SPHERE TENSIOMETRY - A NEW APPROACH TO SIMULTANEOUS AND INDEPENDENT DETERMINATION OF SURFACE-TENSION AND CONTACT-ANGLE

A method for determination of the surface tension and contact angle, based on the measurement of the maximum and minimum forces acting on a sphere in contact with a liquid, is presented. The method is based on the application of the unified tables, developed by model calculations for the force acting on the sphere with preselected values for the contact angle and the dimensionless sphere radius. A computer-controlled measuring system allowing different types of measurements of the force-sphere position curve is described. The experimental results for the surface tension and contact angle on a Herasil I quartz sphere for ethanol, bidistilled water, toluene, and n-hexane are presented. Surface tension values are compared with the values obtained independently using the cylinder tensiometry and drop volume methods. The results obtained for contact angles are compared with values resulting from the application of the method developed by Fieber and Sonntag. (C) 1995 Academic Press, Inc.