Improved space charge suppression in PP/SEBS nanocomposites by controlling MgO nanoparticles with abundant surface defects

Polymer nanocomposite dielectrics have received extensive attention in the field of electrical materials and equipment. Studies have shown that the interface region between the nanoparticles and the polymer matrix has an important influence on the properties of nanocomposites. In this paper, MgO nanoparticles with abundant surface defects (C-MgO) containing a highly effective interface are synthesized by surface carbonization. A ternary nanocomposite is prepared by melt blending with polypropylene (PP) and styrene-(ethylene-co-butylene)-styrene tri-block copolymer (SEBS). The results showed that the size of the prepared concave nanoparticles was around 100nm. The addition of 0.2 phr of C-MgO had the smallest charge accumulation in the PP/SEBS/C-MgO nanocomposites, which greatly reduced the electric field distortion and enhanced the charge release ability. Moreover, the DC breakdown strength was increased to 304kV/mm, which may be due to the introduction of nanoparticles with high surface vacancy defects which provided deep traps. In addition, C-MgO nanoparticles increased the dielectric permittivity. The tensile strength and elongation at break of PP/SEBS/C-MgO composites were significantly increased, due to the rugged structure of the particles, which acted as dispersion stress centers in the polymer matrix. This work helps to develop environmental polymer nanocomposites and promotes the development and application of flexible high-voltage direct-current technology.