Improvement of the electrical properties of LDPE through the assisted electric field

Abstract The insulating polymer with high electrical properties is demanded for the high voltage direct current (HVDC) transmission. Regulating the aggregation structure of the insulating polymer is an effective strategy to improve its electrical properties. In this paper, the effects of the DC assisted electric field on the aggregation structure and electrical properties of low-density polyethylene (LDPE), a typical insulating polymer, were investigated. The LDPE treated with the assisted electric field of 0, 0.1, 0.3, 0.5, 1.0 and 2.0 kV mm −1 were prepared, respectively. Aggregation structure, conductivity, breakdown strength and surface potential decay were characterized. The experimental results show that the assisted electric field is helpful for the increase in spherulite amount and for the reduction in spherulite size, which leads to more deep traps to improve the electrical properties. With the increase in the assisted electric field, the conductivity decreases at first and then increases, whereas the breakdown strength is just the opposite. It is worth noting that the LDPE treated with the assisted electric field of 0.5 kV mm −1 has the lowest conductivity and the highest breakdown strength. This work provides a guideline for the design of electrical insulating polymers.