Thermal resistance of crosslinked and substituted poly(phenylene sulfide)s

Crosslinked and substituted poly(phenylene sulfide)s, prepared by reacting p-chlorosubstituted benzenes with sulfur, were investigated by TG in air. Using the difference method and an assumed first-order calculation, the reaction order, activation energy and frequency factor were determined. The pyrolyses were carried out under nitrogen and in the presence of 5% oxygen. The IR spectra and the sulfur contents of the polymers and pyrolysis products were determined. The highest activation energies were found for unsubstituted polymers. Linear poly(phenylene sulfide) has the best thermal stability, but also the other polymers show rather good stabilities up to 400–500°C. The IR spectra and sulfur-contents of the pyrolysis products suggest stable, condensed, and sulfur containing aromatic intermediates formed during the degradations. The obtained polymers can be manufactured over large temperature ranges by common techniques.