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, b ased 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 co ntact angle and the dimensionless sphere radius. A computer-controlled measuring system allowing different types of measurements of the forc e-sphere position curve is described. The experimental results for the surface tension and contact angle on a Herasil I quartz sphere for et hanol, bidistilled water, toluene, and n-hexane are presented. Surface tension values are compared with the values obtained independently us ing the cylinder tensiometry and drop volume methods. The results obta ined for contact angles are compared with values resulting from the ap plication of the method developed by Fieber and Sonntag. (C) 1995 Acad emic Press, Inc.