Behavior of Radicals on Radiation Crosslinking of Polycarbosilane as SiC Fiber Precursor

Abstract

The behavior of radicals produced in polycarbosilane fiber by γ-ray and electron irradiations was investigated by ESR measurement. The produced radicals were Si and C radicals. At room temperature, most of the radicals reacted with each other, and polycarbosilane molecules were crosslinked under vacuum. Some of radicals, which didn't contribute to the crosslinking, were fairly stable under vacuum, but were well oxidized by the exposure in air. A lot of oxygen was introduced into polycarbosilane fiber with oxidation of the radicals. The radicals decreased by the heat treatment under vacuum. The radical concentration of polycarbosilane fiber heat-treated at 513 K for 10 min under vacuum was below 1% for that before the heat treatment.