Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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Record number 491060
Title Stability Properties of Surfactant-Free Thin Films at Different Ionic Strengths: Measurements and Modeling
Author(s) Lech, F.J.; Wierenga, P.A.; Gruppen, H.; Meinders, M.B.J.
Source Langmuir 31 (2015)9. - ISSN 0743-7463 - p. 2777 - 2782.
DOI https://doi.org/10.1021/la504933e
Department(s) Food Chemistry
Food Technology
VLAG
Publication type Refereed Article in a scientific journal
Publication year 2015
Keyword(s) sodium dodecyl-sulfate - subsequent criticism - hydrophobic forces - standing foams - liquid-films - interface - electrolyte - coalescence - proteins - drainage
Abstract Foam lamellae are the smallest structural elements in foam. Such lamellae can experimentally be studied by analysis of thin liquid films in glass cells. These thin liquid films usually have to be stabilized against rupture by surface active substances, such as proteins or low molecular weight surfactants. However, horizontal thin liquid films of pure water with a radius of 100 µm also show remarkable stability when created in closed Sheludko cells. To understand thin film stability of surfactant-free films, the drainage behavior and rupture times of films of water and NaCl solutions were determined. The drainage was modeled with an extended Derjaguin–Landau–Verwey–Overbeek (DLVO) model, which combines DLVO and hydrophobic contributions. Good correspondence between experiment and theory is observed, when hydrophobic interactions are included, with fitted values for surface potential (¿0,water) of -60 ± 5 mV, hydrophobic strength (Bhb,water) of 0.22 ± 0.02 mJ/m2, and a range of the hydrophobic interaction (¿hb, water) of 15 ± 1 nm in thin liquid films. In addition, Vrij’s rupture criterion was successfully applied to model the stability regions and rupture times of the films. The films of pure water are stable over long time scales (hours) and drain to a final thickness >40 nm if the concentration of electrolytes is low (resistivity 18.2 MQ). With increasing amounts of ions (NaCl) the thin films drain to
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