Dynamic contact angle Wilhelmy plate method

Dynamic contact angles are the angles which can be measured if the three-phase boundary (liquid/solid/vapor) is in actual motion. A Wilhelmy plate is used in dynamic contact angle measurements, and this method is also called the tensiometric contact angle method. It has been extensively applied to solid-liquid contact angle determinations in recent years. In practice, a solid substrate is cut as a thin rectangular plate, otherwise a solid material is... 

In the measurement of dynamic contact angles utilizing the Wilhelmy plate method with water as the probe liquid, the force on the film is given by the Wilhelmy equation ... 

Ram6, E. 1997. The interpretation of dynamic contact angles measured by the Wilhelmy plate method. Journal of Colloid and Interface Science 185 245-251. 

The method is based on Wilhelmy s plate technique for measuring dynamic contact angles. The technique involves the measurement of force as a plate is (automatically) immersed in and then emersed from a liquid at a constant rate. The forces (weight) can be plotted as a function of the immersion depth and, from this, contact angles calculated (Figures 1.26a and b). The Wilhemy s plate technique has been commercialized with computer automation and data-handling features, which has improved its utility considerably. 

Advancing contact angle were measured either by goniometry or Wilhelmy plate method. The former was carried out with an NRL A-100 Contact Angle Goniometer (commercially available through Rame-Hart, Inc). Sample films were prepared from 10 wt% solution in THF, cast into aluminum pans lined with Teflon, and dried in a hood for one week. The films were kept imder inverted beakers in the hood to reduce contact with contaminants. Only the surface formed at the air-solution interface was examined. The Wilhelmy plate method was performed with a Cahn dynamic contact angle analyzer (DCA 312). 

Provides measuring techniques of contact angle, surface tension, interfacial tension, and bubble pressure. Suitable methods for both static and dynamic inteifacial tension of liquids include du Nous ring, Wilhelmy plate, spinning drop, pendant drop, bubble pressure, and drop volume techniques. Methods for solids include sessile drop, dynamic Wilhelmy, single fiber, and powder contact angle techniques. 

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