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In surface science, a tensiometer is a measuring instrument used to measure the surface tension (γ) of liquids or surfaces.Tensiometers are used in research and development laboratories to determine the surface tension of liquids like coatings, lacquers or adhesives.
Surface tension is the tendency of liquid surfaces at rest to shrink into the minimum surface area possible. Surface tension is what allows objects with a higher density than water such as razor blades and insects (e.g. water striders) to float on a water surface without becoming even partly submerged.
'drop') is one of the most common methods for measuring surface tension. The principle is to measure the weight of drops of a fluid of interest falling from a capillary glass tube, and thereby calculate the surface tension of the fluid. We can determine the weight of the falling drops by counting them. From it we can determine the surface tension.
The measurement is performed with a force tensiometer, which typically uses an electrobalance to measure the excess force caused by the liquid being pulled up and automatically calculates and displays the surface tension corresponding to the force. Earlier, torsion wire balances were commonly used.
One of the useful methods to determine the dynamic surface tension is measuring the "maximum bubble pressure method" or, simply, bubble pressure method. [ 1 ] [ 2 ] Bubble pressure tensiometer produces gas bubbles (ex. air) at constant rate and blows them through a capillary which is submerged in the sample liquid and its radius is already known.
An approximate theory was developed by Bernard Vonnegut [3] in 1942 to measure the surface tension of the fluids, which is based on the principle that the interfacial tension and centrifugal forces are balanced at mechanical equilibrium. This theory assumes that the droplet's length L is much greater than its radius R, so that it may be ...
The formation of menisci is commonly used in surface science to measure contact angles and surface tension. In a contact angle measurement, the shape of the menisci is measured with a balance or optically with a digital camera. In a surface tension measurement, the measurement probe has a contact angle of zero and the surface tension can be ...
The magnitude of the capillary force on the plate is proportional to the wetted perimeter, = +, and to the surface tension of the liquid-air interface. A Wilhelmy plate is a thin plate that is used to measure equilibrium surface or interfacial tension at an air–liquid or liquid–liquid interface.
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