Preparation and Properties of One Component RTV Silicone Resin Composed of Polysiloxane Block Copolymer

Abstract

One component room temperature vulcanized (RTV) silicone resin was prepared by combination of a kind of D-T polysiloxane block copolymer with crosslinker and catalyst. Transparent coating with good elastoplasticity without any inorganic filler could be obtained by exposing the RTV silicone to air at room temperature. The structure of D-T block copolymer played an important role in the properties of the cured products. It was synthesized by polycondensation of partially hydrolyzed phenyltrimethoxysilane (phenylsilsesquioxane, T units) with silanol end-capped polydimethylsiloxane (PDMS, D units). The effects of the viscosity of phenylsilsesquioxane and the D/T ratio on the properties of cured product were investigated. When phenylsilsesquioxane (10000cP at 80°C) was used and the D/T ratio was 2.0~2.3, cured products with tensile strength above 2.5MPa and elongation above 70% were prepared. RTV silicone resin composed of such kind of D-T block copolymer had good heat resistance because the existence of phenyl group and the highly cross-linked 3D structure. The Tonset was 387.6°C and the Tmax was 518°C.