| The annual amount of super-clean cross-linking polyethylene (XLPE) cable materials of 110kV and above level is 4000 tons and 10% of the rate of growth every year. At present, only Dow Chemical from the United States and Borealis companies can product in the world. Domestic super-clean cable materials are of great economic benefits and social impact.With development of production technology of 35kV cable insulation materials and impurities detection techniques, it is possible that super-clean cable materials become domestic. Selection to basic Resin is one of the key of developing 110kV XLPE cable materials. Rheological properties and space charge characteristics of resin affect on processing and insulation aging of the basic resin. Four domestic low density polyethylene (LDPE) resins used to product cross-linking polyethylene and two cross-linking polyethylene (XLPE) abroad chosen in this paper are researched.It is shown by extruding test in capillary rheometer that rheological properties of domestic LDPE are worse than XLPE abroad at the material temperature of 125℃, while closed to XLPE abroad at the material temperature of 160℃.In this paper, XLPE is prepared with dicumyl peroxide (DCP) as cross-linker by immersion method. Cross-linked polyethylene and polyethylene sample are placed in vacuum oven at 353K for 2 hours, 24 hours, 48 hours and 72 hours of heat treatment. The space-charge distributions of these samples are measured by pulsed electro-acoustic method. The results show that heterocharge is dominant in XLPE samples for the 2-hour heat treatment and reduced or disappeared gradually after 24 hours and homocharge is dominant instead. Space charge of polyethylene sample is homocharge mainly which its distribution has nothing to do with the time of heat treatment.
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