Influence of physical aging processes on electrical properties of amorphous polymers

Yianakopoulos, G.; Vanderschueren, J.; Niézette, J.; Thielen, A.

doi:10.1109/14.57092

Cited by 20 publications

(8 citation statements)

References 18 publications

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“…At a polarizing field of more than 2 kV/cm a hump and a sharp relaxation peak appeared at lower‐ and higher‐temperature sides of the pronounced broad peak, respectively. The hump is probably related to the so‐called sub‐ T g intermediate relaxation, which has been reported to appear in a number of polymers 27–29. Also, it must be noted that the appearance of a sharp peak at relatively high fields may be explained by the fact that interatomic restraints are reduced sufficiently to permit a nonelastic displacement of neighboring molecules.…”

Section: Resultsmentioning

confidence: 84%

Relaxation phenomenon of poly(vinyl alcohol)/sodium carboxy methyl cellulose blend by thermally stimulated depolarization currents and thermal sample technique

El‐Kader

Shehap

Abo‐Ellil

et al. 2005

J of Applied Polymer Sci

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ABSTRACT:The dipolar relaxation in poly(vinyl alcohol) (PVA), sodium carboxy methyl cellulose (NaCMC s ), and their blends were studied using a thermally stimulated depolarization current (TSDC) technique. The mutual effects of polarization conditions such as heating rate, poling temperature, time, and field on the properties of TSDC were investigated. Quantitative analysis of the experimental data is given in terms of dipolar and space charge polarization. A thermal sampling (TS) technique was applied to decompose the complex relaxations in individual polymers and their blend of 0.5/0.5 wt/wt into its normal distribution components. The activation energy of TS-formed electrets was determined by fitting the experimental curve to Bucci and Fieschi equations. Peak parameters such as activation energy and preexponential factor 0 were obtained. A linear relationship between the activation energy and logarithm of the preexponential factor was found, thus confirming operation of the compensation law. In addition, by using the Eyring equation of the rate theory, the activation enthalpy ⌬H and the activation entropy ⌬S were calculated. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 95: [1342][1343][1344][1345][1346][1347][1348][1349][1350][1351][1352][1353] 2005

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Section: Resultsmentioning

confidence: 84%

Relaxation phenomenon of poly(vinyl alcohol)/sodium carboxy methyl cellulose blend by thermally stimulated depolarization currents and thermal sample technique

El‐Kader

Shehap

Abo‐Ellil

et al. 2005

J of Applied Polymer Sci

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“…The glass and subglass relaxations are usually ascribed to torsional and segmental motions of the amorphous chains [28,29]. The sub-T g has been reported in a number of polymers as a nonequilibrium shoulder on the dissipation curves over the temperature range 300-353 K in low-frequency measurements [30][31][32]. Moreover, one may observe a markedly broadened and shallow relaxation peak associated with the crystalline region at about 423 K. The relaxation peak corresponding to glass transition in pure PVOH may find an acceptable interpretation using several theories, one of which is the free volume theory put forward by Fox and Flory [33,34].…”

Section: Methodsmentioning

confidence: 98%

Dielectric relaxation and dc conductivity on the PVOH-CF3COONH4 polymer system

Castillo

Chacón

Castillo

et al. 2009

Ionics

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In the present paper, the ionic conductivity and the dielectric relaxation properties on the poly(vinyl alcohol)-CF 3 COONH 4 polymer system have been investigated by means of impedance spectroscopy measurements over wide ranges of frequencies and temperatures. The electrolyte samples were prepared by solution casting technique. The temperature dependence of the sample's conductivity was modeled by Arrhenius and Vogel-Tammann-Fulcher (VTF) equations. The highest conductivity of the electrolyte of 3.41×10 −3 ( cm) −1 was obtained at 423 K. For these polymer system two relaxation processes are revealed in the frequency range and temperature interval of the measurements. One is the glass transition relaxation (α-relaxation) of the amorphous region at about 353 K and the other is the relaxation associated with the crystalline region at about 423 K. Dielectric relaxation has been studied using the complex electric modulus formalism. It has been observed that the conductivity relaxation in this polymer system is highly nonexponential. From the electric modulus formalism, it is concluded that the electrical relaxation mechanism is independent of temperature for the two relaxation processes, but is dependent on composition.

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“…5(a)], three relaxation peaks were noticed. The first relaxation peak corresponded to sub‐ T g , which was reported in a nonequilibrium shoulder on the dissipation curves over the temperature range 40–80°C in low‐frequency measurements 18, 19. The intermediate relaxation peak corresponding to T g (α relaxation) was attributed to micro‐Brownian motion of large chain segments.…”

Section: Resultsmentioning

confidence: 77%

Effects of the composition ratio, eosin addition, and γ irradiation on the dielectric properties of poly(vinyl alcohol)/glycogen blends

El‐Kader

Gaafar

Mahmoud

et al. 2008

J of Applied Polymer Sci

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ABSTRACT:The dielectric relaxation spectra of various poly(vinyl alcohol) (PVA)/glycogen blends and irradiated blend samples with 70 wt % PVA content that were undoped and doped with eosin were measured in extended temperature (30-1608C) and frequency (1 kHz to 1 MHz) ranges. Dielectric relaxation spectroscopy separates different molecular groups of a repeating unit of a polymer with respect to the rate of its orientation dynamics. In the high-temperature range (>1008C), the r relaxation, which is associated with the hopping motion of ions in the disordered structure of the biopolymeric material, can be measured. The electric dipole moment and the activation energy of the glass-transition temperature relaxation process were calculated.

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Influence of physical aging processes on electrical properties of amorphous polymers

Cited by 20 publications

References 18 publications

Relaxation phenomenon of poly(vinyl alcohol)/sodium carboxy methyl cellulose blend by thermally stimulated depolarization currents and thermal sample technique

Relaxation phenomenon of poly(vinyl alcohol)/sodium carboxy methyl cellulose blend by thermally stimulated depolarization currents and thermal sample technique

Dielectric relaxation and dc conductivity on the PVOH-CF3COONH4 polymer system

Effects of the composition ratio, eosin addition, and γ irradiation on the dielectric properties of poly(vinyl alcohol)/glycogen blends

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