
Co-reporter:Yihu Song;Qiang Zheng
Macromolecular Symposia 2008 Volume 261( Issue 1) pp:137-143
Publication Date(Web):
DOI:10.1002/masy.200850118
Abstract
Summary: A novel approach of the percolation behavior in conductive composites was proposed on the basis of Landau mean-field theory. The percolation transition is treated as a concentration-derived phase transition of conductive particles from dispersion to flocculation so as to form a dissipative percolating network. A formulation of conductivity as a function of filler volume fraction in the percolation transition region was established, which was validated in high-density polyethylene/carbon black (HDPE/CB) composites from two different laboratories and also in cured epoxy/CB composites of Fournier et al. At high CB concentrations above the percolation threshold, the conductive behavior in HDPE/CB composites follows the statistical percolation theory.
Co-reporter:Yihu Song;Qiang Zheng
Journal of Applied Polymer Science 2007 Volume 105(Issue 2) pp:710-717
Publication Date(Web):2 APR 2007
DOI:10.1002/app.26076
The high-density polyethylene/carbon black (HDPE/CB) composite with a CB volume fraction of 0.113 is isothermally annealed at various temperatures from 116 to 149°C, covering the positive temperature coefficient (PTC) transition and the negative temperature coefficient regions during heating as well as from 149 to 122°C above the reverse-PTC transition during cooling. Influences of annealing temperature on the resistance–temperature and the resistance–time characteristics are discussed. The results show that both the resistance-temperature and the resistance-time characteristics are highly sensitive to the thermal history. Effects of recrystallization of HDPE and redistribution of CB aggregates in HDPE on the performance are discussed. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Co-reporter:Yihu Song;Qiang Zheng
Journal of Applied Polymer Science 2006 Volume 99(Issue 3) pp:1124-1131
Publication Date(Web):18 NOV 2005
DOI:10.1002/app.22294
The time dependences of electrical conduction and self-heating behaviors in high-density polyethylene filled with acetylene carbon black of 0.082 in volume fraction are studied in relation to voltage and ambient temperature. The characteristic decay current constant τi, and the exponential growth time constant for self-heating τg are determined for the samples under voltages U above the critical value Uc for the onset of self-heating. The influences of voltage and ambient temperature on τi and τg as well as the amplitude of the low-resistance to high-resistance switching are discussed on the basis of the random resistor network (RRN) model and the relationship between Uc and the intrinsic resistivity. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1124–1131, 2006
Co-reporter:Yihu Song;Qiang Zheng
Journal of Applied Polymer Science 2006 Volume 101(Issue 6) pp:4418-4422
Publication Date(Web):27 JUN 2006
DOI:10.1002/app.23355
The time dependences of electrical conduction and self-heating in high-density polyethylene/acetylene carbon black composites crosslinked with electron beam irradiation at three different dosages are studied in relation to voltage and ambient temperature. The characteristic decay current constant (τi) and the exponential growth time constant for self-heating (τg) are determined for the samples under voltages (U) above the onset voltage (Uc) of self-heating. The influence of crosslinking on the current decay dynamics, self-heating process, and amplitude of the resistance switching under field action are discussed. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 4418–4422, 2006
Co-reporter:Qiang Zheng
Journal of Polymer Science Part B: Polymer Physics 2006 Volume 44(Issue 14) pp:1979-1984
Publication Date(Web):2 JUN 2006
DOI:10.1002/polb.20856
At the electric–thermal equilibrium state, the nonlinear conduction behaviors of high-density polyethylene/acetylene carbon black composites crosslinked with electron-beam irradiation have been studied in wide ranges of electric field and ambient temperature. Critical electric field E0.5 at the global electrical breakdown and the corresponding apparent resistivity are related to the intrinsic resistivity at given ambient temperatures. The relationship between the nonlinear conduction and the intrinsic positive temperature coefficient effect of resistivity is established by a discussion of E0.5 as a function of the macroscopic resistivity temperature coefficient. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 1979–1984, 2006
Co-reporter:Qiang Zheng
Journal of Polymer Science Part B: Polymer Physics 2005 Volume 43(Issue 18) pp:2484-2492
Publication Date(Web):27 JUL 2005
DOI:10.1002/polb.20529
The electric self-heating and conduction behaviors of a high-density polyethylene/carbon black composite at the electric–thermal equilibrium state are studied. An equation describing the current density/electric-field strength (J–E) characteristic is derived on the basis of an equation proposed for the self-heating temperature as a function of the field strength. The conduction is related to the electronic tunneling and the resistor breakdown due to self-heating that dominate the nonlinear J–E characteristic below and above a critical field strength corresponding to the J maximum, respectively. The influences of the initial structure of the percolation network and the physical state of the matrix on the conduction are also discussed on the basis of scaling arguments of the self-heating and the nonlinear J–E characteristic with respect to the initial resistivity at various ambient temperatures from 19 to 120 °C. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 2484–2492, 2005
Co-reporter:Yihu Song;Qiang Zheng
Polymer International 2004 Volume 53(Issue 10) pp:
Publication Date(Web):22 JUL 2004
DOI:10.1002/pi.1578
The electric self-heating behavior of carbon black (CB) filled high-density polyethylene (HDPE) was studied in relation to the time-dependent current and surface temperature under various voltages and to the voltage-dependent surface temperature at electric–thermal equilibrium. The resistance increase due to self-heating restricts the current flow through the sample and thus stabilizes the electric power and the self-heating temperature to their saturation values, which vary with the voltage. A simple phenomenological model shows that self-heating at electric-thermal equilibrium is involved in the initial resistance, the electric field induced positive temperature coefficient (PTC) transition and the heat dissipation. The influences of annealing and irradiation crosslinking on the self-heating behavior are discussed. Copyright © 2004 Society of Chemical Industry
Co-reporter:Yihu Song;Qiang Zheng;Xiao-Su Yi
Journal of Polymer Science Part B: Polymer Physics 2004 Volume 42(Issue 7) pp:1212-1217
Publication Date(Web):10 FEB 2004
DOI:10.1002/polb.10766
The reversible nonlinear conduction (RNC) in of high-density polyethylene/acetylene carbon black composites with different degrees of crosslinking was studied above room temperature and below the melting point of high-density polyethylene (HDPE). The experimental current density-electric field strength curves can be overlapped onto a master curve, suggesting that the microscopic mechanisms for the appearance of RNC exist regardless of the ambient temperature and the crosslinking degree of the HDPE matrix. The relationship between the crossover current density and the linear conductivity can be explained in the framework of the dynamic random-resistor-network model. According to these results, two electron-tunneling models are suggested to interpret the microscopic conduction behavior. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1212–1217, 2004
Co-reporter:Yihu Song, Qiang Zheng, Qibin Zhang
Journal of Cereal Science (November 2009) Volume 50(Issue 3) pp:376-380
Publication Date(Web):1 November 2009
DOI:10.1016/j.jcs.2009.07.004
The present work aims to investigate the dynamic rheology at small strains and the equibiaxial extensional deformation at large strain of the glycerol plasticized dough of gluten- and glutenin-rich fractions and their mixture as well as the uniaxial tension deformation behavior of the compression molded bioplastics. The influence of glutenin-to-gluten ratio (GGR) on the rheological properties of the glycerol plasticized doughs and the crosslinked bioplastics were investigated. The results showed that the glutenin dough exhibits higher moduli and lower loss factor and equibiaxial deformability in comparison with the gluten dough. Addition of a glutenin-rich fraction to the gluten dough can improve elasticity at small deformation and extensional deformational stress at large deformations but result in reductions in extensibility of the compression molded bioplastics.
Co-reporter:Zuo Min, Yihu Song, Qiang Zheng
Journal of Cereal Science (November 2008) Volume 48(Issue 3) pp:794-799
Publication Date(Web):1 November 2008
DOI:10.1016/j.jcs.2008.06.003
The present work aims to study the influence of reducing agents of sodium bisulfite, sodium sulfite and thioglycolic acid on the equibiaxial extensional deformation of glycerol plasticized wheat gluten and the properties of gluten bioplastics thermo-molded at 125 °C. Moisture absorption, weight loss and water uptake, uniaxial tensile properties (Young's modulus, tensile strength, elongation at break and tensile set), and morphology observations were performed to characterize the physical properties of the thermo-molded gluten bioplastics. The results showed that reducing agents facilitated the viscous flow and restrained the elastic recovery of the plasticized gluten while not hindering the crosslinking reaction of gluten proteins during thermo-molding. On the contrary, reducing agents do not significantly influence moisture absorption, Young's modulus, tensile strength and the morphology of the gluten bioplastics thermo-molded at 125 °C. It is shown that reducing agents are highly effective for tailoring the flow viscosity of the plasticized gluten dough and the mechanical properties of thermo-molded gluten bioplastics.
Co-reporter:Shaomin Sun, Yihu Song, Qiang Zheng
Journal of Cereal Science (November 2008) Volume 48(Issue 3) pp:613-618
Publication Date(Web):1 November 2008
DOI:10.1016/j.jcs.2008.01.005
Glycerol-plasticized wheat gliadin bioplastics were prepared through thermo-molding method. The effect of glycerol content on the morphology and the mechanical properties of wheat gliadin bioplastics was studied. Morphology, tensile properties (tensile strength and elongation at break), dynamic mechanical properties and rheological properties were evaluated in relation to glycerol content. Experimental results reveal that the morphology, the glass transition temperatures (Tg) of both the gliadin-rich and the glycerol-rich domains and the tensile properties are closely linked to the glycerol content. The time–temperature superposition (TTS) fails to be applied to the dynamic loss modulus G″ (all temperatures) and the dynamic storage modulus G′ (above 80 °C) of wheat gliadin bioplastics.
Co-reporter:Yihu Song, Qiang Zheng
Journal of Cereal Science (July 2008) Volume 48(Issue 1) pp:58-67
Publication Date(Web):1 July 2008
DOI:10.1016/j.jcs.2007.08.001
The aim of the present work has been to study the equibiaxial extensional deformation of doughs of gluten- and glutenin-rich fractions containing 40 wt% water subjected to lubricated squeezing flow with four different crosshead speeds at room temperature. The gluten dough shows strain softening and hardening in succession whilst the dough where the gliadins have been removed by alcohol extraction does not show strain hardening behavior but breaks immediately after strain softening. The equibiaxial extensional viscosity decreases with increasing strain rate at given strains, appearing as strain rate thinning behavior, which is stronger in the glutenin dough than in the gluten dough. The large extensibility with strain hardening in the gluten dough is due to the presence of gliadins acting as both plasticizers and promoters for the more extensible networks.
Co-reporter:Yihu Song, Qiang Zheng
Journal of Cereal Science (July 2008) Volume 48(Issue 1) pp:77-82
Publication Date(Web):1 July 2008
DOI:10.1016/j.jcs.2007.08.007
The present work aims to prepare bioplastics from a glutenin-rich fraction; that is, the gluten residue insoluble in 70% (v/v) ethanol. The influence of reducing agents of sodium bisulfite, sodium sulfite and thioglycolic acid on the properties of the glycerol plasticized doughs and the cross-linked bioplastics were investigated. The results showed that reducing agents can be applied to reduce the Young's modulus of the plasticized dough and to improve the Young's modulus of the cross-linked bioplastics. Moisture absorption, weight loss in water, tensile strength, elongation at break and tensile set were studied to characterize the physical properties of the cross-linked bioplastics.
Co-reporter:Shaomin Sun, Yihu Song, Qiang Zheng
Journal of Food Engineering (January 2009) Volume 90(Issue 2) pp:207-211
Publication Date(Web):1 January 2009
DOI:10.1016/j.jfoodeng.2008.06.024
Rheological properties of wheat gliadins in 50% (v/v) aqueous propanol were carried out as functions of gliadin concentration C and temperature. The solutions at 20 g L−1 to 200 g L−1 behave as Newtonian fluids with flow activation energy Ea of 23.5–27.3 kJ mol−1. Intrinsic viscosity [η] and Huggins constant kH are determined according to Huggins plot at C ⩽ 120 g L−1. The results reveal that gliadins are not spherical shaped in 50% (v/v) aqueous propanol and the molecular size tends to increase with temperature due to improved solvation.
Co-reporter:Yihu Song, Yeqiang Tan, Qiang Zheng
Polymer (10 March 2017) Volume 112() pp:35-42
Publication Date(Web):10 March 2017
DOI:10.1016/j.polymer.2017.01.069
Co-reporter:Yiting Xu, Qiang Zheng and Yihu Song
Physical Chemistry Chemical Physics 2015 - vol. 17(Issue 30) pp:NaN19819-19819
Publication Date(Web):2015/06/19
DOI:10.1039/C5CP02463C
Novel nanoparticle ionic liquids (NILs) are prepared by grafting modified nanoparticles with long-chain ionic liquids (ILs). The NIL behaves like a liquid at ambient temperature. We studied the rheological behavior of the IL and NIL over the range of 10–55 °C and found an extraordinary difference between the IL and NIL: a small content of nanosilica (7%) moderately improves the crystallinity by 7% of the poly(ethylene glycol) (PEG) segment in the IL, and it improves the dynamic moduli significantly (by 5 times at room temperature). It retards the decay temperature (by 10 °C) of the dynamic moduli during heating as well. The thermal rheological hysteresis observed during heating–cooling temperature sweeps is ascribed to the melting–recrystallization of the PEG segments. Meanwhile, the IL and NIL express accelerated crystallization behavior in comparison with the oligomeric anion. For the first time, we find that ILs and NILs are able to form nanoparticle-containing spherulites at room temperature after long time aging.
Co-reporter:Jianliang Xiao, Weiyang Lv, Zhou Xie, Yeqiang Tan, Yihu Song and Qiang Zheng
Journal of Materials Chemistry A 2016 - vol. 4(Issue 31) pp:NaN12135-12135
Publication Date(Web):2016/07/07
DOI:10.1039/C6TA04119A
π–π interactions between graphene and organic dyes with a conjugate aromatic structure play a key role in the field of high-efficiency, broad-spectrum adsorbents for the removal of water contaminants. L-Cysteine reduced graphene oxide (RGO-Cys) has a good conjugate structure and dispersity in aqueous solution, endowing it with great adsorption efficiency towards anionic, nonionic and cationic dyes with a conjugate aromatic structure mainly via π–π interactions, as proved by the Raman spectrum and special adsorption experiments. The maximum adsorption capability for anionic indigo carmine (IC) and cationic neutral red (NR) is as high as 1005.7 mg g−1 and 1301.8 mg g−1, respectively, the former being the highest among those reported for adsorbents known to date. The total adsorption amount in mixed dye solutions is even higher (>3500 mg g−1), the highest total capability for simultaneous adsorption of anionic and cationic dyes in their solution mixtures. The π–π stacking adsorption mechanism ensures RGO-Cys to be used as a broad-spectrum adsorbent with high efficiency for many kinds of dye contaminants in water while the remnant carboxyl groups on graphene nanosheets facilitate effective adsorption towards Cu2+ with a capability as high as 139.2 mg g−1, opening up many possibilities for the use of graphene in water cleaning including disinfection, decontamination, and desalination.
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