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Caractérisation expérimentale des instabilités induites par l'évaporation de solvant dans une solution polymère

par Doumenc, Frédéric;Iorio, Carlo Saverio ;Toussaint, Guillaume;Scheid, Benoît ;Guerrier, Béatrice;Allain, Catherine
Editeur scientifique Lefranc, M.;Letellier, C.;Pastur, L.
Référence Compte-rendus de la 9ème Rencontre du Non-Linéaire, Non-Linéaire Publications, Paris, page (75-80)
Publication Publié, 2006

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Résumé :

When drying a polymer/solvent solution, solvent evaporation induces an increasing of polymer concentration and a decreasing of the temperature at the interface. Depending of the physicochemical properties of the solution, this configuration may be hydrodynamically instable. In this study a model system with one polymer and one solvent is considered: Polyisobutylene/Toluene. This system shows density and surface tension variations, with the temperature as well as with the concentration, that leads to an unstable configuration during evaporation. Experimental results of convective patterns at the beginning of the drying, when evaporation flux is important, are presented. Visualizations correspond to top views of the solution surface, with an infrared camera or a video camera using iriodine particles as a tracer. Initial solution thickness was varied from 1 to 13mm. Results show a change from hexagonal cells for small thicknesses to more complex patterns (mixture of rolls and cells) for greater thicknesses. Cells characteristic size grows linearly with the initial thickness for small thicknesses, while a saturation is observed for greater thicknesses.