Simulation study on the correlation between morphology and electrical breakdown in polyethylene

On the basis of the percolation model for electrical breakdown, a theoretical approach was proposed to investigate the correlation between morphology and breakdown strength. By introducing the void sites in the percolation model, it is indicated that tiny nanovoids (below several nm) acting as deep traps lead to a slight increase of breakdown strength, but large nanovoids and sub-microvoids cause an obvious reduction of the breakdown strength and may play an important role in determining it. Moreover, the morphology change was expressed by the aggregation pattern and the orientation of voids. Monte Carlo simulation also confirmed that the breakdown strength changes with the void shape and size distribution, and can be improved by orientation.