Prevention of plasticizer leaching from polymers has been a difficult task. Conventional oily plasticizers (COPs) often migrate from rubber matrix, leading to a poor stability of rubber products and serious environmental problem during long-term use. In the present study, liquid isoprene (LIP) with appropriate molecular weight and no migration was prepared by anionic polymerization. The effects of LIP on the comprehensive properties of carbon black filled polyisoprene rubber (CB/IR) composites were compared with those of one COP, naphthenic oil (NPO). The results showed that LIP reduced the Mooney viscosity and apparent viscosity, and improved the processability of CB/IR composites. LIP improved the mixing efficiency and the dispersion of the CB particles because its compatibility with CB/IR composites was higher than the compatibility of NPO and CB/IR composites. Furthermore, LIP did not migrate from the CB/IR composites because of its participation in the vulcanization reaction. Compared with CB/IR/NPO composites, CB/IR/LIP composites possessed higher mechanical properties, better aging resistance and long-term dimensional stability. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41485.

Two miktoarm star-shaped rubbers with large-volume functional groups of 1,1-diphenylhexyl at the ends of arms (DMS–PB–SBR) and one miktoarm star-shaped rubber with n-butyl groups at the ends of arms (BMS–PB–SBR) were prepared by 1,1-diphenylhexyllithium (DPHLi) and n-butyl lithium as initiators, respectively. The molecular structures and morphological properties of the three rubbers (MS–PB–SBR) were studied and compared with those acquired from the blend consisting of star-shaped solution-polymerized butadiene styrene rubber (S-SSBR) and butadiene rubber (PBR) prepared by ourselves. The results showed that MS–PB–SBR exhibited a more uniform distribution of PBR phase and a smaller phase size of PBR than that of S-SSBR/PBR blend. It is found that MS–PB–SBR composites filled with CB showed the lower Payne effect than that of S-SSBR/PBR/CB composite, suggesting that the MS–PB–SBR/CB composite (particularly the DMS–PB–SBR/CB composites) would possess excellent mechanical properties, high wet-skid resistance, and low rolling resistance. For the studied MS–PB–SBR systems, the contribution of large-volume functional groups at the end of PBR molecular chains to decrease the rolling resistance was larger than that of Sn coupling effect. It is envisioned that the miktoarm star-shaped rubbers with 1,1-diphenylhexyl groups at the molecular ends would be useful for making treads of green tires. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2014, 131, 40002.

The common method for microbial desulfurization is the submerged cultivation method. However, its cost is high because of the high consumption of the medium. To cut costs and improve the desulfurization effect, the new half-submerged cultivation method was used in the microbial desulfurization of waste latex rubber (WLR) by Sphingomonas species With this method, much more WLR was added per unit volume of the culture medium to be desulfurized, and the desulfurization process was done without stirring. The technical conditions, such as the addition of WLR, the addition of polysorbate 80 (Tween 80), and the desulfurization time, for the half-submerged cultivation method were studied, and its desulfurization effect was compared with that of the traditional submerged cultivation method. The results show that the optimum conditions for the half-submerged cultivation method were the addition of 40% w/v WLR in the medium without Tween 80 and desulfurization for 10 days. The X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy results demonstrate that the decreases in the content of sulfur, SC bonds, and SS bonds on the surface of WLR after desulfurization by the half-submerged cultivation method were greater than those after desulfurization by the submerged cultivation method. The composite of waste latex rubber desulfurized by the submerged cultivation method (SDWLR) and styrene–butadiene rubber (SBR) had better mechanical properties than the composite of waste latex rubber desulfurized by the half-submerged cultivation method (HDWLR) and SBR. Scanning electron microscopy photographs showed that the combinations of HDWLR and the matrix were better than those of SDWLR and the matrix. Compared with the submerged cultivation method, the half-submerged cultivation method not only reduced the cost of desulfurization but also improved the desulfurization effect. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 41039.

The dynamic properties, including the dynamic mechanical properties, flex fatigue properties, dynamic compression properties, and rolling loss properties, of star-shaped solution-polymerized styrene–butadiene rubber (SSBR) and organically modified nanosilica powder/star-shaped styrene–butadiene rubber cocoagulated rubber (N-SSBR), both filled with silica/carbon black (CB), were studied. N-SSBR was characterized by ¹H-NMR, gel permeation chromatography, energy dispersive spectrometry, and transmission electron microscopy. The results show that the silica particles were homogeneously dispersed in the N-SSBR matrix. In addition, the N-SSBR/SiO₂/CB–rubber compounds' high bound rubber contents implied good filler–polymer interactions. Compared with SSBR filled with silica/CB, the N-SSBR filled with these fillers exhibited better flex fatigue resistance and a lower Payne effect, internal friction loss, compression permanent set, compression heat buildup, and power loss. The nanocomposites with excellent flex fatigue resistance showed several characteristics of branched, thick, rough, homogeneously distributed cross-sectional cracks, tortuous flex crack paths, few stress concentration points, and obscure interfaces with the matrix. Accordingly, N-SSBR would be an ideal matrix for applications in the tread of green tires. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40348.

Three kinds of star-shaped solution-polymerized styrene–butadiene rubber (S-SSBR) were synthesized by living anionic polymerization using a self-made multifunctional organic lithium initiator. One was S-SSBR with 100% coupling degree. Others were the functionalized S-SSBR which had macromolecular chain-free ends terminated directly (ES-SSBR-1), and macromolecular chain terminated after dissociation in the polymerization solution (ES-SSBR-2) by 3-chloropropyl trimethoxy siloxane. The molecular structure parameters of three kinds of SSBR were determined and the end-functionalized efficiency was calculated. The rheological properties, mechanical properties, and dynamic mechanical properties of ES-SSBR and S-SSBR composites filled with silica (SiO₂)–carbon black (CB) were investigated. The morphology was observed by transmission electron microscopy and high-resolution transmission electron microscopy, and the dispersion of the two kinds of filler in the composites was distinguished by X-ray energy spectrometry. The results showed that the mixing speed of hydrophilic SiO₂ powder in the ES-SSBR was higher than that in the S-SSBR. SiO₂-CB/ES-SSBR composites presented excellent mechanical properties, high wet-skid resistance, and low rolling resistance. Two kinds of nanofiller in the ES-SSBR exhibited outstanding doping nanometer dispersion and good distribution, which indicated that after being coupled and end-functionalized, the two free ends of the macromolecular chains formed chemical bonding with the surface chemical groups of CB and SiO₂, respectively. Accordingly, ES-SSBR was a remarkable energy-saving elastomer. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Microbial desulfurization of waste tyre rubber has been investigated with great efforts since 1990s, because waste rubber has created serious ecological and environmental problems. A microbial desulfurization technique for SBR ground rubber has been developed by a novel sulfur-oxidizing bacterium Sphingomonas sp. The adaptability of Sphingomonas sp. with SBR ground rubber was tested with the amounts of SBR ground rubber varying from 0.5 to 4% g/l. The sol fraction of desulfurized SBR ground rubber increased 70%, compared with SBR ground rubber without desulfurization. Fourier transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR) spectrum and X-ray photoelectron spectroscopy (XPS) analysis of the desulfurized surface of vulcanized SBR flakes revealed that not only the oxidation of crosslinked SS and SC bonds, but also the rupture of CC double bonds had happened to SBR vulcanizates during microbial desulfurization. The cure characteristics, such as scorch time and optimum cure time of natural rubber (NR) vulcanizates filled, were found to decrease with increasing contents of desulfurized SBR ground rubber, due to some reactive groups on its surface. NR vulcanizates filled with desulfurized SBR ground rubber had lower crosslink density and hardness, higher tensile strength and elongation at break, compared with those filled with SBR ground rubber of the same amount. Dynamic mechanical properties indicated that there were better crosslink distribution and stronger interfacial bonding between NR matrix and desulfurized SBR ground rubber. Scanning electron microscope (SEM) photographs showed that the fracture surfaces of NR vulcanizates filled with desulfurized SBR ground rubber had more smooth morphologies. Copyright © 2010 John Wiley & Sons, Ltd.

In this study, the conductive silicone rubber composites filled with nickel-coated graphite (NCG) have been prepared, and their morphology structure, electrical conductivity, electromagnetic interference shielding efficiency (EMI SE), and mechanical properties have been investigated with reference to the NCG filler loading. The mechanical strength of NCG particle was poor that it can be easily ground into smaller particle during the mixing process if the shear force during mixing is large enough. The electrical conductivity of the composites existed an obvious threshold value with the variation of the loading amount of the conductive filler. EMI SE of the composites increases with the decrease of the volume electrical resistivity. The Payne effect can be used to characterize the intensity of the three-dimensional conductive network structure in silicone rubber matrix, and the difference of storage modulus in the low and high shear strain has good linear correlation with the electrical conductivity. So, the electrical conductivity and EMI SE can be estimated by means of the difference of storage modulus obtained from rubber process analysis test. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

The composites of solution polymerized styrene-butadiene rubber (SSBR) filled with SiO₂/carbon black (CB) were prepared by reaction blending. The mechanical and antistatic properties were studied. The morphology and dispersion of the two kinds of nano-fillers in the composites were observed. The results showed that CB presented 30 nm spherical particles and formed filler networks in the SSBR/CB composite. Payne effect of the SSBR/CB composite was large and the antistatic property was excellent; SiO₂ powder presented 20–40 nm irregular particles and also formed filler networks in the SSBR/SiO₂ composite. The internal friction of the SSBR/SiO₂ composite was low, however, the static accumulation was obviously large; SSBR/SiO₂/CB composites exhibited good filler dispersion, high mechanical properties and low internal friction. The rolling resistance, wet-skid resistance and wear resistance are well balanced. Among these, the composite filled with SiO₂/CB in 20/50 achieved the best overall performances. The surface and volume resistivity of the composites was increased with increasing amount of SiO₂. For the researched formulation, the ratio of SiO₂/CB in 35/35 was the percolation threshold for the antistatic property of the composites. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

This study concentrated on microbial desulfurization for NR ground rubber by Thiobacillus ferrooxidans with sulfur oxidizing capacity. NR ground rubber was desulfurizated in the modified 9K medium during the cultivation of T. ferrooxidans. FTIR–ATR and XPS spectra and the increase of SO in the medium indicated that the main chains of the polymer were not broken by T. ferrooxidans, and SS linkages on the surface of ground rubber were partly oxidized to sulfoxide and sulfone, and at last partly oxidized to SO. Cumulative sulfur convention of ground rubber was 16% (w/w), which means 16% of sulfur has been fully oxidized to SO after 20 days' incubation. A sulfur oxidative scheme was proposed to explain the microbial desulfurization by T. ferrooxidans. Physical properties were determined on carbon black enforced SBR vulcanizates compounded with desulfurizated ground rubber of 40 phr loading. Preferable tensile strength and elongation at break were obtained for SBR vulcanizates filled with desulfurizated ground rubber if compared with that one obtained using ground rubber without modification. Scanning electron microscope photographs and DMA results suggested good interface coherence between desulfurizated ground rubber and SBR matrix. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

The vulcanization properties, mechanical properties of hydrogenated nitrile rubber (HNBR) filled with carbon black (N550), zinc dimethacrylate (ZDMA), SiO₂ independently and two of three kinds of fillers together were investigated, respectively. The filler-dispersion was characterized by the transmission electron microscopy (TEM) and dynamic mechanical properties. The results showed that HNBR composite filled with SiO₂ or ZDMA displayed high tensile strength, elongation at break and compression set. The HNBR composite filled with N550 displayed low compression set, tensile strength and elongation at break. The dispersion of SiO₂ in HNBR compound was better than that in HNBR vulcanizates because of SiO₂ particles self-aggregation in vulcanizing processing. ZDMA particles with micron rod-like and silky shape in HNBR compounds changed into near-spherical poly-ZDMA particles with nano size in HNBR vulcanizates by in situ polymerization reaction. The N550 particles morphology exhibited no much change between HNBR compounds and vulcanizates. N550/ZDMA have the most effective reinforcement to HNBR and the appropriate amount of ZDMA is about 25% of total filler amount by weights. The theory prediction for Payne effect (dispersion of the filler) shown by the dynamic properties is identical with actual state observed by TEM. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

The morphological structure and mechanical properties of the star-shaped solution-polymerized styrene-butadiene rubber (SSBR) and organically modified nanosilica powder/star-shaped SSBR co-coagulated rubber (N-SSBR) both filled with silica/carbon black (CB) were studied. The results showed that, compared with SSBR, silica powder could be mixed into N-SSBR much more rapidly, and N-SSBR/SiO₂ nanocomposite had better filler-dispersion and processability. N-SSBR/SiO₂/CB vulcanizates displayed higher glass-transition temperature and lower peak value of internal friction loss than SSBR/SiO₂/CB vulcanizates. In the N-SSBR/SiO₂/CB vulcanizates, filler was dispersed in nano-scale resulting in good mechanical properties. Composites filled with silica/CB doped filler exhibited more excellent mechanical properties than those filled with a single filler because of the better filler-dispersion and stronger interfacial interaction with macromolecular chains. N-SSBR/SiO₂/CB vulcanizates exhibited preferable performance in abrasion resistance and higher bound rubber content as the blending ratio of silica to CB was 20:30. Copyright © 2008 John Wiley & Sons, Ltd.

The proper condensation temperatures of nanosilica powder modified by silane coupling agents such as 3-methacryloxypropyl trimethoxy silane (MEMO), [3-(2-aminoethyl)aminopropyl] trimethoxy silane (AMMO), and bis[3-(triethoxysilyl)propyl] disulfide (TESPD) were measured with Fourier transform infrared. Moreover, the structure and properties of solution-polymerized styrene–butadiene rubber (SSBR) filled with nanosilica powder that was organically modified by the three silane coupling agents at different temperatures were investigated. The results showed that the proper condensation temperatures of nanosilica powder modified by MEMO, AMMO, and TESPD were about 80, 80, and 100°C, respectively. Compared with SSBR filled with silica powder, SSBR filled with silica powder modified by a silane coupling agent exhibited not only better filler-dispersion and mechanical properties but also lower internal friction loss in a selected range of strains. Furthermore, when the organic modification was carried out at the proper condensation temperature, the improvement of the modification effect became more obvious. Among these silane coupling agents, AMMO presented the most remarkable modification effect for nanosilica. The mechanism of modification for silica powder and its enhancement of the properties of SSBR were examined. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

The morphological structure, glass transition, mechanical properties, and dynamic mechanical properties of star-shaped solution-polymerized styrene-butadiene rubber (SSBR) synthesized by a multifunctional organic lithium initiator and SiO₂-SSBR composite (N-SSBR) prepared through adding a small amount of nanosilica modified by silane coupling agent to star-shaped SSBR synthetic solution and co-coagulating, and their nanocomposites filled with 20 phr nanosilica were investigated, respectively. The results showed that the silica particles were well dispersed with nanosize in N-SSBR, which glass-transition temperature (T_g) was 2°C higher than SSBR. N-SSBR/SiO₂ nanocomposite exhibited lower Payne effect and internal friction loss, higher mechanical properties, and its T_g was 2°C higher than SSBR/SiO₂ nanocomposite. N-SSBR might promote the dispersion of nanosilica powder in matrix and could be applied to green tire tread materials. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008