MODIFICATION OF NAPHTHALENE-DERIVED MESOPHASE PITCH WITH BENZOQUINONE

Naphthalene-derived mesophase pitch (NMP) was chemically modified with p-benzoquinone (BQ) at relatively low temperature, then carbonized an d graphitized. An activated Diels-Alder reaction between NMP molecules and BQ occurred at 115 degrees C followed by a dehydration reaction a t 158 degrees C. The modified NMP changed its texture from anisotropic to isotropic with increasing BQ concentration. The carbon yield of mo dified NMP also increased with BQ concentration up to 81.4 from 74.6%. No coalescence of the modified NMP powders was observed during carbon ization and graphitization when modified at BQ/NMP ratios higher than 10/10. The bulk density of the disks molded and carbonized at 1000 deg rees C was a maximum at a 10/10 composition among the four composition s examined. Molecules in NMP were found to increase in molecular size and be substituted by carbonyl groups through the Diels-Alder reaction of BQ. Such molecules lose stacking order and fusibility, forming a m ore isotropic texture, while the carbon yield increases. (C) 1997 Else vier Science Ltd.