Measurement of extensional viscosity by the stretching of viscoelastic liquid columns. Quarterly report, April--June, 1995

Recent work in the field of atomization has explored the breakup of viscoelastic liquids. Studies have observed that viscoelastic liquids are much more resistant to breakup in comparison with Newtonian liquids. This high resistance to breakup has been attributed to the high extensional viscosities that viscoelastic liquids possess. Although extensional viscosity has been identified as having a major influence on the mode of breakup, no studies have yet been successful in correlating spray quality with a parameter that is truly description of the extensional viscosity of viscoelastic liquids. In this study, a new method is used to determine the extensional viscosities of viscoelastic liquids by the stretching of liquid columns. This method is used to show quantitative variations in extensional viscosity as a function of polymer concentration in aqueous solutions of polyacrylamide e10. Results suggest that as polymer concentration is increased, the liquids exhibit extension thickening behavior