Fickian and non-Fickian Diffusion in Solid Polymers

Fickian diffusion is presented for non swelling penetrants, where no relevant deformations and no stresses are involved, as well as for swelling penetrants where deformations and stresses are induced, considering also how to measure stress effects and how to calculate the stress field. Then Non-Fickian Transport is presented discussing a) the effects of swelling and of stresses, b) the structural changes and relaxation, c) the effects of temperature, activity difference, of pre-history and of the sample dimensions. Anomalous diffusion, two stage sorption, case II Transport and Super-Case II transport are discussed in detail