Space charge property at the interface in low-density polyethylene/MgO three-layered nanocomposites

The MgO/low-density polyethylene nanocomposite film and the sandwich-structure LDPE/MgO-LDPE/LDPE nanocomposite film were prepared by melt blending and hot pressing. Based on the Maxwell-Wagner effect, a theoretical model of the three-layer dielectric interface polarization was set up, and the charge density of the three layers of dielectric interface polarization is obtained. Then pulsed electro-acoustic (PEA) is used to study the charge distribution characteristics of the three-layer structure while the breakdown strength of the three-layer structure is tested. The formation and transmission mechanism of the interface charge is systematically analyzed through the above two methods. The results show that the formation of space charge at the interface of sandwich-structure film is likely to be the result of the interaction between the three-layer dielectric polarization effect and the capture charge mechanism at the interface. Compared with the single-layer composite film, the sandwich-structure nanocomposite film has higher breakdown strength, the reason may be that the charge is trapped by the charge trapping mechanism at the interface during the movement of the opposite electrode to form an interfacial space charge, and as the charge accumulates continuously to form a barrier at the interface, the barrier can effectively inhibit the formation of the conductive channel, and the material is improved. The breakdown field is strong.