Influence of nanoparticle surface coating on electrical conductivity of LDPE/Al2O3 nanocomposites for HVDC cable insulations

• Published in: IEEE transactions on dielectrics and electrical insulation 2017, Vol.24 (3), p.1396-1404
• Main Authors: Liu, D., Hoang, A. T., Pourrahimi, A. M., Pallon, L. K. H., Nilsson, F., Gubanski, S. M., Olsson, R. T., Hedenqvist, M. S., Gedde, U. W.
• Format: Article
• Language: English
• Subjects: Aluminum oxide; Coatings; Conductivity; electrical conductivity; HVDC cable insulation; LDPE/aluminum oxide nanocomposites; Nanocomposites; Nanoparticles; particle coating chemistry; particle dispersion; Polymers; Surface treatment
• ISSN: 1070-9878; 1558-4135; 1558-4135
• DOI: 10.1109/TDEI.2017.006310

LDPE/metal oxide nanocomposites are promising materials for future high-voltage DC cable insulation. This paper presents data on the influence of the structure of the nanoparticle coating on the electrical conductivity of LDPE/Al 2 O 3 nanocomposites. Al 2 O 3 nanoparticles, 50 nm in size, were coated with a series of silanes with terminal alkyl groups of different lengths (methyl, w-octyl and n-octadecyl groups). The density of the coatings in vacuum was between 200 and 515 kg m -3 , indicating substantial porosity in the coating. The dispersion of the nanoparticles in the LDPE matrix was assessed based on statistics for the nearest-neighbor particle distance. The electrical conductivity of the nanocomposites was determined at both 40 and 60°C. The results show that an appropriate surface coating on the nanoparticles allowed uniform particle dispersion up to a filler loading of 10 wt.%, with a maximum reduction in the electrical conductivity by a factor of 35. The composites based on the most porous octyl-coated nanoparticles showed the greatest reduction in electrical conductivity and the lowest temperature coefficient of electrical conductivity of the composites studied.