Do you want to publish a course? Click here

Effect of the adsorption component of the disjoining pressure on foam film drainage

111   0   0.0 ( 0 )
 Added by Roumen Tsekov
 Publication date 2012
  fields Physics
and research's language is English




Ask ChatGPT about the research

The present work is trying to explain a discrepancy between experimental observations of the drainage of foam films from aqueous solutions of sodium dodecyl sulfate (SDS) and the theoretical DLVO-accomplished Reynolds model. It is shown that, due to overlap of the film adsorption layers, an adsorption component of the disjoining pressure is important for this system. The pre-exponential factor of the adsorption component was obtained by fitting the experimental drainage curves. It corresponds to a slight repulsion, which reduces not only the thinning velocity as observed experimentally but corrects also the film equilibrium thickness.



rate research

Read More

53 - D.S. Dean , R.R. Horgan 2004
In this paper we consider the two-loop calculation of the disjoining pressure of a symmetric electrolytic soap film. We show that the disjoining pressure is finite when the loop expansion is resummed using a cumulant expansion and requires no short distance cut-off. The loop expansion is resummed in terms of an expansion in g=l_B/l_D where l_D is the Debye length and l_B is the Bjerrum length. We show that there there is a non-analytic contribution of order g*ln(g). We also show that the two-loop correction is greater than the one-loop term at large film thicknesses suggesting a non-perturbative correction to the one-loop result in this limit.
We study macroion adsorption on planar surfaces, through a simple model. The importance of entropy in the interfacial phenomena is stressed. Our results are in qualitative agreement with available computer simulations and experimental results on charge reversal and self-assembling at interfaces.
The effect of oxygen adsorption on the local structure and electronic properties of monolayer graphene grown on SiC(0001) has been studied by means of Low Energy Electron Microscopy (LEEM), microprobe Low Energy Electron Diffraction (muLEED) and microprobe Angle Resolved Photoemission (muARPES). We show that the buffer layer of epitaxial graphene on SiC(0001) is partially decoupled after oxidation. The monitoring of the oxidation process demonstrates that the oxygen saturates the Si dangling bonds, breaks some Si-C bonds at the interface and intercalates the graphene layer. Accurate control over the oxidation parameters enables us to tune the charge density modulation in the layer.
In manuscript arXiv:1703.08719 [cond-mat.soft], it was claimed that the well-known deduction of Tolmans law is not rigorous, since Tolmans argument implies that two different definitions of the surface tension, called $gamma$ and $bargamma$ in the manuscript, coincide. This claim is retracted as it can be shown by free-energy minimization that $gamma = bargamma$ indeed holds for the Laplace radius. Joachim Gross, Philipp Rehner, Carlos Vega, O{}ivind Wilhelmsen, and the anonymous reviewers of The Journal of Chemical Physics contributed to finding the mistake in the manuscript.
We discuss instabilities of fluid films of nanoscale thickness, with a particular focus on films where the destabilising mechanism allows for linear instability, metastability, and absolute stability. Our study is motivated by nematic liquid crystal films; however we note that similar instability mechanisms, and forms of the effective disjoining pressure, appear in other contexts, such as the well-studied problem of polymeric films on two-layered substrates. The analysis is carried out within the framework of the long-wave approximation, which leads to a fourth order nonlinear partial different equation for the film thickness. Within the considered formulation, the nematic character of the film leads to an additional contribution to the disjoining pressure, changing its functional form. This effective disjoining pressure is characterised by the presence of a local maximum for non-vanishing film thickness. Such a form leads to complicated instability evolution that we study by analytical means, including application of marginal stability criteria, and by extensive numerical simulations that help us develop a better understanding of instability evolution in the nonlinear regime. This combination of analytical and computational techniques allows us to reach novel understanding of relevant instability mechanisms, and of their influence on transient and fully developed fluid film morphologies.
comments
Fetching comments Fetching comments
mircosoft-partner

هل ترغب بارسال اشعارات عن اخر التحديثات في شمرا-اكاديميا