Studies on sprosiloxane oligomers and polysila hydrocarbons

Abstract

Boron and silicon containing polymers/oligomers have gained importance, in recent years, as they offer many advantages compared to polymers containing only boron/silicon. On pyrolysis in inert atmosphere they give mixed non-oxide ceramics, which possess better high temperature properties and oxidation resistance compared to simple non-oxide ceramics. Hence, they are used as high temperature coatings, thermal protective systems, matrix resins and high temperature elastomers. The aim of the work embodied in the thesis has been to develop thermally stable borosiloxane oligomers and evaluate them as precursors for ceramics and study their end-uses for space applications. Another class of preceramic polymers is polysilahydrocarbons, which contain silicon and carbon in the backbone. In addition to the investigation on borosiloxane oligomers, the present thesis focuses on the thermal degradation behavior of polysilahydrocarbons and their evaluation as atomic oxygen resistant coating for low earth orbit space structures.