Electromechanical responses of dielectric elastomer composite actuators based on natural rubber and alumina

The deflection responses of the dielectric elastomer actuators are investigated under the electrical field strengths between 0 and 650 V/mm at room temperature (27°C). The Standard Thai Rubber 5L (STR 5L)/aluminum oxide (Al₂O₃) composite (60 wt% Al₂O₃) cross-linked with 1 wt% dicumyl peroxide (DCP)/Irganox 1076 and cured at 170°C starts to deflect toward the anode side at the yield electrical field strength of 200 V/mm; the degree of bending increases monotonically with increasing electrical field strength of up to 650 V/mm. As the applied electric field is released, the elastomer composite recovers its original position and shape. The X-ray diffraction pattern of the STR 5L/Al₂O₃ composite (60 wt% Al₂O₃) cross-linked with 1 wt% DCP/I 1076 and cured at 170°C suggests that the highly ionic conductive Al₂O₃ generates the dipole moments in addition to that of the elatomer matrix. Scanning electron microscope micrograph of the composite shows a fairly uniform distribution of alumina particles in the natural rubber (STR 5L) matrix.