Michael Wegener

TL;DR: An overview is provided on the preparation of cellular polymers by physical foaming, on their charging by "microstorms", on their piezo- and pyroelectricity, and on analogies to ferroelectrics.

TL;DR: In this paper, the influence of the corona-charging process on the piezoelectric transducer coefficient d33 of a cellular electret film has been investigated, and the effect of the gas inside the voids has also been studied.

TL;DR: In this paper, controlled inflation experiments were carried out on cellular polypropylene films, and the resulting elastical and electromechanical parameters were determined; the elastic modulus in the thickness direction shows a minimum with a corresponding maximum in the electromachanical transducer coefficient.

TL;DR: In this article, the authors demonstrate the controlled inflation of cellular polypropylene films by means of separate pressure and temperature treatments, which has significant potential for inflating large-area transducers for electromechanical and electroacoustical applications.

TL;DR: In this paper, an optimized sequence of steps for preparing such ferroelectrets from commercial non-voided poly(ethylene terephthalate) (PETP) films by means of foaming with CO2, biaxial mechanical stretching, controlled void inflation, and bipolar electric charging was reported.