Reinforcement and antioxidation effects of antioxidant functionalized silica in styrene–butadiene rubber

In order to improve the dispersion of silica in rubber matrix and to avoid volatility and extractability of the antioxidants, antioxidant functionalized silica is synthesized through reaction of precipitated silica and antioxidant coupling agent which is synthesized by (3-glycidyloxypropyl)trimethoxysilane (A-187) and N-phenyl-1,4-phenylenediamine (PPDA). This antioxidant functionalized silica with different antioxidant content is then incorporated into styrene–butadiene rubber (SBR) to study their reinforcement and antioxidation effects. The tensile strength of these composites is much higher than that of neat silica/SBR, and increases with increasing antioxidant content. It is close to that of bis(triethoxysilylpropyl)tetrasulfane (TESPT) modified silica/SBR when the antioxidant content exceeds 3.9% (by weight to silica). Furthermore, SBR filled with antioxidant functionalized silica has greatly improved stability in thermal oxidative ageing and damp heat ageing.