Co-reporter:Sizhu Wu;Bin Dong;Youping Wu;Liqun Zhang
Industrial & Engineering Chemistry Research May 4, 2016 Volume 55(Issue 17) pp:4919-4929
Publication Date(Web):2017-2-22
DOI:10.1021/acs.iecr.6b00214
High-concentration reduced graphene oxide (RGO) solution was produced using gelatin (Gel) as the stabilizer and subreductant and hydrazine hydrate (HHA) as the main reductant. The Gel-HHA-RGO nanosheets exhibited excellent colloidal dispersibility and stability in alkaline condition. The Gel-HHA-RGO filled natural rubber (NR) composites were prepared by water-based solution casting. Well-organized interconnected RGO networks were constructed throughout the NR matrix, which played an important role in determining the properties of composites. The tensile modulus and dynamic storage modulus were improved by several orders of magnitude with increasing RGO content. Meanwhile, a dramatic increase in electrical conductivity with a low percolation threshold of 0.21 vol % was perceived. Strain-sensing tests revealed that the RGO/NR composites exhibited outstanding strain sensitivity and repeatability, which could be used to detect the cyclic movements of human joints. The results are promising in the rubber industry to guide the fabrication of highly sensitive and stretchable strain sensors for engineering application.
Co-reporter:Huanyu Zhang, Jianping DengYouping Wu
ACS Sustainable Chemistry & Engineering 2017 Volume 5(Issue 1) pp:
Publication Date(Web):November 23, 2016
DOI:10.1021/acssuschemeng.6b02018
This contribution reports a novel category of sustainable aldehyde-containing magnetic microspheres (ACMMs) prepared through suspension polymerization. For preparing the ACMMs, lignin-derived vanillin methacrylate (VMA) was used as biobased monomer, while methacrylated-Fe3O4 NPs were used as magnetic supplier. The resulting microspheres were proved to have remarkable magnetic property and adsorption capacity toward paraanisidine, which was employed as a representative of amines. The maximum adsorption was found to be up to 433 mg/g (559 mg/g in theory). Also noticeably, the adsorption was realized by forming a reversible Schiff base under mild conditions. Desorption processes were performed conveniently, proving that the ACMMs can be easily recycled. This work demonstrates the remarkable potentials of ACMMs to be used as scavenger resins in absorbing amines. Also worthy to be highlighted is that the abundant aldehyde groups enable the microspheres to be a promising platform for further preparing functional polymers by employing the Schiff base structure as linking parts, e.g. as biomaterials for immobilizing enzymes.Keywords: Aldehyde; Biomass; Magnetic spheres; Polymers; Schiff base;
Co-reporter:Bin Dong, Liqun Zhang, Youping Wu
Polymer Testing 2017 Volume 63(Volume 63) pp:
Publication Date(Web):1 October 2017
DOI:10.1016/j.polymertesting.2017.08.035
The dimensions of reinforcing filler is a key factor in influencing the fracture and fatigue of rubbers. Here, the fracture and fatigue resistance of natural rubber (NR) filled with different dimensional carbon-based fillers including zero-dimensional spherical carbon black (CB), one-dimensional fibrous carbon nanotubes (CNTs) and two-dimensional planar graphene oxide (GO) were explored. To obtain equal hardness, a control indicator in the rubber industry, the amounts of CB, CNTs, and GO were 10.7 vol%, 1.2 vol%, and 1.6 vol%, respectively. J-integral and dynamic fatigue tests revealed that NR filled with CB exhibited the best quasi-static fracture resistance and dynamic crack growth resistance. The much higher hysteresis loss of NR filled with CNTs weakened its fatigue resistance. The planar GO played a limited role in preventing crack growth. Furthermore, digital image correlation revealed that NR filled with CB had the highest strain amplification level and area at the crack tip, which dissipated the most local input energy and then improved the fracture and fatigue performance.
Co-reporter:Zheng Sun;Qiang Huang;Liqun Zhang;Youzhi Wang;Youping Wu
RSC Advances (2011-Present) 2017 vol. 7(Issue 62) pp:38915-38922
Publication Date(Web):2017/08/08
DOI:10.1039/C7RA07321F
The filler–rubber interface is crucial in preparing ideal filled rubber composites. Interface modifiers are typically used for enhancing silica–rubber interactions and facilitating silica dispersion. In this work, trimethylolpropane tris(3-mercaptopropionate) (TMPMP) was found to be particularly effective in dispersing silica and the mechanism was investigated. Furthermore, the mercapto groups of TMPMP were reacted in gradient with the vinyl groups of vinyltriethoxysilane (VTES), which formed a series of interface modifiers with enhanced modifier–silica interactions and reduced modifier–rubber interactions. After applying the modifiers in silica filled rubber composites, the Payne effect, bound rubber content, dispersion morphology, mechanical and viscoelastic properties were studied. The results indicated that the interface modifiers with multiple functional groups were capable of purposefully balancing the interactions between rubber and silica, which brought about flexibility to optimize composite properties.
Co-reporter:Zheng Sun, Qiang Huang, Youzhi Wang, Liqun Zhang, and Youping Wu
Industrial & Engineering Chemistry Research 2017 Volume 56(Issue 6) pp:
Publication Date(Web):January 23, 2017
DOI:10.1021/acs.iecr.6b04146
The low surface energy of silicone rubber (SiR) makes it difficult to blend SiR with conventional rubbers such as solution styrene−butadiene rubber (SSBR) and natural rubber. In this study, to enhance the interface interaction between SiR and SSBR, trimethylolpropane tris(3-mercaptopropionate) (TMPMP) was carefully chosen to couple SiR and SSBR by in situ thiol-ene click reactions between mercapto groups of TMPMP and vinyl groups of SiR and SSBR. The reaction of TMPMP with SiR and SSBR was characterized via torque–time curves, element analysis, and the dissolving–swelling test. Accordingly, a two-step strategy was proposed to prepare SiR/SSBR composites. Transmission electron microscopy indicated that the two-step strategy reduced the phase domain size of the blend. The composite exhibited higher mechanical properties and lower hysteresis. The results would extend SiR applications.
Co-reporter:Huanyu Zhang, Xueyong Yong, Jinyong Zhou, Jianping Deng, and Youping Wu
ACS Applied Materials & Interfaces 2016 Volume 8(Issue 4) pp:2753
Publication Date(Web):January 11, 2016
DOI:10.1021/acsami.5b11042
The contribution reports the first polymeric microspheres derived from a biomass, vanillin. It reacted with methacryloyl chloride, providing monomer vanillin methacrylate (VMA), which underwent suspension polymerization in aqueous media and yielded microspheres in high yield (>90 wt %). By controlling the N2 bubbling mode and by optimizing the cosolvent for dissolving the solid monomer, the microspheres were endowed with surface pores, demonstrated by SEM images and mercury intrusion porosimetry measurement. Taking advantage of the reactive aldehyde groups, the microspheres further reacted with glycine, thereby leading to a novel type of Schiff-base chelating material. The functionalized microspheres demonstrated remarkable adsorption toward Cu2+ (maximum, 135 mg/g) which was taken as representative for metal ions. The present study provides an unprecedented class of biobased polymeric microspheres showing large potentials as adsorbents in wastewater treatment. Also importantly, the reactive aldehyde groups may enable the microspheres to be used as novel materials for immobilizing biomacromolecules, e.g. enzymes.Keywords: adsorbent; biomass; polymer microspheres; Schiff-base; vanillin
Co-reporter:Zijian Zheng, Jianxiang Shen, Jun Liu, Youping Wu, Liqun Zhang and Wenchuan Wang
RSC Advances 2016 vol. 6(Issue 34) pp:28666-28678
Publication Date(Web):14 Mar 2016
DOI:10.1039/C6RA01827K
Tuning the viscoelasticity of polymeric materials by incorporating nanoparticles (NPs) has received considerable scientific and technological interests. Contrary to increasing the energy dissipation for damping materials, here we direct our attention to study how to decrease the energy dissipation of elastomer nanocomposites (ENCs) under periodic dynamic loading–unloading cycles. Through molecular dynamics simulation, we firstly simulate the pure cis-polybutadiene (cis-PB) system, by calculating the mean-squared end-to-end distance and the radius of gyration as a function of the chain length, the diffusion coefficient of polymer chains as a function of the temperature, the glass transition temperature, the stress–strain curves at different strain rates and temperatures, the tension–recovery and compression–recovery curves at various cross-linking densities. These results validate the accuracy of the united atom model and force-field of cis-PB. Then we show that the incorporation of flexible nanoparticles (NPs) such as graphene nanoribbons and carbon nanotubes can effectively decrease the dynamic hysteresis loss, by taking advantage of the reversible mechanical deformation of the anisotropic NPs. This effect can be further strengthened by the stronger interfacial interaction, higher loading and larger size of this kind of NPs. The underlying reason stems from the synergistic motion between the NPs and their surrounding polymer chains, leading to much smaller internal friction. This work may open up potential opportunities to fabricate high-performance polymer nanocomposites, such as energy-saving ENCs tailored for tire tread.
Co-reporter:Jie Liu;Ru Cheng;Jianping Deng;Youping Wu
Polymers for Advanced Technologies 2016 Volume 27( Issue 2) pp:169-177
Publication Date(Web):
DOI:10.1002/pat.3615
Chiral, pH-responsive hydrogels are constructed by poly(ethylene glycol) diacrylate/α-cyclodextrin (PEGDA/α-CD) inclusion complex and L-N-acryloyl-alanine or D-N-acryloyl-alanine (L-NAA or D-NAA) by an effective free radical polymerization approach. PEGDA containing two C=C end groups was used simultaneously to introduce α-CD units in the resulting hydrogels and to serve as a cross-linking agent, by which forming the designed hydrogels in quantitative yield. Hydrophilic α-CD moieties acted as pore-forming agent, while the L(D)-NAA-based polymer chains bearing –COOH groups enabled the hydrogels to display remarkable swelling–deswelling behavior in response to pH variation. The chiral NAA monomer-derived polymer chains rendered the hydrogels with intriguing optical activity, according to circular dichroism spectra. Scanning electron microscopy revealed the uniformly porous microstructures of hydrogels. More remarkably, the L-NAA-based hydrogels preferentially adsorbed trans-4-hydroxy-d-proline and preferentially released trans-4-hydroxy-l-proline, while D-NAA-based hydrogels provided opposite results. The hydrogels also demonstrated remarkable enantioselective release ability towards chiral drug ibuprofen. Copyright © 2015 John Wiley & Sons, Ltd.
Co-reporter:Bin Dong, Chang Liu, Liqun Zhang and Youping Wu
RSC Advances 2015 vol. 5(Issue 22) pp:17140-17148
Publication Date(Web):02 Feb 2015
DOI:10.1039/C4RA17051B
Exfoliated graphene oxide (GO) reinforced natural rubber (NR) composites were prepared by a simple and promising latex co-coagulation method. Latex co-coagulation realized the complete exfoliation and uniform dispersion of GO in a NR matrix. The quasi-static fracture and dynamic fatigue behaviors of the composites were investigated. Mechanical properties and J-testing were used to characterize the fracture resistance, and fatigue tests were carried out under cyclic conditions of constant strain. Results revealed that with increasing GO sheet content, the mechanical properties, fracture initiation and propagation resistance were all highly improved. A much higher reinforcing efficiency of GO sheets than that of traditional fillers was realized. Fatigue crack growth resistance was remarkably enhanced with the incorporation of only 1 phr GO sheets. The relatively weak fatigue resistance of composites filled with 3 phr and 5 phr GO was attributed to their high hysteresis loss and tearing energy input. It revealed that GO sheets would be promising fillers in preparation of rubber composites with high fracture and fatigue resistance at low filler content.
Co-reporter:Bin Dong;Chang Liu;Yonglai Lu;Youping Wu
Journal of Applied Polymer Science 2015 Volume 132( Issue 25) pp:
Publication Date(Web):
DOI:10.1002/app.42075
ABSTRACT
The quasi-static fracture and dynamic fatigue behaviors of natural rubber composites reinforced with hybrid carbon nanotube bundles (CNTBs) and carbon black (CB) at similar hardness values were investigated on the basis of fracture mechanical methods. Mechanical measurement and J-integral tests were carried out to characterize the quasi-static fracture resistance. Dynamic fatigue tests were performed under cyclic constant strain conditions with single-edged notched test pieces. The results indicate that synergistic effects between CNTBs and CB on the mechanical properties, fracture, and fatigue resistance were obtained. The composite reinforced with 3-phr CNTBs displayed the strongest fatigue resistance. The synergistic mechanisms and dominating factors of quasi-static and dynamic failure, such as the dispersion state of nanotubes, hybrid filler network structure, strain-induced crystallization, tearing energy input, and viscoelastic hysteresis loss, were examined. The weakest fatigue resistance of the composite filled with 5-phr CNTBs was ascribed to its strikingly high hysteresis, which resulted in marked heat generation under dynamic fatigue conditions. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42075.
Co-reporter:Ru Cheng, Jie Liu, Peng Xie, Youping Wu, Jianping Deng
Polymer 2015 Volume 68() pp:246-252
Publication Date(Web):26 June 2015
DOI:10.1016/j.polymer.2015.05.034
•Chiral, pH-sensitive hydrogels contained both chemical and physical cross-linking.•The hydrogels showed enantio-differentiating release performance toward prolines.•The hydrogels showed enantioselective release toward racemic ibuprofen drug.Both pH-sensitive hydrogels and chiral hydrogels have evoked large interest in recent years. In the study, we designed and prepared a novel type of hydrogels simultaneously showing pH-sensitivity and chirality. Such hydrogels were prepared by free radical co-polymerization using N-acryloyl-l-alanine as chiral hydrophilic monomer and octadecyl acrylate as hydrophobic monomer, with K2S2O8 as initiator and N,N′-methylenebisacrylamide as chemical cross-linking agent. The obtained hydrogels exhibited remarkable pH-sensitive swelling ability in water. The optical activity of the hydrogels was characterized using circular dichroism spectroscopy. More interestingly, the hydrogels showed enantio-differentiating release ability towards proline enantiomers, in which d-proline was preferentially released. The hydrogels also demonstrated remarkable enantio-differentiating release ability toward chiral drug ibuprofen.
Co-reporter:Huajun Huang;Chunni Chen;Dongyue Zhang;Jianping Deng;Youping Wu
Macromolecular Rapid Communications 2014 Volume 35( Issue 9) pp:908-915
Publication Date(Web):
DOI:10.1002/marc.201400046
Co-reporter:Peng Xie, Xuan Liu, Ru Cheng, Youping Wu, and Jianping Deng
Industrial & Engineering Chemistry Research 2014 Volume 53(Issue 19) pp:8069
Publication Date(Web):April 23, 2014
DOI:10.1021/ie500538x
Both chiral hydrogels and pH-sensitive hydrogels have received considerable attention in recent years. In the present study, we combined the two intriguing concepts, i.e., chirality and pH sensitivity, in one single hydrogel. Such hydrogels were prepared via free radical copolymerization using chiral N-acryloyl-l-alanine (NAA) as monomer, the inclusion complex of glycidyl methacrylate (GMA) and hydroxypropyl-β-cyclodextrin (HP-β-CD) as comonomer, N,N′-methylenebis(acrylamide) as cross-linking agent, and K2S2O8 as initiator. The hydrogels were successfully obtained and exhibited remarkable swelling in water and pH responsivity. The hydrogels were characterized by circular dichroism and UV–vis absorption spectroscopies, demonstrating the optical activity of the hydrogels. The hydrogels performed chiral recognition and enantiodifferentiating release abilities toward proline enantiomers, in which l-proline was preferentially adsorbed whereas d-proline was preferentially released. The present study established a platform for preparing versatile, in particular, optically active hydrogels. Noticeably, the hydrogels are expected to find practical applications as novel materials for chiral drugs delivery.
Co-reporter:Xuan Liu, Ru Cheng, Jianping Deng and Youping Wu
RSC Advances 2014 vol. 4(Issue 90) pp:48796-48803
Publication Date(Web):19 Sep 2014
DOI:10.1039/C4RA07476A
A novel type of magnetic composite particles was constructed using helical poly(n-hexyl isocyanate) and Fe3O4. For this purpose, well-defined 4-ethynylbenzyloxy-terminal poly(n-hexyl isocyanate)s (PHIC–CCs) were synthesized via coordination polymerization by using an organotitanium catalyst. The PHIC–CCs were characterized by GPC, FT-IR and 1H NMR techniques. UV-vis absorption spectra demonstrated that the PHIC–CCs adopted dynamic helical structures in tetrahydrofuran. Azide-modified magnetic Fe3O4 nanoparticles (Fe3O4@N3 NPs) were prepared through the reaction between 3-azidopropyltrimethoxysilane and oleic acid-coated magnetic Fe3O4 NPs. The obtained clickable PHIC–CC and Fe3O4@N3 NPs were subjected to the Cu-catalyzed azide/alkyne cycloaddition for synthesizing the anticipated Fe3O4@PHIC composite NPs. FT-IR, TGA and TEM techniques confirmed the formation of the magnetic composite nanoparticles. UV-vis absorption spectra demonstrated that the PHIC chains coated on the magnetic Fe3O4 NPs adopted dynamic helical structures. XRD measurements revealed that coating PHIC chains on Fe3O4 nanoparticles did not change the phase properties of Fe3O4 nanoparticles. The Fe3O4@PHIC composite NPs showed a saturation magnetization of 17.8 emu g−1 and the expected rapid magnetic responsivity.
Co-reporter:Bin Dong, Chang Liu, You-Ping Wu
Polymer Testing 2014 Volume 38() pp:40-45
Publication Date(Web):September 2014
DOI:10.1016/j.polymertesting.2014.06.004
J-integral theory and fatigue testing were adopted to investigate the fracture and fatigue properties of silica/carbon black (CB)/natural rubber composites with total filler content of 50 phr. Critical J-value JIC and tearing modulus TR, were obtained. JIC, as an indicator of crack initiation resistance, was dependent on the pre-cut length. TR was related to the crack propagation of the composite. With increasing the silica/CB ratio, both JIC and TR were enhanced, indicating that the resistance to crack initiation and propagation were improved. The strain energy density at a fixed strain decreased with an increase in the silica/CB ratio. Fatigue testing under constant tensile strain conditions demonstrated that the composite with higher silica/CB ratio exhibited lower cyclic crack growth rate and longer fatigue life. This was in accordance with the results of TR, JIC and strain energy density of the composite, hence TR, JIC and strain energy density of the composite can be used to predict its fatigue properties.
Co-reporter:Xuan Liu, Haiyang Zhang, Ru Cheng, Jianping Deng, Youping Wu
Synthetic Metals 2014 Volume 195() pp:167-176
Publication Date(Web):September 2014
DOI:10.1016/j.synthmet.2014.05.023
•A novel type of helical polymer brushes was constructed.•4-Ethynylbenzyloxy-containing poly(n-hexyl isocyanate)s were synthesized.•The polymer brushes showed chiral recognition ability.4-Ethynylbenzyloxy-containing poly(n-hexyl isocyanate)s (defined as M-PHICs) were synthesized via coordination polymerization by using organotitanium catalyst. The M-PHICs were characterized by GPC, FT-IR, NMR, mass spectrometry (MALDI-TOF MS) and elemental analysis techniques. UV–vis spectra demonstrated that the M-PHICs adopted reversible helical structures in solution. The obtained M-PHICs were then used as macromonomers and subjected to Rh-catalyzed coordination polymerization to form helical polymer brushes composed of helical polyacetylene backbones and meanwhile helical poly(n-hexyl isocyanate) pendants. Additionally, the M-PHICs underwent catalytic copolymerizations with chiral N-propargyl-(S)-camphanamide (M1), to form copolymer brushes consisting of polyacetylene backbones and PHIC pendants. GPC, FT-IR and NMR confirmed the formation of the two types of helical polymer brushes. UV–vis spectra indicated that both the polyacetylene backbones and the PHIC pendants in the (co)polymer brushes adopted dynamic helical structures. Circular dichroism effects demonstrated that the presence of chiral M1 units led to preferred-handed helical conformations in the polyacetylene backbones in the copolymer brushes. The copolymer brushes recognized (S)-(−)-1-phenylethylamine in the two enantiomers, demonstrating the potentials of such copolymer brushes in chiral recognition and chiral resolution.
Co-reporter:Ke-Lu Xiang, Pu-Yu Xiang, You-Ping Wu
Materials & Design 2014 57() pp: 180-185
Publication Date(Web):
DOI:10.1016/j.matdes.2013.12.044
Co-reporter:Lu Shi;Peng Xie;Zhimin Li;Youping Wu;Jianping Deng
Macromolecular Chemistry and Physics 2013 Volume 214( Issue 12) pp:1375-1383
Publication Date(Web):
DOI:10.1002/macp.201200729
Co-reporter:Lei Wang;Yi-Qing Wang;Li-Qun Zhang
Journal of Applied Polymer Science 2013 Volume 127( Issue 1) pp:765-771
Publication Date(Web):
DOI:10.1002/app.37781
Abstract
Rectorite (REC) powders modified by butadiene-styrene-vinyl pyridine rubber (VPR) were prepared by spray drying, designated as REC-VPRs. X-ray diffraction (XRD), Scanning electron microscope (SEM), and transmission electron microscopy (TEM) analyses showed that in the REC-VPRs, VPR did not intercalate into the intergallery of layers. However, compared with REC, the layers of REC-VPRs had more wrinkles and piled loosely. To strengthen the interfacial interaction between VPR and REC, a REC-VPR was treated by volatilized hydrochloric acid, resulting in the formation of ion bonds between REC and VPR, according to Fourier transform infrared spectra measurements. XRD analyses revealed that the intercalated structure emerged in acid treated REC-VPR filled styrene-butadiene rubber (SBR). However, the better dispersion was observed for the SBR composite filled with REC-VPR without acid treatment, indicating that a proper interfacial interaction between REC and VPR is the key to improve the dispersion of REC layers in SBR. Acid treatment did not improve the tensile and tear strengths of the SBR composite filled with REC-VPR. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci., 2013
Co-reporter:Lei Wang;Pu-Yu Xiang;Li-Qun Zhang
Journal of Applied Polymer Science 2013 Volume 128( Issue 4) pp:2578-2584
Publication Date(Web):
DOI:10.1002/app.38574
Abstract
Epoxidized natural rubber (ENR) was introduced into rectorite (REC)/carbon black/natural rubber (NR) nanocomposites by two ways: (1) the direct incorporation of ENR and (b) the incorporation of a spray-dried REC/ENR compound. Transmission electron microscopy and X-ray diffraction analysis showed that the REC layers presented a nanodispersion structure in the REC/ENR compound. The vulcanization characteristics indicated that ENR increased the crosslinking density of the composites. The stronger reaction between the REC layers and ENR was verified by Fourier transform infrared spectroscopy in the spray-dried REC/ENR compound blended with NR versus that in the REC/NR master batch blended with ENR. As a result, the physical properties, such as the mechanical properties, cutting and chipping resistance, and abrasion resistance, of the composites were greatly increased by the addition of the REC/ENR compound. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Co-reporter:Bin Wang, Jian Hua Ma, You Ping Wu
Materials & Design 2013 49() pp: 802-807
Publication Date(Web):
DOI:10.1016/j.matdes.2013.01.047
Co-reporter:Jian-Hua Ma;Yuan-Xia Wang;Li-Qun Zhang
Journal of Applied Polymer Science 2012 Volume 125( Issue 5) pp:3484-3489
Publication Date(Web):
DOI:10.1002/app.36710
Abstract
A novel, effective approach to improve the cutting and chipping resistance (CCR) of carbon black (CB)-filled styrene butadiene rubber (SBR) composite was reported in this study. CCR of SBR was dramatically improved more than 30% by addition of 4 phr nanodispersed clay (NC), while not decreasing the stress at 100% and the Shore A hardness of the composite. The curing characteristics, loss tangent (tan δ), and the strength of filler network of the composites were further measured by a Disk Oscillating Rheometer and a rubber processing analyzer, respectively. It was found that the addition of NC led to a slightly lower crosslink density, higher tan δ, and stronger filler network, which contributed to the higher CCR. Therefore, the novel layered NC is more efficient in improving CCR when compared with CB. The results are expected to promote the application of NC in rubber industry. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Co-reporter:Xuan Liu, Jianping Deng, Youping Wu, Liqun Zhang
Polymer 2012 Volume 53(Issue 25) pp:5717-5722
Publication Date(Web):30 November 2012
DOI:10.1016/j.polymer.2012.10.023
Co-reporter:Chen Ji, Shuai-Shuai Song, Li-Qun Zhang, You-Ping Wu
Carbohydrate Polymers 2011 Volume 86(Issue 2) pp:581-586
Publication Date(Web):15 August 2011
DOI:10.1016/j.carbpol.2011.04.076
Water-swellable composites were prepared by blending sodium acrylate (NaAA), additives, and chloroprene rubber (CR)/starch masterbatch which was pre-formed by latex compounding method. The effects of the content of dicumyl peroxide (DCP) on the properties of the composites were investigated. We found that an increase in DCP amount led to a large increase in water swelling ratio and meanwhile a decrease in the mass loss ratio. Further, the composites were swollen uniformly in water and thus kept their original shapes well. The hardness and stresses at 100% and 300% increased with the increase in DCP amount. The addition of DCP facilitated the homopolymerization of NaAA while decreased the esterification reaction between NaAA and CR, which was verified by vulcanization curves, DSC and FT-IR. The morphology of the composites before and after water immersion was observed by optical transmission microscopy and indicated that the starch was homogenously dispersed in the composites.
Co-reporter:Yuan-Xia Wang, You-Ping Wu, Wen-Ji Li, Li-Qun Zhang
Applied Surface Science 2011 Volume 257(Issue 6) pp:2058-2065
Publication Date(Web):1 January 2011
DOI:10.1016/j.apsusc.2010.08.129
Abstract
The wet skid resistance (WSR) of SSBR/BR(solution styrene–butadiene rubber/butadiene rubber) composites filled with carbon black, silica, and nano-diamond partly replacing carbon black or silica, respectively, was measured with a portable British Pendulum Skid Tester (BPST). A dynamic mechanical thermal analyzer was used to obtain the viscoelasticity of the composites. A 3D scanning white-light interfering profilometer was used and the scratch test performed to characterize surface roughness and micro-roughness, respectively, of the composites. WSR of the silica-filled composite was better than that of the carbon black-filled one, and further enhancement of WSR was obtained by replacing silica with nano-diamond. Tan δ of the composites at 0 °C, 10 Hz, and tensile strain of 2% did not show good correlation with WSR. The surface roughness of the composites had effects on WSR. The scratch test indicated that the higher the hardness of the filler in the composite, the higher the micro-hardness and the better the WSR. Therefore, the surface micro-hardness of the composites is an important factor affecting WSR, besides viscoelasticity and surface roughness.
Co-reporter:Shuai-Shuai Song;Hong-Bin Qi
Polymers for Advanced Technologies 2011 Volume 22( Issue 12) pp:1778-1785
Publication Date(Web):
DOI:10.1002/pat.1671
Abstract
The effects of the amounts of starch, sodium acrylate (NaAA) and dicumyl peroxide (DCP) on the properties of chloroprene rubber (CR)/starch/NaAA composites prepared by melting method were investigated. The results showed that the addition of starch improved the mechanical properties, but decreased the water-absorbing capacity of the composite, most likely due to the decrease in the local concentration of the main water-absorbing material sodium polyacrylate and the increase in crosslinking density of the composite resulting from the reaction between starch and CR. This reaction was verified by the vulcanized curves, DSC curves, and the cut surface morphology. The as-prepared composite demonstrated higher water-absorbing capacity, resulting from the incorporation of NaAA. The mechanical properties decreased with increasing the DCP loading, and the water-absorbing ratio is the maximum at 1.0 phr DCP. The tensile strength of the composite decreased significantly after water immersion, due to the absorbed water acting as a plasticizer. The extracted component from composites after water immersion is mainly sodium polyacrylate according to Fourier transform infrared (FT-IR) spectroscopy analysis. The morphology of the composites before and after water immersion was observed by optical transmission microscopy (OTM). The results indicated that the starch exhibits a good dispersion state, and the water-absorbing capacity results primarily from sodium polyacrylate. Copyright © 2010 John Wiley & Sons, Ltd.
Co-reporter:Yuan-Xia Wang, Jian-Hua Ma, Li-Qun Zhang, You-Ping Wu
Polymer Testing 2011 Volume 30(Issue 5) pp:557-562
Publication Date(Web):August 2011
DOI:10.1016/j.polymertesting.2011.04.009
The present article revisits the role of viscoelasticity in wet skid resistance (WSR) of rubber composites by comparing the effects of carbon black (CB) and silica on WSR. WSR was determined with a British Pendulum Skid Tester on a wet ground glass surface. Under shear and tensile modes, tanδ of the composites was measured at 0 °C and 10 Hz over a wide range of strain (0.7%–10%) via a dynamic mechanical analyzer. For CB-filled composites with nearly the same hardness, a high correlation coefficient (R2 = 0.98) between WSR and tanδ under both shear (0.7%–10%) and tensile (4%–7%) modes was obtained. Tanδ at tensile strain of 4% was thus adopted as a parameter to characterize viscoelasticity. For rubber composites with rough surface, WSR and tanδ showed a high correlation in styrene butadiene rubber (SBR) composites individually filled with CB and silica, while for rubber composites with smooth surface, a high correlation was also observed but did not depend on the type of filler. Silica-filled SBR composites showed higher WSR, when compared with those filled with CB, mainly due to the higher nanohardness of silica. All the above results demonstrate that WSR can be predicted from viscoelasticity for composites with similar surface roughness and micro-hardness.
Co-reporter:You-Ping Wu;Gui-Hua Liang;Li-Qun Zhang
Journal of Applied Polymer Science 2009 Volume 114( Issue 4) pp:2254-2260
Publication Date(Web):
DOI:10.1002/app.30649
Abstract
The influence of starch on the properties of carbon-black-filled styrene–butadiene rubber (SBR) composites was investigated. When the starch particles were directly melt-mixed into rubber, the stress at 300% elongation and abrasion resistance decreased evidently with increasing starch amount from 5 to 20 phr. Scanning electron microscopy observations of the abrasion surface showed that some apparent craters of starch particles were left on the surface of the composite, which strongly suggested that the starch particles were large and that interfacial adhesion between the starch and rubber was relatively weak. To improve the dispersion of the starch in the rubber matrix, starch/SBR master batches were prepared by a latex compounding method. Compared with the direct mixing of the starch particles into rubber, the incorporation of starch/SBR master batches improved the abrasion resistance of the starch/carbon black/SBR composites. With starch/SBR master batches, no holes of starch particles were left on the surface; this suggested that the interfacial strength was improved because of the fine dispersion of starch. Dynamic mechanical thermal analysis showed that the loss factor at both 0 and 60°C increased with increasing amount of starch at a small tensile deformation of 0.1%, whereas at a large tensile strain of 5%, the loss factor at 60°C decreased when the starch amount was varied from 5 to 20 phr. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Co-reporter:Yong Ma, Qi-Fang Li, Li-Qun Zhang and You-Ping Wu
Polymer Journal 2007 39(1) pp:48-54
Publication Date(Web):December 1, 2006
DOI:10.1295/polymj.PJ2006085
EPDM/organic clay (OC) nanocomposites were prepared by melt blending. XRD results showed that if OC mixed with EPDM matrix, macromolecule chains are difficult to intercalate into the layers while stearic acid (SA) could easily intercalate into the OC interlayers under pretreating conditions (S-OC) and expand the interlayer spacing 2.6 nm of OC to a wider distance of 3.9 nm; EPDM could not further expand the distance of S-OC during the followed mixing process and the structure SA intercalating into OC is kept. TEM observation showed S-OC improved the dispersion of OC in EPDM, and FT-IR results indicated the esterification reaction occurred between carboxyl groups of SA and hydroxyl groups of OC, which was believed to be the driving force of SA intercalation. The tensile strengths of the nanocomposites are improved with increasing amount of SA, and the stresses at low strain are almost the same, due to the physical interaction between OC and EPDM macromolecules.
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