Electrode composition and partial discharges and their role in the breakdown of dielectric elastomer films

The dielectric breakdown strength of the elastomer films used in dielectric elastomer actuators and generators (DEA & DEG) limits the peak actuation strains and maximum efficiency that can be achieved by these electromechanical transducers. In order to reduce the likelihood of failure during their operation, the factors that lead to breakdown should be well understood. Recent efforts in this area have focused on electromechanical and thermal effects that lead to breakdown, however degradation and ultimately breakdown caused by partial discharge activity represent another key way an insulating material can fail. This work presents partial discharge data collected from the VHB4910 (3M) acrylic elastomer, tested using solid stainless steel electrodes, solid graphite electrodes, and powdered carbon electrodes. It is found that degradation due to partial discharge activity does play a role in the breakdown of the samples tested using solid electrodes, and that their detection could provide an indication of the degradation that leads to breakdown. However when powdered carbon electrodes are used, significantly more partial discharge activity occurs between the carbon particles of the electrode on the surface of the dielectric. This obscures the detection of the partial discharges occurring due to internal defects that cause damage to the dielectric.