Effect of TiO₂Particle Shape and Deformation Rate on Permittivity of Silicone Elastomer Composite

The power generation output of a dielectric elastomer (DE) energy harvesting device can be enhanced by increasing the permittivity of the DE sheet. It has already been confirmed that the permittivity of the DE sheet can be increased by filling it with high-permittivity particles, but the permittivity of the DE sheet shows a stretch dependence, i.e., decreasing when the DE sheet is stretched. Moreover, the effect of the particle shape (aspect ratio) on the stretch-dependent permittivity of DE sheet is unclear. In this study, we filled the silicone rubber sheets by TiO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>particles with high and low aspect ratio, respectively, and the relative permittivities of them were measured under different stretch state. Then the effective permittivity of DE sheet filled with rod-like particles was calculated by using finite-element method. The DE sheet filled with TiO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>particles (high aspect ratio) has a high permittivity, while due to the alignment of the particles, it shows a high decrease rate in the permittivity when it is stretched, which in turn results in a decrease of power generation output. The power generation output cannot be further improved compared with the DE sheet filled with TiO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> particles with low aspect ratio.