Wilhemy plate method

Interaface by the Wilhemy Plate Method Alternate Protocol 2 Static Interfacial Tension Determination at a Liquid/Gas D3.6.4... 

STATIC INTERFACIAL TENSION DETERMINATION AT A LIQUID/GAS INTERFACE BY THE WILHEMY PLATE METHOD... 

Methods. All experiments were performed at 25°C. Critical micelle concentrations were determined using the maximum bubble pressure method on a SensaDyne 6000 surface tensiometer. Dry nitrogen was used as the gas source for the process and was bubbled through the solution at a rate of 1 bubble/sec. Cmc s measured using the Wilhemy plate method were in agreement with those obtained from the bubble tensiometer however, the bubble pressure method was used since it is less susceptible to error due to impurities and the nitrogen environment makes pH control easier. 

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. 

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