Possibility of non-destructive detection of electrochemical migration in epoxy resin by the pulsed electroacoustic method

Abstract

Pulsed electroacoustic (PEA) method was applied as a nondestructive method to detect electrochemical migration in a sheet of epoxy resin and a sheet of laminate consisting of the same resin and a paper/phenol-resin composite. A significant decrease in the amount of negative charge was observed at the interface between the resin and the composite when the sample was the laminate. This is assumed to be due to the progress of electrochemical migration in the thickness direction. On the other hand, such a change in charge density was hardly observed when the sample was a sheet of epoxy resin. The electric field intensity in the epoxy resin layer in the laminate is assumed to be significantly enhanced, since the resistivity is much higher in the epoxy resin than in the composite. This seems to be the main reason why the electrochemical migration was induced only in the epoxy layer in the laminate. This means that observation of electrochemical migration in epoxy resin by the PEA method becomes possible by forming a laminate structure using the epoxy resin and paper/phenol-resin composite.

Research progress on space charge characteristics in polymeric insulation

“…13,14 Space charge characteristics obtained by the PEA method are compared and summarized in this paper, mainly but not exclusively for polyolefin and epoxy resin. On one hand, we provide information helpful for comparing space charge results under various different conditions, and for defining appropriate measurement conditions of own experiments, in order to better estimate the behavior of internal charges, 15 monitor electrochemical migration, 16 and ageing 17 in our polymeric insulation. On the other hand, the summarized results may also be a guide for the development of optimized filled polymer materials with respect to suppressing the harmful space charge.…”