Berlin 2005 – wissenschaftliches Programm

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DF: Dielektrische Festkörper

DF 3: FV-internes Symposium „Polare Polymere und Ferroelektrete“

DF 3.2: Vortrag

Samstag, 5. März 2005, 09:10–09:30, TU C130

Charged polymer foams as piezoelectric transducer materials: Enhancement of piezoelectric properties by optimisation of the elastic properties, the internal charging and the stacking of ferroelectret films — •Michael Wegener — Department of Physics, University of Potsdam, Am Neuen Palais 10, 14469 Potsdam, Germany, mwegener@rz.uni-potsdam.de

Ferroelectrets are foams of electret polymers with an anisotropic cellular structure. In ferroelectrets, an internal void charging leads to charge layers of opposite polarity at opposite void surfaces. The charged voids represent large macroscopic dipoles which can be deformed by application of mechanical stresses or electric fields yielding a direct or inverse piezoelectric response of the polymer foam. During the last five years, the preparation, the structural modification and the electric charging of ferroelectrets have been investigated in detail. Here, several approaches to the optimisation of polymer-foam ferroelectrets are described and discussed, such as (i) the variation of elastic properties by structural modification with suitable inflation procedures, (ii) the optimised electric charging, taking into account the electric field threshold for micro-discharges within the voids, and (iii) the enhancement of the piezoelectric activity by stacking two or more foamed polymer-film ferroelectrets.