CHEMICAL MODELING ANALYSIS OF POLY(ARYL ETHER SULFONE) THERMAL-STABILITY THROUGH COMPUTER-GENERATED REACTION-MECHANISMS

Pyrolysis of two representative poly(aryl ether sulfones) (PAES) with anti without the isopropylidene link revealed its important role in co ntrolling the overall thermal stability. This was probed quantitativel y by the development of mechanistic pyrolysis models for single compon ents and model compound mixtures of phenyl sulfone (PS), phenyl ether (PE) and 2,2-diphenylpropane (DPP). Model development on the computer allowed ''on-the-fly'' calculation of species' properties using comput ational quantum chemistry. This also provided quantitative values of m odel parameters. The reactivity differences of the polymers were inter preted in terms of the predicted changes in the product spectra when P S and PE were pyrolyzed with and without the reactant DPP. The increas ed selectivity to benzene and the decreased selectivity to (phenylsulf onyl)biphenyl with DPP present suggested an increase in the ratio of b ond scission to bond formation that accounted for the decreased tenden cy of the isopropylidene-containing PAES for molecular weight increase and gel formation, two global measures of thermal stability.