Abstract:Effects of different cross-linking temperatures (150 ℃/10 min, 170 ℃/10 min, 200 ℃/10 min and 250 ℃/10 min) on the gel content, thermal extensibility, tensile properties and electrical properties peroxide cross-linked polyethylene insulation materials with medium voltage of selected 26/35 kV were investigated in the research. The results show that XLPE sample is in poor surface quality and low gel content at the cross-linking temperature of 150 ℃, indicating that the XLPE sample has low cross-linking degree. With increasing the cross-linking temperature from 150 ℃ to 200 ℃, the gel content of XLPE samples is increased, indicating that the crosslinking degree increases with the increase of cross-linking temperature. The thermal extensibility and tensile strength of XLPE samples are significantly improved to 45% and 26 MPa with the increase of cross-linking degree. However, the gel content of XLPE sample decreased with the increase of cross-linking temperature from 200 ℃ to 250 ℃, which result from the occurrence of over cross-linking at the temperature. Due to the existence of over cross-linking, the thermal extensibility and tensile strength of XLPE sample are decreased.