Effect of rubber-filler interactions on the properties of silica filled styrene-butadiene rubber

Abstract

In this work, the effect of rubber-filler interactions on dynamic properties of solution-polymerized styrene-butadiene rubber (SSBR) filled by in-situ modified silica was studied. It was observed that the in-situ modification of silica was an effective way to enhance the SSBR-silica interactions. A better dispersion of silica in rubber matrix was contributed to the increase of tan δ at 0 ℃ and the decrease of tan δ at 60 ℃, suggesting the improvement of the performance in rolling resistance and wet grip behavior. As far as the polymerization method was concerned, emulsion-polymerized SBR (ESBR) was chosen for comparison with SSBR. In the silica filled rubber system, ESBR exhibited relatively high hysteresis compared to SSBR. This was attributed to better dispersion of silica in SSBR proved by lower magnitude Payne effect and more bound rubber content, which was probably caused by its macrostructure, i.e. controlled molecular weight and nearly monodispersed molecular weight distribution. The third factor considered in this paper was the coupling ratio of SSBR. With the increasing of coupling ratio, the magnitude of Payne effect was lowered and thus less hysteresis was observed. The higher molecular weight derived from higher coupling ratio was considered as the key factor for the better dispersion of silica. The high coupling ratio can improve rubbers performance without sacrificing their processabilities.