CHEMICAL-REACTIONS IN THE STABILIZATION OF MESOPHASE PITCH-BASED CARBON-FIBER

Model compounds based on anthracene were used to study the chemical reactions taking place during stabilization of mesophase pitch-based carbon fiber. Methyl- and hydro- groups were found to accelerate the oxidation reaction, and also to react with carbonyl groups. Linking reactions that produced high-molecular-weight compounds took place both in air and nitrogen. Similarities in heat-evolution profile were observed in the oxidation of a real pitch and a model pitch consisting of 80% anthracene, 10% dimethylanthracene, and 10% dihydroanthracene. Studies of off-bases produced in stabilization of a pitch-based fiber showed off-gases to be limited to H2O, CO2, and CO (H-2 would not have been detected). At a given temperature, H2O evolution eventually diminished to zero; however, it could be re-started by increasing temperature. The stabilization exotherm was largely associated with H2O production. Carbon-gas production was independent of H2O production, and appeared to be a surface reaction.