Comprehensive and multifaceted study of the electrical properties of nano-composite insulating material

为了解低密度聚乙烯(LDPE)/纳米氧化镁(MgO)纳米复合材料的空间电荷形成和击穿机理，研究了直流预应力对其击穿强度、空间电荷分布和导电电流的影响。LDPE的直流击穿强度(FB)随直流预应力的增加而降低。这可能是因为LDPE的大部分通过产生类似于带电的预应力的包而变得更具导电性。而LDPE/MgO纳米复合材料的DC-FB则随着直流预应力场的增大而增大，这表明由于纳米复合材料中的电荷俘获而产生的电极附近空间电荷控制的导电电流与击穿密切相关。

To understand the space charge formationand the breakdownof low-density polyethylene (LDPE) / nano-sized magnesium oxide(MgO) nanocomposite materials, the breakdown strength,the space charge distribution and conduction current influenced by DC prestress were investigated. DC breakdown strength (Fb) of LDPE decreased with increase of DC prestress. This is probablybecause the bulk of LDPE became more conductive condition by the generation of a packet like chargeduring the prestress. On the other hand, DC-Fb of LDPE/MgO nanocomoposite increased with increase of DC pre-stress field.It was suggested that the conduction current controlled by the space charge near the electrodesdue to charge trapping of MgO nanofiller closely relatedto the breakdown.