Dynamic mechanical analysis and interpretation of molecular motions in polyarylates

Molecular motions in polyarylates synthesized from substituted bisphenols have been investigated by dynamic mechanical analysis. Substitution at the ring carbon atom results in a more pronounced enhancement in glass transition temperature (Tg) as compared to substitution at the bridge carbon atom. The enhancement in mono and disubstituted polyarylates is more consistent than that in the case of polycarbonates and polysulfones. The β transition has been shown to result from defects in the polymer samples. The molecular motion responsible for the τ transition in polyarylates has been shown to be more iocalized than in the case of polycarbonates. Introduction of the phthalide ring in the isopropylidene unit of bisphenol‐A molecule results in splitting of the τ transition peak into two. The results have been compared with those reported for other bisphenol‐based polymers, viz. polycarbonates and polysulfones, and explained on the basis of the structural attributes of the polymers.