Rheological Properties of Three Solutions. Part II. Relaxation and Growth of Shear and Normal Stresses

Abstract

The same three solutions used in Part I were used to measure stress relaxation after the cessation of steady simple shear flow and stress growth after the onset of steady simple shear flow. Both shear and normal stress difference responses were measured. In addition, “interrupted flow,” a turret-shaped function for the velocity gradient, was studied. The data are used to evaluate the three rheological models considered in Part I. These models all make the same predictions for stress relaxation. They differ markedly in their predictions for stress growth; the OWFS model predicts no overshoot, the WJFLMB model predicts a single overshoot, and the Spriggs 4-constant model predicts oscillatory behavior. The models satisfactorily describe the stress relaxation data but fail to describe the stress growth data.