Influence of OMMT on Surface Breakdown of Epoxy Resin in Liquid Nitrogen

Epoxy resin is employed as the main insulation materials or support components in the high-temperature superconducting (HTS) system. But surface breakdown of epoxy resin threatens the safe operation of the HTS system. Introducing organic montmorillonite (OMMT) into epoxy resin is an effective way to improve the resistance of surface breakdown. The OMMT with fraction of 0, 1, 3, 5, and 7 wt% is filled into the epoxy resin to investigate the conductivity properties, partial discharge, and trap distribution characteristics. The results shows that the conductivity of epoxy resin is reduced by incorporating OMMT into the matrix, and the smallest value is obtained with the filler content of 5 wt%. The modified partial discharge (PD) properties are related to trap distribution of epoxy resin/OMMT composites, which is with larger trap energy level and trap density than the pure epoxy resin one in liquid nitrogen. However, the PD resistance is decreased with filler content increasing from 5 wt% to 7 wt%, which is associated with the reducing trap energy level and trap density induced by the overlapping of OMMT. The research establishes the foundation for design and development of advanced polymer nanocomposites for HTS system.