Corona-induced partial discharges, internal charge separation and electromechanical transducer properties in cellular polymer films

Michael Wegener, Mika Paajanen, Werner Wirges, Reimund Gergard-Multhaupt

Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientificpeer-review

40 Citations (Scopus)


Recently, porous or cellular polymer films have received a lot of interest as materials for sensor and actuator applications. Films of cellular polypropylene have shown superior electromechanical thickness response when compared to conventional non-porous piezoelectric polymer materials. The electromechanical effect in cellular films originates from electrical discharges across internal gas-filled cells during preparation. The resulting charge separation is different from the charge-separation and dipole-orientation processes in non-cellular piezoelectric films. The aim of this work is to study the relationship between the partial discharges inside the cellular PP and its piezoelectric response. The focus is on the physical effects in the film at the threshold voltage that leads to a piezoelectric response. We studied the effects of charging voltage and charging time on partial discharges, surface potential and piezoelectric coefficient for a few cellular-film grades with different thicknesses. Also, the visible electroluminescence from numerous spots across the film surface during corona charging has been studied.
Original languageEnglish
Title of host publicationProceedings, 11th International Symposium on Electrets
PublisherIEEE Institute of Electrical and Electronic Engineers
ISBN (Print)0-7803-7560-2
Publication statusPublished - 2002
MoE publication typeA4 Article in a conference publication
Event11th International Symposium on Electrets, ISE11 - Melbourne, Australia
Duration: 1 Oct 20023 Oct 2002


Conference11th International Symposium on Electrets, ISE11


  • cellular film
  • gas content
  • electret
  • piezoelectricity
  • gas diffusion expansion

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