A CRITICAL REVIEW: SURFACE AND INTERFACIAL TENSION MEASUREMENT BY THE DROP WEIGHT METHOD

Abstract

The drop weight method has been used as a standard method for surface and interfacial tension measurement. However, lack of appropriate guidelines in using this method has resulted in errors. The specific objective of this critical review is to present the experimental setup, the limitations on the correction factors, and the principle of the drop weight method. Mathematical models of correction factors were evaluated by using a proposed error analysis. The use of the proposed Lee-Chan-Pogaku model and HG-Equation 2 for correction factor determination is suggested. However, further investigations would be required to justify the validity of the correction factors at low r/V ^1/3 range and their use for viscous fluids. The physics of drop detachment is complicated; more investigations would be required to form a rigid theory of this method.

Keywords:

• Drop weight correction factors
• Drop weight method
• Error analysis
• Interfacial tension
• Mathematical model
• Surface tension

Acknowledgments

The authors would like to thank the Ministry of Higher Education, Malaysia (Fundamental Research Grant Scheme: FRG 0075-TK-1/2006), for providing the financial support for this study. The authors also wish to express their gratitude to the colleagues and collaborators who have contributed to the development of this study.

Notes

Bold number indicates the best model of the r/V ^1/3 range where the model was developed (refer to Table II).

^a Mean error (ME) =  where n = number of data, k = degree of freedom (Strenge, 1969).

^b Coefficient of cariation (CV) =  where  = average value of Y _Experiment (Wilkinson and Kidwell, 1971).

^c Average absolute deviation (AAD) = .

^d Maximum absolute deviation (MAD) = maximum value of the absolute deviation between experimental data and calculated data.