Radiation-Induced Graft Polymerization of 4-Vinylpyridine on Polyethylene

Abstract

4-Vinylpyridine was grafted on polyethylene films of different thicknesses by the direct irradiation method using a Co-60 γ-irradiation source. Addition of different amounts of solvents such as methyl ethyl ketone and cyclohexanone was found to decrease the swelling and the grafting extent on polyethylene. The dependence of the rate of graft polymerization on the thickness of the films was studied. The rate of grafting was found to decrease with increasing film thickness and a first order dependence was obtained. The effect of radiation dose on some of the mechanical properties of the ungrafted and grafted polyethylene was examined. It was found that low doses cause an increase in elongation due to a degradation process of polyethylene chains. At high doses, elongation tends to decrease again due to crosslinking, while the tensile load is not affected. Low grafting percents of 4-vinylpyridine on polyethylene lead to a marked decrease in elongation of the grafted polymer, with almost no change in the tensile load. Increasing the extent of grafting causes a significant increase in the tensile load and almost the same decrease in elongation as for the low grafted polymer.