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  • 1
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 33 (1995), S. 2245-2252 
    ISSN: 0887-6266
    Keywords: dielectric relaxation ; viscoelastic relaxation ; relaxation dynamics ; polymer relaxation ; glassy relaxation ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: In this work we compare four dielectric relaxation models that explicitly include the viscoelastic properties of the environment to define the dielectric relaxation process. These models are the Debye, Gamant, DiMarzio-Bishop, and the Havriliak-Havriliak models. Debye's model assumes a Newtonian viscosity and solves the hydrodynamic problem exactly leading to the venerable Debye function. Gamant's used heuristic arguments to include a time-dependent viscosity. These results lead to a splitting of the relaxation process. DiMarzio-Bishop solved the hydrodynamic equations which included a time-dependent viscosity exactly and applied the results to poly(n-octyl methacrylate). The Havriliak-Havriliak approach is based on statistical mechanics arguments that take into account strain energy which is associated with the polarization process. This model also requires a knowledge of the viscoelastic properties of the system. The results of the four models are compared. © 1995 John Wiley & Sons, Inc.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
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  • 2
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 35 (1997), S. 1887-1897 
    ISSN: 0887-6266
    Keywords: dielectric relaxation ; correlation functions ; polymer relaxation ; alpha processes ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Recently, tables of parameters used to represent experimental dielectric relaxation data as well as autocorrelation functions have become available. The experimental and autocorrelation function data were represented with the Havriliak-Negami function using rigorous statistical techniques. These tables include not only parameters and their temperature dependencies, but also the confidence intervals for all of the parameters. The important parameters for this work are the two shape parameters, α and β, which represent the width and skewness of the relaxation process, respectively. A comparison is made between the experimental data and several autocorrelation functions by calculating the minimum distance (in units of standard deviations) between the experimental values of αβ parameters for a specific polymer and the αβ parameters corresponding to the autocorrelation functions reported in these tables. Quantities derived from these minimum distances (a distribution function and an error function) are reported for each of the autocorrelation functions. These results are discussed in terms of the basic assumptions of the mode coupling theory. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35: 1887-1897, 1997
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
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