Evaluation of polymers designed for radiation processing

Five types of commercially available polyethylene (PE) and some selected blends with components supporting cross-linking were radiation cross-linked. Mechanical properties and gel fraction were determined upon electron beam irradiation to such a dose that induces about 60% gel fraction. It was confirmed that for easily cross-linked PEs strength at break usually was growing and for polyethylenes less susceptible to radiation cross-linking – was reduced. Similar dependence was found for elongation at break. It was confirmed that for polyethylenes demonstrating high strength at break the efficiency of radiation cross-linking is limited. Additionally, for selected polymeric materials, stress relaxation and accelerated thermal aging were estimated. In order to enhance cross-linking yield some blends with EVA copolymer (ethylene-vinyl acetate) were prepared. On the basis of the literature data, the influence of crystalline regions on cross-linking and mechanical properties was discussed as well.