Oxidative protection of carbon fibers with poly(carborane-siloxane-acetylene)

Linear carborane-siloxane-acetylenic polymers have been synthesized as precursor materials for thermosets and ceramics for composite applications up to 500 and 1500°C, respectively, in an oxidizing environment. The novel linear polymers have the advantage of being extremely easy to process and convert into thermosets or ceramics since they are either liquids at room temperature or low melting solids and are soluble in most organic solvents. Carbon fibers coated with poly(carborane-siloxane-acetylene) forms a protective barrier against oxidation at elevated temperatures. The novel polymer when used as a matrix material (ceramic) was found to protect the carbon fibers from oxidative breakdown. Boron appears to be the key to the unique oxidative stability of the composite compositions. Oxidative studies were performed by thermogravimetric analyses.