Photodegradation and stabilization of styrene-butadiene-styrene rubber

Photooxidative degradation and stabilization of a polystyrene-block-polybut adiene-block-polystyrene thermoplastic elastomer using a polychromatic UV l ight in air at 60 degrees C has been studied by monitoring the appearance o f the hydroxyl and carbonyl groups in Fourier transform infrared spectrosco py. The extent of photooxidative degradation in different samples has been compared. The rate of photooxidation was also estimated in the presence of different concentrations of 2,6-di-tert-butyl-4-methylphenol [BHT], 2-(2'-h ydroxy-5'-methylphenyl)benzotriazole [Tinuvin P] and tris(nonylphenyl) phos phite [Irgafos TNPP], and 1,2,2,6,6-pentamethyl piperidinyl-4- acrylate was grafted onto the surface of the SBS film. The kinetic evolution of the oxi dative reaction was determined. The morphological changes upon irradiation in the solution cast SBS films were studied by scanning electron microscopy . Based on the experimental data a suitable photooxidative degradation mech anism also has been proposed. (C) 2000 John Wiley & Sons, Inc.