Reinforcement of natural rubber by silica generated in situ

Abstract

New method to produce in situ silica in natural rubber (NR) matrix was developed for a NR/silica composite material, and the good reinforcement effect of the silica was observed on the NR vulcanizate. The silica was generated by the sol-gel reaction of tetraethoxysilane before crosslinking, which gave a homogeneous dispersion of in situ-generated silica particles in the NR matrix. This method is expected to be an industrially practical technique. It is estimated that the concentration of silanol groups on the silica surface were smaller than those on the conventional silica surface. Therefore, the silica-silica interaction of in situ silica seems to be weaker than that of silica-rubber to result in better dispersion compared with the conventional silica. The results suggest that NR which is a renewable resource and in situ silica omposite has much potential as a“green”material and a useful system for studying the reinforcement mechanism of inorganic filler onto NR.