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Polar and Dispersive Liquid Components

The process for measuring the polar and dispersive components of liquids is quite tedious, and there is relatively little published data. The measurement process is described in Robert Good's chapter in

Contact Angle, Wettability, and Adhesion, K. L. Mittal, VSP, ISBN 90-6764-157

This volume, edited by Kash Mittal, also has as good a list of liquid component valves as can be found anywhere.

Beyond the tedium of the measurement, the primary reason few liquids are reported is that only a few liquids are useful in contact angle measurements anyway. Generally speaking, these are the liquids listed in the FTA database distributed with the software. These few liquids satisfy the following criteria for usefulness in contact angle measurements:

  • High surface tension. Unless their surface tension is high, they will spread to low or zero contact angles on most solid surfaces. Once the liquid reaches a zero contact angle, no further information is available.

  • Not reactive with solid. The test liquid can not dissolve, or react with, or absorb into the solid.

  • Safe. The liquid must be relatively safe to use.

Note there is no use characterizing a low surface tension liquid that is going to have a zero, or essentially zero, angle on the surface. Such a liquid will create instabilities in the equations used to solve for a solid's components, such as the Owens-Wendt or Lewis acid/base equations.