POLYSTYRENE PHOTOOXIDATION .2. A PSEUDOWAVELENGTH EFFECT

The photoproducts formed in polystyrene photooxidized by exposure to long wavelengths (lambda greater-than-or-equal-to 300 nm) or short wavelength (lambda = 253.7 nm) absorbing in the IR range were identified and reported in the preceding paper. It was shown that, despite some differences in the distribution of oxidation photoproducts, the same products were obtained. The present paper reports on complementary experiments carried out at a different temperature and on microspectrophotometric determination of the photoproduct profiles. The apparent differences resulting from the short- or long-wavelength irradiation are attributed to the diffusion of the low molecular weight photoproducts. A general mechanism accounting for the photooxidation of the polystyrene at short or long wavelengths is given.