A Tensiometer because it is applicable to physics is the instrument used to measure the surface tension ( ) from liquids or surfaces. Tensiometers are used in laboratory research and development to determine liquid surface tension such as coatings, lacquer or adhesive. Further application of tensiometers is the monitoring of industrial production processes such as cleaning of components or electroplating.
Video Tensiometer (surface tension)
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Goniometer/Tensiometer
Surface scientists generally use an optical Goniometer/Tensiometer to measure surface tension and liquid surface tension using a pendant or sessile drop method. A drop is produced and captured using a CCD camera. The drop profile is then extracted, and the advanced software routine then matches the theoretical Young-Laplace equation to the experimental degradation profile. Surface tension can then be calculated from the fitting parameter. Unlike other methods, this technique requires only a small amount of fluid making it suitable for measuring expensive liquid interface tensions.
Du NoÃÆ'¼y Ring Tensiometer
This type of tensiometer uses a platinum ring that is immersed in a liquid. When the ring is pulled out of the liquid, the force required is accurately measured to determine the surface tension of the liquid. This method is well established as indicated by a number of international standards on it such as ASTM D971. This method is widely used for measuring interfacial stresses between two liquids but must be taken into account to ensure that the platinum rings are not formatted.
Wilhelmy Plate Tensiometer
The Wilhelmy Plat tensiometer requires plates to make contact with liquid surfaces. It is widely regarded as the simplest and most accurate method for measuring surface tension. Due to the wetted platinum plate length, surface tension readings are usually very stable compared to alternative methods. As an added benefit, Wilhelmy's plate can be made from also from paper for disposable use. For the measurement of the interface voltage, the buoyancy of the probe needs to be taken into account which complicates the measurement.
Du NoÃÆ'¼y-Padday Method
This method uses a rod that is lowered to a test liquid. The rod is then pulled out of the liquid and the force required to pull the rod is measured appropriately. This method is not standard but is sometimes used. The Du NoÃÆ'¼y-Padday Rod Drag Tensiometer will take measurements quickly and will work with liquids with various viscosities. Interfacial tension can not be measured.
Tensiometer bubble pressure
Due to the internal fluid draw strength, the air bubbles in the liquid are compressed. The resulting pressure (bubble pressure) rises on a decreasing bubble radius. The bubble pressure method uses this bubble pressure higher than in the surrounding environment (water). The gas stream is pumped into capillaries that are immersed in a liquid. The bubbles generated at the end of the capillary tip continue to become larger on the surface; thus, the bubble radius decreases.
Pressure rises to the maximum level. At this point the bubble has reached the smallest radius (capillaryradius) and begins to form the hemisphere. Beyond this point the bubble rapidly increases in size and immediately bursts, tearing off the capillaries, thus allowing new bubbles to develop at the end of the capillary. During this process the pattern of characteristic pressure develops (see figure), which is evaluated to determine the surface tension.
Due to its easy handling and low cleaning efforts of pressure-bubble tensiometers, it is a common alternative to monitor the concentration of detergents in the cleaning or electroplating process.
Maps Tensiometer (surface tension)
See also
- Surface tension
- Young-Laplace's Equation
- Capillary action
- Piezometer
- Pierre Lecomte du Nouy
References
External links
Media related to Tensiometer (surface tension) in Wikimedia Commons
- Surface tension and how to measure it
- Surface tension of process parameters
- Wilhelmy basic method
Source of the article : Wikipedia
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