Effect of gamma irradiation on ethylene-octene copolymers produced by constrained geometry catalyst

Elastomeric ethylene-octene copolymers of differing molecular weights and comonomer content were exposed to 25 kGy of gamma radiation from 60Co source in an inert atmosphere. Tests were performed to evaluate the changes in the chemical, physical, and mechanical properties. All properties showed a dependence on both composition and molecular weight. The effect of gamma irradiation is most noticeable in the mechanical properties such as the tensile modulus and elongation to break. The combination of the low octene-1 content and high molecular weight leads to higher post irradiation tensile modulus. FTIR spectroscopy studies indicate that formation of unsaturated chemical moities after irradiation of samples with same molecular weight occurs more readily in the lower octene-1 content copolymers. While at constant composition there is a preference for the higher molecular weight copolymers. The low molecular weight and low octene content copolymer showed some evidence of polymer chain scission as the dominant effect