Dielectric relaxations in drawn semi-crystalline poly(ethylene terephthalate)

Dargent, Éric; Santais, J.J; Saiter, Jean‐Marc; Bayard, J.; Grenet, J.

doi:10.1016/0022-3093(94)90623-8

Cited by 24 publications

(13 citation statements)

References 6 publications

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“…Thermally stimulated depolarization currents ͑TSDC͒ measurements on PET samples show a peak at temperatures higher than the ␣ peak associated with the glass transition, 9,11,12,[24][25][26] in agreement with measurements on many other polymeric systems. This is the so-called peak, which is attributed to space-charge polarization.…”

Section: A Permittivity Formalismsupporting

confidence: 80%

Electrical conductivity effects in polyethylene terephthalate films

Neagu¹,

Pissis

Apekis

2000

Journal of Applied Physics

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Influence of the relaxation of Maxwell-Wagner-Sillars polarization and dc conductivity on the dielectric behaviors of nylon 1010Electrical conductivity effects in biaxially stretched polyethylene terephthalate ͑PET͒ films of 6 m thickness and 68% degree of crystallinity were investigated by means of dielectric relaxation spectroscopy in the frequency range 10 Ϫ2 -10 6 Hz and at temperatures higher than the glass transition temperature ͑ϳ85°C͒ up to 190°C. The formalisms of complex permittivity, electric modulus, and impedance were employed to analyze the experimental data. The results are discussed in terms of dc conductivity, conductivity current relaxation, interfacial Maxwell-Wagner-Sillars polarization, peak, space-charge polarization, and electrode polarization. They are compared with the predictions of models for the electrical and dielectric properties of ion-conducting polymers. The dc conductivity values determined from dc measurement, from ac conductivity plots and from complex impedance plots agree well with each other. Their temperature dependence is described by the Vogel-Tammann-Fulcher equation and classifies PET as a fragile system.

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Section: A Permittivity Formalismsupporting

confidence: 80%

Electrical conductivity effects in polyethylene terephthalate films

Neagu¹,

Pissis

Apekis

2000

Journal of Applied Physics

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“…7,8 The second one is located above 120°C and the position, the polarity of the current and the exact nature are still the subject of controversy in literature. [9][10][11][12][13][14][15][16][17][18][19][20][21] In previous papers 7, 22,23 we have reported on the changes of the TSDC spectra for PET when the measurements are performed in vacuum or in ambient air in the temperature range 20-120°C. It was observed that TSDC spectra for different polymers were influenced by the nature of the gaseous charging environment [24][25][26][27] and by the mechanical motions in the sample.…”

Section: Introductionmentioning

confidence: 99%

Nonisothermal and isothermal discharging currents in polyethylene terephthalate at elevated temperatures

Neagu¹,

Marat-Mendes

Neagu³

et al. 1999

Journal of Applied Physics

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Articles you may be interested inThe contribution of dipoles and space charge to low temperature relaxation in polyethylene terephthalate Combined isothermal and nonisothermal dc measurements to analyze space-charge behavior in dielectric materials J. Appl. Phys. 97, 044103 (2005); 10.1063/1.1847703On the nature of thermally stimulated discharge current spectra in polyethylene terephthalate Formation and relaxation of poled order in dye doped polystyrene probed by isothermal and nonisothermal current measurements Analysis of the thermally stimulated discharge current around glass-rubber transition temperature in polyethylene terephthalateThe thermally stimulated discharge current and the isothermally final discharging current have been measured, in vacuum and in different ambient gases for ''as-received'' polyethylene terephthalate specimens, in order to understand the nature of the origin of the released current in the temperature range from glass-rubber transition temperature up to 220°C. The behavior of the samples thermally treated in oxygen, in nitrogen and in ambient air was analyzed, the gases have been used for detecting the localized states in the material. The current spectrum is determined by the space-charge existing in the as-received sample, and by the adsorbed and/or absorbed gases and water vapors. The movement of the ions, resulting from the interaction of the adsorbed and absorbed gases with the parasitic space charge, in the field produced by the space charge, is responsible for observed change in polarity of the current during nonisothermal and/or isothermal measurements and for the appearance of the or space-charge peak. This movement is considered to be thermally activated with a field-modified activation energy. The calculated activation energy, for the sample thermally treated in oxygen at different temperatures, was in the range (0.9-2.3)Ϯ0.1 eV. From the isothermal discharging current measurements, values for the exponent of time in the range from 0.04 to 0.7 were obtained suggesting a dispersive transport of the charge. The total charge density stored in the material is about 4ϫ10 Ϫ5 C and the corresponding trap density approximately 10 23 /m 3 . This charge is substantially larger than that determined by the pulsed electroacoustic method.

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“…For sample B, an extra peak appears at a temperature higher than Tp. It has been shown that this last transition appears as soon as anisotropy is induced in the sample [18]. For samples C, D and E, a pre-ot-peak, called or', was observed.…”

Section: Resultsmentioning

confidence: 94%

The glass transition

Dargent¹,

Cabot²,

Saiter³

et al. 1996

Journal of Thermal Analysis

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This work deals with a comparison of data obtained from differential scanning calorimetry (DSC) and thermally stimulated depolarization current (TSDC) investigations. Measurements were performed on various poly(ethylene terephthalate) films: a wholly amorphous, a thermally crystallized and drawn samples.For each specimen, the TSDC complex spectra, resolved into elementary ones, led to the determination of the classical compensation temperature (To). The glass transition temperature (Tg) and the fictive equilibrium temperature (Tf) were determined by means of DSC. It appears that Tc is different from Tg and very close to Tr.

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Dielectric relaxations in drawn semi-crystalline poly(ethylene terephthalate)

Cited by 24 publications

References 6 publications

Electrical conductivity effects in polyethylene terephthalate films

Electrical conductivity effects in polyethylene terephthalate films

Nonisothermal and isothermal discharging currents in polyethylene terephthalate at elevated temperatures

The glass transition

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