Rheological Applications of a Drop Elongation Experiment

A new method for determining the extensional flow properties of polymer solutions and melts is proposed and analyzed. The physical principle behind the method is that when a fluid drop is placed in a rotating field of a higher density fluid it will experience axisymmetrical extension or contraction when the rotational speed is varied with time. Under rather general conditions, an analysis is possible of the dynamic response of the drop in terms of measurable and controllable variables. This gives rise to a number of different steady and transient extensional flow experiments. Such experiments are described, and a specific unsteady experiment is used to verify the assumptions of the analysis and to indicate the quantitative accuracy of the method.