Surface scientists commonly use an optical goniometer/tensiometer to measure the surface tension and interfacial tension of a liquid using the pendant or sessile drop methods. A drop is produced and captured using a CCD camera. The drop profile is subsequently extracted, and sophisticated software routines then fit the theoretical Young-Laplace equation to the experimental drop profile. The surface tension can then be calculated from the fitted parameters. Unlike other methods, this technique requires only a small amount of liquid making it suitable for measuring interfacial tensions of expensive liquids.[1]
A du Noüy tensiometerDu Noüy tensiometer in liquid.
This type of tensiometer uses a platinum ring which is submersed in a liquid. As the ring is pulled out of the liquid, the force required is precisely measured in order to determine the surface tension of the liquid.
The method is well-established as shown by a number of international standards on it such as ASTM D971. This method is widely used for interfacial tension measurement between two liquids but care should be taken to make sure to keep the platinum ring undeformed.
The Wilhelmy plate tensiometer requires a plate to make contact with the liquid surface. It is widely considered the simplest and most accurate method for surface tension measurement. Due to a large wetted length of the platinum plate, the surface tension reading is typically very stable compared to alternative methods. As an additional benefit, the Wilhelmy plate can also be made from paper for disposable use. For interfacial tension measurements, buoyancy of the probe needs to be taken into account which complicates the measurement.
This method uses a rod which is lowered into a test liquid. The rod is then pulled out of the liquid and the force required to pull the rod is precisely measured. The method isn't standardized but is sometimes used. The Du Noüy-Padday rod pull tensiometer will take measurements quickly and will work with liquids with a wide range of viscosities. Interfacial tensions cannot be measured.
Bubble pressure tensiometeredit
Bubble pressure method to measure the dynamic surface tension of liquids
Due to internal attractive forces of a liquid, air bubbles within the liquids are compressed. The resulting pressure (bubble pressure) rises at a decreasing bubble radius. The bubble pressure method makes use of this bubble pressure which is higher than in the surrounding environment (water). A gas stream is pumped into a capillary that is immersed in a fluid. The resulting bubble at the end of the capillary tip continually becomes bigger in surface; thereby, the bubble radius is decreasing.
The pressure rises to a maximum level. At this point the bubble has achieved its smallest radius (the capillary radius) and begins to form a hemisphere. Beyond this point the bubble quickly increases in size and soon bursts, tearing away from the capillary, thereby allowing a new bubble to develop at the capillary tip. It is during this process that a characteristic pressure pattern develops (see picture), which is evaluated for determining the surface tension.
Because of the easy handling and the low cleaning effort of the capillary, bubble pressure tensiometers are a common alternative for monitoring the detergent concentration in cleaning or electroplating processes.
^de Gennes, PG, Brochard-Wyart, F and Quere D, "Capillarity and Wetting Phenomena: Drops, Bubbles, Pearls, Waves", 2004, p58
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May 04, 2024
tensiometer, surface, tension, confused, with, goniometer, extensometer, tension, meter, tensometer, article, with, regards, soil, science, tensiometer, soil, science, surface, science, tensiometer, measuring, instrument, used, measure, surface, tension, liqui. Not to be confused with Goniometer Extensometer Tension meter or Tensometer For the article with regards to soil science see Tensiometer soil science In surface science a tensiometer is a measuring instrument used to measure the surface tension g of liquids or surfaces Tensiometers are used in research and development laboratories to determine the surface tension of liquids like coatings lacquers or adhesives A further application field of tensiometers is the monitoring of industrial production processes like parts cleaning or electroplating Contents 1 Types 1 1 Goniometer Tensiometer 1 2 Du Nouy ring tensiometer 1 3 Wilhelmy plate tensiometer 1 4 Du Nouy Padday method 1 5 Bubble pressure tensiometer 2 See also 3 References 4 External linksTypes editGoniometer Tensiometer edit Surface scientists commonly use an optical goniometer tensiometer to measure the surface tension and interfacial tension of a liquid using the pendant or sessile drop methods A drop is produced and captured using a CCD camera The drop profile is subsequently extracted and sophisticated software routines then fit the theoretical Young Laplace equation to the experimental drop profile The surface tension can then be calculated from the fitted parameters Unlike other methods this technique requires only a small amount of liquid making it suitable for measuring interfacial tensions of expensive liquids 1 Du Nouy ring tensiometer edit Main article Du Nouy ring method nbsp A du Nouy tensiometer nbsp Du Nouy tensiometer in liquid This type of tensiometer uses a platinum ring which is submersed in a liquid As the ring is pulled out of the liquid the force required is precisely measured in order to determine the surface tension of the liquid The method is well established as shown by a number of international standards on it such as ASTM D971 This method is widely used for interfacial tension measurement between two liquids but care should be taken to make sure to keep the platinum ring undeformed Wilhelmy plate tensiometer edit Main article Wilhelmy plate The Wilhelmy plate tensiometer requires a plate to make contact with the liquid surface It is widely considered the simplest and most accurate method for surface tension measurement Due to a large wetted length of the platinum plate the surface tension reading is typically very stable compared to alternative methods As an additional benefit the Wilhelmy plate can also be made from paper for disposable use For interfacial tension measurements buoyancy of the probe needs to be taken into account which complicates the measurement Du Nouy Padday method edit Main article Du Nouy Padday method This method uses a rod which is lowered into a test liquid The rod is then pulled out of the liquid and the force required to pull the rod is precisely measured The method isn t standardized but is sometimes used The Du Nouy Padday rod pull tensiometer will take measurements quickly and will work with liquids with a wide range of viscosities Interfacial tensions cannot be measured Bubble pressure tensiometer edit nbsp Bubble pressure method to measure the dynamic surface tension of liquids Due to internal attractive forces of a liquid air bubbles within the liquids are compressed The resulting pressure bubble pressure rises at a decreasing bubble radius The bubble pressure method makes use of this bubble pressure which is higher than in the surrounding environment water A gas stream is pumped into a capillary that is immersed in a fluid The resulting bubble at the end of the capillary tip continually becomes bigger in surface thereby the bubble radius is decreasing The pressure rises to a maximum level At this point the bubble has achieved its smallest radius the capillary radius and begins to form a hemisphere Beyond this point the bubble quickly increases in size and soon bursts tearing away from the capillary thereby allowing a new bubble to develop at the capillary tip It is during this process that a characteristic pressure pattern develops see picture which is evaluated for determining the surface tension Because of the easy handling and the low cleaning effort of the capillary bubble pressure tensiometers are a common alternative for monitoring the detergent concentration in cleaning or electroplating processes See also editStalagmometric method Surface tension Young Laplace equation Capillary action Piezometer Pierre Lecomte du Nouy Interfacial rheologyReferences edit de Gennes PG Brochard Wyart F and Quere D Capillarity and Wetting Phenomena Drops Bubbles Pearls Waves 2004 p58External links edit nbsp Media related to Tensiometer surface tension at Wikimedia Commons Retrieved from https en wikipedia org w index php title Tensiometer surface tension amp oldid 1145833851, wikipedia, wiki, book, books, library,
