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In this study, the effect of blending on physical and electrical properties of low-density polyethylene (LDPE) was investigated. Two kinds of LDPEs whose densities are evaluated to be 0.9179 g/cm3 and 0.9192 g/cm3, respectively, were used and blended according to different blend ratios. The LDPE with a blend ratio of 50 wt% had the lowest impulse breakdown strength, F BImp, at 30°C. However, the LDPE with a blend ratio of 50 wt% also had the highest F BImp at 90°C among all specimens. The DC breakdown strength, F BDC, decreased with the increase of the blend ratio at 30°C but increased at 60°C and 90°C. However, the F BDC did not depend on the blend. The current densities for all specimens were almost the same at 30°C, but decreased with a blend ratio up to 75 wt% at 90°C. By analyzing X-ray diffraction (XRD) patterns, we found that the crystal size in the (020) plane increased with a blend ratio up to 50 wt%, and the LDPE with a blend ratio of 50 wt% had the largest crystal size in the (020) plane among all specimens. It was found that the F BImp was strongly related to the crystal size in the (020) plane.

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A study has been carried out about the electrical conduction properties of LDPE and XLPE film for power cables. As for increase of temperature, the current density of LDPE is increased with constant d o in low electric field, but changes with exponential function in high electric field. The tunnel current of prebreakdown region is shifted toward low field as much as thermal excitation energy. XLPE showes dominant electrical conduction properties by thermal excitation energy in low electric field, and transformation of the electron is resisted by the crystal in high electric field.