Ferroelectric-to-paraelectric phase transition of vinylidene fluoride-trifluoroethylene copolymer

Yamada, Takeshi; Ueda, Toshinobu; Kitayama, Toyoki

doi:10.1063/1.328783

Cited by 188 publications

(65 citation statements)

References 33 publications

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“…Subsequently, this peak was proven to correspond to the Curie point (Furukawa, Date, Fukada, Tajitsu and Chiba, 1980; Yamada, Ueda and Kitayama, 1981), and many detailed studies have been conducted from various viewpoints. In these copolymer samples, which differ from the case of PVDF, crystals of a ferroelectric nature can be obtained directly by melt-crystallization at atmospheric pressure without any mechanical or electrical treatments.…”

Section: Introductionmentioning

confidence: 97%

Pressure effect on phase transition in ferroelectic polymers

Matsushige

1989

Phase Transitions

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Pressure effects of phase transition behaviour in two kinds of ferroelectric polymers of poly(viny1idene fluoride), PVDF, and copolymers of vinylidene fluoride and trifluoroethylene, (VDFFrFE), are discussed.In the case of PVDF, several high-pressure treatments including a high-pressure annealing and a uniaxial compression were shown to induce a crystal transformation from a non-polar Form I1 crystal to a polar Form I crystal, which has ferroelectric characteristics and high piezoelectric activity. In addition, substantial pressure effects on ferroelectric phase transition points as well as crystal structures were observed for (VDFDrFE) copolymers with different VDF contents. The most significant pressure effects were observed for copolymer samples with unstable ferroelectric structures at atmospheric pressure. From high-pressure X-ray and Raman scattering studies, these pressure effects were suggested to originate from the pressure-induced conformational transition from gauche to trans in the molecular chains.

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Section: Introductionmentioning

confidence: 97%

Pressure effect on phase transition in ferroelectic polymers

Matsushige

1989

Phase Transitions

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“…Piezo-and pyroelecticity in ␤-PVDF results thus from alignment of dipoles by a static electric field and/or trapped charges injected during the poling process [3]. The ␤-PVDF structure is highly oriented; it has orthorhombic unit cells with a space group Cm2m (C 2v ) with a planar zig-zag (all-trans) chain conformation and parallel CF 2 dipole moments of the adjacent chains parallel to the crystallographic b-axis.…”

Section: Introductionmentioning

confidence: 99%

Characterization of poled and non-poled β-PVDF films using thermal analysis techniques

2004

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Abstract␤-poly(vinylidene fluoride)-␤-PVDF-exhibits ferroelectric properties due to the special arrangement of the chain units in the crystalline phase. The ferroelectric phase can be optimised by poling the original stretched film, that tends to align the randomly organised crystallites against the applied field. In this work, polarised and non-polarised ␤-PVDF from the same batch are characterised by mechanical tests and a series of thermal analysis techniques, including DMA, TMA and DSC. The films exhibit mechanical anisotropy, and in the longitudinal direction the poled film presents larger mechanical properties, due to the higher structural organisation. Poled and non-poled show similar crystallinity levels but the melting temperature probed by DSC is higher for the non-poled film; for both films the melting peak exhibits a complex shape, indicating a heterogeneous crystalline organization. Two relaxation processes were found (␤ and ␣ c ) by dynamic mechanical analysis (DMA). The ␤ process, attributed to segmental motions in the amorphous phase, appears at the same temperature in both directions, but its intensity was found to be higher for the films tested in the longitudinal direction. For a given direction, the poled films exhibit lower peaks, due to the more organised amorphous structure. At higher temperature, the ␣ c -relaxation was related to the contraction of the films in the longitudinal direction during heating, recorded by thermal mechanical analysis (TMA). The onset of molecular mobility within the crystalline phase allows for cooperative diffusion processes in the amorphous phase, generating the randomisation of the initially oriented structure.

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“…Some effort to characterize the ferro-to paraelectric transition in PVDF/F3Et copolymers as a function of temperature, mainly by means of WAXD, infrared and dielectric studies, has been reported [9][10][11][12][15][16][17]. There are still, however, some questions remaining concerning the understanding of the detailed microstructural mechanism through phase transformation.…”

Section: Discussionmentioning

confidence: 97%

Temperature dependence of microhardness in the 70/30 polyvinylidene fluoride-trifluorethylene copolymer: New structural aspects of the curie transition

Martínez‐Salazar

Câmara

Cabarcos

et al. 1988

Colloid & Polymer Sci

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A combined X-ray diffraction and microhardness investigation of the 70/30 polyvinylidene fluoride-trifluorethylene copolymer was carried out as a function of temperature. The changes in microhardness are interpreted in terms of variations in lattice spacing of the ferro-and paraelectric phases, crystallinity and long period. The changes of microhardness with temperature show four distinct temperature regions. In addition to a low temperature range, in which microhardness decreases exponentially with temperature, the ferroparaelectric Curie transition involves a faster hardness decrease. At higher temperature, the sudden microhardness rise is ascribed primarily to an increase of crystal thickness within the remnant paraelectric phase. Near the melting point, the fusion of thinner crystals leads to a range in which microhardness decreases exponentially again.

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Ferroelectric-to-paraelectric phase transition of vinylidene fluoride-trifluoroethylene copolymer

Cited by 188 publications

References 33 publications

Pressure effect on phase transition in ferroelectic polymers

Pressure effect on phase transition in ferroelectic polymers

Characterization of poled and non-poled β-PVDF films using thermal analysis techniques

Temperature dependence of microhardness in the 70/30 polyvinylidene fluoride-trifluorethylene copolymer: New structural aspects of the curie transition

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