A deformation model for Case II diffusion

Case II diffusion in glassy polymers is considered in terms of a deformation model. The process is controlled by the mechanical response of the glass just ahead of the sharp front to an osmostic swelling stress. The important factor governing the establishment of the sharp solvent front is taken to be the concentration dependence of the creep response time. These ideas are set in the context of existing models for diffusion in glassy polymers, and experimental evidence is presented to support the deformation mechanism.