Papers by Author: Katell Derrien

Abstract: Diffusion of fluids in polymers may lead to swelling, which induces stress-diffusion coupling. A simple coupling model is considered, where boundary conditions only are altered, and it leads to a sigmoidal water-uptake curve for a plate in water. Several other models are studied, which are able to induce similar sorption curves by using various boundary conditions, but comparisons between other predictions of the models reveal significant differences. Eventually, none of the models considered is able to reproduce all features of the coupling model.

Abstract: When moisture uptake in a polymer is associated with swelling, it induces stresses which interact with the entire diffusion process. This coupling is addressed in this paper, which extends immediately to the diffusion of other fluids, like solvents. First, the generalized chemical potential is used to analyze the effect of stresses on the moisture capacity of polymers, and a relation is derived as a function of material parameters. Then, the interactions between stress and diffusion before saturation is reached, are explored. Various effects are predicted on the classical sorption test, such as an evolution of the boundary condition with time, and a sorptiondesorption hysteresis.