J. Phys. II France
Volume 6, Numéro 5, May 1996
Page(s) 697 - 711
DOI: 10.1051/jp2:1996206
J. Phys. II France 6 (1996) 697-711

Analysis of Relaxation Functions Characterized by a Broad Monomodal Relaxation Time Distribution

Taco Nicolai1, Jean Christophe Gimel1 and Robert Johnsen2

1  Laboratoire de Physico Chimie Macromoléculaire, Faculté des Sciences, Université du Maine, 72017 le Mans Cedex, France
2  Department of Physical Chemistry, University of Uppsala, 75121 Uppsala, Sweden

(Received 10 October 1995, received in final form 26 December 1995, accepted 2 February 1996)

We demonstrate the advantage of using the so-called generalized exponential (GEX) function for the analysis of relaxation functions characterized by a monomodal broad relaxation time distribution. We give a number of characteristics of this function and compare it to two functions that are currently widely for this type of analysis: the Kohlraush-Williams-Watt and the Havriliak-Negami functions. The main advantages of the GEX-function are that it can be used easily both in the time and the frequency domain, and that it has a relatively simple expression for the corresponding relaxation time distribution. Three important applications are discussed: the glass transition dynamics, and the relaxation of concentration fluctuations in dilute and concentrated solutions of broad distributions of selfsimilar particles. In the latter two cases the relation between the parameters of the GEX-function and the molecular characteristics of the solutions is made explicit.

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