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Suche nach „[R.] [Wache]“ hat 2 Publikationen gefunden
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    NachhaltigF: Angewandte Naturwissenschaften und WirtschaftsingenieurwesenS: TSZ Weißenburg

    Beitrag (Sammelband oder Tagungsband)

    G. Kofod, H. Stoyanov, M. Kollosche, S. Risse, H. Ragusch, D. McCarthy, R. Wache, Dmitry Rychkov, M. Dansachmüller

    Molecular level materials design for improvements of actuation properties of dielectric elastomer actuators

    Proceedings of SPIE 7976

    2011

    DOI: 10.1117/12.880981

    Abstract anzeigen

    Dielectric elastomer actuators are soft electro-mechanical transducers with possible uses in robotic, orthopaedic and automotive applications. The active material must be soft and have a high ability to store electrical energy. Hence, three properties of the elastic medium in a dielectric elastomer actuator affect the actuation properties directly: dielectric constant, electric breakdown strength, and mechanical stiffness. The dielectric constant of a given elastomer can be improved by mixing it with other components with a higher dielectric constant, which can be classified as insulating or conducting. In this paper, an overview of all approaches proposed so far for dielectric constant improvement in these soft materials will be provided. Insulating particles such as TiO2 nanoparticles can raise the dielectric constant, but may also lead to stiffening of the composite, such that the overall actuation is lowered. It is shown here how a chemical coating of the TiO2 nanoparticles leads to verifiable improvements. Conducting material can also lead to improvements, as has been shown in several cases. Simple percolation, relying on the random distribution of conducting nanoparticles, commonly leads to drastic lowering of the breakdown strength. On the other hand, conducting polymer can also be employed, as has been demonstrated. We show here how an approach based on a specific chemical reaction between the conducting polymer and the elastomer network molecules solves the problem of premature breakdown which is otherwise typically found.

    NachhaltigF: Angewandte Naturwissenschaften und WirtschaftsingenieurwesenS: TSZ Weißenburg

    Beitrag (Sammelband oder Tagungsband)

    G. Kofod, D. McCarthy, H. Stoyanov, M. Kollosche, S. Risse, H. Ragusch, Dmitry Rychkov, M. Dansachmüller, R. Wache

    Materials science on the nano-scale for improvements in actuation properties of dielectric elastomer actuators

    Proceedings of SPIE 7642

    2010

    DOI: 10.1117/12.847281

    Abstract anzeigen

    We discuss various approaches to increasing the dielectric constant of elastomer materials, for use in dielectric elastomer actuators. High permittivity metal-oxide nano-particles can show elevated impact compared to larger size particles, but suffer from water uptake. Composites with conducting particles lead to extremely high permittivity caused by percolation, but they often suffer early breakdown. We present experiments on approaches combining metal-oxides and metal particles, which compensate for the drawbacks, and may lead to useful DEA materials in which all relevant properties are technologically useful. The key seems to be to avoid percolation and achieve a constant nearest-neighbor separation.