Swelling in the mechanically loaded polymer networks

Abstract

Swelling of crosslinked polymers is treated as a set of correlated processes of diffusion of a solvent and deformation of a polymer matrix. A polymer and a solvent are assumed to be incompressible media. In this case, the chemical-potential gradient of a solvent, which is the driving force for diffusion, can be presented as divergence of the symmetric second-rank tensor or osmotic stress tensor. In contrast to the chemical potential, this tensor is a well-defined thermodynamic function of the state of the polymer-solvent system. Equations and boundary conditions for the description of swelling of polymer networks under different modes of mechanical loading are formulated in terms of the osmotic stress tensor. A general theory is illustrated for the description of the kinetics of swelling of a flat sample under the conditions of fixed uniaxial tensile drawing.