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DY: Dynamik und Statistische Physik
DY 34: Poster
DY 34.78: Poster
Montag, 7. März 2005, 15:30–18:00, Poster TU D
The break up of capillary bridges of complex liquids — •Rainer Sattler — Universität des Saarlandes, Geb. 38, 3.OG, Pf. 151150, 66041 Saarbrücken
The break up of capillary bridges of complex liquids is investigated first on a falling droplet and second in a capillary break up extensional rheometer (CABER). The latter describes a set up where a small amount of liquid is placed between two plates that are torn apart rapidly. In between a capillary bridge is formed that breaks up after the formation of an elastic filament. Both methods allow a determination of the elongational viscosity. We present conditions for experimental parameters under which both experiments are equivalent or not. The elongational viscosity ηe can be defined similar to the shear viscosity ηs and is given for Newtonian liquids by the so called Trouton ratio ηe/ηs=3. For polymer solutions this factor can be higher by several orders of magnitude. But experimental data as well as theoretical understanding of the physical mechanisms of these phenomena are still very limited.