Mechanical Properties Simulation of Hydrogenated SBR by Coarse-grained Molecular Dynamics Method

Abstract

Recently, we have developed a very high strength rubber by hydrogenation of styrene-butadiene rubber (SBR). Hydrogenated SBR represents the changes of stress-strain curve and viscoelastic property from conventional SBR. The changes seem to be related to an increment of entanglement density with hydrogenation. To analyze mechanical properties of crosslinked rubbers, coarse-grained molecular dynamics (CGMD) simulation has been frequently used. However, Kremer-Grest model, one of the most famous CG models, uniquely determines an entanglement density of polymer melt and isn’t suitable for studying hydrogenated SBR. Therefore, we performed CGMD simulations using KremerGrest model with angle potential in order to confirm whether the stress-strain curves and the tanδ master curves of the simulations fit that of the experiments for SBR. In this study, we made crosslinked rubber models of hydrogenated and non-hydrogenated SBRs with entanglement densities corresponding to experimental values of viscoelastic measurements. The calculated values of the stress-strain curves and the tanδ master curves roughly match the experimental values. Therefore, we conclude that the increment of entanglement density plays an important role in the changes of mechanical properties by hydrogenation of SBR.