Thermoplastic isotactic polypropylene/ethylene-octene polyolefin copolymer nanocomposite for recyclable HVDC cable insulation

Abstract

Thermoplastic materials represent the future trend of high voltage direct current (HVDC) cable insulation because of their recyclability and the absence of cross-linking by-products. The current work reports the advances of using inorganic nanoparticles to enhance the thermal, mechanical and DC electrical properties of thermoplastic HVDC insulation, which is composed of isotactic polypropylene (iPP) and ethylene-octene polyolefin copolymer (POE). SiO 2 nanoparticles with four types of surface chemistry were selected to prepare iPP/POE nanocomposites with different loading. The effect of SiO 2 nanoparticles on the morphology, supramolecular structure, crystallization and melting behavior, dynamic mechanical properties, tensile strength, elongation at break, space charge behavior, adsorption currents and breakdown strength were investigated. It demonstrates that the nanoparticle surface chemistry show significant influence on the spherulite size, crystallization temperatures, ductility, space charge behavior and breakdown strength of the nanocomposites. This comprehensive work suggests that tailoring the surface chemistry of nanoparticles is important to achieve desirable properties in the dielectric polymer nanocomposites.