Determination of Interfacial Tension from the Profile of a Pendant Drop Using Computer-Aided Image Processing

The reliability of the method described in the preceding paper (B. Song and J. Springer, J. Colloid Interface Sci. 183, in press, 1996) for the determination of surface and interfacial tension (IFT) of liquid-fluid systems from the profile of a pendant drop has been studied experimentally. Influences on the resultant IFT values from factors such as the location of the drop profile and illumination conditions are considered. The reproducibility and accuracy of the measurement method were examined by measuring the time dependence of polyethylene glycol (PEG600)/air and water/air systems and by determining the temperature dependence of the polyethylene glycol (PEG6000)/N2 and LD (low-density) polyethylene/N2 systems. The effect of drop vibrations on the accuracy of the method is discussed.