Maleic diamides as photostabilizers for polystyrene

Some condensation maleic diamide adducts were prepared, characterized, and evaluated as photostabilizers for polystyrene. The potency of these diamides was determined by measuring the extent of weight loss (%), formed gel as well as the average molecular weights M¯V of the soluble fractions of the degraded polymers. The results indicated a good stabilizing effect of these products compared with the commercial UV absorber, phenyl salicylate. FTIR spectra of both neat and photoirradiated stabilized polystyrene gave an explanation of some photodegraded products of polystyrene. A probable radical mechanism is proposed to account for the stabilizing action of the diamide derivatives as photostabilizers.