Correlation between trap parameters and breakdown strength of polyethylene/alumina nanocomposites

This paper focuses on the effect of trap parameters on dc breakdown properties of LDPE/Al ₂ O ₃ nanocomposites. The thermally stimulated discharge current (TSDC) measurement was conducted to characterize the trap parameters of specimens, including trap level and trap density. The experimental results indicated that incorporating of nanoAl ₂ O ₃ into LDPE changes the trap level and density, which presents that the deep trap level initially increases and then decreases, and the shallow trap level increases with the increase of nanoparticle loading. At 5 wt%, the deep and shallow trap levels are almost the same value. Moreover, the trap density initially decreases and then increases with increasing nanoparticle loadings. The dc breakdown strength initially increases and then decreases with increasing loadings, which corresponding to the variation of the deep trap depth. The enhancement of dc breakdown strength is attributed to the increase in deep trap levels and the increase in trap density. It should be noted that the dc breakdown properties would be improved steadily in a vicinity of 5 wt% nanocomposites with the same deep and shallow trap level.