High-temperature Oxidation of Carborane-Siloxane-Acetylene-based Polymer

A processable new thermosetting polymer containing carborane and siloxane groups with acetylenic linkages was examined for antioxidative properties during high-temperature oxygen exposure. Samples of the polymer were annealed in argon or air at 320–400°C or argon at 900°C and oxidized at 400 and 500°C. Their structure and composition were analyzed by scanning electron microscopy, x-ray photoelectron spectroscopy, scanning Auger microprobe scattering and Raman microprobe scattering. Samples heated to 400°C in argon exhibited little or no inorganic segregation, but developed surface layers of boron and silicon oxide when heated to 400°C in air. Samples annealed in argon to 900°C and then oxidized at 500°C for up to 100 h developed a continuous silicon oxide surface layer with almost no underlying boron oxide. The layer retarded oxidation of the sample bulk at 500°C.