Dielectric properties of wool and horn containing absorbed water

Algie, J. E.; Gamble, R. A.

doi:10.1007/bf01498578

Cited by 24 publications

(7 citation statements)

References 36 publications

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“…9 A appears good for the Using Eq. 6 under the assumption that ec and kc depend little on temperature already mentioned, we obtain d/do = Zco/Eor, (7) where d and do are the piezoelectric constants at temperatures T, and T2, respectively, and c and c0 are the elastic constants at T7 and T2, respectively. If T7 = -150 and T2= O0C, we obtain dl/do 1.7 by substituting the values of Z/e0 -1.4 and c/co -1.2 (at dry state from Fig.…”

Section: Piezoelectric Models Of Keratinmentioning

confidence: 57%

“…Further, Feughelman adsorbed water but also protein itself. Algie et al (7) and Haly proposed a series-zone model (18) accounting further found dielectric loss peaks due to water for wool, for the postyield region of the load-extension curve, and and discussed the molecular mechanism of the dielectric afterwards Feughelman (19) improved the model by relaxation.…”

Section: Introductionmentioning

confidence: 99%

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Water in keratin. Piezoelectric, dielectric, and elastic experiments

Maeda

1989

Biophysical Journal

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To investigate actions of water in keratin, the piezoelectric, dielectric, and elastic constants are measured at 10 Hz, at temperatures between -160 and 150 degrees C, and at various hydration levels. From changes in the piezoelectric, dielectric, and dynamic mechanical parameters with moisture content (m.c.), we have identified three regimes (I, II, and III) in the hydration of water for keratin. At high hydration (21% m.c.) around 0 degree C, the piezoelectric constants for keratin steeply decrease with increasing temperature. This may be attributed to interfacial polarization which is strongly related to self-associated water molecules (particularly regime III water) just around crystalline helical regions which can exhibit the stress-induced, i.e., piezoelectric, polarization and may be attributed to electrode polarization induced by the increase of mobile ions in the amorphous matrix region, some of which would be released from their trapped states just around the piezoelectric phase by the regime III water. With increasing hydration, the elastic constants for keratin are found to increase below -70 degrees C and decrease above -70 degrees C. This suggests a viscoelastic transition of the keratin structure due to bound water (regime II water). The piezoelectric, dielectric, and elastic loss peaks are found at around -120 degrees C for hydrated keratin, believed to be due to tightly bound water (regime I water), which acts only to stiffen the keratin structure. The adsorption regions of water in keratin are discussed by a piezoelectric two-phase model, which consists of piezoelectric and nonpiezoelectric phases. It is proposed that water molecule would at least adsorb in the nonpiezoelectric phase.

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Section: Piezoelectric Models Of Keratinmentioning

confidence: 57%

Section: Introductionmentioning

confidence: 99%

Water in keratin. Piezoelectric, dielectric, and elastic experiments

Maeda

1989

Biophysical Journal

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“…14 Figure 14 shows the temperature dependence of tan ␦ for the wool sample. The maximum found at the temperature, which is below the glasstransition temperature for wool can be connected to the dielectric ␤-process due to the motions of side chains 11,12 and the alignment of dipoles, such as the water molecules. 2 The values of the loss tangent maxima for the investigated materials are shown in Table III.…”

Section: A the Temperature Dependence Of Relative Dielectric Permeabmentioning

confidence: 97%

Dielectric investigation of some woven fabrics

Cerović¹,

Dojčilović²,

Asanovic³

et al. 2009

Journal of Applied Physics

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In this paper, we have investigated the temperature dependence of dielectric properties (relative dielectric permeabilities and dielectric tangents of losses) for woven fabrics of hemp, jute, flax, cotton, polyester (PES), cotton-PES mixture, and wool. The measurements have been carried out at a temperature range from −50 to 50 °C in the electric periodic field at a frequency 1 MHz in vacuum. For the same specimens, the values of the dielectric properties have also been measured at an air temperature of 21 °C and at relative humidities of 40%, 60%, and 80%. At different frequencies from 80 kHz to 5 MHz, the dielectric properties have been measured at a relative humidity of 40% and at a temperature of 21 °C. An investigation of the dielectric properties of woven fabrics can provide a better understanding of the relation between the dielectric properties of woven fabrics and the different raw material compositions, temperatures, relative air humidities, and frequencies for specimens. Hence, this investigation helps to improve textile material properties.

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“…In natural polymers, such as keratin [13,14] or elastin [15], various effects, plasticization, water clustering, protonic conductivity, etc., are superimposed. At higher water contents and low frequencies, both e' and e" increase, indicating that the increasing losses cannot be simply attributed to the onset of ohmic conductivity.…”

Section: Discussionmentioning

confidence: 99%

DC dielectric study of polyethylene/CaCO3 composites

Bánhegyi¹,

Hedvig²,

Karasz

1988

Colloid & Polymer Sci

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The dielectric properties of composite samples prepared by polymerizing ethylene on the surface of filler are compared to those of mechanical mixtures consisting of CaCO3 and ultra high molecular weight polyethylene. After presenting the normalized master curves of AC dispersion and loss measured at different relative humidities, the field strength dependence of the 50 Hz AC and DC responses were studied. With one exception, the effect is small. Thermally stimulated polarization (TSP) and depolarization (TSD) curves are presented; the peak appearing on the TSP curves of the samples stored under ambient conditions is interpreted as a result of water desorption. The high temperature DC conductivity and the depolarization current density are higher in the composites and mechanical mixtures than in the matrix. The dielectric properties of the wet filler particles were calculated from the measured composite and matrix data using various mixture formulae. The results can be understood and interpreted if the dielectric properties of adsorbed water are described by the cluster theory of dielectric relaxation.

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Dielectric properties of wool and horn containing absorbed water

Cited by 24 publications

References 36 publications

Water in keratin. Piezoelectric, dielectric, and elastic experiments

Water in keratin. Piezoelectric, dielectric, and elastic experiments

Dielectric investigation of some woven fabrics

DC dielectric study of polyethylene/CaCO3 composites

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