Shear Rate Dependence of the Association of High Molecular Weight Macromolecules in Dilute Solution

Abstract

Dilute solutions of flexible, high molecular weight macromolecules in nearly θ solvents have been demonstrated to have an increase of their relative viscosity above a critical shear rate, depending on the concentration^1,2. In the same time, a non linear dependence of the reduced viscosity ⁿsp/^c is observed. Such a variation may be explained by an association process^3,4,5,6. In this paper, we intend to apply the procedure described in our recent work⁵, at different shear rates to the following materials which have shown shear thickening²: Polystyrenes in decalin and polyethyleneoxide WSR301 in water. Calculations have been carried out in dimerization and multimerization cases. But only the dimerization appears to be compatible with the experimental results. The molecular weights of the polystyrene samples are listed in table II. We have made the assumption that the Huggins constant k_H is nearly independent on the degree of association.