Layer Stacking of Mesophase in Early Stages of Carbonization

Abstract

The layer stacking and the optically anisotropic texture of a mesophase were clarified by using X-ray diffractometric and microscopic methods. The mesophase was obtained from four kinds of starting materials: coal tar pitch (KA), virgin reduced crude (SL), poly (vinyl chloride) (PVC) and 3, 5-xylenol-formaldehyde resin (XF), by heat-treatment of various residence times up to 24 hr at fixed temperatures (370 or 430° C). The mesophase obtained by a long time heat-treatment contains 40-50% of the total carbon atoms in its layer stacks (Fig.11). The average stacking. units are consisted of about 3 layer planes (Fig.9, 10) and locate at the intervals of 15-25Å each other (Fig.4). The parallel alignment of the stacking units in the c-axis direction becomes much better when the optically anisotropic texture in the mesophase develops uniformly in wide region and results a fibrous pattern.