RHEOLOGICAL BEHAVIOR FOR LARGE AMPLITUDE OSCILLATORY MOTION

The dependence of the complex viscosity of four viscoelastic fluids (three polymer solutions and one polymer melt) on strain amplitude has been studied for large amplitude oscillatory motion using a Weissenberg Rheogoniometer. In addition, criteria for a linear velocity profile have been derived and two viscoelastic models have been tested. Both the dynamic viscosity and the dynamic storage modulus decrease with increasing strain amplitude, with the latter showing a much larger decrease. The relative decrease in both functions was found to be only slightly dependent on the fluid and on the frequency of oscillation. Both models (the Bird-Carreau model and the modified OWFS model) were unable to predict the data adequately. © 1969.