Capillary meniscus dynamometry - Method for determining the surface tension of drops and bubbles with isotropic and anisotropic surface stress distributions
| Autor: | Eddie G. Pelan, Nikola Alexandrov, Theodorus Berend Jan Blijdenstein, Krassimir D. Danov, Krastanka G. Marinova, Simeon D. Stoyanov, Peter A. Kralchevsky, Rumyana D. Stanimirova |
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| Jazyk: | angličtina |
| Rok vydání: | 2015 |
| Předmět: |
Capillary pressure
Capillary action Bubble 02 engineering and technology 010402 general chemistry 01 natural sciences Protein adsorption layers Biomaterials Surface tension Colloid and Surface Chemistry Optics Materials Testing Surface Tension VLAG Non-uniform surface tension business.industry Chemistry Drop (liquid) Surface stress Isotropy Mechanics 021001 nanoscience & nanotechnology Drop shape analysis 0104 chemical sciences Surfaces Coatings and Films Electronic Optical and Magnetic Materials Surface stress balances Pendant drops and buoyant bubbles Anisotropic interfacial layers Normal surface 0210 nano-technology business Physical Chemistry and Soft Matter |
| Zdroj: | Journal of Colloid and Interface Science 440 (2015) Journal of Colloid and Interface Science, 440, 168-178 Journal of Colloid and Interface Science |
| ISSN: | 0021-9797 |
| Popis: | The stresses acting in interfacial adsorption layers with surface shear elasticity are, in general, anisotropic and non-uniform. If a pendant drop or buoyant bubble is covered with such elastic layer, the components of surface tension acting along the "meridians" and "parallels", σ(s) and σ(φ), can be different and, then, the conventional drop shape analysis (DSA) is inapplicable. Here, a method for determining σ(s) and σ(φ) is developed for axisymmetric menisci. This method, called 'capillary meniscus dynamometry' (CMD), is based on processing data for the digitized drop/bubble profile and capillary pressure. The principle of the CMD procedure for data processing is essentially different from that of DSA. Applying the tangential and normal surface stress balance equations, σ(s) and σ(φ) are determined in each interfacial point without using any rheological model. The computational procedure is fast and could be used in real time, during a given process. The method is applied to determine σ(s) and σ(φ) for bubbles and drops formed on the tip of a capillary immersed in solutions of the protein HFBII hydrophobin. Upon a surface compression, meridional wrinkles appear on the bubble surface below the bubble "equator", where the azimuthal tension σ(φ) takes negative values. The CMD method allows one to determine the local tensions acting in anisotropic interfacial layers (films, membranes), like those formed from proteins, polymers, asphaltenes and phospholipids. The CMD is applicable also to fluid interfaces (e.g. surfactant solutions), for which it gives the same surface tension as the conventional methods. |
| Databáze: | OpenAIRE |
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