Berlin 2008 – wissenschaftliches Programm

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DF: Fachverband Dielektrische Festkörper

DF 2: Electric, electromechanical and optical properties I

DF 2.3: Vortrag

Montag, 25. Februar 2008, 11:00–11:20, EB 107

Hybrid Elastomers with Improved Electromechnical Properities — Torsten Finnberg and •Bernd-Joachim Jungnickel — Deutsches Kunststoff-Institut, Darmstadt, Germany

Dielectric elastomers are a promising material for solid-state actuators due to the high energy density which can be stored, the short response times, and the high obtainable strain. That strain is based on the Maxwell effect. It has the same electric field dependence as electrostriction but is ruled by the ratio between dielectric permittivity and Youngs modulus of the material. A technologically feasible route to optimise the electro-mechanical performance of a dielectric elastomer is consequently to increase its dielectric constant by blending with a high dielectric constant filler without simultaneous increase in stiffness. In doing that, hybrids of polydimethylsiloxane filled with nano-scaled titanium dioxide were prepared. The influence of the filler content on the mechanical, dielectric, and electro-mechanical behaviour was investigated. The dielectric constant increased linearly with filler contents up to 10 wt-%. On the other hand, the elastic modulus of the hybrids decreased slightly in that composition range. The electro-mechanical coupling coefficient exhibited consequently a maximum for a filler level of 6 wt-% where it increased by 140 % with respect to that of the unfilled material. The approach enables to tune the mechanical and electro-mechanical properties of a dielectric elastomer to a desired ratio.