Development of dielectric elastomers and blends for actuator applications

Abstract

This study evaluated and characterized the many types of dielectric elastomers and poly (p-phenylene)/dielectric elastomers blends towards the electroactive application. Dielectric elastomers films and AR71/PPP blends were prepared and investigated as an electroactive polymer. The acrylic elastomers (AR70, AR71, AR72) possess linearly positive storage modulus responses or sensitivities with increasing temperature and dielectric constant. On the other hand, the styrene copolymers (SAR, SBS, SIS) attain the maximum storage modulus responses or sensitivties at the glass transition temperature of the hard segments. For AR71/PPP blends, the dynamic moduli, G ' and G" of each blend, are higher than those of pure AR71. In addition, The effects of dielectric constant and DC/AC electric field strength on the deflection angle and the dielectrophoresis force of acrylic elastomers and styrene copolymers were investigated. As a DC electric field is applied, five elastomers, with the exception of SAR, deflect towards the anode side of the electrodes. For these elastomers, internal dipole moments are generated under electric field leading to the attractive force between the elastomers and the anode. SAR contains metal impurities (Cu and Zn) as determined by EDX. Their presence introduces a repulsive force between the Cu²⁺ and Zn²⁺ ions and the aniodic electrode, leading to the bending towards the neutral electrode. The dielectrophoresis forces of the six elastomers generally increase with increasing electric field strength, and increase monotonically with the dielectric constants. For an AC electric field, the deflection angle and the dielectrophoresis force increase with amplitude but decreases with increasing freqency under AC electrical field. The opitmum thickness for acrylic elastomer is 0.25 mm which gives the highest deflection angle and force. For AR71/doped PPP blends, the cut-off frequency of each blend are higher than those of pure AR71. The conductive particles act as a filler and can be used to improve the electromechanical responses at high frequency