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CPP: Chemische Physik und Polymerphysik

CPP 18: Poster: Polymer Blends, Heterogeneous Systems, Colloids and Nanoparticles, Interfaces, Polyelectrolytes

CPP 18.12: Poster

Wednesday, April 4, 2001, 12:30–15:00, AT1

Direct and inverse piezoelectric properties of porous space-charge electrets in multi-layer systems — •Michael Wegener, Werner Wirges, Kristin Richter, Wolfgang Künstler, and Reimund Gerhard-Multhaupt — University of Potsdam, Department of Physics, ACMP, Am Neuen Palais 10, D-14469 Potsdam

In recent years, strong piezoelectric properties were discovered in heterogeneous space-charge electrets such as porous polytetrafluoroethylene (PTFE) or cellular polypropylene (PP). The observed piezoelectric coefficients are up to one order of magnitude higher than in poly(vinylidene fluoride) (PVDF). A possible mechanism for the piezoelectricity in such materials with heterogeneous mechanical properties is non-homogeneous charging, as already proposed in the seventies. In order to optimize the piezoelectric effect and to use porous PTFE as a space-charge polymer electret in sensor applications, it is useful to prepare the samples as combinations of porous and non-porous electrets. Here, we present different approaches for preparing such multi-layer systems. We report results on the charging process, on the thermal charge stability, and on the resulting direct and inverse piezoelectric activities in various layer systems of porous and non-porous polymers.