| Abstract: | Dielectric loss measurements have been applied to study the short-wave (λ = 254 nm) and long-wave (λ > 300 nm) photooxidation of polystyrene which had been prepared using both free radical and anionic initiator. The high-frequency loss peak, attributable to carbonyl products of oxidation is a sensitive monitor of the rate of oxidation, the sensitivity being greater than that of manometric measurements. The data are specific to carbonyl compounds and the technique is particularly suitable for studying the surfaces, on which most of the above photooxidation occurs with polystyrene. Effects of radiation intensity and oxygen pressure were also studied. The measurements have permitted a more detailed study of the long-wave photooxidation process than has previously been undertaken, and the results emphasize differential reactivities of radically and anionically prepared polymers. Results are interpreted in terms of initiation by both impurities and charge-transfer complexes. |
