1-5. Study on the Aggregation States of Coal Molecules at Solid State

Abstract

Pyridine insoluble extract fraction (PI-0) obtained from CS_2/NMP mixed solvent (1:1 by volume) extraction of Upper Freeport coal is partially insoluble in the mixed solvent. But in the presence of tetrabutylammoniumacetate (TBAA), PI-0 became almost completely soluble in the mixed solvent and NMP. After removal of the solvents and TBAA from the solution, the recovered PI (PI-1) was found to be completely soluble in the mixed solvent and NMP. The difference of solubility between PI-0 and PI-1 was attributed to their different aggregation states. FTIR, XRD, DSC and thermomechanical analysis (TMA) were employed to characterize the two solid PIs with different aggregation states. The results suggest that PI-1 is a less aggregated structure compared to PI-0.