Concentration fluctuations and coupling to stress relaxation in viscoelastic binary solutions

Dynamics and coupling of concentration fluctuations to longitudinal stress relaxation in a viscoelastic binary polymer solution have been analyzed using nonequilibrium thermodynamics. The calculation supplements the result previously obtained by this author using the Bearman–Kirkwood hydrodynamic equation for a multicomponent system. We have shown that the dynamics of concentration fluctuations is affected by the stress modulus of the solution only when there is a difference in the specific volume between polymer and solvent components. The present work also extends Bearman–Kirkwood’s result by further relating the partial longitudinal stress modulus of the polymer to the total longitudinal stress modulus of the polymer solution.