Measurement of surface and interfacial tension using pendant drop tensiometry

Joseph David Berry, Michael J Neeson, Raymond Riley Dagastine, Derek Y C Chan, Richard Francis Tabor

Research output: Contribution to journalArticleResearchpeer-review

307 Citations (Scopus)

Abstract

Pendant drop tensiometry offers a simple and elegant solution to determining surface and interfacial tension - a central parameter in many colloidal systems including emulsions, foams and wetting phenomena. The technique involves the acquisition of a silhouette of an axisymmetric fluid droplet, and iterative fitting of the Young-Laplace equation that balances gravitational deformation of the drop with the restorative interfacial tension. Since the advent of high-quality digital cameras and desktop computers, this process has been automated with high speed and precision. However, despite its beguiling simplicity, there are complications and limitations that accompany pendant drop tensiometry connected with both Bond number (the balance between interfacial tension and gravitational forces) and drop volume. Here, we discuss the process involved with going from a captured experimental image to a fitted interfacial tension value, highlighting pertinent features and limitations along the way. We introduce a new parameter, the Worthington number, Wo, to characterise the measurement precision. A fully functional, open-source acquisition and fitting software is provided to enable the reader to test and develop the technique further.
Original languageEnglish
Pages (from-to)226-237
Number of pages12
JournalJournal of Colloid and Interface Science
Volume454
DOIs
Publication statusPublished - 2015

Keywords

  • Pendant drop
  • Drop shape analysis
  • Tensiometry
  • Surface tension
  • Interfacial tension
  • Bond number

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