Effects of byproducts of crosslinking agent on space charge formation in polyethylene - comparison between acetophenone and α-methylstyrene

We have examined the effects of acetophenone and α-methylstyrene on the space charge evolution in PE. The samples tested are additive-free LDPE sheets. The important conclusions obtained are as follows: (1) Positive charges are easy to migrate from the byproduct-existing region to the non-existing region, while negative charges are difficult. (2) Positive charge migration is easier in the LDPE sheet soaked into α-methylstyrene than in the one soaked into acetophenone, which is probably due to the difference in permeation velocity of the two byproducts. (3) The values of mobility and conductivity calculated from the space charge profiles agree with the assumption that ionic carriers are responsible for the conduction in the byproduct-existing region.