Influence of Carbon Felt on Mesophase Formation of Petroleum Pitch

The influence of carbon felt on the mesophas formation in a petroleum pitch was investigated at 400°C for various residence times by the observation under polarized light microscope, and by the measurements of weight loss and amount of volatile matter in the pitch. Carbon felt used had been heat-treated at 2000°C.The mesophase formation in the pitch matrix was remarkably delayed by the existence of carbon felt except the preferential formation of mesophase at the periphery of fibers (about 10 μm thick). The mesophase spherules thus formed showed no obvious coalescence. After 12 hours at 400°C, the pitch was carbonized in a globular type texture in the existence of felt, while the pitch heat treated alone gave a coarse fibrous texture. This suggests that the felt acts to prevent the convection of fluid matrix, resulting to retard a gas bubble formation. The difference in microstructure was also detected by optical microscope, that is, mosaic type texture for the mixture of pitch coke and felt, and needle like texture for pitch coke itself. No difference in graphitization behavior was detected by X-ray diffraction measurements between the mixtures and the pitch cokes.