Photo-oxidation of ABS at long wavelengths (lambda>300 nm)

ABS (acrylonitrile-butadiene-styrene) films were exposed to radiation with long wavelength (lambda > 300 nm, O-2). The photo-oxidation of the terpolymer ABS has been studied in comparison with the photo-oxidation of the homopolymers polystyrene (PS) and polybutadiene (BR) recently investigated. The photo-thermal oxidation of the BR component is implicated as the initiation site for the photodegradation of ABS. In the first steps of irradiation, products resulting from the photo-thermal oxidation of ABS, identified using FTIR and UV-visible spectroscopy as well as chemical derivatization reactions, are essentially those of the elastomeric phase. In secondary steps, radical species formed in BR photo-oxidation are shown to photo-induce the oxidation of the styrenic phase. HPLC analysis of the low molecular weight fragments - obtained after irradiation of ABS, BR and PS films - reveals the oxidation of the PS component in terpolymer ABS while the homopolymer PS shows no oxidation. (C) 1997 Elsevier Science Limited.