Oxidation of polyisoprene on catalytically active substrates controlled by oxygen diffusion

Abstract

Oxidation of polyisoprene films of thickness ranging from 5 to 100 μm deposited on copper, brass, steel, duraluminum, or quartz glass substrates has been investigated between 80 and 150°C. At 150°C the initial rate of oxidation is five times lower on copper than on quartz glass. The activation energy of the initial oxidation rate for a film 60 μm thick is 13.4±4 on copper and 70±9 kJ mol-1 on quartz. The diffusion coefficients of copper ions in polyethylene have been determined; their temperature dependence obeys the Arrhenius Law. An equation has been derived which describes the rate of oxidation as a function of film thickness and takes into account the diffusion of copper ions from the substrate into the polymer layer. © 1992.