Octene-1 linear low density polyethylene photooxidation

Abstract

Low-temperature thermooxidation and photooxidation at long wavelengths (λ > 300 nm) of octene-1 linear low density polyethylene have been examined. It is shown that both oxidations proceed according to mechanisms which are very similar to those thought to occur in free radical low density polyethylene presenting a low content of vinylidene unsaturation. Hydroperoxidation in the α-position to the vinylidene groups gives rise to isolated hydroperoxide groups that absorb at 3550 cm⁻¹ and are stable at 85°C. A parallel hydroperoxidation occurs on the saturated chain affording hydrogen-bonded hydroperoxides which are fairly unstable at 85°C. In photooxidation at long wavelengths both hydroperoxides are produced and readily photolysed. Variations in the number of branch points which provoke large variations in density have no significant influence on the photooxidation rate.