Dielectric behaviors of some polyvinyl esters

Ishida, YIchi; Matsuo, Masato; Yamafuji, Kaoru

doi:10.1007/bf01499637

Cited by 101 publications

(34 citation statements)

References 16 publications

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“…The latter, especially, could be due to some extent to the inherent inaccuracies of reproduction of t h e diagrams. (6)). The normalised graph reveals some departures from the common curve for highfrequency points corresponding to the lowest temperatures, suggesting the existence of another loss mechanism the peak is very clear --the ratio of slopes is 3:1, the width 2 = 3.2 decades.…”

Section: Review Of Experimental Datamentioning

confidence: 93%

“…We begin with loss data for polyethylene terephthalate, 5% crystalline, due to Ishida et aL (6). These data cover the temperature range from -71.7°C to 23.0°C, Fig.…”

Section: Review Of Experimental Datamentioning

confidence: 99%

“…(6)) Figure 2b) T h e normalised curve fitted separately for the lower frequency range (locus 1) and for the higher frequency range (locus 2). T h e chaindotted line is constructed so that the sum of this line and of the negative slope coincides with the experimental points show similar loss properties.…”

Section: Introductionmentioning

confidence: 99%

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A new model of dielectric loss in polymers

Jonscher

1975

Colloid & Polymer Sci

151

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Section: Review Of Experimental Datamentioning

confidence: 93%

“…We begin with loss data for polyethylene terephthalate, 5% crystalline, due to Ishida et aL (6). These data cover the temperature range from -71.7°C to 23.0°C, Fig.…”

Section: Review Of Experimental Datamentioning

confidence: 99%

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A new model of dielectric loss in polymers

Jonscher

1975

Colloid & Polymer Sci

151

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“…Those values may correspond to those of the a-relaxation process in pure PV Ac already reported by several authors. 8 ' 9 It has been reported 10 those of undiluted polymers. Judging from the concentration dependence of f m .…”

Section: Experiments Al Resultsmentioning

confidence: 99%

“…It reaches the value observed for the pure polymer, i.e., 60 kcal/mol. 8 The entropy of activation, LJS* is also obtained from eq 2. The value thus obtained of T LJS* at -20°C, is also shown in this figure.…”

Section: Experiments Al Resultsmentioning

confidence: 99%

Dielectric Properties of Polymer–Solvent Systems

Nojiri

Okamoto

1971

Polym J

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ABSTRACT:Measurements of the dielectric absorption of solutions, poly(vinyl acetate) -toluene and poly(vinyl chloride)-dioxane systems were carried out. Based on the effects of temperature, frequency, and concentration of the polymer in the dielectric absorption, the mechanism of this absorption is discussed. The frequency at which the maximum loss occurs depends largely upon the concentration of the polymer. This dependence is described successfully in terms of the free volume model. The activation enthalpy and entropy of this dielectric relaxation process were obtained as functions of the volume fraction of the polymer. These values increase with the volume fraction of the polymer and approach those for the a-relaxation process observed in pure polymers. The variation of free energy with volume fraction in this process can be explained by the change of free volume. Observed relaxation times show apparent molecular weight dependence and this effect can also be explained in terms of the free volume variation.KEY WORDS Dielectrics / Polymer Solution / Poly(vinyl acetate) / Poly(vinyl chloride) / Concentration / Molecular Weight / Free Volume / Free Energy of Activation / a-Process / Dielectric properties have been studied extensively by many investigators both experimentally and thoretically. A theoretical analysis of the dielectric relaxation process of polymer solutions has been given by Rouse, 1 Bueche,2 and Zimm 3 (R-B-Z theory). Their calculations treated the molecular motion of polymer for a very simplified model in which only the motion of the subchain was considered. In the actual cases, however, it sometimes occurs that other motions such as small scale or local motions in the subchain play an important role in dielectric behavior. Recently, Work,et al.,4 have reported that some of the dielectric relaxation process of polymer solutions should be ascribed to the local motion of polymer chains. Their study was made on polymers with dipoles attached rigidly to the chain backbone. It is said that the observed dielectric behavior for polymers 5 whose dipoles are parallel to the chain direction can be explained by the R-B-Z theory. Further extensive study indicates, however, that this model does not hold for the dielectric behavior of poly(propylene oxide)6 solutions.In the present work, dielectric measurements on polymer-solvent systems, poly(vinyl acetate) (PY Ac)-toluene, and poly(vinyl chloride) (PVC)-dioxane for· various polymer concentrations have been carried out. Those polymers have flexible main chains with one component of the dipole vector perpendicular to the chain direction.The mechanism of the dielectric relaxation process of those polymer solutions is discussed by using the free volume model or the rate process theory. EXPERIMENT AL APPARATUS AND PROCEDUREDielectric measurements of PY Ac solutions and PVC solutions were carried out over the frequency range from 30 Hz to 150 MHz by using a conventional transformer bridge and a twin T bridge. In these measurements, cylindrical and parallel plate e...

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Combined dielectric spectroscopy and thermally stimulated currents studies of the secondary relaxation process in amorphous poly(ethylene terephthalate)

Ménégotto

Demont

Bernès

et al. 1999

J. Polym. Sci. B Polym. Phys.

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The dielectric secondary β relaxation process of poly(ethylene terephthalate) has been investigated by dielectric spectroscopy (DS) and thermally stimulated currents (TSC). To analyze the broad and asymmetric DS spectra, without previous assumptions on the shape and the number of overlapped loss components constituting the β relaxation, a description in terms of a distribution of relaxation times (DRT) has been used. The Tikhonov regularization method has been used to extract the DRT from DS data. At lower frequency, the TSC technique revealed two components in the β relaxation process. The TSC spectra are experimentally resolved into elementary Debye processes by using the fractional polarization method. A set of elementary relaxation times with relaxation strength Δεi as statistical weight of TSC–DRT have been calculated. The temperature shifts of the DRT obtained from both dielectric techniques are analyzed. Whereas the maximum and the lower time wing of the DRT obtained from DS correspond to the β2 process resolved by TSC and associated to the noncooperative motions of carbonyl groups, the upper time wing of DRT extracted from DS is in accordance with the β1 process resolved by TSC and assigned to the cooperative motions of phenyl rings. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 3494–3503, 1999

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Dielectric behaviors of some polyvinyl esters

Cited by 101 publications

References 16 publications

A new model of dielectric loss in polymers

A new model of dielectric loss in polymers

Dielectric Properties of Polymer–Solvent Systems

Combined dielectric spectroscopy and thermally stimulated currents studies of the secondary relaxation process in amorphous poly(ethylene terephthalate)

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