Electrical properties of adhesives designed for smart debonding by a pulsed discharge method

Facile techniques are required for the debonding of polymeric adhesives from metals for material recycling. A promising solution is a pulsed discharge debonding method. In this approach, a pulsed discharge with a high voltage is applied to the system over a short time. Rapid expansion of gasified materials and shock-wave emissions are produced from the discharge passage, which results in debonding. A drawback of the conventional pulsed discharge method is that it must be conducted in water, otherwise, the pulsed discharge creeps along the material surface without destroying the adhesion. In this study, filler was added to the structure adhesive for the effective pulsed discharge debonding of metal adherend. Epoxy resins with fillers of carbon black, copper and barium titanate particles were fabricated, and their properties and adhesive strength before and after application of the pulsed discharge were investigated. We succeeded in introducing the pulsed discharge inside the adhesive by adding 3.4 vol% of carbon black to the epoxy adhesive; the rapid expansion of gasified adhesion that was caused by the discharge, resulted in debonding. The threshold volume fraction of carbon black for effective pulsed discharge inside the adhesive was discussed based on the percolation model with experimental data.