Charging Properties and Time-temperature Stability of Innovative Polymeric Cellular Ferroelectrets

G.C. Montanari, F. Ciani, A. Motori, Mika Paajanen, R. Gerhard-Multhaupt, M. Wegener

Research output: Contribution to journalArticleScientificpeer-review

18 Citations (Scopus)

Abstract

After appropriate mechanical and electrical treatments, some cellular polymers become able to retain space charge for a long time, i.e. they acquire electret behavior. The electrical treatment consists of charging under high levels of DC electric field.
The mechanical treatment, based on the application of stretching forces to cellular polymer slabs that were before expanded under pressurized gas, affects the cavity size and shape, and therefore also the effectiveness of the charging process itself.
An investigation of charging mechanisms, as well as of mechanical treatment, is therefore fundamental for optimizing the ferro- and piezo-electret properties. The aim of this paper is to discuss the effect of the physical dimension of the cavities on the charging behavior of cellular ferroelectrets and to focus on the time-temperature stability for two families of polymeric cellular ferroelectrets based on polypropylene (PP) and on a cyclo-olefin copolymer (COC).
Emphasis will be given to the stretching process and in particular to the expansion rate applied during the manufacturing process (which affects the radial dimension and the height of the cavities, respectively). Space-charge and partial-discharge measurements as a function of time and temperature are the main tools to infer the influence of the cavity size on charging and stability characteristics
Original languageEnglish
Pages (from-to)238-248
JournalIEEE Transactions on Dielectrics and Electrical Insulation
Volume14
Issue number1
DOIs
Publication statusPublished - 2007
MoE publication typeA1 Journal article-refereed

Keywords

  • ferroelectric materials
  • partial discharges
  • piezoelectric films
  • space charge

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