Grafting and Space Charge Characteristics of XLPE-g-Diacetone Acrylamide

Recently, with the continuous development of flexible DC transmission technology and the proposal of global energy Internet strategy, it is imperative to further improve the operating voltage level of HVDC power cables represented by XLPE insulation. The problems of space charge accumulation and electric field distortion have been widely concerned by researchers. According to existing studies, grafting modification technology of polarity group makes the material have a significant DC performance improvement effect, but most of the grafted small molecule compounds have low gasification temperature, so it is difficult to directly adapt to the existing production process, unable to achieve the purpose of crosslinking reaction and small molecule grafted in one step. In this paper, a small molecule compound, DAAM, with high gasification temperature and strong polarity was selected to graft modified XLPE material. Through the torque rheologic curve, thermal extension test, gel content measurement and stress-strain test, it is concluded that the grafting process hardly inhibits the cross-linking reaction of the materials, and maintains excellent mechanical and physical properties. The infrared spectrum result shows that DAAM molecules are successfully grafted onto PE. According to the theoretical calculation, the deep trap energy level can be introduced into the graft modified material, which makes it have excellent high temperature space charge characteristics.