Capacitance dilatometry for the in-situ controlled expansion process of the cellular polymer-filler composites (ferroelectrets)

Johann Leonhartsberger, Harald Salhofer, Reinhard Schwödiauer, Simona Bauer-Gogonea, Siegfried Bauer, Reinhard Fostner, Gerhard Eder, Mika Paajanen, Hannu Minkkinen, Jaakko Raukola

    Research output: Contribution to journalArticleScientificpeer-review

    7 Citations (Scopus)

    Abstract

    Ferroelectrets are unusual composites, consisting of a closed-cell polymer-filler foam structure. Ferroelectrets behave like ferroelectric materials during and after internally charging the voids of the cellular structure. In order to optimize the electromechanical properties of ferroelectrets, the voids within the cellular polymer composite are expanded in a controlled manner in a high pressure gas chamber. Thereby, the gas pressure is first increased, subsequently released and finally the expanded structure is stabilized by a heat setting treatment at elevated temperatures. Capacitance dilatometry provides an easy means for the in-situ monitoring of the multi-step foaming process, and therefore allows for the control of the degree of foaming. The mechanical stabilization of the expanded cellular polymer composite structure is explained in terms of the enhanced crystallinity as a result of the heat setting process.
    Original languageEnglish
    Pages (from-to)181-187
    Number of pages7
    JournalFerroelectrics
    Volume331
    Issue number1
    DOIs
    Publication statusPublished - 2006
    MoE publication typeA1 Journal article-refereed

    Keywords

    • piezoelectricity
    • ferroelectricity
    • polymer-filler composites

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