Modulus of swollen coal gels

Compression measurements on coal particles that have been exhaustively extracted and swollen in pyridine are reported. The particles shaw a viscoelastic response, with the initial elastic modulus showing a decrease with increase in temperature, while the overall modulus increases with temperature. These results are interpreted in terms of coal being a macromolecular network consisting of relatively stiff chains that over short, time spans do not have time to relax. The typical entropic response (i.e,, modulus increasing with temperature) is only observed at longer times. These results are consistent with the idea that coal is a macromolecular network and not an associated structure.