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Quelques processus dynamiques aux interfaces polymères

Abstract : This theoretical work presents three topics of research which deal with various dynamic processes at polymeric interfaces. 1) Dewetting of thin polymer films : we present a theoretical model for the dewetting of thin polymer films coated on a low-energy substrate. Assuming that the shear-thinning properties of these films can be described by a Cross-type constitutive equation, we analyze the front morphology of the dewetting film, and characterize the time evolution of the dry region radius, and of the rim height. Different regimes of growth are expected, depending on the initial film thickness, and on the power-law index involved in the constitutive equation. We then compare our predictions with recent experimental results obtained by Debrégeas and by Reiter. 2) Adhesion between a viscoelastic material and a solid surface : we present a qualitative analysis of the dissipative processes during the failure of the interface between a viscoelastic polymer and a solid surface. We reassess P.-G. de Gennes' "viscoelastic trumpet" model, and show that the experimentally observed enhancement of fracture energy is due to local dissipative processes near the crack-tip, but also originates from far-field viscous dissipation in the bulk material. We compare some of our theoretical predictions with experimental results by T. Ondarçuhu about the viscoelastic adhesion between a polydimethylsiloxane polymer melt and a glass surface~: in particular, the expected dependence of the fracture energy versus separation rate is confirmed by the experimental data, and the observed changes in the concavity of the crack profile are in good agreement with our simple model. 3) Multiple structure and dynamics of the interface between melts in a three-species polymer system : in this part, we analyze, in terms of conservation and continuity laws, the evolution of concentration profiles at the interface between two dissimilar polymer blocks, with distinct compatibilities between the three components. The specificities of interdiffusion processes between polymers arise from the entropic or enthalpic nature of their driving force, depending on the compatibility of the considered components. It is found that such a system exhibits a peculiar morphology of interface, with three distinct zones of various chemical compositions and broadening laws.
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https://tel.archives-ouvertes.fr/tel-00009740
Contributor : Florent Saulnier <>
Submitted on : Tuesday, July 12, 2005 - 1:49:24 PM
Last modification on : Friday, May 29, 2020 - 3:59:52 PM
Long-term archiving on: : Friday, April 2, 2010 - 9:58:21 PM

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  • HAL Id : tel-00009740, version 1

Citation

Florent Saulnier. Quelques processus dynamiques aux interfaces polymères. Dynamique des Fluides [physics.flu-dyn]. Université Pierre et Marie Curie - Paris VI, 2003. Français. ⟨tel-00009740⟩

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