Capillary breakup rheometry

Capillary breakup rheometry is an experimental technique used to assess the extensional rheological response of low viscous fluids. Unlike most shear and extensional <a href="/facts/Rheometer/tn2DmtEo">rheometers</a>, this technique does not involve active stretch or measurement of stress or strain but exploits only surface tension to create a uniaxial extensional flow. Hence, although it is common practice to use the name rheometer, capillary breakup techniques should be better addressed to as indexers.
Capillary breakup rheometry is based on the observation of breakup dynamics of a thin <a href="/facts/Fluid_thread_breakup/rQ6YU0yB">fluid thread</a>, governed by the interplay of capillary, viscous, inertial and elastic forces. Since no external forcing is exerted in these experiments, the fluid thread can spatially rearrange and select its own time scales. Quantitative observations about strain rate, along with an apparent <a href="/facts/Extensional_viscosity/qaJRumsk">extensional viscosity</a> and the breakup time of the fluid, can be estimated from the evolution of the minimal diameter of the filament. Moreover, theoretical considerations based on the balance of the forces acting in the liquid filament, allow to derive information such as the extent of <a href="/facts/Non-Newtonian/jX8ldWJa">non-Newtonian</a> behaviour and the relaxation time.
The information obtained in capillary breakup experiments are a very effective tool in order to quantify heuristic concepts such as "stringiness" or "tackiness", which are commonly used as performance indices in several industrial operations.
At present, the unique commercially available device based on capillary breakup technique is the CaBER.

Capillary breakup rheometry open-in-new

Capillary breakup rheometry