Accession Number : ADA137446

Title :   Hysteresis in Copolymers of Vinylidene Fluoride and Trifluoroethylene.

Descriptive Note : Technical rept.,

Corporate Author : NATIONAL BUREAU OF STANDARDS WASHINGTON DC POLYMER SCIENCE AND STANDARDS DIV

Personal Author(s) : Davis,G T ; Broadhurst,M G ; Lovinger,A J ; Furukawa,T

PDF Url : ADA137446

Report Date : Jan 1984

Pagination or Media Count : 33

Abstract : Copolymers of vinylidene fluoride (VDF) and trifluoroethylene (TrFE), with more than 50 mole percent VDF exhibit D-E hysteresis loops at room temperature which are much sharper than those exhibited by various crystal phases of the PVDF homopolymer. For the copolymer samples investigated here, appreciable conductivity develops at elevated temperatures which in the presence of electric fields leads to trapped charges in the polymer film, These charges then prevent the switching of dipoles at values of electric field that were applied, the room temperature hysteresis is greatly reduced and polarization through the thickness of the film is highly non-uniform. Upon heating the copolymers above the ferroelectric to paraelectric transition temperature, the polarization is destroyed, the space charges are apparently released and room temperature hysteresis is restored. Experiments with aluminum and gold electrodes and with mica blocking electrode lead to the conclusion that the charges are generated internally and are not injected from the electrodes.

Descriptors :   *Copolymers, *Polyvinylidenes, *Ethylene, *Fluoropolymers, *Hysteresis, Fluorides, Electrical properties, Displacement, Phase transformations, Piezoelectricity, Polarization, Pyroelectricity, Space charge, Conductivity, High temperature, Electric fields, Trapping(Charged particles), Polymeric films, Transition temperature, Electrodes, Dipoles, Orientation(Direction)

Subject Categories : Physical Chemistry
      Plastics

Distribution Statement : APPROVED FOR PUBLIC RELEASE