Study of a plasticized-unoriented P(VF2/VF3) (73/27 mol %) copolymer. II. The effects of poling on the piezoelectric and ferroelectric properties of slow-cooled films

✍ Scribed by David L. Winsor; Jerry I. Scheinbeim; Brian A. Newman

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 169 KB
• Volume: 37
• Category: Article
• ISSN: 0887-6266
• DOI: 10.1002/(sici)1099-0488(19990101)37:1<29::aid-polb3>3.0.co;2-q

✦ Synopsis

The ferroelectric properties of unoriented films of a random copolymer of vinylidene fluoride with trifluoroethylene (73/27 mol %) as a function of plasticizer concentration, tricresyl phosphate (TCP), were examined. The percentages of dopant chosen were 5% and 10% by weight and a comparison was made with undoped films. The mechanical and thermal properties of these films were examined both before and after poling. Electric field poling induced the all-trans chains of the ferroelectric phase to pack in a more compact crystal structure, and also produced an increase of 7°C in the Curie transition temperature (T c ). The results of piezoelectric coefficient measurements (d 31 and e 31 ), X-ray diffraction analysis, and DSC thermal investigations provided insights into the ferroelectric nature of these plasticized copolymer films. In the films with 5% dopant, the crystallinity and remanent polarization decreased by 15% and 50%, respectively, when compared to the undoped films, yet showed a 21% increase in piezoelectric coefficient, d 31 . Contrary to this behavior, films doped at 10% TCP, with Ϸ 55% crystallinity, indicated almost no remanent polarization.