Temperature Stability of DC Conductivity and Breakdown of Crosslinked LLDPE

In this paper, a way to improve the temperature stability of DC conductivity and breakdown characteristics of polyethylene (PE) is proposed using a crosslinked linear low density polyethylene (LLDPE). The ratio of DC conductivity, as well as breakdown strength values under 90 to 30°C is used to determine the temperature stability of DC properties. The closer it is to 1, the better the performance of temperature stability. The results show that when using crosslinked-LLDPE material, the ratio of DC conductivity under 90 to 30°C is 10.5, while it is 461.6 for crosslinked-LDPE samples with the same DCP content. And the ratio of DC breakdown strength is 0.97 for crosslinked-LLDPE, while it is 0.32 for crosslinked-LDPE. The gel permeation chromatography (GPC) method, hot-set test, differential scanning calorimetry (DSC) analysis and scanning electron microscopy (SEM) images show that the fine arrangement and smaller molecular weight between crosslinks of molecular and morphology structure that LLDPE owns contribute to the improvement in comparison with LDPE. The findings may contribute a solution to the development of HVDC power cable insulation materials.