Phase Control of BR/SBR Blends by Silica Particles

Abstract

A phase control of butadiene rubber (BR)/styrene-butadiene rubber (SBR) blends was examined by using silica particles. The phase structure of the blends was qualitatively evaluated from transmission electron microscope (TEM) observation and temperature dependence of mechanical tanδ. It was found that the temperature dependence of tanδ was dependent on the size of agglomerate formed by silica particles in the blend. The vulcanized blends with small agglomerates showed a single tanδ peak suggesting a pseudo-miscible state. The vulcanized blends with large agglomerates showed two tanδ peaks corresponding to the Tgs of BR and SBR. The mutual dissolution of BR and SBR phases above the UCST line where the vulcanization was carried out might be disturbed by large agglomerates formed by silica particles in the blends.