Improved DC Insulation Performance of XLPE With Graftable Voltage Stabilizer

Voltage stabilizers have the potential to improve the overall insulation properties of polymeric cables, but the poor compatibility with the polymer matrix limits their practical application. In this work, the reaction of 2,4-dihydroxybenzophenone (DHBP) with maleic anhydride (MAH) provides a novel and reactive aromatic ketone voltage stabilizer 4-(4-benzoyl-3-hydroxyphenoxy)-4-oxobut- 2-enoic acid denoted by MDVS, which can be grafted onto the backbone of polyethylene (PE) during the cross-linking process. The physicochemical and dc insulation properties of the cross-linked PE grafted with different addition of MDVS (XLPE-g-MDVS) are investigated, and the underlying mechanism is discussed. In comparison with the pristine XLPE, substantially suppressed space charge accumulation and decreased electrical conductivity are obtained in the XLPE-g-MDVS materials. As the content of MDVS is 1.2 wt%, XLPE-g-MDVS materials exhibit higher breakdown strength than that of the pristine XLPE. Furthermore, the graftable voltage stabilizer MDVS presents more efficient stabilizing effect than conventional voltage stabilizer DHBP before and after high-temperature degassing. Thermally stimulated current (TSC) tests and quantum chemical calculations are consistent with the experimental results of insulation properties, illustrating that capture and trap mechanisms cooperate in the improvement of XLPE dc insulation performance.