HIGH-TEMPERATURE OXIDATION OF CARBORANE-SILOXANE-ACETYLENE-BASED POLYMER

A processable new thermosetting polymer containing carborane and silox ane groups with acetylenic linkages was examined for antioxidative pro perties during high-temperature oxygen exposure. Samples of the polyme r were annealed in argon or air at 320-400 degrees C or argon at 900 d egrees C and oxidized at 400 and 500 degrees C. Their structure and co mposition were analyzed by scanning electron microscopy, x-ray photoel ectron spectroscopy, scanning Auger microprobe scattering and Raman mi croprobe scattering. Samples heated to 400 degrees C in argon exhibite d little or no inorganic segregation, but developed surface layers of boron and silicon oxide when heated to 400 degrees C in air. Samples a nnealed in argon to 900 degrees C and then oxidized at 500 degrees C f or 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 degrees C.