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Coalescence of contaminated water drops at an oil/water interface: Influence of micro-particles

Malmazet, Erik de and Risso, Frédéric and Masbernat, Olivier and Pauchard, Vincent Coalescence of contaminated water drops at an oil/water interface: Influence of micro-particles. (2015) Colloids and Surfaces A: Physicochemical and Engineering Aspects, 482. 514-528. ISSN 0927-7757

(Document in English)

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Official URL: http://dx.doi.org/10.1016/j.colsurfa.2015.06.044


The effect of micro-particles and interface aging on coalescence of millimetre-sized water drops with an oil/water interface is studied over long times. The system is not pure and interface contamination grows with time, resulting in a slow but continuous decrease of interfacial tension over time (from 35 to 10 mN/m), which is measured in situ using an original technique. Without added micro-particles, coalescence times are randomly distributed and uncorrelated to drop diameter or interfacial tension. In presence of 10 !m size hollow glass particles at the oil/water interface, coalescence times become more reproducible and show a clear dependence upon drop diameter and interface aging. Results are consistent with a classical drainage model assuming that the critical thickness at which interstitial film ruptures scales as the micro-particle diameter, a result that tends to validate the bridging scenario. Interestingly, the film retraction speed during the coalescence process does not follow theoretical predictions in a planar geometry. High-speed imaging of the retracting film reveals that the hole rim is bending upward while retracting, resulting in a strong slowdown of retraction speed. This is caused by the difference of interfacial tension between oil/drop freshly formed interfaces and the aged oil/water interface.

Item Type:Article
Additional Information:Thanks to Elsevier editor. The definitive version is available at http://www.sciencedirect.com The original PDF of the article can be found at : http://www.sciencedirect.com/science/article/pii/S0927775715300637
HAL Id:hal-01332242
Audience (journal):International peer-reviewed journal
Uncontrolled Keywords:
Institution:French research institutions > Centre National de la Recherche Scientifique - CNRS (FRANCE)
Université de Toulouse > Institut National Polytechnique de Toulouse - Toulouse INP (FRANCE)
Other partners > SINTEF (NORWAY)
Université de Toulouse > Université Toulouse III - Paul Sabatier - UT3 (FRANCE)
Laboratory name:
Deposited On:15 Jun 2016 12:38

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