Styrene-butadiene Rubber Vulcanizates Research Articles

Synergistic effect of a new binary accelerator system on curing characteristics and properties of styrene–butadiene rubber vulcanizates

Synergistic effect of a new binary accelerator system on curing characteristics and properties of styrene–butadiene rubber vulcanizates

Modified waste rubber powders filled styrene butadiene rubber toward the combination of high elasticity and low mechanical hysteresis

Waste recycled rubber (RR) powders are modified with modifier and low-temperature mechanochemical devulcanization (LTMD) method, and filled into styrene butadiene rubber (SBR) to improve its elasticity and reduce its mechanical hysteresis. The incorporation of modified RR (MRR) could accelerate SBR vulcanization, improve the crosslinking density of SBR and promote the compatibility of MRR in the matrix. Furthermore, it could also improve the tensile strength of SBR vulcanizates and weaken the Mullins effect by reducing their overall hysteresis, softening and energy loss. Such method realizes the high-value recovery of RR, reduces the mechanical hysteresis of rubber composites and improves the elasticity.

Mechanical properties of pyrolysis carbon black in rubber compound application

Waste tire pyrolysis is a thermal decomposition process that converts waste tires into liquid fuel which also produce by product material such as producer gas, pyrolysis carbon black (CBp), and steel wire. Nowadays, carbon black produced by pyrolysis is being employed as a low-grade carbon base fuel. The technical feasibility of using CBp as a substitute for commercial carbon black N330 in styrene-butadiene rubber (SBR) was investigated in the study. The researcher also looked at how the composition ratio of CBp and N330 affected the mechanical characteristics of rubber in comparison to the outcomes of pure carbon black N330. It was discovered that the low composition ratio of 20% CBp and 80% N330 (R-2) had comparable Mooney viscosity to that of N330 carbon black, as well as the highest torque (MH) and torque increment (ΔM) values, but increased CBp content led to increased rubber viscosity and decreased cure time due to sulfur residues CBp was inferior to N330 in its effect on reinforcement. With an increase in CBp content, the tensile strength, shear strength, and elongation at break of SBR vulcanizates decreased considerably, while the hardness increased. Consequently, the CBp value evaluated for hardness applications provides significant manufacturing cost savings.

Loading conditions impact on the compression fatigue behavior of filled styrene butadiene rubber

Abstract Fatigue failure, commonly encountered in rubber materials, is a critical issue. In this study, the compression fatigue tests of filled styrene-butadiene rubber (SBR) under different loading conditions were performed, applying cylindrical specimens. A stress–strain curve and modulus drop curves were generated by nine fatigue loading cases, covering different R ratios in the range of 0 < R < 1. The temperature variation in the process of compression fatigue was explored. Three different approaches were applied to investigate the fatigue life of the SBR (it is used twice hence abbreviation should be used) vulcanizates. These methods were validated in assessing the fatigue failure of the specimens. According to the experimental fatigue life, a fatigue life prediction model based on strain amplitude as the damage parameter was established. The results demonstrated that both R ratio and strain amplitude could affect the fatigue life. For all the loading cases, the fatigue life generally increases with the increase of R ratio. Under the compression loading condition, the narrower range of strain and the lower mean strain are beneficial to the fatigue resistance of rubbers, which also indicates a larger pre-load provides much higher fatigue resistance. During the fatigue loading, the temperature rises rapidly until it reaches a peak value, then drops slightly, and finally reaches a plateau.

Effects of antimicrobial agents on the processing and performance properties of rubber material formulations with no cytotoxicity

AbstractThe present work aims to develop antimicrobial rubber for safe industrial toys. For this purpose, natural rubber (NR) and synthetic rubber as styrene butadiene rubber (SBR) and ethylene propylene diene monomer (EPDM) were examined. Rubber and their ingredients as well as antimicrobial agents (doxycycline and cephalexin) were mixed in a rubber mixer. The rheological properties of compounded rubber were studied, and the curing time was determined. Mechanical properties and cytotoxicity were evaluated at optimally cured rubber compounds. Scanning electron micrographs of vulcanizates showed good dispersion of ingredients throughout the investigated matrices. Rheology study for the investigated vulcanizates in presence of tested antimicrobial species exhibited no significant change in their flow behaviors. It is significant to remember that the desired physical characteristics of rubber products, including their chemical and mechanical characteristics (elongation at break and tensile strength) enhanced when doxycycline and cephalexin are present, depending on their nature and concentration. Similar results were obtained for both the SBR and EPDM rubber vulcanizates. The cytotoxicity of the prepared vulcanizates towards human normal retina cell line (RPI‐1) indicated good safety of these rubber products. Furthermore, developed rubber vulcanizates showed good antimicrobial efficacy towards the test bacteria and fungi strains.”

Carbon Nanotubes Networking in Styrene‐Butadiene Rubber: A Dynamic Mechanical and Dielectric Spectroscopy Study

AbstractThe study of the reinforcement network in elastomer compounds is one of the most relevant issues for the application of these materials because their properties are strongly dependent on the obtained morphology. To this regard, the viscoelastic and dielectric behavior of vulcanized styrene butadiene rubber (SBR) reinforced with different amounts of carbon nanotubes (CNT) have been investigated and compared with the vulcanized unfilled SBR and the vulcanized SBR samples reinforced with a conventional amount of carbon black (40 phr). Differential scanning calorimetry (DSC) measurements have been carried out to highlight possible differences of the glass transition temperatures for all the reinforced compounds. The percolation threshold value of the nanocomposite samples has been estimated by dielectric analysis. Finally, dynamic mechanical analysis (DMA) measurements have been performed in tensile mode in the temperature range of −60 to 80 °C to obtain bothE′ andE′′. From these experimental data, the master curve for each sample has been estimated by using the time–temperature superposition principle in combination with the vertical shift approach. From the analysis of this latter, the activation energy, associated to the thermal movement of the reinforcement network, has been calculated to better elucidate the reinforcement mechanism in the nanocomposites.

Recycling of Bagasse as an Agricultural Waste and its Effect as Filler on Some Mechanical and Physical Properties of SBR Composites

Abstract In the present study, a series of mixes based on different concentrations of carbon black (CB) as a reinforcing filler and sugarcane bagasse as supplementary filler, were investigated to examine their effects on the mechanical properties of styrene butadiene rubber (SBR) composites. To this end, the first group of mixes deals with the effect of different concentrations of CB ranging from 0 to 80 phr at fixed bagasse concentration of 25 phr. The second group of mixes involves the addition of bagasse with concentrations varying from 10 to 50 phr at 10 intervals with fixed CB concentration of 40 phr. The sizes of the employed ground bagasse powder (GBP) in all prepared formulations ranged from 20 to 180 μm. In addition, 2.5 phr of maleic anhydride (MA) was added to enhance the interfacial adhesion between SBR and agricultural waste fillers (i. e. bagasse). Tensile strength, elongation at break, modulus at 100% elongation, resilience, hardness (Shore A), abrasion and degree of swelling of the rubber vulcanizates were studied. The prepared samples were also analyzed by scanning electron microscopy (SEM) to show the distribution of fiber and the occurrence of fiber-matrix adhesion. The optimum concentration of bagasse to be used simultaneously with CB in SBR composites was found to be 30 phr. Overall, it was found from the obtained results that the addition of GBP up to 50 phr is feasible without impairing the mechanical properties of SBR vulcanizates.

Influence of the Silica Specific Surface Area and Ionic Liquids on the Curing Characteristics and Performance of Styrene-Butadiene Rubber Composites.

In this work, we present the effect of silica’s specific surface area (180 m2·g−1 and 380 m2·g−1, respectively) on the crosslinking of styrene–butadiene rubber (SBR) composites, as well as their crosslink density and functional properties, such as thermal stability, damping behavior, resistance to thermo-oxidative aging, and tensile properties. Ionic liquids (ILs) with a bromide anion and different cations, i.e., 1-butyl-3-methylimidazolium (Bmi), 1-butyl-3-methylpyrrolidinium (Bmpyr), and 1-butyl-3-methylpiperidinium (Bmpip), were used to enhance the cure characteristics of SBR compounds and the functional properties of SBR vulcanizates. It was proven that apart from the silica’s specific surface area, the filler–polymer and filler–filler physical interactions have a significant impact on the vulcanization kinetics of silica-filled SBR composites. Additionally, the performed studies have shown that ILs positively affected the dispersion of silica’s particles and reduced their ability to form agglomerates in the elastomer matrix, which enhanced the functional properties of the SBR vulcanizates.

Zinc Complexes with 1,3-Diketones as Activators for Sulfur Vulcanization of Styrene-Butadiene Elastomer Filled with Carbon Black.

Zinc oxide nanoparticles (N-ZnO) and zinc complexes with 1,3-diketones of different structures were applied instead of microsized zinc oxide (M-ZnO) to activate the sulfur vulcanization of styrene-butadiene rubber (SBR). The influence of vulcanization activators on the cure characteristics of rubber compounds, as well as crosslink density and functional properties of SBR vulcanizates, such as tensile properties, hardness, damping behavior, thermal stability and resistance to thermo-oxidative aging was explored. Applying N-ZnO allowed to reduce the content of zinc by 40% compared to M-ZnO without detrimental influence on the cure characteristic and performance of SBR composites. The activity of zinc complexes in vulcanization seems to strongly depend on their structure, i.e., availability of zinc to react with curatives. The lower the steric hindrance of the substituents and thus the better the availability of zinc ions, the greater was the activity of the zinc complex and consequently the higher the crosslink density of the vulcanizates. Zinc complexes had no detrimental effect on the time and temperature of SBR vulcanization. Despite lower crosslink density, most vulcanizates with zinc complexes demonstrated similar or improved functional properties in comparison with SBR containing M-ZnO. Most importantly, zinc complexes allowed the content of zinc in SBR compounds to be reduced by approximately 90% compared to M-ZnO.

Preparation of lignin‐based filling antioxidant and its application in styrene‐butadiene rubber

AbstractA novel filling antioxidant (Lig‐g‐RT) to improve the mechanical properties and antiaging performance of styrene‐butadiene rubber (SBR) composites was prepared by grafting antioxidant intermediate p‐aminodiphenylamine (RT) on the surface of lignin via the linkage of silane coupling agent. Fourier transform infrared (FTIR) and thermogravimetric analysis (TGA) measurements confirmed that RT was successfully grafted on the surface of lignin to produce the functionalized Lig‐g‐RT which shows a better thermal stability than lignin. Compared with SBR/lignin composite, the SBR/Lig‐g‐RT composite using latex co‐precipitation method exhibits a much better filler dispersion, which contributes to the maintain of the physical mechanical properties of SBR vulcanizates. Moreover, the SBR/Lig‐g‐RT vulcanizate exhibits less chemical crosslink concentration and higher entanglement density than SBR/lignin vulcanizate according to the Mooney–Rivlin model analysis. In addition, the stabilizing effect of lignin/Lig‐g‐RT on the carbon‐black filled SBR vulcanizates is comparable with that of commercial antioxidant N‐1,3‐dimethylbutyl‐N′‐phenyl‐p‐phenylenediamine (4020), especially the SBR vulcanizate filled with 10 phr Lig‐g‐RT obtains the optimum thermo‐oxidative aging properties. This functionalized Lig‐g‐RT not only provides an intramolecular synergistic antiaging effect for SBR vulcanizates and an improvement of filler dispersion, but greatly extends the comprehensive utilization of industrial lignin.

Compressive Fatigue Behavior of Gum and Filled SBR Vulcanizates.

The influence of carbon black on physical mechanical properties, compressive fatigue life, and the temperature changes during compression fatigue process of styrene-butadiene rubber (SBR) vulcanizates were explored. A series of unfilled and filled SBR compounds were prepared, and the compressive fatigue behaviors of the vulcanizates were performed on a mechanical testing and simulation (MTS) machine. The top surfaces of the filled SBR were imaged using scanning electron microscopy (SEM) after 105 cycles of compressive fatigue. The filled SBR shows greater compressive fatigue resistance than the unfilled SBR. The incorporation of carbon black into SBR improves the creep resistance. The best compressive fatigue resistance for the filled SBR was achieved by the addition of 30 phr carbon black. With the increase of carbon black content, the energy dissipation and the heat build-up increase simultaneously. Furthermore, SEM images of the vulcanizates suggest that the crack propagation mechanism of the unfilled and the filled SBR was different. For the unfilled SBR, due to periodical compressive stress, the polymer chains can be destroyed, and the cracks can be easily initiated and propagated, showing serious damage on the top surfaces of the specimen. However, for the filled SBR, the carbon black agglomeration around the cracks can greatly delay the generation of the cracks, decrease the fatigue damage, and ultimately improve the fatigue resistance.

Influence of n-ZnO Morphology on Sulfur Crosslinking and Properties of Styrene-Butadiene Rubber Vulcanizates.

This paper examines the influence of the morphology of zinc oxide nanoparticles (n-ZnO) on the activation energy, vulcanization parameters, crosslink density, crosslink structure, and mechanical properties in the extension of the sulfur vulcanizates of styrene-butadiene rubber (SBR). Scanning electron microscopy was used to determine the particle size distribution and morphology, whereas the specific surface area (SSA) and squalene wettability of the n-ZnO nanoparticles were adequately evaluated using the Brunauer–Emmet–Teller (BET) equation and tensiometry. The n-ZnO were then added to the SBR in conventional (CV) or efficient (EV) vulcanization systems. The vulcametric curves were plotted, from which the cure rate index (CRI) rate of the vulcanization and the activation energy were calculated. The influence on the mechanical properties of the SBR vulcanizates was stronger in the case of the EV curing system than when the CV curing system was used. Of the vulcanizates produced in the EV curing system, the best performance was detected for n-ZnO particles with a hybrid morphology (flat-ended rod-like particles on a “cauliflower” base) and high SSA. Vulcanizates produced using the CV curing system showed slightly better mechanical properties after the addition of nanoparticles with a “cauliflower” morphology than when the rod-like type were used, irrespective of their SSA. In general, nanoparticles with a rod-like structure reduced the activation energy and increased the speed of vulcanization, whereas the cauliflower type slowed the rate of the process and the vulcanizates required a higher activation energy, especially when using the EV system. The crosslink structures were also more clearly modified, as manifested by a reduction in the polysulfidic crosslink content, especially when n-ZnO activators with a rod-like morphology were applied.

Understanding H2O2-Induced Thermo-Oxidative Reclamation of Vulcanized Styrene Butadiene Rubber at Low Temperatures

Recombination reactions often occur in the process of chemical, thermal, or mechanical degradation of vulcanized styrene butadiene rubber (SBR), which hinders the recycling efficiency of waste tire...

Effect of the silica-rubber interface on the mechanical, viscoelastic, and tribological behaviors of filled styrene-butadiene rubber vulcanizates

In this research, the effects of the surface modification of silica by low-molecular-weight hydroxyl-terminated polybutadiene (HTPB) are compared with those of bis(3-triethoxysilylpropyl)tetrasulfide (TESPT) on the mechanical, viscoelastic, and tribological properties of styrene-butadiene rubber (SBR) vulcanizates. Both modifiers have the ability to make covalent bonds with the rubber matrix, but with different interfacial characteristics controlling the final properties. The results displayed improvements in the tribological behavior of both modified silica-filled vulcanizates over pristine silica- and carbon black-filled vulcanizates. However, the HTPB modification method, despite providing a finer dispersion of the silica in the rubber, did not result in better tribological properties for the vulcanizates compared with those of the TESPT modification method. It was discussed that the HTPB modifier did not enhance tribological properties, especially abrasion resistance, as much as the TESPT modifier did because of the soft and flexible interface that was created in the presence of the HTPB modifier, in contrast to the rigid interface in the presence of TESPT. Molecular structure of silica surface modifiers greatly controls the performance of silica-filled styrene-butadiene rubber (SBR) through interfacial characteristics of the composites. Soft nature of low molecular-weight hydroxyl terminated polybutadiene (HTPB) and small number of its covalent bounds to the rubber matrix was compared with large number of rigid covalent bounds made between bis(3-triethoxysilylpropyl)tetrasulfide (TESPT) and rubber. Despite the better dispersion of silica modified with the former, the latter ensures higher transfer of stress to particles at large strains, inducing improved strength and abrasion resistance to composites.

Some studies on the effect of bagasse concentration on the mechanical and physical properties of SBR composites

This work aims to avoid pollution of the environment resulting from ashes accumulated due to the burning of agricultural wastes. Also, it aims to reduce the cost without impairing the mechanical properties of rubber vulcanizates. For this reason, this work was carried out as a possible solution by incorporation of cellulose fibers derived from bagasse waste as reinforcing fillers in rubber composites. Besides, it aims at reporting an investigation on a series of mixtures based on natural ground bagasse powder (GBP) and carbon black (CB) as reinforcing fillers to study their effects on the mechanical and physical properties of styrene butadiene rubber (SBR) composites. The GBP obtained from the grinding machine has a selective grain size distribution ranging from about 20 µm to 180 µm. In addition, 2.5 phr of added maleic anhydride was used to improve the interfacial adhesion between SBR and agricultural waste fillers (i.e. bagasse). Tensile strength, elongation at break, modulus at 100% elongation, resilience and hardness (Shore A), degree of swelling, and thermal properties of the rubber vulcanizates were studied. The prepared samples were also analyzed by X-ray diffractometer and scanning electron microscopy. The advantage of choosing the 25 phr bagasse concentration as a pivoting factor makes the road clearer to investigate that the optimum concentration of bagasse to be used simultaneously with CB in SBR composites is 30 phr. Furthermore, it was found from the obtained results that the addition of GBP up to 50 phr is possible without impairing the mechanical properties of SBR vulcanizates.

PERFORMANCE EVALUATION OF HYPERELASTIC MODELS FOR CARBON-BLACK–FILLED SBR VULCANIZATES

ABSTRACTThe performance of four recently developed hyperelastic material models (HM models) was evaluated by using stress–stretch relationships of filled styrene butadiene rubber vulcanizates with different contents of carbon black (CB) tested under uniaxial tension (UT), pure shear (PS), and equi-biaxial tensile (BT) conditions. The stress–stretch relationships for the PS and BT tests were obtained with a specially designed specimen having higher accuracy than those obtained with an ordinary specimen. The performances of the HM models were compared via the following three evaluations: (1) ability to reproduce the UT, PS, and BT tests; (2) ability to predict the PS and BT test results with material constants identified from the UT test; and (3) correlation between the identified material constants and CB contents. The evaluations based on a combination of the stress–stretch relationships with high accuracy and four recently developed HM models revealed that the HM model activates only the I1 term, which is the first invariant of the right Cauchy–Green tensor, exhibiting good reproducibility and predictability.

The Effect of Network Structure on Compressive Fatigue Behavior of Unfilled Styrene‐Butadiene Rubber

The effect of network structure on dynamic compressive fatigue behavior and static compressive mechanical properties of styrene‐butadiene rubber (SBR) were investigated. A series of SBR compounds with different amounts of sulfur and dicumyl peroxide (DCP) were prepared, and their crosslinking densities were calculated using the Flory–Rehner equation. Compressive fatigue resistance and creep behavior of the vulcanizates were performed on a mechanical testing and simulation (MTS) machine. The fatigue damage surface of SBR vulcanizates before and after a dynamic compressive fatigue test was observed with a scanning electron microscopy (SEM). The results suggested that the surface of the samples was badly damaged as the number of compressive cycles increased. By comparison, compressive fatigue caused less surface damage to sulfur‐cured SBR than to peroxide‐cured SBR. The peroxide‐cured SBR samples showed higher energy dissipation than sulfur‐cured SBR during cyclic compression. The peroxide‐cured SBR showed lower creep strain and compression set than the sulfur‐cured SBR. The ‐Sx‐ linkages provided by the sulfur curing system allow dynamic compressive deformation but suffer from poor static compressive resistance. However, the carbon‐carbon linkages from DCP are irreversible and provide higher resistance to static compressive stress, but they do not show obvious dynamic compressive fatigue resistance.

Cradle-to-cradle approach to waste tyres and development of silica based green tyre composites

This work is about simultaneous devulcanization and chemical functionalisation of waste styrene butadiene rubber vulcanizate (SBR) using thermo-mechanical treatment and sulphide based multifunctional devulcanizing agent. The as-grown compounds are reinforced with nano-silica and re-vulcanized to prepare rubber composites. The curing and processing characteristics, and mechanical performance are further compared with those of conventional silica based green tire formulations. The extent and quality of devulcanized rubber are monitored through the measurement of sol content, inherent viscosity of sol fraction, cross-link density and degree of devulcanization as a function of cross-link density. By our method based on restoring the curing and other processing parameters, the revulcanized composites offer ∼11 MPa tensile strength, ∼26 MPa tear strength together with elongation at break value as much as 450 %. Such values are comparable with those of the composites consisting of the associated fresh components of the systems. Surprisingly, the higher storage modulus and lower tan⁡δ of SBR-devulcanized SBR-silica composite as compared with standard counterpart sample (SBR-silica composite) confirms magnificent dynamic mechanical performance of the composites. This work may pave a new route for reuse of waste tyre in tyre production.

Effects of tension fatigue on the structure and properties of carbon black filled-SBR and SBR/TPI blends

Abstract The aim of this study was to explore the impact of tension fatigue on the structure and properties of filled SBR and SBR/TPI blends. The effect of tension fatigue on the dynamic properties of carbon black-filled styrene-butadiene rubber (SBR) and SBR/trans-1,4-polyisoprene (SBR/TPI) blend vulcanizates were investigated by dynamic mechanical analysis (DMA). The Mooney-Rivlin analysis of tensile stress-strain data is used for the determination of a rubber network crosslink density. The fatigue fracture surface of SBR/TPI vulcanizates was observed with a scanning electron microscopy (SEM). The crystallinity of TPI in carbon black-filled SBR/TPI (80/20) was characterized by X-ray diffraction (XRD). The results showed that the incorporation of TPI into SBR vulcanizates influences the fatigue properties of the blend vulcanizates. The blend vulcanizates showed optimum fatigue properties with 20 phr TPI. With increasing fatigue cycles, the tensile properties and crosslink density of SBR vulcanizates were decreased substantially. Compared with that of SBR vulcanizates, the tensile properties and crosslink density of SBR/TPI (80/20) blend vulcanizates changed little with the increase in fatigue cycles, and tan δ and E′ decreased gradually with the fatigue cycles. There was a sharp decrease in the E′ and tan δ curve in the temperature range of 40 ~ 60°C. The XRD diffraction peak corresponding to 3.9 Å broadened when the fatigue cycles were increased to 1 million times, and a new peak with inter-planar spacing at 7.6 and 4.7 Å appeared.

The rheometric, mechanical and morphological properties of carbon black filled styrene butadiene rubber vulcanizates in presence of alkanolamide

Properties of carbon black (CB)-filled styrene-butadiene rubber (SBR) vulcanizates include rheometric, mechanical and morphological in presence of alkanolamide were studied. The synthetic rubber was filled by CB at a settled loading at thirty parts per hundred rubber (phr). The alkanolamide was derived from ethanolamine and refined bleached deodorized palm stearin and it was incorporated into CB-filled SBR at one, three, five and seven phr. From the results, it was found that alkanolamide was a rubber chemical as a co-curing and plasticizing material. As a co-curing material, it reduced the times to cure and scorch of filled SBR vulcanizates. As a plasticizing material, it reduced minimum torque or viscosity but raised the elongation at break. The properties of torque difference, tensile moduli, hardness, tensile strength and resilience of CB-filled SBR vulcanizates were also raised due to the presence of alkanolamide. The presence of a five phr of alkanolamide was the optimum concentration for CB-filled SBR whatever was tested by morphological study. The fractured vulcanizate of CB-filled SBR with the five phr of alkanolamide demonstrated greatest surface roughness and matrix tearing.