Charge Conduction Characteristics of Polypropylene Under High Electric Field and Its Influence Mechanism on Dielectric Properties

Under high electric field strength, the charge transport within PP dielectric will generate a Coulomb potential field, which significantly affects the dielectric polarization process. There is an intrinsic connection between charge accumulation and the degradation of dielectric constant. In this paper, the influence relationship of the charge transport process on dielectric properties was studied. Firstly, a bipolar carrier transport-polarization correlation model under high electric field was established to calculate the effect of space charge on the dielectric properties of PP. Under low fields, charges mainly accumulate near PP electrodes, while under high fields, charges migrate to the dielectric center, inducing significant electric field distortion. Local space charge accumulation leads to a notable decrease in dielectric constant. A capacitor model was further built based on the above model to study the effects of space charge on the electric field distribution and dielectric constant of the capacitor. Electric field distortion in the capacitor is mainly concentrated at electrode edges. When space charge density reaches 30 C/m³, the effective electric field decreases by 6.75 kV/mm, and the dielectric constant drops to 95% of its initial value. Finally, the mechanism underlying the reduction in dielectric constant induced by space charge-regulated polarization was clarified.