Study on Water-Tree Aging Characteristics of MAH Grafted Crosslinked Polyethylene

Abstract Modifying crosslinked polyethylene (XLPE) insulation materials through Physical or chemical means can improve their water-tree resistance. To explore this enhancement, MAH-grafted XLPE (XLPE-g-xphrMAH, where x=1.0, 1.5 and 2.0) was prepared using a melt blending and grafting modification method, employing low-density polyethylene (LDPE) with varying MAH doping contents. The accelerated aging experiments on water trees were conducted using the water blade electrode method. The findings indicated that the modification through MAH grafting notably suppresses water tree aging in XLPE. Among the samples tested, XLPE-g-1.0phrMAH demonstrated the most effective inhibition of water tree formation, displaying the shortest water tree length. Characterizing the dielectric properties of XLPE-g-xphrMAH samples, revealed that MAH-grafted XLPE leads to an increase in both the relative dielectric constant and the dielectric loss factor. At 50 Hz power frequency, XLPE-g-xphrMAH samples exhibit a relative permittivity below 2.28 and a dielectric loss factor below 0.001. Moreover, the AC breakdown field strength increases by 3.89%, suggesting that XLPE-g-1.0phrMAH displays outstanding insulation performance.