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【Coal-tar pitch, a feedstock which can be heat-treated to create graphite, is composed of very complex molecules. Coal-tar pitch is a precursor of many useful carbon materials (e.g., graphite, carbon fibers, electrodes and matrices of carbon/carbon composites). Modified coal-tar pitch (MCTP) was prepared using two different heat-treatment methods and their properties were characterized and compared. One was prepared using heat treatment in nitrogen gas; the other was prepared under a pressure of 350 mmHg in air. The MCTPs were investigated to determine several properties, including softening point, C/H ratio, coke yield, formation of anisotropic mesophase and viscosity. The MCTPs were subject to considerable changes in chemical composition due to condensation and polymerization in the used-as-received coal-tar pitch after heat-treatment under different conditions. The MCTPs showed considerable increases in softening point, C/H ratio, and coke yield, compared to those of as-received coal-tar pitch. The MCTP formed by heat-treatment in nitrogen showed isotropic phases below $350^{\circ}C$ for 1 h of soaking time. However, MCTP heat-treated under high pressure (350 mmHg) showed isotropic phases below $300^{\circ}C$ , and showed anisotropic phases above $350^{\circ}C$ , for 1 h of soaking time. The viscosity of the MCTPs increased with increase in their softening points.】

Coal tar is the primary feedstock of premium graphitizable carbon precursor. Coal tars are residues formed as by-products of thermal treatments of coal. Coal tar pitches were prepared through two different heat treatment schedules and theirproperties were characterized. One was prepared with argon and oxidation treatment with oxygen; the other was prepared withoxygen treatment at low temperature and then argon treatment at high temperature; both used coal tar to prepare coal tar pitches.To modulate the properties, different heat treatment temperatures (300~400 o C) were used for the coal tar pitches. The preparedcoal tar pitches were investigated to determine several properties, such as softening point, C/H ratio, coke yield, and aromaticityindex. The coal tar pitches were subject to considerable changes in chemical composition that arose due to polymerization afterheat treatment. Coal tar pitch showed considerable increases in softening point, C/H ratio, coke yields, and aromaticity indexcompared to those characteristics for coal tar. The contents of gamma resin, which consists of low molecular weight compoundsin the pitches and is insoluble in toluene, showed that the degree of polymerization in the pitches was proportional to C/H ratio.Using an oxidizing atmosphere like air to prepare the pitches from coal tar was an effective way to increase the aromaticityindex at relatively low temperature.Key wordscoal tar, coal tar pitch, softening point, C/H ratio, coke yield.