Dresden 2006 – wissenschaftliches Programm
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CPP: Chemische Physik und Polymerphysik
CPP 11: POSTER Disperse Polymer Systems
CPP 11.23: Poster
Dienstag, 28. März 2006, 17:00–19:00, P3
Voiding - a way to increase the piezoelectric activity of polyamide 11 - films? — •Alexander Kremmer, Werner Wirges, Peter Frübing, and Reimund Gerhard-Multhaupt — Institut für Physik, Universität Potsdam, Am Neuen Palais 10, 14469 Potsdam
After quenching from the melt and cold drawing polyamide 11 (PA11) - films form ferroelectric domains. The ferroelectric domains are oriented in the field direction by poling above the coercive field (75 MV/m) and the polymer becomes piezo- and pyroelectric. A remanent polarization of 50 mC/m2 and a piezoelectric d33 coefficient of 4 pC/N are obtained. At room temperature the piezoelectric effect is relatively small compared with other ferroelectric polymers, however, it shows a better thermal stability. The orientation in the ferroelectric domains can be destroyed only through melting above 185 ∘C. The small piezoelectric effect is related to the high elastic modulus (2 GPa). Experiments are presented, which were performed in order to reduce the elastic modulus by voiding with supercritical CO2. First the gas is dissolved in the polymer under high pressure (150 bar). Then the films are annealed at 170 ∘C in order to expand the gas rapidly and to stabilise the voids before the gas diffuses out of the film. The piezo- and pyroelectric properties are investigated.