Using Sapphire Platelets to Increase the Electrical Breakdown Strength of Elastomers

Electrical breakdown of dielectrics limits the electrostatic energy that can be stored in a capacitor as well as the maximum attainable deformation strain that can be produced in dielectric elastomer actuators. Breakdown typically occurs by the nucleation of a filamentary breakdown path followed by its propagation until catastrophic breakdown occurs when the filament shorts out the electrodes. We demonstrate that layers of very thin (< 1 micron) aluminum oxide platelets, orientated perpendicular to the macroscopic electric field direction, can increase the breakdown strength of a commercially available PDMS elastomer. Phase-field modeling confirms that aligned high aspect ratio platelets can deflect the propagation of filaments and delay failure.