Viscoelastic diffusion

A constitutive equation is proposed for the viscoelastic diffusion flux, and this equation is used to calculate sorption curves for differential step-change sorption experiments. The predictions of the theory are shown to be consistent with eight experimental observations that report a wide range of diffusional behaviors for polymer-solvent systems. (C) 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 1529-1547, 2001.