DIELECTRIC-RELAXATION AND DISTRIBUTION FUNCTION OF RELAXATION-TIMES IN DILUTE COLLOIDAL SUSPENSIONS

This paper describes an empirical approach to the theoretical distribution function of relaxation times (DFRT) that best characterizes the dielectric behaviour of colloidal suspensions, according to the model proposed by DeLacey and White (E.H.B. DeLacey and L.R. White, J. Chem. Soc., Faraday Trans. 2, 77 (1981) 2007; DW hereafter). It is well known that this model predicts a dielectric response that cannot be given in terms of a single relaxation time for the system, even if the colloidal particles are homogeneous spheres. Hence, the suspension must be characterized by a distribution of relaxation times; the dielectric response of a dilute colloidal suspension is described in this work using a reasonable DFRT, and the results are compared to the predictions of the DW model. It is demonstrated that such a DFRT is also a suitable approximation to the results obtained using more recent theories, incorporating into the explanation of the dielectric properties of the suspension the possibility of surface conductivity in the inner part of the double layer.