Dynamic viscoelastic measurement of coal extracts and residues

Goonyella coking coal was extracted with tetrahydrofuran (THF), chloroform, N-methyl-2-apyrrolidinone (NMP), pyridine, and a 1:1 (v/v) carbon disulfid e/N-methyl-2-pyrrolidinone (CS2/NMP) mixed solvent. Temperature-variable dy namic viscoelastic measurement was carried out for the extracts and residue s obtained. The thermoplasticity in residues obtained by chloroform or NMP extractions significantly decreased compared to that of the raw coal despit e the fact that the extraction yields, 2.7 and 5.4 wt % (daf), respectively , were low. A further decrease in thermoplasticity was observed for residue s obtained in high yield with pyridine (20.6 wt %) and CS2/NMP (42.8 wt %). On the other hand, the thermoplastic state was observed in the range 260-5 00 degreesC for the pyridine soluble (Sox-PS) fraction obtained from pyridi ne Soxhlet extraction, while the thermoplasticity for the pyridine insolubl e fraction (PIMS) obtained from pyridine fractionation of the CS2/NMP extra ct fraction was significantly smaller and similar in value to that for resi dues left after chloroform or NMP extractions, despite the fact that the PI MS originally was a component of a solvent-soluble fraction. The role of so lvent-soluble components on the thermoplasticity of coals is discussed base d on these results and results of an earlier study.