Diffusion in Semi‐Crystalline Polymers and Polymer Networks

Abstract Diffusion in semi‐crystalline polymers and polymer networks often generates crystallization or dissolution processes or changes in the conformation of the network chains so that the diffusion mostly cannot be described by the Fickian law (“Non‐Fickian” diffusion). To discuss the local change of polymer conformation the flux of diffusion has to be transformed in the polymer‐fixed reference frame. Different constraints including diffusion induced anisotropic states and decoupled processes in this reference frame generate a steady state of the total flux of diffusion of solvent molecules even in infinite extended systems. This steady state diffusion is consistent with a two‐dimensional diffusion process in the polymer‐fixed reference frame.