New aspects of photodegradation and photooxidation of polystyrene

Abstract

-Polystyrene is degraded, oxidized and discolored when exposed to sunlight under atmospheric conditions. The chemical effects are ascribed to hydroperoxy, 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 photooxidation data for polystyrene film, conclusions on the oxidation and degradation 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.

Photodegradation and photostabilization of polymers, especially polystyrene: review

“…Photooxidative degradation of polymers, which include processes such as chain scission, crosslinking and secondary oxidative reactions, and takes place via radical processes, similar to thermal oxidation reactions (Ranby and Rabek 1981; Carlsson et al 1976; Mc Kellar & Allen 1979; Rnby and Lucki 1980). …”

“…Industrially, the yellow discoloration is an important adverse effect of the ageing of polystyrene, e.g. during exposure outdoors (Geuskens et al 1978a1978b; Weir 1978; Lucki and Rnby 1979; Rnby and Lucki 1980). …”

Modification of polystyrene surface in aqueous solutions

“…The mechanisms that are involved in the modification of PS, such as photo-oxidation/degradation and swelling, have been described in the literature [3,4,62,63]. However, the mechanisms by which the chemical and structural modification of PS film occurs in the presence of PBS are not clear.…”

“…The bands at 1737 cm À1 , 1660 cm À1 , and 1632 cm À1 could be assigned to carbonyl/carboxyl groups, and the bands at 1468 cm À1 and 1417 cm À1 to the aliphatic CH 2 deformations. The detailed assignments of these peaks are given in Table 2 [1,[4][5][6][7]25].…”

“…Extensive reports are available on the photodegradation of PS [1][2][3][4][5][6][7]. On exposure to natural sunlight, PS has been found to undergo oxidative degradation through photo-induced excitation as a result of absorbing ultraviolet (UV) radiation (295-400 nm) [2].…”