Thermal piezoelectric stability of poled uniaxially-and biaxially-oriented poly(vinylidene fluoride

Johnson, Guy; Blyler, L. L.; Crane, G. R.; Gieniewski, C.

doi:10.1080/00150198108238672

Cited by 28 publications

(15 citation statements)

References 11 publications

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“…where 3 and M 3 are the susceptibility and molar mass of chlorine ( 3 ϭ Ϫ20.1 ϫ 10 Ϫ6 emu/mol. 33 The calculated susceptibility values according to eqs.…”

Section: Magnetic Susceptibilitymentioning

confidence: 99%

“…Tawansi and colleagues 15 investigated the role of filler ion (Fe 3ϩ ) configuration and spin electron density on the microwave response of PVDF films, using the electron spin resonance (ESR) spectra. 16 The effect of equal amounts of FeCl 3 and CuCl 2 mixed fillers on the ESR, electronic and magnetic properties of PVDF, has been studied. 17 It was found that Lorentzian ESR signal, due to the Fe 3ϩ singly filled PVDF system, exhibits a significant deformation in the case of Fe 3ϩ and Cu 2ϩ multifilled PVDF system.…”

Section: Introductionmentioning

confidence: 99%

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Effect of valence electron spin polarization on the physical properties of CuCl2-filled poly(vinylidene fluoride) as a microwave modulator

Tawansi

Ayad

Abdelrazek

1999

J. Appl. Polym. Sci.

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Infrared and optical spectra, differential thermal analysis, dc electrical resistivity, magnetic susceptibility, electron spin resonance, and microwave response of CuCl 2 -filled poly(vinylidene fluoride) (PVDF) films, over the filler mass fraction range 0.05 Յ W Յ 0.4, were measured. The infrared spectra evidenced the presence of ␤-phase, for all of the filler levels with main deformations of 20% (for W ϭ 0.25) and 30% (for other filler levels) head-to-head and tail-to-tail units, which were considered as polaron and bipolaron defects. Optical activity was mainly influenced by PVDF structure. Differential thermal analysis revealed dipole relaxation and premelting endothermic peaks. A quasi-one-dimensional interpolaron hopping was thought to proceed in the direct current electric conduction, with a hopping distance less than the distance between two successive head-to-head sites. A temperature-independent Pauli paramagnetic behavior was observed, confirming the presence of induced energy bands due to CuCl 2 filling. Most of the observed electron spin resonance signals were antisymmetric, with superimposed repels due to the hyperfine interactions characterizing PVDF. The obtained linear dependence of the isotropic hyperfine coupling constant (⌬A`), for Cu(II), on average g-factor, implied that ⌬A`is a measure of the valence electron spin polarization. An octahedral or distorted octahedral configuration was suggested for Cu(II). The present system is a good microwave modulator.

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“…where 3 and M 3 are the susceptibility and molar mass of chlorine ( 3 ϭ Ϫ20.1 ϫ 10 Ϫ6 emu/mol. 33 The calculated susceptibility values according to eqs.…”

Section: Magnetic Susceptibilitymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effect of valence electron spin polarization on the physical properties of CuCl2-filled poly(vinylidene fluoride) as a microwave modulator

Tawansi

Ayad

Abdelrazek

1999

J. Appl. Polym. Sci.

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“…PVDF is well known as a strong piezoelectric and ferroelectric material [2,3]. It exhibits interesting features such as: microwave modulation, nonlinear optical properties [4], infrared to visible converter [5], electromagnetic wave [6], gas [7], temperature [8] and pressure sensor [9]. It is nonrejectable in human tissues; therefore it has important medical applications.…”

Section: Introductionmentioning

confidence: 99%

Effect of NaCl filler on ferroelectric phase and polaron configurations of PVDF films

Elashmawi

2007

Cryst. Res. Technol.

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Polyvinyldene fluoride (PVDF) films filled with NaCl of mass fraction range 1 ≤ W ≤ 6 % were prepared by casting technique. Their crystalline structure, thermal, optical properties and Electron spin resonance (ESR) were examined. X-ray diffraction (XRD) and differential thermal analysis (DTA) measurements indicated a maximum ferroelectric β-phase increment at 4%. DTA was used to identify the phase transition temperatures, the order of reaction and the activation energy of melting. The UV-Visible optical absorption implied a minimum value of the estimated optical energy gap at W = 4%. ESR spectra contained a Lorentizian signal exhibiting a minimum value of the symmetry factor at W = 4%. The energy levels of the optical gap boundaries were though to contribute to ESR transitions.

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“…Box 568337, Orlando, FL 32856. long-term exposure of the PVDF films at these higher temperatures has been shown to result in a reduction in piezoelectric activity [4], [5]. This loss of activity depends on the logarithm of the aging time and continues over many decades of aging time [5]. The application of large hydrostatic pressures also decreases the activity of a sample, but no irreversible loss is seen except in the case of highly voided samples [6].…”

mentioning

confidence: 99%

mentioning

confidence: 99%

Piezoelectric properties and temperature stability of poly(vinylidene fluoride-trifluorethylene) copolymers

Stack¹,

Ting²

1989

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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Absfract-Piezoelectric measurements were made on several copolymers of vinylidene fluoride and trifluoroethylene having a vinylidene fluoride concentration in the range of 65 to 75 percent. The hydrostatic g constant showed only a slight dependence on pressure, and pressures up to 35 Megapascal (MPa) caused no apparent loss of the piezoelectric activity. A significant increase in the value of the hydrostatic g constant was observed both at temperatures above and considerably below the room temperature.The anomalous result obtained upon cooling below the room temperature may be attributed to the glass transition temperature of the trifluoroethylene comonomer. Temperature aging studies were performed at high temperatures using films of these copolymers. A significant loss of piezoelectric activity occurred after long-time exposure. Isothermal studies at various aging temperatures revealed that this decay continued over a long time span. The aging behavior characteristically followed a linear dependence on the logarithm of aging time.

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Thermal piezoelectric stability of poled uniaxially-and biaxially-oriented poly(vinylidene fluoride

Cited by 28 publications

References 11 publications

Effect of valence electron spin polarization on the physical properties of CuCl2-filled poly(vinylidene fluoride) as a microwave modulator

Effect of valence electron spin polarization on the physical properties of CuCl2-filled poly(vinylidene fluoride) as a microwave modulator

Effect of NaCl filler on ferroelectric phase and polaron configurations of PVDF films

Piezoelectric properties and temperature stability of poly(vinylidene fluoride-trifluorethylene) copolymers

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