Extensional Rheometry via Flow through an Abrupt Contraction: a Short Review
Christopher W. Macosko ^{1, a)
1)} Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Ave. Minneapolis, MN 55455 USA.

^a) Corresponding author: macosko@umn.edu

Abstract. This review assesses the advantages and limitations of extensional rheometry using flow through an abrupt contraction. Analyses used to estimate extensional viscosity from entrance pressure drop and flow rate measurements are reviewed. These are compared with each other and to results from other extensional rheometers. A great advantage of entrance flow extensional rheometry is that it is perhaps the easiest method to obtain extensional data, especially with complex and industrial fluids such as hot melt adhesives, dough, emulsions and polymer melts, since it is readily adapted to standard capillary rheometers. Disadvantages are that the flow is not homogeneous and shear is always present. Nonetheless, pressure drop through an abrupt contraction can be especially useful in quickly ranking extensional effects between different material formulations.