Thesis (M.Sc.)-- Chulalongkorn University, 2010

Carbon black (CB) and silica have been used as the reinforcement fillers of rubber composites. As the each filler possesses its own advantages, the use of silica/CB blends could increase the mechanical, dynamic properties, oil resistance and compression set. However, the appropriate silica/CB ratio giving rise to the optimum properties needs to be study. In this work, the effect of silica/CB hybrid filler on mechanical properties of SBR/NBR blends were studied and the variables are blending ratio of SBR/NBR blends, filler content and ratio of silica/CB hybrid filler. The combination of sulfur and dicumylperoxide as vulcanizing systems was employed. To improve interaction between silica and rubber matrix, 3 types of silane coupling agent, γ-mercaptopropylmethoxysilane, γ- glycidoxypropyltrimethoxysilane and vinyl-tris-(2-methoxyethoxy) silane were used. The effects of silica/CB hybrid filler and coupling agent in rubber compound on tensile strength, modulus, and compression set and oil resistance were analyzed. This rubber blends (SBR/NBR=30/70) with 50 phr silica/CB hybrid filler modified with γ-mercaptopropyltrimethoxysilane, γ-glycidoxypropy-lmethoxysilane, vinyltris-( 2-methoxyethoxy) silane exhibited good mechanical properties oil resistance and compression set and could be used as o-ring for motor oil medium resistance (ASTM oil no.1 and brake fluid).