Space Charge Behavior under Different Electric Fields in Acrylic Elastomer

Electroactive polymers (EAP) are regarded as excellent dielectrics for energy transducers. For some applications, the applied voltage has a dc component and space charge may accumulate and distort the local electric field in the dielectric. The transport and accumulation of space charge is linked to critical dielectric properties, such as breakdown, polarization and electrical ageing. Few studies can be found in the literature related to the space charge mechanism in EAP. Therefore, it is the intention of this paper to analyze the space charge dynamics of a typical acrylic EAP, VHB 4910, while varying the applied electric field and the mechanical strain perpendicular to the electric field. The results show, even at a relatively low applied field of 5 kV/mm, the accumulation of a large amount of heterocharge in front of the cathode, resulting in a two-fold increase of the electric field at the cathode – EAP interface. The effect of applied mechanical strain is an even further increase of the amount of heterocharge and the resulting electric field. The strong enhancement of the local electric field is expected to seriously affect the breakdown strength of the actuator.