Influence of controlled morphology on space charge accumulation by using linear polyethylene blends

Abstract

Space charge measurements have been performed on model samples where the morphology is controlled by blend composition and thermal pretreatment. A low molar mass linear polyethylene fraction (L2; M/sub W/=2200 g/mol) has been blended with a high molar mass linear polyethylene. L2 was either completely segregated after isothermal crystallization or showed a limited degree of cocrystallization with the higher molar mass grade after rapid cooling from the melt. The mass crystallinity (w/sub c/) varied between 65 and 90% depending on the L2 content and the thermal pretreatment. w/sub c/ increased with increasing L2 content and was significantly higher for the isothermally crystallized samples. Space charge measurements (PEA) showed that the space charge accumulation increased strongly with increasing L2 content and thus also with increasing crystallinity. At a specified degree of crystallinity, the space charge accumulation decreased with increasing crystallization temperature.