Insights into the Complex Prebreakdown Actuation of Silicone Elastomers and its Influence on Breakdown Behavior

Dielectric elastomer transducers can be applied in many different applications, but their current use is limited by either their electrical breakdown strength or by electromechanical instabilities in the case of soft elastomers. The breakdown process is never a single, simple process but rather-most likely-an ensemble of thermoelectric processes taking place in both elastomer and electrode materials, coupled with mechanical and potentially also chemical degradation. In this work, by using a high-speed camera, we follow silicone-based dielectric elastomers undergoing a ramp-up in voltage close to electrical breakdown strength, with differently constructed elastomers and electrodes. As such, we present experimental insights into the electromechanical processes immediately before the dielectric breakdown of elastomers and identify three different actuation mechanisms taking place prior to electrical breakdown, denoted prebreakdown actuation in the following. The prebreakdown actuation mechanisms observed herein include film thinning and stretching, as well as the formation of bubble- and ring-shaped structures from the elastomer surface, respectively. We furthermore present a theoretical explanation for the observed actuation mechanisms.