Effect of rosin to coal-tar pitch on carbonization behavior and optical texture of resultant semi-cokes

Coal-tar pitch was modified with rosin, and carbonization behavior of the modified pitches and optical texture of resultant semi-cokes were studied in this paper. The carbonization behavior was studied by thermogravimetric analysis (TGA) and Fourier transform infrared (FTIR) spectroscopy techniques, respectively. The optical texture of resultant semi-cokes was characterized by polarized-light microscopy. The results show that there are marked differences in the carbonization behavior of coal-tar pitch and the modified pitches. The modification results in a small decrease in carbonization yield by 1.2–3.2% when rosin content is kept at 5–15 wt.% of coal-tar pitch. The modified pitches have functional groups of cycloparaffin, double bonds, and carboxyl group, which gradually disappear and aromatization degree increases with increasing heat treatment temperature. Moreover, the modification contributes to a notable improvement in the optical texture of resultant semi-cokes which varies from coarse-grained mosaics to domains.