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Descripción
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| Thin polymer films are often used in advanced technological applications either as homogeneous coatings or as structured functional layers. Their stability and potential use is mostly determined by the wettability properties of the substrate and is well understood for single component liquids. However, in many relevant applications the film consists of a binary mixture such as a polymer blend. For such systems the dynamics of the decomposition within the film and of the dewetting of the film itself may couple. This allows for new pathways of structuring like decomposition induced dewetting [1]. We present a model for thin films of binary mixtures, such as polymer blends, with free surfaces that allows the study of the coupling between profile evolution and decomposition. The model is based on model-H [2] describing the coupled transport of concentration (convective Cahn-Hilliard equation) and momentum (Navier-Stokes-Korteweg equations) fields supplemented by boundary conditions at the substrate and the free surface. After determining homogeneous and vertically stratified base states of free surface films of polymer mixtures we analyse their linear stability with respect to lateral perturbations [3]. For purely diffusive transport, an increase in film thickness either exponentially decreases the lateral instability or entirely stabilizes the film. The inclusion of convective transport leads to a further destabilization as compared to the purely diffusive case. In some cases the inclusion of convective transport and the related widening of the range of available film configurations (it is then able to change its surface profile) change the stability behavior qualitatively [4]. We furthermore present results regarding the dependence of the instability on several other parameters, namely, the Reynolds number, the Surface tension number and the ratio of the typical velocities of convective and diffusive transport. SM and UT acknowledge support by the EU via a FP7 Marie Curie Reintegration Grant (PERG04- GA-2008-234384) and ITN [PITN-GA-2008-214919 (MULTIFLOW)], respectively. [1] R. Yerushalmi-Rozen, T. Kerle, and J. Klein. Science. 285, 1254-1256, 1999. [2] D.M. Anderson, G.B. McFadden, and A.A. Wheeler. Ann. Rev. Fluid Mech. 30, 139-165, 1998. [3] U. Thiele, S. Madruga, and L. Frastia. Phys. of Fluids. 19, 122106, 2007. [4] S. Madruga and U. Thiele. Physics of Fluids. 21, 122106, 2009. | |
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Internacional
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Nombre congreso
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International Marangoni Association Conference IMA5 |
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Tipo de participación
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960 |
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Lugar del congreso
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Revisores
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Si |
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ISBN o ISSN
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00-0000-000-0 |
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DOI
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Fecha inicio congreso
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07/07/2010 |
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Fecha fin congreso
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10/07/2010 |
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Desde la página
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86 |
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Hasta la página
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86 |
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Título de las actas
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International Marangoni Association Conference IMA5 http://www.ima5.u-psud.fr/program_ima5.pdf |