Highly Anisotropic Dielectric Elastomer Composites.

摘要

Electroactive polymers (EAP) constitute a growing class of polymers that are able to change their shape under electrical stimulation. Among the various categories of EAPs, Dielectric EAPs (D-EAP) offer tremendous potential in lightweight materials based actuators for emerging technologies, especially in micro-robotics. One of the many challenging issues in the practical implementation of D-EAPs is requirement of large and directional actuation response at low electric fields.;In this research, we demonstrate a simple, yet versatile unidirectional fiber reinforced dielectric elastomer composite, referred to as Anisotropic D-EAP with tunability (ADEPT) for directional and enhanced actuation response. ADEPT composites are fabricated with acrylic elastomer as matrix and with a wide range of reinforcement fibers of varying properties such as polyurethane, polyamide and ceramic In order to discern the influence of the reinforcement on the actuation behavior in the ADEPT composites, electromechanical responses are evaluated at practical and moderate electric field of 85 kV/mm. ADEPT composites are capable of achieving remarkably high directional strains of about 60, 47, and 32 % with 2-3 v/v% polyurethane (PU), 1.80 v/v% polyamide (PA), and 0.09 v/v% ceramic fibers, respectively, with high coupling efficiencies in the range of 60-75%. The response is significantly higher when compared to the benchmark VHB acrylic (200% prestrained VHB 4905) of 19% strain with 50% coupling efficiency.;ADEPT composites also provide broad tunable mechanical as well as actuation performance suitable for impedance matching in a wide variety of applications. The electromechanical instability behavior of the ADEPT composites has also been studied to understand their failure behavior. The ADEPT composite seem to survive the electromechanical instability along the direction perpendicular to the reinforcement, while in the opposite direction it fails as a stiff dielectric with increasing modulus.