“…Carboxylfunctionshave been implicated _nthe crosslinking of coals during at relatively low temperatures (Suuberg et al, 1985; Serio el a!, 1987), and Solomon and coworkers (Solomon et al, 1990) have been able to model the pyrolytic loss of solvent swelling by including one additional crosslink in the network for every CO2 evolved. Moreover, pretreatments that have been found to be effective in promoting liquefaction, have also shown a corresponding decrease in the early CO_ evolution (Serio et al, 1990). These results strongly suggest that carboxyi functions are involved in the low-temperature crosslinking of coals.…”