We analyze different flow regimes of a filament formed by extrusion of a material through a cylindrical die. We deduce that the elongational yield stress of a simple yield stress fluid (i.e., with negligible thixotropy effects) can be determined from the mass of the droplet after filament breakage and an estimation of the critical radius at pinch-off at the solid-liquid regime transition. We demonstrate that such a simple characterization is relevant in a relatively wide range of extrusion velocities, i.e., this velocity slightly affects the drop mass in this range. For the simple yield stress fluids used, Carbopol gel, clay-water paste at different concentrations, and emulsion, covering a large range of yield stress values (50–1000 Pa), the elongational yield stress appears to be equal to the simple shear yield stress times a factor equal to about . As a consequence, this simple test may be used to obtain, almost instantaneously and without sophisticated apparatus (a syringe and a balance are sufficient), a good estimate of the shear yield stress of simple yield stress fluids. In that case, the main source of uncertainty (up to about 20%) is the value of the critical radius at the solid-liquid transition. Finally, we review the operating conditions (material properties and extrusion characteristics) for which we can expect this approach to be valid.
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Instant yield stress measurement from falling drop size: The “syringe test”
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March 2023
Research Article|
March 01 2023
Instant yield stress measurement from falling drop size: The “syringe test”
A. Geffrault;
A. Geffrault
1
Lab. Navier, Ecole des Ponts, Univ Gustave Eiffel, CNRS
, 77420 Marne la Vallée, France
2
MAST-CPDM, Univ Gustave Eiffel
, 77420 Marne la Vallée, France
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H. Bessaies-Bey;
H. Bessaies-Bey
2
MAST-CPDM, Univ Gustave Eiffel
, 77420 Marne la Vallée, France
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N. Roussel;
N. Roussel
1
Lab. Navier, Ecole des Ponts, Univ Gustave Eiffel, CNRS
, 77420 Marne la Vallée, France
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P. Coussot
P. Coussot
a)
1
Lab. Navier, Ecole des Ponts, Univ Gustave Eiffel, CNRS
, 77420 Marne la Vallée, France
a)Author to whom correspondence should be addressed; electronic mail: philippe.coussot@univ-eiffel.fr
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a)Author to whom correspondence should be addressed; electronic mail: philippe.coussot@univ-eiffel.fr
J. Rheol. 67, 305–314 (2023)
Article history
Received:
August 30 2022
Accepted:
November 05 2022
Citation
A. Geffrault, H. Bessaies-Bey, N. Roussel, P. Coussot; Instant yield stress measurement from falling drop size: The “syringe test”. J. Rheol. 1 March 2023; 67 (2): 305–314. https://doi.org/10.1122/8.0000557
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