Effect of a coupling agent on the properties of hemp‐hurd‐powder‐filled styrene–butadiene rubber

Styrene–butadiene rubber (SBR) composites filled with hemp hurd powder (HP) were prepared with bis(3‐triethoxysilylpropyl) tetrasulfide (Si69) as a coupling agent. The effects of the filler content and coupling agent on the curing characteristics and dynamic mechanical properties of the composites were studied. The results indicate that with increasing filler loading, the torque values increased and the curing time decreased. The mechanical properties improved with increasing filled HP content up to 60 phr. Usually, long fibers led to a sharp decrease in the toughness of the composites, whereas short fibers, such as HP, had a positive effect on the elongation at break within the loading range studied. The extent of the filler–matrix interaction and the scanning electron micrographs of the fractured surfaces confirmed that the addition of Si69 improved the interfacial interaction between HP and the SBR matrix, which led to an increase in the maximum torque and the mechanical properties. Moreover, the coupling agent was helpful in dispersing the filler in the rubber matrix. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Mechanical properties of gamma‐irradiated styrene‐butadiene rubber/acid‐treated vermiculite clay/maleic anhydride nanocomposites

Nanoparticle vermiculite (VMT) clay was prepared by treatment with hydrochloric acid. Styrene‐butadiene rubber (SBR) nanocomposites were prepared by mixing different contents (2.5, 5, 7.5, and 10 phr) of untreated (VMT) and acid‐treated (DVMT) vermiculite clay, respectively. In addition, different contents (3, 7, and 10 phr) of maleic anhydride (MA) as compatibilizer were mixed via direct melt compounding in internal mixer. The effect of gamma irradiation, VMT clay, and MA contents on the mechanical properties was studied. The acid‐treated VMT clay was characterized by x‐ray diffraction (XRD), transmission electron microscopy (TEM), and Fourier transform infrared (FT‐IR) spectroscopy. Meanwhile, the SBR/VMT composites, SBR/DVMT, and SBR/DVMT/MA nanocomposites were characterized via crosslinking density and tensile mechanical testing and FT‐IR spectroscopic analysis. The results indicated that good yield of nanoparticle vermiculite was achieved when the acid treatment was carried out for 120 h. In addition, the results showed that the presence of DVMT clay improved the chemical bonding in the SBR nanocomposites and hence their mechanical properties. The highest improvement was obtained when the contents of DVMT clay, MA, and irradiation dose were 10 phr, 3 phr, and 100 kGy, respectively. POLYM. ENG. SCI., 59:355–364, 2019. © 2018 Society of Plastics Engineers     

Hybridized reinforcement of natural rubber with silane‐modified short cellulose fibers and silica

Natural‐rubber‐based hybrid composites were prepared by the mixture of short cellulose fibers and silica of different relative contents with a 20‐phr filler loading with a laboratory two‐roll mill. The processability and tensile properties of the hybrid composites were analyzed. The tensile modulus improved, but the tensile strength and elongation at break decreased with increasing cellulose fiber content. The scorch safety improved with the addition of 5‐phr cellulose fiber in the composites. The Mooney viscosity significantly decreased with increasing cellulose fiber content. To modify the surface properties of the cellulose fiber and silica fillers, a silane coupling agent [bis(triethoxysilylpropyl)tetrasulfide, or Si69] was used. The effects of Si69 treatment on the processing and tensile properties of the hybrid composites were assessed. We found that the silane treatment of both fillers had significant benefits on the processability but little benefit on the rubber reinforcement. The strength of the treated hybrid composite was comparable to that of silica‐reinforced natural rubber. Furthermore, to investigate the filler surface modification and to determine the mixing effects, infrared spectroscopic and various microscopic techniques, respectively, were used. From these results, we concluded that the fillers were better dispersed in the composites, and the compatibility of the fillers and natural rubber increased with silane treatment. In conclusion, the hybridized use of short cellulose fibers from a renewable resource and silica with Si69 presented in this article offers practical benefits for the production of rubber‐based composites having greater processability and more environmental compatibility than conventional silica‐filler‐reinforced rubber. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Silica‐modified SBR/BR blends

The purpose of this article is that the silica‐modified SBR/BR blend replaces natural rubber (NR) in some application fields. The styrene‐butadiene rubber (SBR) and cis‐butadiene rubber (BR) blend was modified, in which silica filler was treated with the r‐Aminopropyltriethoxysilane (KH‐550) as a coupling agent, to improve mechanical and thermal properties, and compatibilities. The optimum formula and cure condition were determined by testing the properties of SBR/BR blend. The properties of NR and the silica‐modified SBR/BR blend were compared. The results show that the optimum formulawas 80/20 SBR/BR, 2.5 phr dicumyl peroxide (DCP), 45 phr silica and 2.5 mL KH‐550. The best cure condition was at 150°C for 25 min under 10 MPa. The mechanical and thermal properties of SBR/BR blend were obviously modified, in which the silica filler treated with KH‐550. The compatibility of SBR/BR blend with DCP was better than those with benzoyl peroxide (BPO) and DCP/BPO. The crosslinking bonds between modified silica and rubbers were proved by Fourier transform infrared analysis, and the compatibility of SBR and BR was proved by polarized light microscopy (PLM) analysis. The silica‐modified SBR/BR blend can substitute for NR in the specific application fields. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011.     

Short fibers as reinforcement of rubber compounds

The effect of aramid, glass and cellulose short fibers on the processing behavior, crosslinking density and mechanical properties of natural rubber (NR), ethylene‐propylene‐diene terpolymer rubber (EPDM) and styrene‐butadiene rubber (SBR) has been investigated. Two fiber percentages (10 and 20 phr) were added to the rubber. The results have shown that the above‐mentioned fibers, especially aramid fibers, are effective reinforcing agents for these rubbers, giving rise to a significant increase in mechanical properties, such as tensile modulus and strength, and tear and abrasion resistance. Moreover, a significant decrease in the time to reach 97% of curing, t′_c (97) is observed, which indicates that the fibers tend to increase the vulcanization rate, regardless of the rubber used. Fibers give also rise to an increase in crosslinking, especially the aramid fibers.     

Accelerated aging of elastomeric composites with vulcanized ground scraps

The aim of this work is to study the effect of thermal aging on the mechanical, dynamic‐mechanical, and chemical properties of SBR (styrene‐butadiene rubber) composites filled with SBR industrial rubber scraps. Eight composites with varying proportions (10–80 phr) of the SBR ground scraps (SBR‐r) were prepared and subjected to accelerated aging in an air‐oven. The composites were evaluated, and the results were compared with a control sample (base formulation with 0 phr of SBR‐r), before and after thermal aging. The accelerated aging led to a decrease in the mechanical properties as a result of an increase in the stiffness of the material, related to an increase in the crosslink density. However, these properties were not affected by the addition of rubber scraps up to 50 phr, either before or after aging. The increase in the glass transition temperature of the composites after aging, measured using dynamic mechanical analysis, confirmed the occurrence of a postcrosslinking process. Fourier transform infrared spectroscopy and crosslink density revealed that the aging mechanism was dependent on the SBR‐r content. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Influence of chemical treatments on cellulose fibers for use as reinforcements in poly(ethylene‐co‐vinyl acetate) composites

This work evaluates different chemical treatments on cellulose fibers as reinforcement agents in poly(ethylene‐vinyl acetate) (EVA) composites. The cellulose fibers were prepared with three chemical modifications using triethoxyvinylsilane, acetic anhydride (AA), and glycidyl methacrylate (GMA). Composites were prepared with 10 phr of cellulose fibers by means of extrusion and hot press conformation. The fiber treatment levels were successfully demonstrated through Fourier transform infrared spectroscopy with the appearance of characteristic bands in each chemical group, and scanning electron micrographs showed altered textures on the surfaces, polymerized material and fiber agglomerations after the chemical treatments that were most evident in the AA and GMA treatments. The composites reinforced with treated fibers showed improvement in their mechanical properties at the yield points and were reduced in deformation. When activated with dicumyl peroxide, the mechanical properties were even more improved and the interface regions exhibited better interactions between the cellulose fibers and the EVA matrix. POLYM. COMPOS., 37:1991–2000, 2016. © 2015 Society of Plastics Engineers     

Fly‐ash particles and precipitated silica as fillers in rubbers. II. Effects of silica content and Si69‐treatment in natural rubber/styrene–butadiene rubber vulcanizates

This article explored the possibility of using silica from fly‐ash particles as reinforcement in natural rubber/styrene–butadiene rubber (NR/SBR) vulcanizates. For a given silica content, the NR : SBR blend ratio of 1 : 1 (or 50 : 50 phr) exhibited the optimum mechanical properties for fly‐ash filled NR/SBR blend system. When using untreated silica from fly‐ash, the cure time and mechanical properties of the NR/SBR vulcanizates decreased with increasing silica content. The improvement of the mechanical properties was achieved by addition of Si69, the recommended dosage being 2.0 wt % of silica content. The optimum tensile strength of the silica filled NR/SBR vulcanizates was peaked at 10–20 phr silica contents. Most mechanical properties increased with thermal ageing. The addition of silica from fly‐ash in the NR/SBR vulcanizates was found to improve the elastic behavior, including compression set and resilience, as compared with that of commercial precipitated silica. Taking mechanical properties into account, the recommended dosage for the silica (FASi) content was 20 phr. For more effective reinforcement, the silica from fly‐ash particles had to be chemically treated with 2.0 wt % Si69. It was convincing that silica from fly‐ash particles could be used to replace commercial silica as reinforcement in NR/SBR vulcanizates for cost‐saving and environment benefits. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Influence of starch on the properties of carbon‐black‐filled styrene–butadiene rubber composites

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     

Curing characteristics and mechanical properties of alkali‐treated grass‐fiber‐filled natural rubber composites and effects of bonding agent

To improve adhesion between fiber and matrix, natural rubber was reinforced with a special type of alkali‐treated grass fiber (Cyperus Tegetum Rox b). The cure characteristics and mechanical properties of grass‐fiber‐filled natural rubber composites with different mesh sizes were studied with various fiber loadings. Increasing the amount of fibers resulted in the composites having reduced tensile strength but increased modulus. The better mechanical properties of the 400‐mesh grass‐fiber‐filled natural rubber composite showed that the rubber/fiber interface was improved by the addition of resorcinol formaldehyde latex (RFL) as bonding agent for this particular formulation. The optimum cure time decreased with increases in fiber loading, but there was no appreciable change in scorch time. Although the optimum cure time of vulcanizates having RFL‐treated fibers was higher than that of the other vulcanizates, it decreased with fiber loading in the presence of RFL as the bonding agent. But this value was lower than that of the rubber composite without RFL. Investigation of equilibrium swelling in a hydrocarbon solvent was also carried out. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3151–3160, 2006     

Understanding the role of ZnO as activator in SBR vulcanizates: Performance evaluation with active,nano, and functionalized ZnO

This study investigates (ZnO)s with different surface features as vulcanization activators in unfilled SBR vulcanizates. ZnO is termed the best activator due to its fast reaction kinetics. A high release of ZnO into the environment harms marine ecosystems, and most ZnO production goes to the rubber sector; therefore, reducing ZnO amount is essential. Active, nano and functionalized ZnO compared to conventional ZnO in SBR matrix; concentration optimized based on curing, mechanical, physical, and dispersion analyses. The Arrhenius equation approximated the cure curve's kinetic constant and activation energy. Crosslink density measured by swelling experiment and solvent freezing point depression. Nano ZnO was used from 0.5 to 2phr, active ZnO from 1 to 4phr, and functionalized ZnO from 1 to 3phr compared to 5phr of conventional ZnO. The tensile strength of N1.5, F1.5, and A2 SBR increased by 5%, 26%, and 18% compared to C5SBR, whose elongation at break improved by 30%, 7%, and 23%. The data were analyzed using tukey HSD post hoc test. Regarding mechanical properties and curing characteristics, 2phr active, functionalized, and 1.5phr nano ZnO is analogous to 5phr conventional ZnO in an unfilled SBR matrix. The quantity of ZnO in rubber vulcanizates decreased successively by 60%, 60%, and 70%.     

木质素/蒙脱土复合物在丁苯橡胶中的应用研究

通过絮凝沉降法制备了木质素/蒙脱土复合物(CLM),将其跟丁苯橡胶(SBR)机械共混制备了SBR/CLM复合材料,并对其微观结构、硫化特性、交联密度、力学性能、热氧老化性能以及热稳定性进行研究。结果表明:木质素与蒙脱土的相互作用提高了CLM与SBR相容性;随着CLM用量的增加,焦烧时间与正硫化时间逐渐增加,复合材料的力学性能逐渐增大,老化性能及热稳定性也得到改善。     

Mechanical and morphological properties of cellular NR/SBR vulcanizates under thermal and weathering ageing

The effects of addition of two chemical blowing agents in cellular rubber blend of natural rubber (NR) and styrene‐butadiene rubber (SBR) at a fixed blend ratio of 1 : 1 on cure characteristics, and mechanical and morphological properties were invesigated. The chemical blowing agents used in this work were Oxybis (benzene sulfonyl) hydrazide (OBSH) and Azo dicarbonamide (ADC). Three different fillers, fly ash (FA) particles, precipitated silica, carbon black (CB) at their optimum concentrations of 40 phr were used, the FA and silica particles being chemically treated by bis‐(3‐triethoxysilylpropyl) tetrasulphide. The results suggested that the overall cure time decreased with OBSH and ADC contents. The OBSH was more effective in cure‐acceleration of the NR/SBR blend than the ADC. The NR/SBR vulcanized foams produced by OBSH and ADC agents had closed‐cell structures. The specific density and mechanical properties of the blend tended to decrease with increasing blowing agent content. The CB gave NR/SBR foams with smaller cell size, better cell dispersion, and higher mechanical properties than the precipitated silica and FA particles. The heat ageing and weathering resulted in an increase in tensile modulus and hardness, but lowered the tensile strength, ultimate elongation and tear strength. The elastic recovery for cellular NR/SBR vulcanizates with FA was superior to that with CB and silica, the elastic recovery of the blends decreasing with blowing agent content. Resilience property was improved by the presence of gas phases. The optimum concentration of OBSH and ADC to be used for NR/SBR vulcanizates was 4 phr. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Preparation and characterization of elastomer‐based nanocomposite gels using an unique latex blending technique

Nanocomposite (NC) gels based on natural rubber (NR) and styrene butadiene rubber (SBR) were prepared by using a unique latex blending technique. These NC gels were prepared by first blending the water swollen unmodified montmorillonite clay (Na⁺‐MMT) suspension into the respective latices followed by prevulcanization to generate crosslinked nanogels. Use of water assisted fully delaminated Na⁺‐MMT suspension resulted in predominantly exfoliated morphology in the NC gels, as revealed by X‐ray diffraction study and transmission electron microscopy. Addition of Na⁺‐MMT significantly improved various physical, mechanical and thermal properties of these NC gels. For example, 6 phr of Na⁺‐MMT loaded NR based NC gels registered 54% and 200% increase in tensile strength and Young's modulus, respectively, compared to the unfilled NR gels. SBR based NC gels also showed similar level of improvement in mechanical properties. Mechanical properties of NC gels prepared using this route were also compared with the NC gels prepared by co‐coagulation and conventional curing technique and found to be superior. In the case of dynamic mechanical properties, NC gels showed higher glass transition temperatures along with a concomitant increase in storage moduli, compared to the unfilled gels. These Na⁺‐MMT reinforced NC gels also exhibited markedly improved thermal stability. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Application of nano‐zinc oxide master batch in polybutadiene styrene rubber system

The properties of nano‐zinc oxide master batch filled butadiene styrene rubber (SBR) systems were researched in comparison with those of common zinc oxide and nano‐zinc oxide filled systems. First, the nano‐zinc oxide master batch was prepared and the cure characteristics of three different kinds of zinc oxide filled SBR composites were studied; second, the mechanical properties and wear resistance were compared; then, the improved mechanical properties were confirmed by dynamic mechanical properties and transmission electron microscopy. Finally, the zinc oxide amount reducing mechanism was analyzed. Results show that nano‐zinc oxide master batch filled SBR system has better mechanical properties than those of nano‐zinc oxide and common zinc oxide filled systems, which is due to the improved dispersion by master batch mixing technology. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 922–930, 2006     

Wood flour as a secondary filler in carbon black filled of styrene butadiene/chlorosulphonated polyethylene rubber blend

A study is reported which aims to identify the optimum contents of wood flour (WF) to be introduced into styrene butadiene/chlorosulphonated polyethylene (SBR/CSM) rubber blend compounded with carbon black. A range of composite properties are considered including cure characteristics and mechanical properties, as well as the adhesion strength (rubber‐to‐metal bonding) behavior. Processing characteristic such as maximum torque increases with increasing of the concentration of WF up to 40 phr in SBR/CSM blend, whereas the scorch time and optimum cure time decreases. Results indicated that the tensile strength and tensile modulus, as well as shore hardness of the SBR/CSM composite in which SBR is predominant, increase in a compliance with the increase of WF. Adhesion strength value on peel between metal and WF filled SBR/CSM rubber blend increases when the filling level increases and the maximum value were observed at 40 phr of WF. The enhancement in mechanical properties was supported by data of crosslink density in these samples obtained from swelling measurement. Addition of WF was recommended as an economical and ecological benefit to industries as the properties of the rubber/carbon black composites remained unchanged with increasing WF content. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers.     

Preparation,characterization, and application of NR/SBR/Organoclay nanocomposites in the tire industry

The natural rubber/styrene butadiene rubber/organoclay (NR/SBR/organoclay) nanocomposites were successfully prepared with different types of organoclay by direct compounding. The optimal type of organoclay was selected by the mechanical properties characterization of the NR/SBR/organoclay composites. The series of NR/SBR/organoclay (the optimal organoclay) nanocomposites were prepared with various organoclay contents loading from 1.0 to 7.0 parts per hundreds of rubber (phr). The nearly completely exfoliated organoclay nanocomposites with uniform dispersion were confirmed by transmission electron microscopy (TEM) and X‐ray diffraction (XRD). The results of mechanical properties measurement showed that the tensile strength, tensile modulus, and tear strength were improved significantly when the organoclay content was less than 5.0 phr. The tensile strength and the tear strength of the nanocomposite with only 3.0 phr organoclay were improved by 92.8% and 63.4%, respectively. It showed organoclay has excellent reinforcement effect with low content. The reduction of the score and cure times of the composites indicated that the organoclay acted as accelerator in the process of vulcanization. The incorporation of a small amount of organoclay greatly improved the swelling behavior and thermal stability, which was attributed to the good barrier properties of the dispersed organoclay layers. The outstanding performance of co‐reinforcement system with organoclay in the tire formulation showed that the organoclay had a good application prospect in the tire industry, especially for the improvement of abrasion resistance and the reduction of production cost. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Friction and wear behavior of styrene butadiene rubber‐based composites reinforced with microwave‐devulcanized ground tire rubber

In this work, the tribological properties of a new material obtained by revulcanization with styrene butadiene rubber (SBR) and devulcanized ground tire rubber (GTR) were investigated. GTR was devulcanized using the microwave method at a constant power while varying the microwave exposure time. Devulcanized rubber (DV‐R) and untreated GTR were revulcanized by mixing with SBR at different rates (10, 30, 50 phr). To determine friction and wear characteristics of the samples, pin (ball) on disc and abrasion tests were conducted. Scanning electron microscopy (SEM) was employed to observe the worn surfaces of the composites to correlate the experimental test results to the wear mechanisms. All of these tests and experiments were performed on original vulcanized rubber samples for comparison. The composites exhibited different friction and wear behavior due to morphology, dispersion behavior and devulcanization functionalization of ground tire rubber. In general, DV‐R/SBR composites exhibited improvement in both mechanical and tribological properties. However, the enhanced compatibility of DV‐R resulting from the specific chemical coupling of DV‐R with SBR was crucial for the mechanical, friction and wear properties. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42419.     

Fly ash particles and precipitated silica as fillers in rubbers. I. Untreated fillers in natural rubber and styrene–butadiene rubber compounds

In this study, we investigated the effects of untreated precipitated silica (PSi) and fly ash silica (FASi) as fillers on the properties of natural rubber (NR) and styrene–butadiene rubber (SBR) compounds. The cure characteristics and the final properties of the NR and SBR compounds were considered separately and comparatively with regard to the effect of the loading of the fillers, which ranged from 0 to 80 phr. In the NR system, the cure time and minimum and maximum torques of the NR compounds progressively increased at PSi loadings of 30–75 phr. A relatively low cure time and low viscosity of the NR compounds were achieved throughout the FASi loadings used. The vulcanizate properties of the FASi‐filled vulcanizates appeared to be very similar to those of the PSi‐filled vulcanizates at silica contents of 0–30 phr. Above these concentrations, the properties of the PSi‐filled vulcanizates improved, whereas those of the FASi‐filled compounds remained the same. In the SBR system, the changing trends of all of the properties of the filled SBR vulcanizates were very similar to those of the filled NR vulcanizates, except for the tensile and tear strengths. For a given rubber matrix and silica content, the discrepancies in the results between PSi and FASi were associated with filler–filler interactions, filler particle size, and the amount of nonrubber in the vulcanizates. With the effect of the FASi particles on the mechanical properties of the NR and SBR vulcanizates considered, we recommend fly ash particles as a filler in NR at silica concentrations of 0–30 phr but not in SBR systems, except when improvement in the tensile and tear properties is required. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 2119–2130, 2004     

Physicomechanical properties of irradiated SBR latex polymer‐modified cement mortar composites

This study investigated the effect of styrene–butadiene‐rubber (SBR) latex/cement ratio as well as γ‐irradiation dose on physicomechanical properties of cement mortar. Specimens were prepared with a different SBR/cement mass ratio of 2.5, 5, 10, 15, and 20. Two curing methods were used: wet cure and dry cure. The best specimens were irradiated to doses of 10, 30, and 50 kGy. The compressive strength, total porosity, and bulk density were studied. The result indicated that the compressive strength, total porosity, and the bulk densities of the composites decrease with increase in the polymer cement ratios. In addition, it was observed that the compressive strength of irradiated polymer‐modified cement mortar composites was improved with the increase in the γ‐irradiation dose, and the compressive strength of mix‐cured samples was higher than those wet‐cured samples at any irradiation dose. X‐ray diffraction, thermogravimetric analysis, acid attack, and microstructure of SBR‐modified cement mortar were characterized. J. VINYL ADDIT. TECHNOL., 26:144–154, 2020. © 2019 Society of Plastics Engineers