Oxidized Asphalt Preparation And Characterization

Coal-tar based medium pitches are thermally oxidized by means of air blowing. The effects of oxidation temperature, oxidation time and air quantity consumed on the softening point and coking value of coal-tar pitches are investigated. Ithasbeen found that the oxidative polymerization process is homogeneous and take place at a constant rate. The softening point and coking value of oxidized pitches are directly proportional to the oxidation temperature and oxidation time. The increases in the consumed air volume help to decrease the oxidation temperature and shorten the oxidation time.The oxidation effects of medium pitches and modified pitches are comparatively studied. It has been found that the light-weight components in medium pitches are more beneficial to the conduction of oxidization crosslinking reactions. The oxidative polymerization rate of medium pitches is larger than that of modified pitches. The oxidation pitches prepared from the medium pitches have higher content of -resin.The conversion rules of oxidation pitch components during the oxidative polymerization modification are investigated. The results indicate that the conversion of toluene insoluble and quinoline insoluble components in the oxidation pitches during the oxidative polymerization have some laws. Its instruction meaning in the oxidization processes of coal-tar pitches has been pointed out.The behavior of oxidative polymerization modification of coal-tar pitch has been investigated. Oxidization treatment increases evidently the oxygen content of coal-tar pitches. The dehydrogenation polymerization reactions take place during the oxidization modification. Oxidization results in the evident increment of coking value of coal-tar pitches. Througn the thermo-gravimetric analysis of oxidation pitch, the reaction process of pyrolytic condensation of oxidation pitch has been studied comparatively. The results indicate that, oxidization enhances the catalytic coking condensation of coal-tar pitches.