SELF-DIFFUSION OF WATER IN GELATIN GELS .1. MACROSCOPIC MEASUREMENTS BY TRACER TECHNIQUE

The one-dimensional diffusion of water from a reservoir into gelatin gels of different concentrations phi was investigated. In full agreement with calculations based on the concept of an effective medium, it is shown that the self-diffusion coefficient D of water in the asymptotic region, kR < 1 (k = screening constant, R = radius of diffusible particles), varies as D/D0 (phi = 0) = 1 - 1.87 square-root phi, if D (phi = 0) = 1.35 x 10(-5) cm2 s-1. The function D (T) is of the Arrhenius type, with the value of the activation energy, E(A) = 4.1 kcal mol-1, close to that of bulk water.