We constructed three-dimensional molecular aggregation models of coals to clarify the mechanism of thermal relaxation behavior of coal. First, average molecular structures of four fractions were determined, which were obtained by solvent extraction with magic solvent (mixed solvent of CS2/NMP), acetone, and pyridine. Then, by molecular dynamics simulation, the three-dimensional molecular aggregation models were constructed, and their densities at various temperatures were calculated. The models were valid enough to describe the difference between glass transition temperatures of coals, and enabled us to analyze the variation of molecular interaction forces at arbitrary temperatures.
