RHEOTENS MASTERCURVES AND ELONGATIONAL VISCOSITY OF POLYMER MELTS

In a Rheotens experiment, the tensile force needed for elongation of a n extruded filament is measured as a function of the draw ratio. For t hermo-rheologically simple polymer melts, the existence of Rheotens-ma stercurves was proved by Wagner, Schulze, and Gottfert (1995). Rheoten s-mastercurves are invariant with respect to changes in melt temperatu re and changes in the average molar mass. By use of purely viscous mod els, we convert Rheotens-mastercurves of a branched and a linear polye thylene melt to elongational viscosity as a function of strain rate. T he resulting elongational viscosity from constant force extension expe riments is found to be in general agreement with what is expected as s teady-state viscosity of polyethylene melts measured in either constan t strain-rate or constant stress mode.