Non-Fickian mass transport through polymers: A viscoelastic theory

Abstract
The non-Fickian mass transport behaviour observed in polymers is described based on a non linear viscoelastic constitutive equation for the diffusive flux, containing a single relaxation time. The resulting non linear hyperbolic mass transport problem is numerically solved and the influence of the diffusive Deborah number is analyzed. The proposed model has the ability to represent both Case I1 and anomalous diffusion, as well as the frequently observed overshoot and oscillations in the weight uptake around the final equilibrium value.