Effects of coupling agent and filler dispersion on V-t characteristics of epoxy/silica nanocomposites

Epoxy/silica nanocomposites were investigated to clarify the effects of coupling agents and the degree of filler dispersion as for treeing breakdown V-t characteristics and PD (partial discharge) resistance performances. In the former case, it was clarified that homogeneous dispersion is critical to obtain satisfactory V-t characteristics, and that the addition of silane coupling agent would help improve such characteristics further. In the latter case, on the other hand, the simple dispersion was sufficient to improve PD resistance, which is considered to be less sensitive to the degree of dispersion and the introduction of coupling agents. In order to help make such difference clear, observation was conducted on the state of nano filler dispersion and treed regions by SEM and TEM. Explanation was postulated on how nano fillers act on propagation of trees and progress of PD erosion.