Enhanced electrical properties of styrene-grafted polypropylene insulation for bulk power transmission HVDC cable
Hao Yuan, Shixun Hu, Yao Zhou, Chao Yuan, Wenbo Song, Qing Shao, Hongwei Shi, Juan Li, Jun Hu, Qi Li, Jinliang He
Abstract
Polypropylene (PP) is considered to be a rather promising material for HVDC cable insulation. Grafting modi-fication has proved to be an effective method on the electrical property improvements of PP. This paper reports on the highly-enhanced electrical properties of styrene-grafted polypropylene (PP-g-St) and their related mechanism. The influence of grafting styrene on crystallization structures, thermal properties and electrical properties of PP-g-St are characterized and analyzed. These results show that PP-g-St exhibits remarkably enhanced DC volume resistivity, suppressed space charge accumulation and improved DC breakdown strengths as compared to PP. Crystallization observation shows PP-g-St has small, imperfect spherulites with indistinct boundaries, which is strongly correlated to enhanced electrical properties. This study provides an effective grafting strategy to design high-performance HVDC cable insulation materials for bulk power transmission systems.