Peculiarities of high-temperature dielectric relaxation in vinylidene fluoride – hexafluoropropylene copolymers

Kochervinskiĭ, V. V.; Malyshkina, I. A.

doi:10.1016/j.jnoncrysol.2009.09.034

Cited by 14 publications

(4 citation statements)

References 18 publications

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“…In view of the possible measuring errors of the amplitude of permittivity introduced by humidity, thickness measurement, pressure etc., the characteristic frequency shows more reliability for the characterisation of temperature dependence. It has been demonstrated in previous research that the temperature dependence of the characteristic frequency of side chain relaxation coincides with the following Arrhenius relation [37]:…”

Section: Temperature Dependence Variation Of Polarisation Processsupporting

confidence: 57%

{f}_{A}=A\hspace*{.5em}\mathrm{exp}\left(-\frac{{E}_{\mathrm{a}}}{kT}\right)\quad

where

A

is associated with the concentration of a charge carrier involved in the process.

T

and

k

represent the temperature and the Boltzmann constant, respectively.…”

Section: Variation Of Relaxation Processesmentioning

confidence: 72%

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Non‐destructive thermal ageing evaluation of P (VDF‐HFP) film based on broadband dielectric response

Wang

Gao³

et al. 2022

High Voltage

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Capacitors and sensors based on polymer dielectric materials are key components in electrical systems and electronic devices. Considering the temperature rise during operation, an effective evaluation method for the thermal ageing of polymer matrix is urgently needed. P(VDF-HFP) film with a thickness of 20 μm is manufactured by solution casting and a thermal ageing experiment up to 1000 h is conducted. Dielectric responses of wide ranges of temperatures and frequencies are measured for samples with different ageing durations. The universal relaxation law and Dissado-Hill dielectric response model are applied to further investigate the results. The characteristics of individual processes are obtained, which demonstrate that the main chain relaxation following the Vogel−Fulcher −Tammann equation and side chain relaxation following the Arrhenius equation both remain unchanged after thermal ageing. However, the activation energies of those two processes change significantly during the process and show different variation trends. The activation energy of the side chain relaxation gets larger monotonically due to the influence of annealing and the breaking of crystalline region. As a result, a non-destructive evaluation method for the thermal ageing of P(VDF-HFP) is proposed accordingly.

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Section: Temperature Dependence Variation Of Polarisation Processsupporting

confidence: 57%

{f}_{A}=A\hspace*{.5em}\mathrm{exp}\left(-\frac{{E}_{\mathrm{a}}}{kT}\right)\quad

where

A

is associated with the concentration of a charge carrier involved in the process.

T

and

k

represent the temperature and the Boltzmann constant, respectively.…”

Section: Variation Of Relaxation Processesmentioning

confidence: 72%

Non‐destructive thermal ageing evaluation of P (VDF‐HFP) film based on broadband dielectric response

Wang

Gao³

et al. 2022

High Voltage

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“…As numerous data on the dielectric relaxation show [18], the elec trical properties of crystallizing polymers with iono genic impurities must be considered in terms of Maxwell-Wagner polarization and near electrode polarization. In regards to the considered ferroelec tric polymer, this approach leads to dielectric non linearity [19] and the appearance of giant low fre quency dielectric dispersion [20][21][22].…”

Section: Introductionmentioning

confidence: 99%

Polarization of block textured films of ferroelectric copolymers of vinylidene fluoride with tetrafluoroethylene in an external field

et al. 2014

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The polarization of oriented films of the ferroelectric copolymer of vinylidene fluoride and tet rafluoroethylene in a sinusoidal electric field is studied. In low fields, the copolymer behaves as a linear dielectric whose permittivity nonlinearly increases with the amplitude of the alternating field. This behavior is related to the preferential orientation of the dipole moment of the chain along the normal to the surface and to the monocrystal structure formation. In higher fields, the hysteresis behaves formally coincidently with the behavior of an antiferroelectric. The important role of through stressed chains in the amorphous phase in the initiation of domains of a new direction in polar crystals is observed. Increased adsorption of water molecules on the surface of a polarized film is found and is attributed to the formation of the final den sity of the stable polarization charge on it.

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“…Validity of this hypothesis is testified by the following facts. In PVDF and its copolymers revealed the giant dielectric dispersion, which may be associated with the relaxation of space charge (Kochervinskii, Malyshkina, Markin, & Gavrilova, 2007;Kochervinskii, Malyshkina, Gavrilova, Sulyanov, & Bessonova, 2007;Kochervinskii & Malyshkina, 2010). According to these works, "quasi-free" charges begin freeing in the temperature of the secondary transition.…”

Section: Journal Of Materials Science Researchmentioning

confidence: 98%

Structural Aspects at Phase Transitions in Ferroelectric Copolymers of Vinylidenefluoride and Tetrafluoroethylene

Kochervinskiĭ¹,

Kozlova²,

Бессонова³

et al. 2014

JMSR

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Permittivity and conductivity low-voltage temperature dependences of a ferroelectric copolymer of vinylidenefluoride VDF with tetrafluoroethylene TFE in the ferroelectric to paraelectric phase transition range were investigated. The as received films obtained by crystallization from a solution had the metastable structure shown in particular in coexistence of ferroelectric and paraelectric phases below a Curie point. Temperature dependences of electrical characteristics in the first and second cycles of heating differ. Low glass transition (−40 ºC) facilitate intensive micro-Brownian chains mobility in the amorphous phase at ambient temperatures and above. As per the x-ray and spectroscopic data, the first heating cycle will result in a recrystallization process for molecular structure improvement. Asymmetry of temperature dependence of a dielectric susceptibility in a vicinity of "order-disorder" phase change is found out. For the first time paid attention to the fact that for crystalline polymer ferroelectrics interpretation of the parameters of the temperature dependences of the dielectric susceptibility in the cycle of heating near the phase transition point should take into account the possibility of the premelt processes. First the method of IR spectroscopy shows that the melting of ordered structures, emerging secondary crystallization is accompanied by a change of the basic parameters (frequency position, the integral intensity and half-width) component of the doublet of valence vibrations of С-Н groups. Such structural changes lead to the emergence of "anomalies" on the temperature dependences of conductivity.The phase transition ferroelectric to paraelectric mechanism research is usually done on copolymers P(VDF-TrFE), in which Curie point T c and melting point T m considerably differ (Wang, 1988; Nalva, 1995;Kochervinskii, 1999) more often. In this paper, the order-disorder transition is investigated on copolymer VDF-TFE of composition 71/29 for which both a chain chemical microstructure , and crystallographic parameters (Kochervinskii, 2010) had being studied earlier. It was shown, that in the copolymer isotropic films been crystallized from a low-boiling solvent at room temperature, T c and T m temperate values differ slightly. It was founded out, that the order-disorder transition having the first kind phase transition type. The electric parameter anomalies in the close proximity to a ferroelectric-paraelectric transition are depends on www.ccsenet.org/jmsr

show abstract

Peculiarities of high-temperature dielectric relaxation in vinylidene fluoride – hexafluoropropylene copolymers

Cited by 14 publications

References 18 publications

Non‐destructive thermal ageing evaluation of P (VDF‐HFP) film based on broadband dielectric response

Non‐destructive thermal ageing evaluation of P (VDF‐HFP) film based on broadband dielectric response

Polarization of block textured films of ferroelectric copolymers of vinylidene fluoride with tetrafluoroethylene in an external field

Structural Aspects at Phase Transitions in Ferroelectric Copolymers of Vinylidenefluoride and Tetrafluoroethylene

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