The Experimental Study Of The Polarization And Depolarization Of Non Linear Polymer Composite Dielectrics

Non-linear insulation materials are those materials, for which the electric conductivity and/or relative dielectric constant are/is varied with electric field. Because of the excellent processing property and electric insulation performance, polyethylene has been widely applied in the fields of electrical and electronic insulation. In this paper, low density polyethylene (LDPE) as the base material filling the silicon carbide (SiC) was prepared to non-linear composite materials. The author measured polarization current under an applied DC electric field and the depolarization current after short circuit, and made its preliminary study of polarization and depolarization features.To study the polarization behavior of polymer matrix non-linear composite dielectrics, it is necessary to study polarization current and depolarization current of composite materials under various concentrations, different electric field strength and different temperature. According the need, in support of existing software systems, this paper developed a set of the polarization (depolarization) current hardware test system of adjustable temperature and adjustable electric field strength. Inspired by our group"three-step conductance model of the composites", this paper make the sample come to the superficial treatment that the pressed platy sample will be polished the upper and lower surface. Then this paper will compare and analyse the relaxation timeτof depolarization current before and after polishing the surface, in order to achieve the further objective of the mechanism of depolarization. This paper measured the polarization and the depolarization current of composite materials with time domain dielectric spectroscopy method, and detailed analyzed characteristics of the polarization and depolarization in different concentrations, electric field strength and temperature. In addition, the use of the"multiple segment method"that depolarization current curve will be multiple segmented, which causing non-Debye relaxation process can be used by Debye relaxation method, get more meaningful relaxation timeτ, and achieve a deeper understanding of the non-linear composite polarization (depolarization) features through the analysis ofτ.