ANALYSIS OF RELAXATION FUNCTIONS CHARACTERIZED BY A BROAD MONOMODAL RELAXATION-TIME DISTRIBUTION

We demonstrate the advantage of using the so-called generalized expone ntial (GEX) function for the analysis of relaxation functions characte rized by a monomodal broad relaxation time distribution. We give a num ber of characteristics of this function and compare it to two function s that are currently widely used for this type of analysis: the Kohlra ush-Williams-Watt and the Havriliak-Negami functions. The main advanta ges of the GEX-function are that it can be used easily both in the tim e and the frequency domain, and that it has a relatively simple expres sion for the corresponding relaxation time distribution. Three importa nt applications are discussed: the glass transition dynamics, and the relaxation of concentration fluctuations in dilute and concentrated so lutions 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.