Silica-filled Styrene-butadiene Rubber Compounds Research Articles

Determination of the crosslink density of silica-filled styrene butadiene rubber compounds by different analytical methods

AbstractThe crosslink density of rubber compounds has a great effect on the properties of the final product. For this reason, a suitable characterization method is required to understand and optimize the final performance of rubber materials. Four different experimental techniques were used to determine the crosslink density of silica-filled styrene butadiene rubber composites: equilibrium swelling experiments, stress–strain measurements using the Mooney–Rivlin theory, freezing point depression temperature tests and Temperature Scanning Stress Relaxation (TSSR) measurements. The evaluation of these different techniques shows that the results obtained follow a similar trend for all four methods. The results from the Mooney-Rivlin and TSSR measurements correlate the best. These two techniques are the least affected by the presence of fillers and are the less time-consuming ones. Furthermore, they also show the best correlation with the mechanical properties of the studied compounds.

The role of reduced graphene oxide as a secondary filler in improving the performance of silica-filled styrene-butadiene rubber compounds

The role of reduced graphene oxide as a secondary filler in improving the performance of silica-filled styrene-butadiene rubber compounds

Effect of Sulfur Variation on the Vulcanizate Structure of Silica-Filled Styrene-Butadiene Rubber Compounds with a Sulfide-Silane Coupling Agent.

The vulcanizate structure of filled compounds is affected by filler–rubber interactions (FRI) and the chemical crosslink density (CCD) of the matrix rubber. In particular, in filled compounds using a silica–silane system, FRIs due to silica–rubber coupling are a major influencing factor for the vulcanizate structure and physical properties. In this study, the effect of sulfur variation on the vulcanizate structure of silica-filled solution styrene–butadiene rubber compounds using a sulfide–silane coupling agent was studied. The vulcanizate structure according to sulfur variation was quantitatively analyzed using the swelling test and Flory–Rehner and Kraus equations. As the sulfur content increased, both FRI and the CCD increased, and it was confirmed that sulfur variation influenced the silica–rubber coupling efficiency through increased FRI. In addition, field emission scanning electron microscope images showed that increased FRI contributed to improvements in silica dispersion, abrasion resistance, and energy loss characteristics.

Silica-filled styrene-butadiene rubber in the existence of palmitamide: vulcanization properties and reinforcement index

By applying one semi EV vulcanization system; the influences of palmitamide on vulcanization properties and reinforcement index of silica-filled styrene-butadiene rubber (SBR) compounds were observed. The palmitamide was lab-prepared from urea and palmitic acid and added into the silica-filled SBRat1, 3, 5 and 7phr. It was revealed that the palmitamide was a curative material which decreased theoptimum cure timebut increased the maximum and change in torques of the silica-filled SBR compounds. The bigger the palmitamide loading, the shorter was the optimum cure time. It was also revealed that palmitamide was an extra plasticizing material which decreased minimum torque. The reinforcement index, tensile moduli and tensile strength were increased up to a 3.0 phr of palmitamide concentration. The enhancement in those properties was due to the enhancement in crosslinks as well as cure state of the compounds of silica-filled SBR.

Enhancing the reinforcing efficiency of silica on styrenebutadiene rubber through the use of palmitamide

In this paper, enhancing the reinforcing efficiency of silica on styrene-butadiene rubber (SBR) compounds through the use of palmitamide was carried-out. The palmitamide was laboratory prepared from palmitic acid and urea and loaded into the silica-filled SBR compounds at 1, 3, 5 and 7 phr. It was found that palmitamide exhibited modulus and tensile strength enhancements; the tensile modulus at 100% and tensile strength were enhanced, especially up to a three phr of palmitamide concentration. It was revealed that the modulus and tensile enhancements were attributed to the enhancing of reinforcing efficiency of silica on the SBR through the use of palmitamide as a curative and plasticizing rubber chemical which increased the degree of silica dispersion, interactions SBR to silica as well as cure state. From scanning electron microscopy (SEM) or morphology test, it was proved that the SEM image of silica-filled vulcanizates with 3 phr of palmitamide exhibited the greatest matrix tearing lines that indicated the greatest degree of filler dispersion and interactions between SBR to silica.

Effects of palmitamide on cure and tensile properties of styrene butadiene rubber

A semi EV curing system was applied for studying the effects of palmitamide on cure and tensile properties of silica-filled styrene-butadiene rubber (SBR) compounds. The palmitamide was prepared from palmitic acid and urea. As an additive material, the palmitamide was added into the silica-filled SBR at 0.0, 1.0, 3.0, 5.0 and 7.0 parts per hundred rubber (phr.). It was found that the palmitamide acted as a curative additive material which decreased the scorch and cure times but increased the difference in torque of the silica-filled SBR compounds. The higher the palmitamide loading, the shorter the scorch and cure times were. It was also found that the palmitamide acted as an internal plasticizer material which decreased the minimum torque. The tensile moduli and tensile strength were increased but the elongation at break was decreased up to a 3.0 phr. of palmitamide loading. From the swelling test, the improvements in tensile properties were attributed to the improvements in crosslink density as well as the cure state of the silica-filled SBR compounds.

Durability assessment via residual strength and viscoelastic observations on filled rubber compounds

AbstractBecause rubber compounds are widely used under cyclic loading conditions, such as tire applications, their fatigue behaviour has been studied for a long time. Two main stages are commonly considered in studying rubber fatigue: crack nucleation and crack growth. Not many studies exist on the residual strength of rubber subsequent to fatigue loading. In this study, the residual strength method is used to model fatigue behaviour of carbon black‐filled and silica‐filled styrene‐butadiene rubber (SBR) compounds. Samples are subjected to repeated fatigue loading (ie, nonzero mean stress) using different strain amplitudes and then subjected to uniaxial constant crosshead rate, relaxation, and creep tests to assess their residual strength and viscoelastic behaviours respectively. The residual strength results are compared with typical S‐N curves. Initial relaxation rates, initial creep rates, asymptotic relaxation values, and secondary creep rates are plotted as functions of fatigue cycle number to understand the viscoelastic behaviours of carbon black and silica‐filled SBR compounds as affected by fatigue processes.

The Effect of Surface Area of Silicas on Their Reinforcing Performance to Styrene-butadiene Rubber Compounds

The effect of the surface area of silicas on their reinforcing performance to styrene-butadiene rubber (SBR) compounds was systematically investigated. The feasibility of the Brunauer-Emmett-Teller surface area (SBET) as a parameter representing the characteristics of the silicas was discussed compared to the mesopore volume, c value, oil absorption, and uptake of silane. The increase in SBET of silicas caused a considerable increase in Mooney viscosity, minimum torque, and hysteresis loss of the silica-filled SBR compounds, while significantly enhancing their abrasion property. These changes were explained by the attrition between the hydrophilic silica surface and the hydrophobic rubber chains. As expected, the change in SBET did not induce any remarkable changes in the cure, processing, tensile, and dynamic properties of the silicafilled SBR compounds because the crosslinking density of the rubber chains mainly determined these properties.

Effect of carbon nanotubes with different lengths on mechanical and electrical properties of silica-filled styrene butadiene rubber compounds

Carbon nanotubes (CNTs) having three different lengths of 5, 30, and 100μm were added to silica-filled styrene butadiene rubber (SBR) compounds in order to investigate the effect of the CNT addition on the dynamic and electrical properties. The amounts of CNTs were 1, 2, 4, and 7phr, while the amount of silica was set high at 80phr to clearly demonstrate the performance of the CNTs as fillers. The effect of CNTs on the silica-filled SBR compounds on the tensile properties is not significant, but the addition of longer CNTs with high loading severely deteriorated the dynamic properties, but considerably enhanced electrical conductivity. The medium loading of CNTs in silica-filled SBR compounds is suitable for the improvement of the electrical conductivity without severely sacrificing the dynamic properties.

Properties of silica‐filled styrene‐butadiene rubber compounds containing acrylonitrile‐butadiene rubber: The influence of the acrylonitrile‐butadiene rubber type

AbstractBecause silica has strong filler‐filler interactions and adsorbs polar materials, a silica‐filled rubber compound exhibits poor dispersion of the filler and poor cure characteristics in comparison with those of a carbon black‐filled rubber compound. Acrylonitrile‐butadiene rubber (NBR) improves filler dispersion in silica‐filled styrene‐butadiene rubber (SBR) compounds. The influence of the NBR type on the properties of silica‐filled SBR compounds containing NBR was studied with NBRs of various acrylonitrile contents. The composition of the bound rubber was different from that of the compounded rubber. The NBR content of the bound rubber was higher than that of the compounded rubber; this became clearer for NBR with a higher acrylonitrile content. The Mooney scorch time and cure rate became faster as the acrylonitrile content in NBR increased. The modulus increased with an increase in the acrylonitrile content of NBR because the crosslink density increased. The experimental results could be explained by interactions of the nitrile group of NBR with silica. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 385–393, 2002

Influence of the silica content on rheological behaviour and cure characteristics of silica‐filled styrene–butadiene rubber compounds

AbstractRheological behaviour and cure characteristics of silica‐filled styrene–butadiene rubber (SBR) compounds and SBR compounds filled with both silica and carbon black with different silica contents were investigated. Rheocurves of the time versus the torque of the compounds showed specific trends with the silica content. For the compounds with low silica content (less than 50 phr), the torque decreased immediately after the steep increase at the initial point of the rheocurve and then increased very slowly. For the compounds with high silica content (more than 50 phr), the rheographs showed two minimum torque points; the torque decreased immediately after the steep increase at the start point of the rheocurve and then increased sharply before reaching the second minimum point. This can be explained by the strong filler–filler interaction of silica. The minimum torque of the compound increased slightly with an increase of the silica content up to 50 phr silica content and then increased appreciably. For the silica‐filled compounds, cure times of the t02, t40, and t90 became shorter with an increase of the filler content. For the compounds filled with both silica and carbon black (total filler content of 80 phr), the cure times became longer with an increase of the silica content ratio.© 2001 Society of Chemical Industry

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.