Crystalline Morphology Effects on Space Charge Accumulation in Polypropylene under DC Voltage

Polypropylene (PP) has been widely studied as an insulating material with broad application prospects in high-voltage engineering. The morphological characteristics of PP have a certain influence on the accumulation of space charge. In the present work, unmodified and 0.1wt% alpha ($\alpha$) nucleating agent-added PP were thermally treated at 130 °C to re-crystallize the samples, and two types of $\alpha$ crystals with different internal structures were obtained. Using the principle of the pulsed electroacoustic (PEA) method, the effect of re-crystallization on charge accumulation was investigated. It was found that when recrystallization occurs, the increase of the mesophase in the PP crystallization leads to an increase in charge traps, which leads to an increase in total charge accumulation. Moreover, the change in the internal microstructure of the $\alpha$ crystal has no change in the accumulation of space charge.