Universität Stuttgart

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Publication Type: search.filters.UBSTyp.KonferenzbeitragSubject: search.filters.subject.530Institute: search.filters.UBSInstitut.Sonstige EinrichtungInstitute: search.filters.UBSInstitut.1. Physikalisches InstitutStart date: 1990End date: 1992

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    Electric-field profiles in corona- or electron-beam-charged and thermally treated Teflon PTFE, FEP, and PFA films
    (1992) Gerhard-Multhaupt, Reimund; Eberle, Gernot; Xia, Zhongfou; Yang, Guomao; Eisenmenger, Wolfgang
    Charge spreading in three different types of Teflon electrets was studied by means of piezoelectrically generated pressure steps, FEP and PFA samples corona-charged at room temperature usually exhibited only a surface charge layer. Uniform charge spreading throughout the bulk was found in FEP charged at or heated to high temperatures. Charge spreading was much less prominent in PFA because of a smaller retrapping efficiency. In PTFE (polytetrafluorethylene), charges from the surface and the rear electrode were injected into the bulk during charging at any temperature. Electron-beam-deposited charge layers broadened significantly upon heating.
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    ItemOpen Access
    Polarization profiles of electron-beam polarized VDF-TrFE copolymer films
    (1990) Schilling, Doris; Glatz-Reichenbach, Joachim; Dransfeld, Klaus; Bihler, Eckardt; Eisenmenger, Wolfgang
    In order to understand more clearly the poling mechanism in ferroelectric polymers, the PPS-technique was applied to copolymer films of vinylidenefluoride with trifluoroethylene P(VDF-TrFE), poled by a focused monoenergetic electron beam. Charges were injected in a well-defined way into the polymer films and thus provided information on the influence of externally introduced electrical charges on the poling process in ferroelectric polymers. The electron beam poling of P(VDF-TrFE) films is shown to produce very high values of polarization up to 180 mC/m2, which exceeds those produced in β-PVDF by electron irradiation by a factor of three. The distribution of the polarization across the film thickness is rather asymmetric, especially for samples irradiated with 20- and 30-KeV electrons. This may be caused by the rising electrical conductivity in samples with increasing electron energy. The annealing of the copolymer films before the poling procedure leads to a systematic increase of the polarization, with T a having its steepest rise around Tc.