Improved Surface Electrical Strength of EPDM Samples by Surface-grafted Voltage Stabilizer

Voltage stabilizer can improve the electrical tree resistance and breakdown strength of polymeric insulation. But the use of voltage stabilizers to improve the surface properties of polymeric insulation is not explored. EPDM, as a commonly used reinforced insulation material in cable accessories, has a very low breakdown strength along its surface, which is very incompatible with the electrical strength of its body. Herein, the surface of EPDM sample is modified by surface-grafting of a voltage stabilizer (AOHBP) to improve the electrical strength of EPDM-XLPE interface. Based on the free radical reaction thermally initiated by dicumyl peroxide, the surface grafting of voltage stabilizer AOHBP on the surface of EPDM was achieved by liquid diffusion and subsequent free radical grafting. ATRIR test results show that the voltage stabilizer has been grafted onto the EPDM surface. According to the results of AC and DC interfacial breakdown test using EPDM-XLPE double layer samples under pressure, the surface breakdown voltage of the modified sample is significantly higher than that before modification. Surface grafting of functional organic compounds such as voltage stabilizers may pave a new way for the surface modification of polymer insulating materials.