Influence of Grafting Maleimide on the Insulating Properties in Polypropylene

Polymer dielectrics with high thermal conductivity and low dielectric loss are highly attractive for applications in the electric and electronic industry. In this paper, polypropylene modified by grafting with maleimide (PP-g-Mal) and the related mechanism of the enhanced electrical properties is studied. The microstructure, DC conductivity, breakdown strength and space charge behavior of the nanocomposites were investigated. Based on the characterization of microstructure and trap characteristics, the mechanism of regulating the charge carrier transport process and the electrical properties of the PP-g-Mal is explained. The spherulite structure of PP is destroyed by the maleimide branches, and the interfacial interaction is increased by the PP-g-Mal, which reduces the charge mobility and raises the charge injection barrier so as to suppress space charge accumulation. This work may pave a way for tailoring the high temperature electrical properties of polymeric insulation material.