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Moussabilité des mélanges d’huiles

Abstract : Knowing that the Marangoni effect plays a major role in stabilizing foams produced without surfactant, we have developed an innovative setup in order to study quantitatively Marangoni flows at the surface of a liquid. Moreover, this experiment provides an experimental tool that can detect the presence of surface active agents at liquid/gas interfaces with a high sensitivity. In parallel, we have studied the foamability of binary mixtures of alkane and toluene. Indeed, even though these oils taken separately do not foam, the binary mixture can have a high foamability. In fact, the proportion of the two species at the liquid/gas interface is not the same because the sites at the surface do not have the same energies than the sites in volume. A modification of the thickness of a liquid film composed of a binary mixture would result in a modification of the ratio of the number of sites accessible by molecules surface-to-volume. Such a thinning is thus disadvantaged. Finally, we have studied the foamability of model systems of crude oil, namely solutions composed of asphaltenes dispersed in oil mixtures. Asphaltenes are endogenous colloidal species of crude oils with well-known interfacial properties at water/oil and solid/oil interfaces. Using the setup developed to study the Marangoni effect, we have shown that at concentrations not exceeding 5wt% of asphaltenes, the latter do not adsorb significantly at oil/gas interfaces. However, we demonstrate that the stability of the alkane/toluene foams is increased by the presence of asphaltenes: we suggest that this effect results from the osmotic pressure induced in the liquid films by the colloidal aggregates of asphaltenes.
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  • HAL Id : tel-02946262, version 1

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Mélanie Arangalage. Moussabilité des mélanges d’huiles. Matière Molle [cond-mat.soft]. Sorbonne Université, 2018. Français. ⟨NNT : 2018SORUS128⟩. ⟨tel-02946262⟩

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