The effect of crystallization conditions on radiation-induced cross-link formation in polyethylene

Publisher Website
Google Scholar
Abstract
The early preliminary conclusions concerning the differences in the radiation-induced gelation behaviour between bulk and single crystals and the effect of lamellar packing in various single crystal preparations of polyethylene have been substantiated by an extensive systematic examination. Smaller but analogous differences in behaviour were also found between specimens melt crystallized under different conditions. The effect of primary crystallization conditions, and that of annealing on gelation, as well as of existing cross-links on subsequent annealing were also examined. The solubility measurements were supplemented by measurements of intrinsic viscosity, of the amount of hydrogen evolved and to a greater extent by electron spin resonance examination of radical concentrations and decay rates. It emerged that the folds are preferred sites of reaction, cross-linking occurring either between the folds belonging to different lamellae or within the folds in the same lamellae dependent on the quality of interlamellar contact. Attention is drawn to the fact that radiation-induced gelation could potentially be used for characterizing molecular coordination in polymers.