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CPP: Chemische Physik und Polymerphysik

CPP 11: POSTER Disperse Polymer Systems

CPP 11.12: Poster

Dienstag, 28. März 2006, 17:00–19:00, P3

Polyethylene-terephthalate ferroelectrets: Foam preparation and piezoelectric properties — •Michael Wegener, Werner Wirges, Axel Mellinger, Olena Voronina, and Reimund Gerhard-Multhaupt — University of Potsdam, Department of Physics, Am Neuen Palais 10, D-14469 Potsdam, Germany

Novel cellular polyethylene-terephthalate (PETP) films have been prepared and investigated as alternative ferroelectrets. Ferroelectrets are polymer-air composites with a cellular structure and with electrically charged void surfaces where charges of opposite polarity form large macroscopic dipoles [1]. The change of void (and thus dipole) sizes during application of mechanical stress generates a piezoelectric activity of several hundred pC/N as demonstrated on polypropylene foams [1] and as recently reported for PETP foams [2], a second ferroelectret material.

Here, we describe several methods for foam preparation, such as voiding during treatment in supercritical carbon dioxide or during stretching of filler-loaded polymer sheets as well as procedures for foam-structure optimisation, such as stretching and inflation. Furthermore, we describe charging procedures for charging of void surfaces. Finally, we discuss the piezoelectric and elastic properties of the new ferroelectret materials.

[1] M. Wegener and S. Bauer, Microstorms in cellular polymers: A route to soft piezoelectric transducer materials with engineered macroscopic-dipoles, ChemPhysChem 6, 1014-1025 (2005).

[2] M. Wegener, W. Wirges, and R. Gerhard-Multhaupt, Piezoelectric polyethylene terephthalate (PETP) foams - Specifically designed and prepared ferroelectret films, Adv. Eng. Mat., accepted for publication.