Annealing effect on the morphology of polyethylene materials and the tree initiation voltage

This paper presents the effects of different annealing conditions on the tree initiation of polyethylene (PE) films. It is well known that electrical trees are greatly influenced by the morphological structure in semi-crystalline polymers. Samples of PE films, including low-density PE, linear low-density PE and high-density PE have been measured. It was found that after re-crystallizing the crystallinity and the thickness of lamella increase, while the size change of the spherulites is invisible. It was also found that the tree initiation voltage increases after re-crystallizing. Finally we found that the increase of tree initiation voltage can be inherently related with the increase of the thickness of lamellae