Incorporation of hydrodynamic interaction forces to molecular statistical theory of temporary polymer networks in solution

Abstract

Molecular statistical theory of temporary polymer networks is an integrated approach to describe the rheological behavior of such networks based on information at a molecular level. Predictions of the theory regarding the dependence of viscometric functions on shear rate in stationary shear flow are at satisfactory accord with measurements. However, due to the exceeding complexity of the descriptive equations, their formulation and assessment has been performed so far only for cases where hydrodynamic interaction is negligible. In the present work, this effect is included in the model equations through the Oseen tensor. Incorporating the hydrodynamic interaction for the case of simple shear flow of two different polystyrene solutions, leads to theoretical results that agree a little better with experimental values, in terms of viscometric functions. Moreover, a non-zero negative value of the second normal-stress difference is predicted. For the case of elongation flow of the same polystyrene solutions there are no experimental results to compare with, so the appraisal of the theory was based solely on the reasonable dependence of the computed elongation viscosity on elongation rate.