Abstract - Polystyrene is degraded, oxidized and discolored when exposed to sun-
light under atmospheric conditions. The chemical effects are ascribed to hydro-
peroxy, hydroxyl and carbonyl group formation. Chemical and spectroscopic data
are not specific enough for identification of these different groups. Therefore,
we have studied the photo-oxidation of the model compound 2-phenyl—butane. The
resulting oxidized compounds have been separated and analyzed using a combined
gas chromatograph-mass spectrometer. Mechanisms for the photo-oxidation of the
model compounds have been proposed. By comparing these results with photo-
oxidation data for polystyrene film, conclusions on the oxidation and degrada-
tion of the polymer have been outlined, including the carbonyl and hydroxyl
group formation. The yellowing of the polymer is largely caused by phenyl ring
opening reactions, for which probable mechanisms are suggested.
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