Photooxidation of polybutadiene at long wavelengths (λ > 300 nm)

Abstract

Polybutadiene (BR) films were exposed to radiation of long wavelength (λ > 300 nm). Products resulting from the photooxidation of BR have been identified using various techniques such as FTIR and UV spectroscopy, and chemical derivatisation reactions. The decrease of permeability to oxygen of BR films during irradiation makes it necessary to study the vacuum photothermal decomposition of hydroperoxides that are the primary oxidation products. Results show that two successive steps are involved in the transformation of BR films on irradiation. In the first stage, when oxygen can diffuse through the irradiated film, photooxidation reactions occur implying the formation of hydroperoxides, α,β-unsaturated species and final saturated carboxylic acid groups. In the second stage, when the diffusion of oxygen through the surface layer is no longer possible because of crosslinking, photolysis reactions of photooxidation products account for the formation of the final products observed.