Breakdown Strength Enhancement and Space Charge Suppression of Low-density Polyethylene by Adding Fluorinated Graphene

Electrical insulating materials with high breakdown strength and low space charge accumulation are very important for the development of high-voltage direct current (HVDC) transmission. In this work, low-density polyethylene (LDPE)-based composites were prepared by adding 0, 0.1, 0.3, and 0.7 wt % fluorinated graphene. The morphology, breakdown strength, space charge distribution, and surface potential decay were characterized. The experimental results illustrate that when the mass fraction of fluorinated graphene increases from 0 to 0.7 wt %, the breakdown strength increases at first and then decreases, whereas the space charge density reduces initially and grows later. The 0.3 wt % composite has the highest breakdown strength, increasing by 54.2%, and the lowest space charge density, reducing by 26.4%, compared with pure LDPE. According to the quantum chemistry calculations and the trap distribution, the effects of fluorinated graphene on charge transport and breakdown strength are revealed. This work is very helpful for improving the electrical properties of polymeric materials.