Block polypropylene/styrene-ethylene-butylene-styrene tri-block copolymer blends for recyclable HVDC cable insulation

Polypropylene (PP) is regarded as the most promising candidate for eco-friendly high-voltage direct current (HVDC) cable insulation material due to its excellent thermal and electrical properties. In this paper, a block polypropylene (BPP) was selected as the matrix and blended with styrene-ethylene-butylene-styrene tri-block copolymer (SEBS) by melt blending. The thermal behavior, dynamic mechanical behavior, crystallization behavior, and mechanical and electrical properties of the BPP/SEBS blends were investigated. It was found that SEBS could efficiently improve the flexibility while maintaining the excellent heat resistance of PPB. Furthermore, adding an appropriate amount of SEBS had a positive effect on suppressing the space charge and increasing the breakdown field strength. For the BPP/SEBS blend containing 20 wt% SEBS, a desirable combination of thermal, mechanical, and electrical properties was achieved. This work may help pave the way for developing eco-friendly PP insulating material in HVDC cable applications. (paper)