DIFFUSION OF MACROMOLECULES: A CONSTITUTIVE THEORY

A constitutive diffusion theory for polymer solutions is proposed based on a thermomechanical mixture theory. A general expression for the diffusion flux in a binary polymer-solvent system is presented. It is shown that the current approach is capable of sorting out various complex diffusion phenomena. In particular, the dependence of the diffusion flux on a gradient of a generalized chemical potential emerges naturally by considering the limit of “weak equilibrium”.