中文摘要：

为研究聚乙烯密度对其直流介电性能的影响,测试了LDPE、MDPE和HDPE的击穿强度、电导特性和空间电荷特性,探讨了结晶形貌及结晶度对材料介电性能的影响。结果表明：聚乙烯的结晶度和片晶敛集度对其电性能有显著影响。随着密度增加,聚乙烯的结晶形态发生变化,片晶厚度增加,敛集度上升,使载流子迁移率降低,从而改善了其直流介电性能,空间电荷注入量减少,击穿强度升高。

英文摘要：

In order to study the effect of density on the DC dielectric properties of polyethylene, the breakdown strength, conductivity, and space charge characteristics of LDPE, MDPE and HDPE were tested. The effect of crystal morphologies and crystallinity on the dielectric properties of the composite was discussed. The results show that the crystallinity and structure of polyethylene have significant effects on its dielectric properties. The crystal morphology changes with the increase of polyethylene density. The compact structure of MDPE and HDPE result in the reduction of carrier mobility, and this may be the key reason why the dielectric properties improve. With the increase of polyethylene density, the amount of injected space charge decreases, and the breakdown voltage increases.