Curie Transition in Copolymers of Vinylidene Fluoride and Tetrafluoroethylene

Murata, Yukinobu; Koizumi, Naokazu

doi:10.1295/polymj.17.1071

Cited by 24 publications

(6 citation statements)

References 16 publications

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“…A shoulder in the TSC curves below -25oC is assigned to the f3 relaxation of dipole origin. 16 The results of the TSC measurements again rule out ferroelectricity in the quenched samples of the low-VDF copolymers.…”

Section: Absence Of Ferroelectricity In Quenched Samples Of Low-vdf Cmentioning

confidence: 75%

Structure and Spontaneous Polarization in Fast-Quenched Copolymers of Vinylidene Fluoride and Trifluoroethylene

Oka

Murata

Koizumi

1986

Polym J

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ABSTRACT:Fast quenching from the melt was found to effect greatly the structures and ferroelectric properties of vinylidene fluoride and trifluoroethylene copolymers (P(VDF /TrFE)) in contrast to slow cooling. The results are discussed for high-and low-VDF content divided at about 50 mol% VDF. For the high-VDF copolymers, the quenched samples showed high T, like poled samples, implying an ordered ferroelectric phase. Poling the quenched samples at elevated temperatures produced a ferroelectric polarization the direction of which was restored after cooling from above T,. For the low-VDF copolymers, the quenched samples showed a crystalline phase different from that of the slow-cooled samples, which was found to exist in a metastable state. The quenched samples exhibited no ferroelectricity unlike the slow-cooled samples but poling at elevated temperatures induced pyroelectricity with anomalous temperature dependence. From the present results, the fast quenching seems to produce a phase stable at low temperatures and the poling at elevated temperatures causes crystal growth under an electric field resulting in thermallystable spontaneous polarizations. Crystal structures of the low-VDF copolymers are also speculated based on the present results and published structure models.KEY WORDS Vinylidene Fluoride-Trifluoroethylene Copolymers I Fast Quenching I Melt Crystallization I Ferroelectric Phase Transition I Spontaneous Polarization I Pyroelectricity I Copolymers of vinylidene fluoride and trifluoroethylene (P(VDF/TrFE)) have been extensively studied since the discovery of ferroelectricity in samples with high-VDF content as the first clear example of a ferroelectric polymer.1.2 Ferroelectricity originates in the structural characteristics of the PVDF form I crystal, namely, the all-trans chain conformation for the highest polarization and the pseudohexagonal chain packing to facilitate chain rotation by 60° steps. 3.4 The high-VD F copolymers are of great advantage to the formation of ferroelectricity because the form I crystal is adopted by as-crystallized samples and a high degree of crystallinity is attained by heat treatment. On the other hand, copolymers with VDF content lower than 50 mol% have been found by our study to exhibit intricate ferroelectric behavior, for example, a D-E double hysteresis loop and an abnormally low amount of remanent polarization. 5 Ferroelectricity is a crystal property which is expected to be strongly effected by a method of melt crystallization in semicrystalline polymers, i.e., slow cooling or fast quenching. We have developed a method of fast quenching * Present address:

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Section: Absence Of Ferroelectricity In Quenched Samples Of Low-vdf Cmentioning

confidence: 75%

Structure and Spontaneous Polarization in Fast-Quenched Copolymers of Vinylidene Fluoride and Trifluoroethylene

Oka

Murata

Koizumi

1986

Polym J

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“…The dielectric constant and dissipation factor of PVDF at 25 °C are 8.15−10.46 and 0.005−0.026 at 1 kHz, respectively, while the Curie temperature has been assessed as 197 °C and 195−197 °C …”

Section: Synthesis and Homopolymerization Of Vinylidene Fluoridementioning

confidence: 99%

From Vinylidene Fluoride (VDF) to the Applications of VDF-Containing Polymers and Copolymers: Recent Developments and Future Trends

2009

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“…The TC of PVDF has been widely debated, however most data suggests it to be above the Tm, between 195 °C and 197 °C. 66,67 The TC is regarded as the point when the material loses spontaneous polarization. Therefore, in PVDF this means the polymer chains rotate to reduce the net energy and hence randomize the polarization vector.…”

Section: Reviewmentioning

confidence: 99%

New developments in composites, copolymer technologies and processing techniques for flexible fluoropolymer piezoelectric generators for efficient energy harvesting

Shepelin

Glushenkov

Lussini

et al. 2019

Energy Environ. Sci.

209

165

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Curie Transition in Copolymers of Vinylidene Fluoride and Tetrafluoroethylene

Cited by 24 publications

References 16 publications

Structure and Spontaneous Polarization in Fast-Quenched Copolymers of Vinylidene Fluoride and Trifluoroethylene

Structure and Spontaneous Polarization in Fast-Quenched Copolymers of Vinylidene Fluoride and Trifluoroethylene

From Vinylidene Fluoride (VDF) to the Applications of VDF-Containing Polymers and Copolymers: Recent Developments and Future Trends

New developments in composites, copolymer technologies and processing techniques for flexible fluoropolymer piezoelectric generators for efficient energy harvesting

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