Polymer, Vol.114, 311-318, 2017
Poly(tetrafluoroethylene-hexafluoropropylene) films with high energy density and low loss for high-temperature pulse capacitors
As the most important material of metalized capacitors, dielectric polymers with large energy density (U-e), promising discharging efficiency (eta), and elevated breakdown strength (E-b) are dreadfully requested for energy storage purpose. During the charging and discharging circles, the Joule heat could cause significant temperature rising and undesirable early failure in the capacitors. Few of the known polymeric dielectrics are able to work functionally at temperature over 100 degrees C, especially under high electric field. In present contribution, poly(tetrafluoroethylene-hexafluoropropylene) (P(TFE-HFP)) is fabricated into thin films via hot-pressing followed by uniaxially stretching. At ambient temperature, P(TFE-HFP) films exhibit linear dielectric behaviour like biaxially orientated polypropylene (BOPP). The high T-m and Young's modulus allow P(TFE-HFP) films to work functionally at temperature up to 110 degrees C, whose Eb is over 500 MV/m, U-e is more than 6 J/cm(3) and h is larger than 80%, respectively. The excellent performance suggests that P(TFE-HFP) films may substitute BOPP films to work as dielectric materials at elevated temperature. (C) 2017 Elsevier Ltd. All rights reserved.