Tailoring Polymeric Insulation Materials for DC Cable Dielectrics

Chemical and physical defects are thought to be responsible for trapping of charge carriers in polymeric insulating materials such as crosslinked polyethylene (XLPE). The present work aims at increasing the basic understanding of the effect of physical defects on charge transport. In this paper, two insulating XLPE materials, used in DC and AC high voltage cables, were studied. The results show that DC-XLPE has a relatively lower activation energy than AC-XLPE. The mechanism for reducing the activation energy from physical defect point of view is discussed. A framework leveraged on Anderson localization was developed to elucidate the contribution of localized states due to physical disorder in lowering the activation energy of conductivity. Furthermore, the density functional theory (DFT) computations have been carried out to study the impacts of disorder on PE by copolymerization with different comonomers on the electronic structure. By copolymerizing the PE with various comonomers, more localized states were observed making the physical disorder become more dominant thus the properties of PE can be tailored.