DC Electrical Breakdown of Low-density Polyethylene Nanodielectrics Modulated by Charge Transport and Molecular Displacement

Abstract

The development of high-voltage and high-power cables requires polymeric dielectric materials with excellent insulation properties. Nanodoping is an effective method to promote electrical strength of polymers. This work focuses on the comparison of different breakdown models and reveals the mechanism of electrical breakdown of low-density polyethylene/alumina (LDPE/Al<inf>2</inf>O<inf>3</inf>) nanocomposites, by comparing the simulation results calculated by different models with experimental results. We utilized space charge modulated electrical breakdown with a maximum electric field criterion (SCEBEF), space charge modulated electrical breakdown with a maximum energy gain criterion (SCEBEG), charge transport and molecular displacement modulated electrical breakdown (CTMD) models to investigate how the interaction between nanofillers and polymer enhances the electrical strength of LDPE/Al<inf>2</inf>O<inf>3</inf> nanocomposites. It is found that electrical breakdown fields calculated by CTMD model coincide with experimental results for nanofiller contents ranging from Owt% to 5wt%, and the coincidence is much better than those obtained by SCEBEF and SCEBEG models. The electrical breakdown field of LDPE/Al<inf>2</inf>O<inf>3</inf> nanocomposites is increased by 25.7% compared with the neat LDPE sample, and the breakdown strength can be enhanced at relatively low loadings while it will decrease at relatively high loadings.