Evaluation of Apparent Elongational Viscosity of Dilute Polymer Solution Measured with a Spinline Rheometer

The relationship between apparent elongational viscosity obtained by using a spinline rheometer and a variety of flow conditions in its measurement is investigated for a dilute polymer solution. The numerical calculations are carried out for a FENE-P dumbbell model and the experiments are performed for a 100 ppm aqueous solution of polyacrylamide.Elongational rates and elongational stress are significantly changed along the spinline. The apparent elongational viscosity depends on the flow rate and the spinline length. It is found that this dependence of the apparent elongational viscosity is due to the effect of inertia. Finally, a comparison is made between the apparent elongational viscosity and the steady elongational viscosity.