Investigation of charge transport and breakdown properties in XLPE/GO nanocomposites part 2: Effect of polarity reversal

In this paper, the effect of polarity reversal on the space charge behaviors and breakdown properties of cross-linked polyethylene (XLPE)/graphene oxide (GO) nanocomposites are studied. Five kinds of XLPE based nanocomposites doped with different combinations of GO quantum wells (QWs) and the polycyclic aromatic compounds (PAC) were prepared by mechanical blending. The dynamic space charge distributions and breakdown strength of the XLPE samples under polarity reversal were measured. The experimental results indicate that the injection and accumulation of space charges in XLPE show polarity dependence under polarity reversal. The breakdown strength of the XLPE samples decreases with the increase of the pre-applied hetero-polarity electric field. Both the GO QWs and PAC can inhibit charge transport and improve the breakdown properties of XLPE, and the synergistic effect between the two dopants is observed. As a result, XLPE samples modified by the PAC functionalized GO QWs show a minimum space charge accumulation and the highest breakdown strength under polarity reversal. The quantum chemistry calculation method was employed to clarify the charge transport characteristics in XLPE dielectrics, and the relationship between space charge distributions and breakdown properties of the nanocomposites under polarity reversal was discussed.