Mesophase microstructure of modified coal tar pitch

The coal tar pitch (CTP) was modified to synthesize the pitch mesophase by using 4-methyl benzaldehyde (4-MB) as modifier and p-toluene sulfonic acid (PTS) as catalyst. The polarized microscope was employed to study the optical structure of pyrolyzed substances of the modified CTP and its shapes were observed through SEM. The results show that with different doses of 4-MB, temperature and heating time, the optical texture of pyrolyzed substances varies from coarse-flow anisotropy elongated to domains and in certain conditions, the modification contributes to an improvement in the optical texture which appears many mesocarbon microbeads and the shapes of the modified CTP appear good fibrous structure. Therefore, the modified CTP with 4-MB is promising to become a kind of fine pitch mesophase.