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A phenomenological model for solutions of polyelectrolytes accounting for electromechanical interactions is proposed within the framework of continuum thermodynamics. The modelling involves the conformation of macromolecules in the form of a tensorial "internal variable" and the electric polarization of the solution. The paper aims to demonstrate the possible competition between flow and electricity effects on rigorous phenomenological grounds. Three kinds of dissipative mechanisms are accounted for: viscosity of the solution, electric relaxation and the relaxation of the conformation of macromolecules. Anisotropic effects induced by the applied electric field and flow-induced polarization through changes in conformation are exhibited. These effects are small. By way of application, the problem of the orientation and conformation taken by macromolecules of polyelectrolytes under the combined influence of a simple shear flow and a longitudinal or orthogonal electric bias field is treated in detail and illustrated graphically. Some optical properties are mentioned.

The present study concerns the phenomenon of flow-induced polymer migration. It is shown that Tirrel!'s diffusion flux can be deduced from a macroscopic modelling which involves second-order gradients and a vectorial internal variable related to the microstructure. I n contrast to Tirrell's model, however, a migration may also occur across straight streamlines. The flow down an inclined plane is examined by way of example. The roles played by the microstructure and the second gradients, respectively, are thus exhibited.

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