Effects of pressurized pretreatment on the preparation of mesophase pitch

Spinnable mesophase pitch as a precursor of high-performance carbon fiber was prepared from coal-tar pitch by using two-stage heat treatment, which consisted of pretreatment under pressure as a first stage and successive heat treatment under normal pressure as a second stage. Employing two different types of pressure reactor, a tube bomb and a laboratory autoclave, the effect of the pressurizing system was compared. The pretreatment under pressure of raw pitch was very effective in increasing the yield of mesophase pitch and developing its texture. The structural modification of the pitch induced by the pretreatment is discussed in terms of the chemical reactions of the pitch components.