Dielectric elastomer actuators (DEA) based on Maxwell-stress induced deformation are considered for many potential
applications where high actuation strain and energy are required. However, the high electric field and voltage required
to drive them limits some of the applications. The high driving field could be lowered by developing composite
materials with high-electromechanical response. In this study, a sub-percolative approach for increasing the electromechanical
response has been investigated. Composites with conductive carbon black (CB) particles introduced into a
soft rubber matrix poly-(styrene-co-ethylene-co-butylene-co-styrene) (SEBS) were prepared by a drop-casting method.
The resulting composites were characterized by dielectric spectroscopy, tensile tests, and for electric breakdown
strength. The results showed a substantial increase of the relative permittivity at low volume percentages, thereby
preserving the mechanical properties of the base soft polymer material. Young's modulus was found to increase with
content of CB, however, due to the low volume percentages used, the composites still retain relatively low stiffness, as
it is required to achieve high actuation strain. A serious drawback of the approach is the large decrease of the composite
electric breakdown strength, due to the local enhancement in the electric field, such that breakdown events will occur at
a lower macroscopic electric field.