COMPARATIVE-ANALYSIS OF PITCHES BY EXTROGRAPHY AND THERMAL-ANALYSIS TECHNIQUES

Seventeen pitches differing in origin, preparation method, and foresee able use were fractionated by extrography into classes of compounds. T he distribution of pitch constituents among extrographic fractions all owed one to characterize the various pitches according to their chemic al composition. The pyrolysis of pitches was followed using thermal an alysis techniques (TG, DTG, and DTA). Based on the relative prevalence of different types of reactions, DTA furnished detailed insights into the chemistry of the pyrolysis process, and provided a way of differe ntiating very similar types of pitches. The importance of selecting an adequate heating rate for the joint use of TG, DTG, and DTA was highl ighted. It is concluded that extrography and thermal analysis, used ei ther separately or in conjunction, provide detailed insight into the c hemical composition of pitches, whose knowledge allows one to explain their different pyrolysis behaviours and can help predict their suitab ility for specific applications.