Dielectric behavior of copolymers of vinylidene fluoride and tetrafluoroethylene

Koizumi, Naokazu; Hagino, Jinko; Murata, Yukinobu

doi:10.1080/00150198108238685

Cited by 30 publications

(12 citation statements)

References 16 publications

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“…14 In the preliminary study, 15 we found the Curie transitions for these copolymers with varied TeFE content by thermal and mechanical measurements. However, in our dielectric study 16 of these copolymers, no Curie transition was observed. As the temperature increased, the values of s' and s" increased and showed peaks near melting points.…”

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confidence: 75%

“…In the previous work, s ' and s" increased with increasing temperature and decreasing frequency and were reduced by the electrodialysis which lowered the content of ionic impurity. 16 Thus this dielectric behavior was attributed to the space charge polarization of the ionic impurity. 16 The increase in s' above the Curie transition in these copolymers seems· to be related to the space charge polarization as follow.…”

Section: Resultsmentioning

confidence: 99%

“…16 Thus this dielectric behavior was attributed to the space charge polarization of the ionic impurity. 16 The increase in s' above the Curie transition in these copolymers seems· to be related to the space charge polarization as follow. Most space charges will be trapped on the surface of polar crystals below the Curie transition while released above the transition.…”

Section: Resultsmentioning

confidence: 99%

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Curie Transition in Poled and Unpoled Copolymer of Vinylidene Fluoride and Tetrafluoroethylene

Murata

1987

Polym J

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ABSTRACT:Copolymers of vinylidene fluoride (VDF) and tetrafiuoroethylene (TeFE) with TeFE content ranging from 17.8 to 30."imol% were studied by thermal, dynamic mechanical, and thermally stimulated current measurements. Below the melting point, a small endotherm was observed in differential thermal analysis. Corresponding to the endotherm, a crystalline relaxation, designated as r;, was observed by mechanical measurements. It was inferred that the endotherm and the r; mechanical relaxation were due to the Curie transition. The Curie points of these copolymers were about 50 K lower than those of VDF-trifiuoroethylene (TrFE) copolymers with the same VDF content. In X-ray measurements, it was confirmed that these copolymers took the all-trans crystal structure similar to that of PVDF form I of which the crystal lattice expanded in aand b-axis directions and was disordered in the c-axis repeat in comparison with that for VDFTrFE copolymers. The Curie temperature for poled samples increased by

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confidence: 75%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Curie Transition in Poled and Unpoled Copolymer of Vinylidene Fluoride and Tetrafluoroethylene

Murata

1987

Polym J

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“…(PLZT 8/65/35), is characterized by high dielectric permittivity (3400), high electromechanical coupling (0.65) [2], exhibiting rhombohedral symmetry and diffuse phase transitions [5]. Pure P(VDF/TFE)-(0.98/0.02) obtained by hot-pressing shows relaxation processes in the vicinity of glass transition (~ 303 K) [6,7].…”

Section: Introductionmentioning

confidence: 99%

Dynamic dielectric response of PLZT-P(VDF/TFE) nanocomposites

Olszowy

Markiewicz

Pawlaczyk

et al. 2007

J. Phys.: Conf. Ser.

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Abstract. Dynamic dielectric relaxation of polymer P(VDF/TFE)(0.98/0.02) loaded with lead lanthanum zirconate titanate (Pb 0.92 La 0.08 )(Zr 0.65 Ti 0.35 )O 3 (PLZT 8/65/35) ceramic nanopowders was studied in the frequency range from 100 Hz to 1 MHz and at temperatures from 100 K to 450 K. The PLZT nanopowders were prepared by the sol-gel method using: lead(II)acetate trihydrate, lanthanum acetate hydrate, zirconium(IV)propoxide and titanium(IV)propoxide. The crystallization process of PLZT powders was monitored by means of XRD analysis (Philips PW 3710) using Cu-K α radiation in the range 20 0 ≤ 2Θ ≤ 60 0 . The powders were analyzed before and after burning of the organic remains. The morphology observations of the powders were made using Hitachi S-4700 scanning electron microscope (SEM), and the grain size distributions were measured on a Zetasizer Nano ZS by the DLS method. The PLZT-P(VDF/TFE) composite samples of 0-3 connectivity were prepared from ceramic and polymer powders by the hot-pressing method. The volume fraction of the ceramics Φ amounted 0.1, 0.15 and 0.2. The dielectric response of the ceramics-polymer composite was found as a combination of the responses of pure polymer and the ceramics: (i) the addition of the PLZT ceramics increases the value of the dielectric permittivity ε', (ii) the composite shows the maximum of the permittivity coming from the PLZT ceramics, (iii) the dielectric absorption spectrum of the composites is dominated by the α-relaxation in pure polymer.

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“…16 We studied dielectric behavior of VDF-TeFE copolymers with 10.7 to 30.7mol% TeFE in which no Curie transition was observed. 17 The present work was undertaken to find out the Curie transition for VDF-TeFE copolymers used in the previous work. For this purpose dynamic mechanical and thermal properties were examined for these copolymers with varied degrees of crystallinity.…”

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confidence: 99%