Carbon nanotubes and hexagonal boron nitride nanosheets co-filled ethylene propylene diene monomer composites: Improved electrical property for cable accessory applications

Rubber-based composites based on ethylene propylene diene monomer (EPDM) with excellent non-linear electrical conductivity are preferred to serve as reinforced insulation in cable accessories, which can self-adaptively regulate electric field distribution and avoid electric field concentration due to the non-linear conductivity. The conductive carbon nanotubes (CNT) are filled into EPDM to improve the non-linear conductivity, while the insulating hexagonal boron nitride nanosheets (h-BN) are used to reconcile the electric breakdown strength. The results show that with the increase of CNT loading content, the non-linear conductivity of CNT/h-BN/EPDM composites becomes more prominent, accompanying the decrease of threshold field strength and increase of non-linear coefficient. However, the electric breakdown strength of CNT/h-BN/EPDM composites seriously deteriorates due to the increase of CNT content and temperature. By incorporating 10 wt.% h-BN into the composites, the reduction percentage of breakdown strength can be significantly lowered, which is 19.95% of neat EPDM and 13.74% of CNT/h-BN/EPDM composites at 70°C, respectively. The COMSOL Multiphysics simulation results demonstrate that using the CNT/h-BN/EPDM composite as the reinforced insulation can eliminate the electric field concentration of the cable accessory as well as enable the cable accessory with good lightning shock resistance.