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  • 1
    Electronic Resource
    Electronic Resource
    Theoretical approach and the practice to the evaluation of structural parameters characterizing concentration polarization alongside ion-exchange membranes by means of dielectric measurement (1993)
    Springer
    Colloid & polymer science 271 (1993), S. 766-773 
    Details
    ISSN: 1435-1536
    Keywords: Bias-voltage effect ; concentration polarization ; dielectric relaxation ; electrodialysis ; ion-exchange membrane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract As the application of a dielectric theory proposed previously (J Membrane Sci 64:153–161 (1991)), theoretical formulation and the practical procedure of dielectric analysis are developed to calculate the structural parameters such as the conductivity gradient and the thickness of the concentration polarization layer, the capacitances and the conductances of the two adjoining aqueous phases from the observed dielectric parameters. The procedure of calculation consequent upon the theoretical formulation was applied to double relaxation data observed for cation-exchange membrane systems under application of d.c. bias voltage. As a consequence, the structural parameters of concentration polarization were readily obtained with accuracy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00660093
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Dielectric properties of ion-exchange beads of sulfonic acid type dispersed in aqueous solutions — effect of fixed charge density (1985)
    Springer
    Colloid & polymer science 263 (1985), S. 428-432 
    Details
    ISSN: 1435-1536
    Keywords: Dielectric property ; dielectric relaxation ; permittivity ; electrical conductivity ; ion-exchanger
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Ion-exchange beads with different densities of fixed charges were prepared by sulfoethylation of dextran gel beads. The relative permittivities and the electrical conductivities of the ion-exchange beads in a sodium form were evaluated by a dielectric technique consisting of the following two procedures proposed in a previous study (2): (a) Dielectric measurements for densely packed sediments of the ion-exchange beads; (b) Analysis of the observed dielectric relaxations by means of a theoretical equation of interfacial polarization for suspensions of spherical particles. The deduced permittivities of the ionexchange beads in equilibrium with water were about 60, which is lower than those of outer aqueous phases. The deduced conductirities were of the order of 1 to 10 mS cm−1 and were increased reasonably with the fixed charge density. Closer consideration on these deduced values indicates that no specific interaction exists between the counter ions and the fixed charges irrespective of changes in fixed charge density and temperature.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01410394
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Dielectric approach to polystyrene microcapsule analysis and the application to the capsule permeability to potassium chloride (1984)
    Springer
    Colloid & polymer science 262 (1984), S. 513-520 
    Details
    ISSN: 1435-1536
    Keywords: Dielectric property ; dielectric relaxation ; microcapsule ; permittivity ; polystyrene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract A method of numerical analysis is proposed to determine the phase parameters from dielectric observations of polystyrene microcapsules by using the conductivity at intermediate frequencies between two dielectric relaxations observed. The method was more feasible for the analysis of the microcapsule observations than the method by which the calculation is performed by use of the permittivity at lower frequencies. The method was applied to the dielectric observations of the KCl-loaded microcapsules to obtain the permittivity and the conductivity of the capsule interior, the thickness of the capsule wall, the volume fraction of the suspended capsules and the conductivity of the surrounding aqueous phase. The conductivity of capsule interior was found to be unchanged with time for as long as 3 months. From the results it is concluded that the microcapsules are impermeable to KCl.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01451514
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    Paper (German National Licenses)
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