Pitch-based carbon fibres derived from thermoset fibres oxidized with Cl2 containing air

Mesophase pitch-based carbon fibres thermoset with Cl₂ containing air were studied for their microstructures and physical properties. Carbon fibres thermoset with Cl₂ containing air and heat-treated at 2000C (Cl₂2000) possessed slightly smaller mean sizes of crystallites L _c(0 0 2)s, lower densities, lower tensile moduli of elasticity, and higher tensile strengths than those thermoset with air. X-ray diffraction measurements revealed a somewhat lower degree of preferred orientation of a carbon fibre which was thermoset with Cl₂ containing air. The Cl₂ thermosetting partly disordered the periodic arrangement of crystallites and reduced the crystallite size L _c(0 0 2) of a carbon fibre heat-treated at a lower temperature. A strong temperature dependence of resistivity was shown for Cl₂800, suggesting much disorder in its microstructure due to the Cl₂ thermosetting, and Cl₂1000 and Cl₂1200, respectively showed specific temperature dependencies of resistivities.