Ageing of Silicone‐Based Dielectric Elastomers Prepared with Varying Stoichiometric Imbalance: Changes in Network Structure,Mechanical, and Electrical Properties
1. Institute of Polymer Chemistry, University of Stuttgart, Stuttgart, Germany;2. Robert Bosch GmbH, Corporate Sector Research and Advance Engineering, Renningen, Germany;3. Institute for Electromechanical Design, Technical University of Darmstadt, Darmstadt, Germany;4. Institute of Textile Chemistry and Chemical Fibers (ITCF) Denkendorf, Denkendorf, Germany
Abstract:
Silicone‐based dielectric elastomers are promising dielectric electroactive polymers (DEAPs) applicable to various actuator applications. However, the lack of information concerning their long‐term performance still limits their industrial use. Here, the time‐dependent behavior of silicon‐based DEAPs under electromechanical cycling is investigated. A series of thin silicone films prepared with different stoichiometric imbalances are coated with compliant silver nanowire electrodes and then electromechanically cycled under alternating voltage (Vpp = 2 kV, VDC = 1 kV) over 105 cycles. Afterward, changes in cross‐linking density, elastic modulus, permittivity, and breakdown behavior are examined. With increasing load cycles, electrically induced cross‐linking of the hydrosilane groups occurs, which leads to increased cross‐linking density of the material. Concomitantly, increase in elastic modulus and decrease in permittivity are observed, resulting in a significant deterioration of actuation performance. The measured breakdown strength, which is related to an extrinsic breakdown strength based on electromechanical instability, increases too.
