PHOTOOXIDATION OF ELASTOMERIC MATERIALS .4. PHOTOOXIDATION OF 1,2-POLYBUTADIENE

The photo-oxidation of 1,2-polybutadiene (84% 1,2, 16% 1,4 cis), at long wavelengths (γ > 300 nm), has been studied. Radical addition to the 1,2 double bond is the main oxidation pathway. The tertiary macroradical formed is oxidized to tertiary associated hydroperoxide. Associated hydroperoxides are photolyzed to saturated alcohols or to saturated ketones, absorbing at wavelengths longer than 300 nm, and photo-oxidized to saturated acids. Formation of methylene and methyl groups are revealed by IR analysis during irradiation of the film. The rate of photo-oxidation of 1,2-BR is five times lower than the rate of photo-oxidation of highly 1,4 trans and cis BR which was recently reported in this series (C. Adam, J. Lacoste & J. Lemaire, Poly. Deg. and Stab., 24 (1989) 185). During irradiation of 1,2-BR, competition between cross-linking and chain scission occurs. Cross-linking is due to radical addition while chain scission occurs mainly during formation of ketones and Norrish type I reactions. © 1990.