15.石炭抽出物-溶媒混合系のゾル-ゲル転移と相図

抄録

Upper Freeport (UF) and Illinois No. 6 (IL) coals were extracted with carbon disulfide-N-methyl-2-pyrrolidinone (CS_2-NMP) mixed solvent (1:1 by volume) and the extracts were subsequently fractionated by using pyridine and toluene or acetone. These extracts were mixed with NMP and annealed at 353K. Melting or gel-to-sol transition temperatures of the gelly samples were determined as a function of extracts concentration by using a needle penetrometer. The heats of dissociation of cross-links (ΔH_g) was estimated by applying Eldridg-Ferry equation to the experimental results. It was found that the ΔH_g range from 15 to 21kJ/mol which corresponding to the dissociation energy of hydrogen bonds. The apparent viscosities (η_a) of the samples were estimated by analyzing the penetration-temperature curves based on an existing relationship between the penetration rate and the viscosity. During melting of the gel, η_a is decreased approximately 4 orders of the magnitude by a temperature increase of 20K. The temperature dependency of η_a is described by Andrade's equation. The apparent activation energies for the viscous flows were rather high, i.e., 80-370kJ/mol