Insulation properties enhancement of crosslinked polyethylene by grafting electron‐buffering voltage stabilizers

Abstract Grafting a voltage stabilizer on molecular chains of cross‐linked polyethylene (XLPE) can effectively improve the materials' insulation properties. Four different samples (XLPE, XLPE grafted with the voltage stabilizer, low‐density polyethylene (LDPE) blended with the voltage stabilizer, and LDPE grafted with the voltage stabilizer) are prepared in this paper. Several physicochemical and dielectric tests are performed to investigate the properties of the samples. The results demonstrate that the m‐aminobenzoic acid is successfully grafted onto the XLPE molecular chain. Moreover, the crosslinking and grafting processes are equally important for enhancing the materials' performance of the XLPE. In addition, the grafted voltage stabilizer negligibly affects the gel content and thermal properties of XLPE. However, it increases the crystallinity but decreases the lamella thickness. Moreover, the XLPE grafted with a voltage stabilizer has lower direct current (DC) electrical conductivity, less aggregation of space charge, and higher DC breakdown strength. The trap distribution results indicate that the voltage stabilizer introduces shallow traps in the sample and the quantum chemical calculations describe that the material bandgap is decreased. Thus, the high‐energy charge carriers are buffered by the newly‐introduced traps and the functional groups, leading to the enhanced material properties of the XLPE.