Spinning drop method

<p>The spinning drop method or rotating drop method is one of the methods used to measure <a href="/facts/Surface_tension/EuluYmSM">interfacial tension</a>. Measurements are carried out in a rotating horizontal tube which contains a dense fluid. A drop of a less dense liquid or a gas bubble is placed inside the fluid. Since the rotation of the horizontal tube creates a <a href="/facts/Centrifugal_force/CWgvMw6w">centrifugal force</a> towards the tube walls, the liquid drop will start to deform into an elongated shape; this elongation stops when the interfacial tension and centrifugal forces are balanced. The surface tension between the two liquids (for bubbles: between the fluid and the gas) can then be derived from the shape of the drop at this <a href="/facts/Equilibrium_point/DgbGMPkg">equilibrium point</a>. A device used for such measurements is called a “spinning drop tensiometer”.
</p><p>The spinning drop method is usually preferred for the accurate measurements of surface tensions below 10−2 mN/m. It refers to either using the fluids with low interfacial tension or working at very high angular velocities. This method is widely used in many different applications such as measuring the interfacial tension of polymer blends and copolymers.
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Spinning drop method open-in-new

Spinning drop method