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

Seventeen pitches differing in origin, preparation method, and foreseeable use were fractionated by extrography into classes of compounds. The distribution of pitch constituents among extrographic fractions allowed one to characterize the various pitches according to their chemical composition. The pyrolysis of pitches was followed using thermal analysis 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 differentiating very similar types of pitches. The importance of selecting an adequate heating rate for the joint use of TG, DTG, and DTA was highlighted. It is concluded that extrography and thermal analysis, used either separately or in conjunction, provide detailed insight into the chemical composition of pitches, whose knowledge allows one to explain their different pyrolysis behaviours and can help predict their suitability for specific applications.