Space charge behavior in LDPE/EBA insulation materials for HVDC cables

Polymer blending has been shown to improve the electrical insulation properties of materials, which has good processing performance in practice. In this work, low-density polyethylene (LDPE) was selected as the matrix, and two ethylene-butyl acrylate copolymers (EBA) with similar polarities (BA content) and different molecular weights were selected as fillers. The LDPE/EBA blends with 1 wt% EBA were prepared by melt blending. The crystallization behavior of LDPE/EBA blends was studied by polarizing microscope (PLM) and differential scanning calorimetry. It was observed by PLM that two fillers with different molecular weight promoted the heterogeneous nucleation process of LDPE and produced a mass of uniform small spherulites. The trap characteristics of LDPE/EBA blends were studied by thermal stimulation current (TSC) method, which indicates the introduction of deeper traps in the blends. The space charge behavior of the blends was also studied by pulsed electroacoustic method. The addition of the EBA 1400HN significantly suppress the injection of the homocharge, which reduces the distortion electric field.