Styrene-butadiene Rubber Vulcanizates Research Articles

Oil from tyre pyrolysis as a plasticizer in rubber compounds

The paper presents the results of research on the possibility of using as plasticizers of rubber compounds the heavy fractions of pyrolytic oil obtained in the industrial process of pyrolysis of car tyres. The content of carcinogenic polycyclic aromatic hydrocarbons (PAHs) in the obtained pyrolytic plasticizers was determined. Compounds and vulcanizates of styrene-butadiene rubber (SBR) containing the above plasticizers as well as commercial petroleum derivatives’ plasticizers were prepared for comparative purposes. The basic properties of compounds and vulcanizates containing pyrolytic plasticizers were investigated. The research showed that one fraction of pyrolysis oil meet the requirements of the permitted content of PAHs. SBR blends and vulcanizates have similar properties as in the case of commercial plasticizers.

Interactions Between an Ionic Liquid and Silica, Silica and Silica, and Rubber and Silica and Their Effects on the Properties of Styrene-Butadiene Rubber Composites

An investigation of the effect of an ionic liquid, 1-butyl-3-methylimidazolium tetrafluoroborate (BMI), on the properties of silica reinforced styrene-butadiene rubber (SBR), aimed to correlate the interactions between the ionic liquid and silica, silica and silica, and silica and rubber with the macro-properties and microstructure of SBR and SBR/silica vulcanizates is described. The interaction between the ionic liquid and silica was characterized by differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR), the interaction between silica and silica was characterized by a rubber processing analyzer (RPA), and the interaction between rubber and silica was characterized by the bound rubber content. The FTIR analysis revealed that BMI can react with the hydroxyl groups on the surface of silica, improving the compatibility between the rubber and silica. The RPA and bound rubber testing indicated that the interactions between silica and silica particles were weakened and the interaction between silica and rubber increased with the incorporation of BMI into the SBR rubber. The bound rubber content showed a maximum with a BMI content of 3 phr. At the same time, the dispersion of silica in SBR was improved with the incorporation of BMI. With the increase of BMI content, the curing rate was greatly improved and the crosslink density increased. BMI also increased the tensile strength and abrasion resistance of the SBR vulcanizates. Most important, the BMI significantly improved the dynamic properties of the rubber composites, especially the wet-skid resistance and rolling resistance. However, excessive BMI (beyond 3 phr) acted as a plasticizer and was detrimental to the mechanical properties, resulting in a decrease of tensile strength and abrasion resistance.

Effects of octamethylcyclotetrasiloxane grafting and in situ silica particle generation on the curing and mechanical properties of a styrene butadiene rubber composite.

The reinforcement of octamethylcyclotetrasiloxane (D4) grafted styrene butadiene rubber (SBR-g-D4) with in situ generated silica was performed using the sol–gel reaction of tetraethoxysilane (TEOS) in latex. The characterization of SBR-g-D4 and in situ generated silica reinforced SBR-g-D4 was investigated by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. The grafting efficiency of the styrene butadiene rubber (SBR) was determined by a gravimetric method. It was found that the constant silicon content and the grafting efficiency of SBR were 1.72% and 0.13 wt% when the weight ratio of D4 to SBR was 0.20. The effects of the D4 and in situ generated silica content on the curing characteristics, mechanical properties and morphology of SBR latex were investigated. The mechanical properties of in situ generated silica reinforced SBR-g-D4 vulcanizates were improved significantly compared to raw SBR vulcanizate when the in situ generated silica content was 18.05%. Compared with silica reinforced SBR-g-D4, the tensile strength, wet skid resistance and rolling resistance of the in situ generated silica reinforced SBR-g-D4 were better. This is because of the higher crosslinking degree in the SBR-g-D4 matrix and the strong chemical bond between SBR-g-D4 molecular chains and in situ generated silica. Scanning electron microscopy analysis revealed good silica filler dispersion in all the reinforced SBR-g-D4 vulcanizates.

Dynamic Moduli Mapping of Silica-Filled Styrene–Butadiene Rubber Vulcanizate by Nanorheological Atomic Force Microscopy

Atomic force microscopy (AFM) offers nanoscale mapping of materials’ properties. Especially, our modified AFM termed “nanorheological AFM” enables us to measure the accurate frequency-dependent storage and loss moduli and loss tangent over a sixth-order frequency range without any temperature control at nanoscale resolution. These dynamic properties obtained by nanorheological AFM can be compared with those using bulk dynamic mechanical analysis (DMA) measurements. In this paper, we applied this technique to silica-filled styrene–butadiene rubber (SBR) to investigate the nature of the interfacial rubber region existing between a rubber matrix and silica particles at different temperatures. The dynamics properties of the interfacial rubber region were different from those of matrix rubber regions. The master curve obtained by this technique perfectly coincided with that by bulk DMA. Furthermore, it was found that the behavior of bulk loss tangent could be predicted by the contributions from both matrix and...

Fabrication of composite membranes for pervaporation of tetrahydrofuran-water: Optimization of intrinsic property by response surface methodology and studies on vulcanization mechanism by density functional theory

Response surface methodology (RSM) optimized accelerator-to-sulfur (A/S) ratio was used to synthesize semi efficiently vulcanized styrene butadiene rubber (SBRSEV0) membrane possessing optimum balance between tensile strength (TS) and elongation at break (EAB). In addition, composite membranes, such as SBRSEV8, SBRSEV12 and SBRSEV24, were fabricated via incorporating 8, 12 and 24 wt% carbon black filler (CBF), respectively. The changes in physicochemical properties, as a result of crosslinking and CBF loading, were determined by analyzing CP MAS 13C-NMR, FTIR, TGA, DSC, XRD, FESEM-EDX and crosslink densities. Several bi-/poly-sulfidic products, formed by crosslinking precursors of SBR in accelerated sulfur vulcanization, were examined to ascertain the unambiguous reaction mechanism. In this regard, an extensive density functional theory (DFT) based optimization was conducted to apprehend the relative variation in stabilities of several mono-/poly-crosslinked configurations by measuring dipole moments and ground state energies. Moreover, intrinsic membrane properties, such as partial permeabilities and diffusion coefficients, were measured at varying conditions. RSM was employed to optimize membrane efficiency resulting from individual and/or interactive effects of input variables. For the first time, systematic three-stage RSM based optimization (i.e., TS/EAB, total flux (TF)/separation factor (SF) and partial permeabilities) was used to ensure excellent balance between TS/EAB (5.78 MPa/499.008% at 2.32 and 3.29 wt% of A and S, respectively), minimum TF/maximum SF (36.90 g m–2 h–1/202.46 at 35 °C, 0.97 wt% tetrahydrofuran (THF) and 24 wt% CBF) and minimum/maximum partial permeabilities of water/THF (2.94×10–8/4.64×10–8 Barrer at 35 °C, 0.97 wt% THF and 11.49 wt% CBF).

Study on the effect of silica–graphite filler on the rheometric, mechanical, and abrasion loss properties of styrene–butadiene rubber vulcanizates

Silica–graphite filler was prepared via two-step grafting procedure by grafting silica particles onto the expanded graphite. In the first step, isocyanatopropyltriethoxysilane was chemically introduced onto the silica aggregates, which was followed by grafting onto the expanded graphite via urethane linkage in the second step. Successful grafting of silica aggregates onto the graphite was corroborated using Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The presence of a thin graphene layer on silica aggregates corroborated using transmission electron microscopy confirmed the grafting of silica aggregates onto the graphite surface. Styrene–butadiene rubber (SBR) composites with various silica–graphite loadings were prepared by melt processing technique to generate pristine silica and silica–graphite-filled elastomeric composites. Rheometric cure studies revealed that the torque difference (Δ S) increased with pristine silica loading, when compared to the unfilled SBR system, and this effect is more pronounced on loading silica–graphite filler. Improvements in mechanical properties such as modulus and tensile strength were observed with increasing loading of silica particles and this effect is more pronounced on loading silica–graphite fillers, indicating that this is due to the rise in the elastomer–filler interactions in the silica–graphite-loaded SBR systems. This fact was further corroborated using bound rubber content and equilibrium swelling ratios of the unvulcanized and vulcanized SBR composites.

Study the effect of a polymerizable surfactant on the physico‒mechanical properties of natural rubber (NR) and Styrene butadiene rubber (SBR).

Polymerizable surfactant (methoxy polyethylene glycol methacrylate) (MPM) was synthesized by direct esterification reaction between (methoxy polyethylene glycol) and methacrylic acid and characterized by FTIR spectroscopy and proton nuclear magnetic resonance (1H NMR) spectroscopy. MPM was incorporated natural rubber (NR) and styrene butadiene rubber (SBR) and inspected as antioxidants for mixes vulcanizates to raise their resistant for ageing through storage to increase shelf life time. As well as possible to compare the effect of investigated (methoxy polyethylene glycol methacrylate) (MPM) with the commercial applied antioxidant in the production of rubber, as (2,2,4-trimethyl-1,2-dihydroquinoline[TMQ]. The rheometric and physico mechanical properties of rubber mixes after and before thermal ageing were measured. The results obtained revealed that 1 and 1.5 methoxy polyethylene glycol methacrylate (MPM) parts per 100 of rubber (phr) have superior effect in the protection of NR and SBR vulcanizates respectively.

Effect of High Aspect Ratio Fillers on the Performance of Styrene-Butadiene Rubber

ABSTRACTAmong the many material performance properties of vulcanized elastomers for tire tread application, rolling resistance and wet traction are particularly important since both greatly impact fuel efficiency and traction of a vehicle. Rolling resistance and wet traction are generally negatively correlated, i.e., with the increase in rolling resistance of a tire, its wet traction decreases. Silica nanofillers are often used for achieving the desired balance of wet traction and rolling resistance. However, the high cost of silica limits its wide spread application. In this research we studied the effects of using fillers with different aspect ratios (calculated by dividing the long dimension of a filler by its short dimension) on the performance of vulcanized styrene butadiene rubber (SBR), a common rubber for tire tread application. Three high aspect ratio fillers were used: aragonite calcium carbonate, wollastonite and carbon nanofiber. For comparison purpose, spherical silica filler was also included. We found that the high aspect ratio fillers were efficient in improving the wet traction and rolling resistance as well as enhancing the mechanical energy dissipation of SBR. Among the three high aspect ratio fillers studied, wollastonite provided the best wet traction and rolling resistance balance due to its high aspect ratio and compatibility with the base rubber. The effects of fillers induced crosslinking on the dynamic performance were also discussed.

Carbon nanotube/reduced graphene oxide hybrid for simultaneously enhancing the thermal conductivity and mechanical properties of styrene -butadiene rubber

A novel hybrid of polymer functionalized-carbon nanotube @ reduced graphene oxide (PCNT@RGO) was prepared by reversible addition-fragmentation chain transfer polymerization, esterification reaction and reduction process. PCNT@RGO hybrid as a filler can effectively enhance the thermal conductivity and mechanical properties of styrene-butadiene rubber (SBR) vulcanizate. Remarkably, the tensile strength and stress at 200% extension of the SBR vulcanizate reached as high as 8.8 and 7.7 MPa at PCNT@RGO loading of 3 wt%, increasing by approaching 203% and 450% compared with neat SBR. Furthermore, the vulcanizate also exhibited high thermal conductivity (0.45 W/m K), which is 2.0-fold higher than that of SBR. The improvement in properties could be attributed to the synergetic effect of PCNT and RGO in PCNT@RGO hybrid, strong interfacial between PCNT@RGO and SBR matrix, the large constrained regions and continuous filler networks. Such good performances render the SBR/PCNR@RGO composite appealing for the use in various engineering practices.

Mechanical and thermal behavior of styrene butadiene rubber composites reinforced with silane-treated peanut shell powder

Biocomposites of styrene butadiene rubber (SBR) reinforced with silane-treated peanut shell powder (SPSP) of different filler loadings and particle sizes were prepared by two roll mixing mills with sulfur as a vulcanizing agent. The cure characteristics of composites were studied, and they vulcanized at 160 °C. Test samples were prepared by compression moulding, and their physicomechanical properties, such as tensile strength tear strength, modulus, hardness, and abrasion resistance of SBR vulcanizates, were studied with filler loading 0, 5, 10, 15, and 20 parts per hundred rubber (phr). Composites with 10 phr filler having small particle size exhibited better properties. The interfacial adhesion between filler and matrix has a major role in the properties of composites. Surface modification of PSP was done by silane coupling agent to improve the interfacial adhesion and it characterised by FTIR, XRD, TGA, UV, and SEM. Better properties are shown by the composites with SPSP. Thermal stability of the composites was also determined using thermogravimetric analysis.

Norbornylized soybean oil as a sustainable new plasticizer for rubbers with hybrid fillers

AbstractCarbon black (CB) and precipitated silica are two major reinforcing fillers in rubbers. CB/silica hybrid filler is also widely used in rubbers to provide balanced properties. CB/silica‐hybrid‐filler‐filled styrene‐butadiene rubber (SBR) containing naphthenic oil (NO), soybean oil (SO) and norbornylized SO (NSO) was investigated. The swelling and curing behavior and rheological, mechanical, thermal, aging and dynamic properties were studied and compared with earlier reported data on CB‐ or silica‐filled SBR. NSO provides better scorch safety and faster cure than SO. Compared with NO, the addition of SO and NSO enhances the thermal stability and aging resistance of SBR vulcanizates. SBR/NSO vulcanizates with hybrid filler exhibit a higher tensile and tear strength than SBR/NO and SBR/SO vulcanizates. A synergistic effect in the abrasion resistance of vulcanizates containing the hybrid filler is observed. An increase of sulfur content in the hybrid‐filler‐filled SBR/NSO vulcanizates provides further improvement in abrasion resistance, wet traction and rolling resistance. © 2017 Society of Chemical Industry

TOWARD REPLACEMENT OF PETROLEUM OILS BY MODIFIED SOYBEAN OILS IN ELASTOMERS

ABSTRACT Precipitated silica- and carbon black (CB)-filled styrene-butadiene rubber (SBR) compounds and vulcanizates containing naphthenic oil (NO), soybean oil (SO), and modified soybean oil (MSO) were studied. Gel fraction; crosslink density; bound rubber fraction; curing behavior; and thermal, mechanical, and dynamic properties were compared. Interaction between SO, MSO, and silane coupling agent was also studied. It was shown that the incorporation of SO and MSO had similar effects in both silica- and CB-filled SBR compounds and vulcanizates. SO and MSO were found to consume curatives leading to a lower crosslink density and improved thermal stability of compounds and vulcanizates. In comparison with NO, MSO was found to increase the elongation at break and tensile strength, and the values of tan δ at 10 °C and 60 °C predict an increase of the wet traction performance and the rolling resistance to decrease the modulus and abrasion resistance. After adjusting the recipe, the modulus and abrasion resistance of the silica- and CB-filled SBR/MSO vulcanizates were tremendously increased, and the silica-filled SBR/MSO vulcanizates exhibited a better wet traction performance, a lower rolling resistance, and a better abrasion resistance simultaneously than the silica-filled SBR/NO vulcanizate.

The Effects of Trans-Polyoctylene Rubber (TOR) on the Cure Characteristics and Swelling Behaviour of Activated Carbon Filled Styrene Butadiene Rubber (SBR) Vulcanizates

Compatibilizer is one of the processing aids used for rubber compounding which helps the incorporation of filler in rubber. In this study, the effect of trans-polyoctylene rubber (TOR) as compatibilizer on the cure characteristics and swelling behaviour of activated carbon filled styrene butadiene rubber (SBR) vulcanizates were studied as a function of TOR loading. Both uncompatibilized and compatibilized SBR vulcanizates with different TOR loading (2, 4, 6 and 8 phr) were prepared using two-rolls mill at room temperature. It was observed that the cure time (tc90) of compatibilized SBR vulcanizates was shorter than that of the uncompatibilized SBR vulcanizate and decreased with increasing of TOR loading up to 6 phr. The minimum torque (ML) of the uncompatibilized SBR vulcanizate was lower compared to the compatibilized vulcanizates. In contrast, the uncompatibilized SBR vulcanizate has higher maximum torque (MH) compared to the compatibilized SBR vulcanizates. As the TOR contents increased, the ML increased but MH gradually decreased. It was also reported that the value of cure rate index (CRI) of the compatibilized SBR vulcanizates increased with the increment in addition of TOR. The result also showed that the compatibilized SBR vulcanizates had lower crosslink density than that of the uncompatibilized SBR vulcanizate and slightly decreased with increasing TOR loading.

Biodesulfurization of vulcanized rubber by enzymes induced from Gordonia amicalisa

In this work, Gordonia amicalisa was used to treat two kinds of vulcanized synthetic rubbers, vulcanized isoprene rubber (v-IR) and vulcanized styrene butadiene rubber (v-SBR). The effects of microbial treatment on vulcanized rubbers were evaluated by changes of crosslinking density, sol fraction, morphology, element content and chemical group of treated rubber samples. The results showed that G. amicalisa can break CC bond mainly on v-IR and SS bonds mainly on v-SBR. After microbial treatment of 20 days, the crosslink densities of v-IR and v-SBR decreased by 13.7% and 22.1%, respectively. The carbon content on v-IR surface was decreased by 9.1%. FTIR analysis showed that CC bonds transferred into CO bonds, indicating the main chain scission. Regarding to the v-SBR, sulfur content on its surface was decreased by 22.9%, SS bonds were broken and SO producing, indicating the sulfur crosslink scission. Furthermore, the inducing mechanism of desulfurizing enzyme produce from G. amicalisa was investigated. v-SBR and v-IR were used as enzyme inducers, and dibenzothiophene was used as substrate reacting with desulfurizing-enzyme. The liquid chromatography and ultraviolet spectrum analysis showed that v-SBR was the specific substrates that can induce G. amicalisa to secret desulfurizing enzyme, making desulfurizing reaction happen.

The Effects on Cure Characteristics, Physico-Mechanical Properties and Morphology of Bamboo Activated Carbon Filled Styrene Butadiene Rubber (SBR) Vulcanizates

The role of activated carbon (AC) in rubber compounds was investigated to better understand the reinforcing mechanism. The activated carbon filled styrene butadiene rubber vulcanizates (SBR-AC) using bamboo activated carbon as filler were prepared by using two-roll mill and cured at 160 °C. AC filler loading from 10 to 50 phr (part per hundred rubber) were used in this study. Study into the influences of filler loading on the cure characteristics, swelling behavior, physical properties (hardness and resilience), mechanical properties (tensile properties) and morphology of SBR-AC vulcanizates were carried out. It was observed that SBR-AC vulcanizates has better cure characteristics compared to the styrene butadiene rubber gum vulcanizate (SBR-GV) which is a non-filled vulcanizate. The results showed that the scorch time (ts2) decreased with increasing filler loading. The cure time (tc90) slightly decreased up to 20 phr before a rise as the filler loading increased. The minimum torque (ML) of SBR vulcanizate increased and the maximum torque (MH) decreased up to 20 phr but then increased with increasing filler loading. The cure rate index (CRI) of SBR-GV vulcanizate was higher than that of all SBR-AC vulcanizates. Up to 20 phr of filler loading, the CRI increased before a decline occurred as the filler loading increased. As expected, the hardness value of SBR-AC vulcanizates was higher compared to SBR-GV vulcanizate which has lower resilience. The hardness and crosslink density showed an increasing trend meanwhile the resilience was adversely affected by the increase in filler loading. The tensile properties of SBR-AC vulcanizates also showed improvement in which the tensile strength and modulus at 100% elongation (M100) increased with increasing filler content. It has been proved in morphology study of the tensile fracture surfaces. Bamboo activated carbon showed some potential enhancement on the reinforcing and physical properties as well as mechanical properties of the vulcanizates.

The Effects on the Cure Characteristics and Physical Properties of Bamboo Activated Carbon Filled Styrene Butadiene Rubber (SBR) Compounds

The role of activated carbon (AC) in rubber compounds was investigated to better understand the reinforcing mechanism. The activated carbon filled styrene butadiene rubber vulcanizates (SBR-AC) using bamboo activated carbon as filler were prepared by using two-roll mill and cured at 160 °C. AC filler loading from 10 to 50 phr (part per hundred rubber) were used in this study. Study into the influences of filler loading on the cure characteristics, swelling behaviour and physical properties (hardness and resilience) of SBR-AC vulcanizates were carried out. It was observed that SBR-AC vulcanizates has better cure characteristics compared to the styrene butadiene rubber gum vulcanizate (SBR-GV) which is a non-filled vulcanizate. The results showed that the scorch time (ts2) decreased with increasing filler loading. The cure time (tc90) slightly decreased up to 20 phr before a rise as the filler loading increased. The minimum torque (ML) of SBR vulcanizate increased and the maximum torque (MH) decreased up to 20 phr but then increased with increasing filler loading. The cure rate index (CRI) of SBR-GV vulcanizate was higher than that of all SBR-AC vulcanizates. Up to 20 phr of filler loading, the CRI increased before a decline occurred as the filler loading increased. As expected, the hardness value of SBR-AC vulcanizates was higher compared to SBR-GV vulcanizate which has lower resilience. The hardness and crosslink density showed an increasing trend meanwhile the resilience was adversely affected by the increase in filler loading. Bamboo activated carbon showed some potential enhancement on the reinforcing and physical properties of the vulcanizates.

EFFECT OF MODIFIED KAOLINITE BY USING FATTY ACIDS ON NR- AND SBR-REINFORCED COMPOSITES

ABSTRACTNatural rubber (NR) and styrene butadiene rubber (SBR)–kaolinite clay (KC) composites (NR-KC and SBR-KC) were synthesized and characterized. The interfacial surface between rubber and KC was investigated in the presence of stearic acid (SA), palmitic acid (PA), and oleic acid (OA) coupling agents. A monolayer of modifiers was formed on the surface of KC particles. X-ray diffraction (XRD) was carried out to study the effect of fatty acid coupling agents on KC. Modifier concentrations were determined using an adsorption isotherms technique. Sedimentation rate and volumes of modified KC in toluene were measured. Rheometric characteristic and physico-mechanical properties of rubber composites were investigated. Stress–strain behavior and hardness of NR-KC and SBR-KC composites were studied. Experimental results were compared with calculated results using the Cambridge Engineering Selector program. The XRD patterns showed a decrease in the peak intensity of unmodified KC compared with modified KC, asserting an intercalation process. The optimum concentrations of chemical modifiers are 16 × 10−5, 18 × 10−5, and 37 × 10−5 mol/g for SA, OA, and PA, respectively. Mechanical testing showed that high tensile strength can be obtained in the presence of the SA modifier. The degree and kinetics of equilibrium swelling and soluble fraction for NR and SBR vulcanizates were investigated.

A combined experimental and molecular dynamics simulation study on the structures and properties of three types of styrene butadiene rubber

The styrene/butadiene ratio of styrene butadiene rubber (SBR) greatly affects the inherent characteristics and material performance of the rubber. In this study, SBR vulcanizates comprising the same amount of carbon black and other additives were prepared with raw rubbers with different styrene/butadiene ratios. The mechanical and viscoelastic properties of the vulcanizates were investigated experimentally to analyze their performance as tire tread materials.Besides, atomistic molecular dynamics (MD) simulation of the three SBRs in the bulk amorphous state were performed to study the effect of microstructure on material performance. The free volume, cohesive energy density (CED), mean square displacement (MSD), and glass transition temperature (Tg) of SBR models were simulated. The simulated free volume and Tg were consistent with the experimental results. Importantly, a high correlation between the simulated micro-structural characteristics and macro-performance was obtained by a linear fit of the calculated Fsim and loss factor tan δ values of the vulcanizates at 0 and 60°C from the dynamic mechanical thermal analysis (DMTA) spectrum. The present study hopes to provide theoretical guidance to the chain structure design of SBR for tire tread applications.

Modified soybean oil-extended SBR compounds and vulcanizates filled with carbon black

Soybean oil (SO) was modified through the reaction with dicyclopentadiene (DCPD) to convert carbon double bonds in the soybean oil molecules into norbornyl groups of different ratios. Styrene-butadiene rubber (SBR) compounds with carbon black (CB) containing different extender oils including SO, modified SO (MSO) and naphthenic oil (NO) were prepared for comparison. The gel fraction, crosslink density, bound rubber fraction, curing behavior, thermal, mechanical and dynamic properties and reactions between the SO, MSO and curatives were investigated. It was found that with an increase of the modification level, the gel fraction of the SBR/MSO vulcanizates slightly increased while the crosslink density and bound rubber fraction decreased. The SBR/SO and SBR/MSO compounds and vulcanizates showed a lower glass transition temperature (Tg) and better thermal stability than those of the SBR/NO compounds and vulcanizate. The SBR/MSO compounds exhibited faster curing. Their vulcanizates showed lower modulus and higher elongation at break and tensile strength in comparison with the SBR/NO vulcanizates. The dynamic mechanical analysis of SBR/MSO vulcanizates indicated that use of this rubber in tire tread is expected to improve traction but increase rolling resistance compared to the SBR/NO vulcanizates. After adjusting the curative recipe, the modulus and tensile strength and abrasion resistance of the SBR/MSO vulcanizates with low level of modification were tremendously improved with the tensile strength and elongation at break being significantly higher than that of SBR/NO vulcanizate. The use of this recipe is expected to achieve similar traction and lower rolling resistance compared to the SBR/NO recipe. The addition of MSO to SBR has a promising possibility to replace petroleum oils in the rubber along with improvement of safety in tire production.

Surface modification of sol–gel derived nano zinc oxide (ZnO) and the study of its effect on the properties of styrene–butadiene rubber (SBR) nanocomposites

Very recently, nano zinc oxide (ZnO) has been successfully introduced as a cure activator for the reduction of ZnO level in the rubber industry. The purpose of the present work is to examine the appropriateness of surface-modified nano ZnO in the vulcanization of styrene–butadiene rubber (SBR). In the experimental part, the surface of nano ZnO is modified by stearic acid and bis[3-(triethoxysilyl)propyl]tetrasulfide (Si-69). Si-69-treated nano ZnO causes considerable enhancement in many properties such as maximum rheometric torque, modulus, tensile strength, elongation at break, cross-linking degree of SBR nanocomposite in comparison to conventional ZnO and unmodified or stearic acid-treated nano ZnO. Thermogravimetric analysis (TGA) reveals that Si-69-treated nano ZnO imposes better thermal stability than untreated or stearic acid-treated nano ZnO in the SBR vulcanizates. Morphological study indicates uniform dispersion of Si-69-treated nano ZnO within the SBR matrix and this fact accounts for better mechanical and thermal properties of SBR nanocomposite in the presence of Si-69-modified nano ZnO. This study concludes that Si-69-modified nano ZnO can be effectively applied as cure activator in place of nano ZnO to reduce the ZnO level in SBR compounds. This will lead to both economic advantages and environmental safety in the rubber industry.