Measuring Surface Tension Using the Pendant Drop Method

Abstract

Measuring surface tension between fluids is of a great practical importance in the oil, food, chemical, cosmetic, etc. industries. Also, the measurement of the contact angle tl1at is formed between the fluid interface and a restricting wall are of prime importance in surface science. Instruments that employ the DuNouy ring and Wilhelmy plate methods are in common use at industry and research laboratories but they are very labor intensive. Th ere is a need for a rapid, easy and low cost technique with satisfactory accuracy and reproducibility. Reliable measurement of these parameters require significant computer programming and image analysis. The goal of the project has been the development of a computer program written in Matlab which use the pendant drop method to measure t he surface tension between two fluids. In addition, an experimental setup has been developed to test the accuracy of this method. In the framework of the soft matter, where tl1e surface tension of tl1e fluids plays a key role, the use of more complex and biological fluids make harder to find data a bout how interact these fluids. This is the reason that codes like these are inclispensable tools in these laboratories.