Impact of blend ratio on the properties of graphene oxide‐filled carboxylated acrylonitrile–butadiene rubber/styrene–butadiene rubber blends

Carboxylated acrylonitrile–butadiene rubber (XNBR) and styrene–butadiene rubber (SBR) composites with 3 phr (parts per hundred rubber) graphene oxide (GO) were prepared using a latex mixing method. Effects of XNBR/SBR blend ratios on the mechanical properties, thermal conductivity, solvent resistance and thermal stability of the XNBR/SBR/GO nanocomposites were studied. The tensile strength, tear strength, thermal conductivity and solvent resistance of the XNBR/SBR/GO (75/25/3) nanocomposite were significantly increased by 86, 96, 12 and 21%, respectively, compared to those of the XNBR/SBR (75/25) blend. The thermal stability of the nanocomposite was significantly enhanced; in other words, the temperature for 5% weight loss and the temperature of the maximal rate of degradation process were increased by 26.01 and 14.97 °C, respectively. Theoretical analysis and dynamic mechanical analysis showed that the GO tended to locate in the XNBR phase, which led to better properties of the XNBR/SBR/GO (75/25/3) nanocomposite. © 2017 Society of Chemical Industry     

Overall properties of fibrillar silicate/styrene–butadiene rubber nanocomposites

The mechanical properties, heat aging resistance, dynamic properties, and abrasion resistance of fibrillar silicate (FS)/styrene butadiene rubber (SBR) nanocomposites are discussed in detail. Compared with white carbon black (WCB)/SBR composites, FS/SBR composites exhibit higher tensile stress at definite strain, higher tear strength, and lower elongation at break but poor abrasion resistance and tensile strength. Surprisingly, FS/SBR compounds have better flow properties. This is because by rubber melt blending modified FS can be separated into numerous nanosized fibrils under mechanical shear. Moreover, the composites show visible anisotropy due to the orientation of nanofibrils. There is potential for FS to be used to some extent as a reinforcing agent for rubber instead of short microfibers or white carbon black. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2725–2731, 2006     

Anisotropy of styrene–butadiene rubber

Anisotropy of styrene–butadiene rubber (SBR) was investigated. The anisotropy of the copolymer varies linearly with the styrene content and the ultimate value coincides with that of polystyrene at elevated temperature. From these facts, the transverse configuration of the pendant phenyl group is estimated irrespective of the styrene content of SBR.     

Short-fiber-reinforced styrene–butadiene rubber composites

Processing characteristics, anistropic swelling, and mechanical properties of short-jute-fiber-and short-glass-fiber-reinforced styrene–butadiene rubber (SBR) composites have been studied both in the presence and absence of carbon black. Tensile and tear fracture surfaces of the composites have been studied using scanning electron microscopy (SEM) in order to assess the failure criteria. The effects of bonding agent. carbon black, jute fiber, and glass fiber on the fracture mode of the composites have also been studied. It has been found that jute fiber offers good reinforcement to SBR as compared to glass fibers. The poor performance of glass fibers as reinforcing agent is found to be mainly due to fiber breakage and poor bonding between fiber and rubber. Tensile strength of the fiber–SBR composites increases with the increase in fiber loading in the absence of carbon black. However, in the presence of carbon black a minimum was observed in the variation of strength against fiber loading. SEM studies indicate that fracture mode depends not on the nature of the fiber but on the adhesion between the fiber and the matrix.     

Accelerated ageing of styrene–butadiene rubber nanocomposites stabilized by phenolic antioxidant

Organoclay‐reinforced styrene butadiene rubber (SBR) was subjected to accelerated thermo‐oxidative ageing and its physical properties were compared to the virgin material. The oxidative degradation was studied in absence and in presence of a phenolic antioxidant. Ageing test was conducted at 70°C for 7, 14, and 28 days. Then, mechanical and dynamomechanical properties were measured and related to chemical and morphological changes. The elongation at break of samples without antioxidant was found to decrease whereas the modulus and hardness of SBR and its nanocomposite increased with ageing time. Also, the storage modulus and the glass transition temperature increased monotonously with time. These results were attributed to main chain scission and crosslinks formation. The ageing mechanism, determined by infrared spectroscopy, was independent on the nanoclay presence. When the antioxidant was added, thermo‐oxidative stability markedly increased. The retention in the physical properties upon ageing 28 days suggests that the addition of 0.5–1 phr antioxidant was sufficient to provide stability of SBR nanocomposite with minimum loss in physical properties. Also, SEM images showed no signs of degradation; this demonstrates that the antioxidant protects the surface from oxidative degradation. Moreover, infrared spectroscopy suggests that nanoclay could protect the elastomer surface from deterioration. POLYM. COMPOS., 35:334–343, 2014. © 2013 Society of Plastics Engineers     

Structural morphology and properties of star styrene–isoprene–butadiene rubber and natural rubber/star styrene–butadiene rubber blends

Star styrene–isoprene–butadiene rubber (SIBR) was synthesized with a new kind of star anionic initiator made from naphthalene lithium and an SnCl₄ coupled agent. The relationship between the structure and properties of star SIBR was studied. Star block styrene–isoprene–butadiene rubber (SB‐SIBR), having low hysteresis, high road‐hugging, and excellent mechanical properties, was closer to meeting the overall performance requirements of ideal tire‐tread rubber according to a comparison of the morphology and various properties of SB‐SIBR with those of star random SIBR and natural rubber/star styrene–butadiene rubber blends. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 336–341, 2004     

Dichlorocarbene modification of styrene–butadiene rubber

Dichlorocarbene-modified styrene–butadiene rubber (SBR) prepared by the alkaline hydrolysis of chloroform using cetyltrimethylammonium bromide as a phase-transfer agent resulted in a product that showed good mechanical properties, excellent flame resistance, solvent resistance, and good thermal stability. The activation energy for this chemical reaction calculated from the time–temperature data on the chemical reaction by the measurement of the percentage of chlorine indicated that the reaction proceeded according to first-order kinetics. The molecular weight of the polymers, determined by gel permeation chromatography, showed that chemical modification was accompanied by an increase in molecular weight. The chemical modification was characterized by proton NMR, FTIR studies, thermogravimetric analysis, and flammability measurement. Proton NMR and FTIR studies revealed the attachment of chlorine through cyclopropyl rings to the double bond of butadiene. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 153–160, 1998     

Oil absorbents based on styrene–butadiene rubber

Four oil absorbents based on styrene–butadiene (SBR)—pure SBR (PS), 4‐tert‐butylstyrene–SBR (PBS), EPDM–SBR network (PES), and 4‐tert‐butylstyrene‐EPDM‐SBR (PBES)—were produced from crosslinking polymerization of uncured styrene–butadiene rubber (SBR), 4‐tert‐butylstyrene (tBS), and ethylene–propylene–diene terpolymer (EPDM). The reaction took place in toluene using benzoyl peroxide (BPO) as an initiator. Uncured SBR was used as both a prepolymer and a crosslink agent in this work, and the crosslinked polymer was identified by IR spectroscopy. The oil absorbency of the crosslinked polymer was evaluated with ASTM method F726‐81. The order of maximum oil absorbency was PBES > PBS > PES > PS. The maximum values of oil absorbency of PBES and PBS were 74.0 and 69.5 g/g, respectively. Gel fractions and swelling kinetic constants, however, had opposite sequences. The swelling kinetic constant of PS evaluated by an experimental equation was 49.97 × 10^?2 h^?1. The gel strength parameter, S, the relaxation exponent, n, and the fractal dimension, d_f, of the crosslinked polymer at the pseudo‐critical gel state were determined from oscillatory shear measurements by a dynamic rheometer. The morphologies and light resistance properties of the crosslinked polymers were observed, respectively, with a scanning electron microscope (SEM) and a color difference meter.     

Microstructure analysis of brominated styrene–butadiene rubber

The bromine addition to the SBR double bonds in chloroform at 0°C has been investigated by FTIR, ¹H NMR and DSC techniques. In this case, bromine molecules react exclusively with the polydiene double bonds and the polystyrene units are unaffected. The bromine reacts preferentially with 1,4‐trans double bonds of the polybutadiene segment of SBR. At low bromination level (below 15%) the bromine reacts mainly with the 1,4‐trans double bonds of SBR, while at higher bromination level (up to 30%) the bromine shows the most reactivity toward the vinylic double bond. Above 30%, the addition reaction occurs on 1,4‐trans double bonds. The microstructure of modified and unmodified styrene–butadiene copolymers were fully characterized by ¹H NMR technique. Expanded regions have been utilized to resolve the complex ¹H NMR spectrum and establish the compositional and configurational sequences of styrene–butadiene copolymers. POLYM. ENG. SCI., 47:87–94, 2007. © 2007 Society of Plastics Engineers     

Improvement of properties of silica‐filled styrene–butadiene rubber compounds using acrylonitrile–butadiene rubber

Since silica has strong filler–filler interactions and adsorbs polar materials, a silica‐filled rubber compound has a poor dispersion of the filler and poor cure characteristics. Improvement of the properties of silica‐filled styrene–butadiene rubber (SBR) compounds was studied using acrylonitrile–butadiene rubber (NBR). Viscosities and bound rubber contents of the compounds became lower by adding NBR to the compound. Cure characteristics of the compounds were improved by adding NBR. Physical properties such as modulus, tensile strength, heat buildup, abrasion, and crack resistance were also improved by adding NBR. Both wet traction and rolling resistance of the vulcanizates containing NBR were better than were those of the vulcanizate without NBR. The NBR effects in the silica‐filled SBR compounds were compared with the carbon black‐filled compounds. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 1127–1133, 2001     

氧化石墨烯与白炭黑并用填充丁苯橡胶纳米复合材料的性能

采用乳液共混与机械剪切法制备氧化石墨烯/白炭黑/丁苯橡胶纳米复合材料,并对其综合性能进行研究。结果表明:两种并用填料在橡胶基体中均能达到纳米级分散,且白炭黑粒子填补了氧化石墨烯片层间的空隙。氧化石墨烯的加入延长了复合材料的正硫化时间,改变了其交联密度。氧化石墨烯等量替代白炭黑,可以提高橡胶基体中填料的有效体积分数,改善复合材料的物理性能和动态力学性能。氧化石墨烯的加入使复合材料的耐磨性能显著提高。与白炭黑填充相比,氧化石墨烯/白炭黑填充复合材料的60℃时损耗因子有所降低,能进一步降低滚动阻力,但其0℃的损耗因子也呈现降低趋势,对复合材料抗湿滑性能不利。     

Preparation and properties of styrene‐butadiene rubber nanocomposites blended with carbon black‐graphene hybrid filler

Graphene has become an attractive reinforcing filler for rubber materials, but its dispersion in rubber is still a big challenge. In this work, a novel carbon black‐reduced graphene (CB‐RG) hybrid filler was fabricated and blended with styrene‐butadiene rubber (SBR) via simple two‐roll mill mixing. The prepared CB‐RG hybrids had a microstructure with small CB agglomerates adsorbed onto graphene surfaces. CB acted as a barrier preventing the RG sheets from restacking even after drying. Homogeneous dispersion of graphene sheets in SBR matrix was observed by the mechanical mixing method based on the application of the CB‐RG hybrid fillers. Dynamic mechanical analysis showed that Tg of the SBR/CB‐RG blend was higher than that of the SBR/CB blend indicating strong interfacial interactions between RG and SBR due to the high surface area of graphene and the π‐π interaction between SBR and graphene. The tensile properties of SBR/CB‐RG composites improved significantly and the volume resistivity decreased compared with the SBR/CB blends. The thermal stability of SBR composites filled with CB and CB‐RG showed slight difference. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41309.     

Morphology and mechanical properties of clay/styrene‐butadiene rubber nanocomposites

Based on the character of a clay that could be separated into many 1‐nm thickness monolayers, clay styrene‐butadiene rubber (SBR) nanocomposites were acquired by mixing the SBR latex with a clay/water dispersion and coagulating the mixture. The structure of the dispersion of clay in the SBR was studied through TEM. The mechanical properties of clay/SBR nanocomposites with different filling amounts of clay were studied. The results showed that the main structure of the dispersion of clay in the SBR was a layer bundle whose thickness was 4–10 nm and its aggregation formed by several or many layer bundles. Compared with the other filler, some mechanical properties of clay/SBR nanocomposites exceeded those of carbon black/SBR composites and they were higher than those of clay/SBR composites produced by directly mixing clay with SBR through regular rubber processing means. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 1873–1878, 2000     

Ultraviolet-initiated photografting of glycidyl methacrylate onto styrene–butadiene rubber

Photografting reaction onto styrene–butadiene rubber (SBR) as a function of monomer concentration, grafting method, irradiation time, and the carbon black content has been studied using ultraviolet (UV). Glycidyl methacrylate and benzophenone are used as monomer and initiator, respectively. The occurrence of graft reaction onto SBR surface is identified by infrared attenuated total reflection (IR-ATR) analysis. The degree of monomer graft increases with monomer concentration and tends to level off at high monomer concentration (>8.3M/L). Graft ratio also increases with UV irradiation time. Carbon black content is found as one of important factors that determine the monomer graft efficiency. The amount of monomer graft onto SBR decreases with increasing carbon black content and it is attributed to the reduction of irradiation absorbance due to the presence of carbon black. The occurrence of reaction between glycidyl methacrylate grafted SBR and nylon-6 via melt phase reaction is also identified using IR-ATR analysis. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 1733–1739, 1999     

Thermal and scanning electron microscopy/energy‐dispersive spectroscopy analysis of styrene–butadiene rubber–butadiene rubber/silicon dioxide and styrene–butadiene rubber–butadiene rubber/carbon black–silicon dioxide composites

Silica as a reinforcement filler for automotive tires is used to reduce the friction between precured treads and roads. This results in lower fuel consumption and reduced emissions of pollutant gases. In this work, the existing physical interactions between the filler and elastomer were analyzed through the extraction of the sol phase of styrene–butadiene rubber (SBR)–butadiene rubber (BR)/SiO₂ composites. The extraction of the sol phase from samples filled with carbon black was also studied. The activation energy (E_a) was calculated from differential thermogravimetry curves obtained during pyrolysis analysis. For the SBR–BR blend, E_a was 315 kJ/mol. The values obtained for the composites containing 20 and 30 parts of silica per hundred parts of rubber were 231 and 197 kJ/mol, respectively. These results indicated an increasing filler–filler interaction, instead of filler–polymer interactions, with respect to the more charged composite. A microscopic analysis with energy‐dispersive spectroscopy showed silica agglomerates and matched the decreasing E_a values for the SBR–BR/30SiO₂ composite well. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 2273–2279, 2005     

Rheological behavior of blends of natural rubber and styrene–butadiene rubber latices

The rheological behavior of blends of natural rubber (NR) and styrene–butadiene rubber (SBR) latices has been studied with reference to the effects of blend ratio, shear rate, surface-active agents (casein and sodium carboxymethyl cellulose), and temperature. When the SBR content was less than 50%, the viscosities of the blends appeared to be a nonadditive function of the viscosities of the constituent homopolymers; i.e., a positive deviation was observed. This was due to the structural buildup of the SBR domains. The SBR domains underwent agglomeration and consequently so-called microflocculation took place. The viscosities of all the blends were found to decrease with increase of temperature and shear rate. The increase in temperature and shear rate marginally weakened the structural buildup as evidenced by the lowering of viscosity. As the SBR content in the system increased, the pseudoplasticity of the blend increased. Even in the presence of surface-active agents the blends showed composition-dependent positive deviation. However, surface-active agents marginally reduced the extent of structural buildup by reducing the microflocculation behavior of SBR domains. © 1995 John Wiley & Sons, Inc.     

Study on flammability of montmorillonite/styrene‐butadiene rubber (SBR) nanocomposites

The flammability of montmorillonite (MMT)/SBR nanocomposites, prepared by the technique of cocoagulating rubber latex and clay aqueous suspension, was investigated. Flammability studies, performed on the cone calorimeter, showed that the maximum heat release rate (HRR) of SBR decreased from 1987 to 1442 kw/m² with the introduction of nanoclay (20 phr). This nanocomposite had the lowest mass loss rate and the largest amount of char upon combustion compared with conventional SBR composites with the same clay loading and pure SBR. The permeability properties of MMT/SBR composites were also measured. It was deduced that the lowered permeability was responsible for the reduced mass loss rate and hence the lower HRR. Unfortunately, the oxygen index (OI) of the nanocomposites was not as high as expected. Combination of Mg(OH)₂ and clay was effective for the improvement of both mechanical properties and OI. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 844–849, 2005     

Dynamic mechanical analysis of ethylene–propylene–diene monomer rubber and styrene–butadiene rubber blends

The effects of blend ratio, crosslinking systems, and fillers on the viscoelastic response of ethylene–propylene–diene monomer (EPDM)/styrene–butadiene rubber (SBR) blends were studied as functions of frequency, temperature, and cure systems. The storage modulus decreased with increasing SBR content. The loss modulus and loss tangent results showed that the EPDM/SBR blend vulcanizate containing 80 wt % EPDM had the highest compatibility. Among the different cure systems studied, the dicumyl peroxide cured blends exhibited the highest storage modulus. The reinforcing fillers were found to reduce the loss tangent peak height. The blend containing 40 wt % EPDM showed partial miscibility. The dispersed EPDM phase suppressed the glass‐transition temperature of the matrix phase. The dynamic mechanical response of rubbery region was dominated by SBR in the EPDM–SBR blend. The morphology of the blend was studied by means of scanning electron microscopy. The blend containing 80 wt % EPDM had small domains of SBR particles dispersed uniformly throughout the EPDM matrix, which helped to toughen the matrix and prevent crack propagation; this led to enhanced blend compatibility. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Reinforcement of peroxide‐cured styrene–butadiene rubber vulcanizates by mathacrylic acid and magnesium oxide

Through the neutralization of magnesium oxide (MgO) and methacrylic acid (MAA), magnesium methacrylate [Mg(MAA)₂] was in situ prepared in styrene–butadiene rubber (SBR) and used to reinforce the SBR vulcanizates cured by dicumyl peroxide (DCP). The experimental results show that the mechanical properties, dynamic mechanical properties, optical properties, and crosslink structure of the Mg(MAA)₂‐reinforced SBR vulcanizates depend on the DCP content, Mg(MAA)₂ content, and the mole ratio of MgO/MAA. The formulation containing DCP 0.6–0.9 phr, Mg(MAA)₂ 30–40 phr, and MgO/MAA mole ratio 0.50–0.75 is recommended for good mechanical properties of the SBR vulcanizates. The tensile strength of the SBR vulcanizates is up to 31.4 MPa when the DCP content is 0.6 phr and the Mg(MAA)₂ content is 30 phr. The SBR vulcanizate have good aging resistance and limited retention of tensile strength at 100°C. The SBR vulcanizates are semitransparent, and have a good combination of high hardness, high tensile strength, and elongation at break. The T_g values of the SBR vulcanizates depend largely on the DCP content, but depend less on the Mg(MAA)₂ content and the MgO/MAA mole ratio. The contents of DCP, Mg(MAA)₂, and the MgO/MAA mole ratio have also great effects on the E′ values of the vulcanizates. The salt crosslink density is greatly affected by the Mg(MAA)₂ content and MgO/MAA mole ratio, but less affected by the DCP content. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2667–2676, 2002     

Separation of alkane–acetone mixtures using styrene–butadiene rubber/natural rubber blend membranes

Conventionally vulcanized styrene–butadiene rubber/natural rubber blend membranes were prepared for the pervaporation separation of alkane–acetone mixtures. Swelling measurements were carried out in both acetone and n‐alkanes to investigate the swelling behavior of the membranes. The swelling behavior was found to depend on the composition of the blend. The effects of blend ratio, feed composition, and penetrant size on the pervaporation process were analyzed. The permeation properties have been explained on the basis of interaction between the membrane and solvents and blend morphology. The SBR/NR 70/30 blend membrane showed higher selectivity among all the membranes used. Flux increases with increasing alkane content in the feed composition. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 3059–3068, 1999