Investigation On Property Of Electrical Tree In Crosslinked Polyethylene/Montmorillonite Composites

The power cable is an important component in the power system, and crosslinked polyethylene is widely applied to power cables, as it has excellent heat resistance, chemical resistance and electrical properties. However, insulation performance was falled sharply, because crosslinked polyethylene cables were affected on factors, such as electrical factor, thermal factor, mechanical factor and environmental factor and so on, when the crosslinked polyethylene cable was exerted on high voltage for a long time. The main reason is that electrical tree appeared in the crosslinked polyethylene insulation layer, and the whole cable became invaild. In order to improve property of resisting electrical tree in crosslinked polyethylene, many scholars studied modification methods of crosslinked polyethylene. In this paper, the montmorillonite was chosen to modify crosslinked polyethylene.Crosslinked polyethylene/montmorillonite composites were prepared by peroxide crosslinking method and melting intercalation process, and the processes of electrical tree in initiation and growth were studied by the test system of electrical tree. The results showed that when they were prepared by the same process, property of resisting electrical tree in crosslinked polyethylene was better than polyethylene, comparing polyethylene and crosslinked polyethylene, which showed that electrical trees were inhibited in the crosslinked structure. When the montmorillonite content was the same, property of resisting electrical tree was not exactly the same for composites containing montmorillonites treated with different modifiers, which the pure crosslinked polyethylene was the best, the composite containing montmorillonite treated with stearyl quaternary ammonium was the second, and the composite containing montmorillonite untreated was the worst. It showed that montmorillonites treated with different modifiers were impact on property of resisting electrical tree. To further study montmorillonite treated with octadecyl quaternary ammonium on the impact of property of resisting electrical tree, montmorillonite content was changed in composites. The results showed that the property of resisting electrical tree in crosslinked polyethylene/montmorillonite composites was the best, when montmorillonite content was 1%, and that propertiy of resisting electrical tree was improved, when the content of montmorillonite was appropriate.