EFFECTS OF SILANE COUPLING AGENTS ON STRUCTURE AND PROPERTIES OF SILICA-FILLED SILICONE RUBBER/STYRENE BUTADIENE RUBBER COMPOSITES

Abstract

ABSTRACT Two silane coupling agents, bis-(γ-triethoxysilylpropyl)-tetrasulfide (Si69) and vinyltriethoxysilane (A151), were selected to investigate their effects on structure and properties of silica-filled methyl vinyl silicone rubber (VMQ)/emulsion styrene butadiene rubber (ESBR) composites. The filler–rubber interactions were investigated via bound rubber content and solid-state 1H low-field nuclear magnetic resonance (NMR) spectroscopy, and the mass ratio of VMQ and ESBR in the rubber–filler gel was investigated by thermogravimetric analysis (TGA). The results revealed that VMQ showed a better compatibility with silica than ESBR. Compared with the A151 composite, the composite with Si69 showed the higher content of ESBR in rubber–filler gel, which resulted in the higher bound rubber content and the weaker Payne effect, and it also exhibited higher tensile strength, higher tear strength, better wear resistance, and lower hardness. However, the presence of Si69 reduced the crosslink efficiency of ESBR and completely inhibited the crosslinking of VMQ, which caused the composite to show higher tan δ value at 60 °C than the A151 composite.