Modeling on effects of charging time and recombination on surface potential decay crossover of LDPE

Surface potential decay (SPD) crossover of LDPE (low density polyethylene) is investigated by a dynamic model combining charging, surface charge accumulation, and charge transport processes. The charge continuity and Poisson's equation are solved by a highly stable and fifth order accurate finite difference weighted essentially non-oscillatory method and boundary element method, respectively. The simulations are performed at various charging times and various recombination coefficients. The simulation results show that the SPD crossover properties are influenced by charging times and recombination coefficients. The time for the occurrence of SPD crossover decreases with an increase in charging time, whereas it increases with an increase in recombination coefficient. It is demonstrated that the variation of charging times and recombination coefficients changes the distributions of charge densities and electric field in the bulk of LDPE. The differences of the distributions of charge densities and electric field affect the decay rates of surface potentials, which will determine the SPD crossover properties.