The transport of various penetrants in well characterized, thin sections of coal will be examined at high temperatures (250-400 C) using an Advanced Thermal Analysis System in an effort to investigate the mechanisms of transport in the highly crosslinked network structure of coal and to elucidate the effort of solvents in altering its chemical structure. Experimental Studies will be performed at high temperatures both above and below Tg using thin sections varying in thickness from 20 to 1000 m. In addition we will synthesize highly crosslinked polymers by reaction of multifunctional methacrylates such as di', tri' and tetramethacrylates. Such polymer systems are glassy with high glass transition temperatures and well defined crosslinked structures. They will be swollen both by dynamic and equilibrium studies in the same penetrants as the coal networks. Then, the results from these two investigations will be compared in order to elucidate the nature of the crosslinked coal network structure. Mathematical models will be developed to describe the unusual transport of penetrants (solvents) in coal. These results will have direct applicability in the elucidation of the mass transfer limitations in coal processing, the importance of solvents in altering chemical stability and the mechanisms of molecular dissociation. The requested equipment, Advanced Thermal Analysis System, will be used to analyze the macromolecular coal structure at high temperature. The differential scanning calorimetry module will provide the glass transition temperature of the macromolecular coal network structure as a function of a penetrant content. The thermomechanical and dynamic mechanical analysis components will elucidate the viscoelastic behavior of coal networks below, around and above their glass transition temperature in the presence of penetrants. The thermogravimetric analysis module will be used to obtain penetrant uptake data at high temperature and to decouple the diffusional and relaxational mechanisms.
