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Étude et modélisation de la synthèse du polyamide 6 pour la mise en œuvre de composites thermoplastiques par voie liquide réactive

Abstract : Liquid type processes (RTM, LRI) for thermoplastic composites manufacturing is one of the most promising routes to overcome the limitations due to the high viscosity of thermoplastic polymers. In this process, the matrix is obtained via in situ polymerization of its low-viscosity monomer after impregnation of the fibrous reinforcement. This study focused on polyamide 6 (PA6) obtained by anionic ring-opening polymerization of ε-caprolactam. The distinctive aspect of this reaction resides in the coupling between chains polymerization and their crystallization, both thermo-dependent, exothermic and driving the viscosity of the reactive mixture.The kinetic characterization of this coupling by DSC allowed for a better understanding of phenomena interaction, revealing notably a specific crystallization kinetic at low temperature. This database, complemented by a study of physicochemical properties of synthesized PA6, has been used to model the underlying phenomena. A new coupling equation has been proposed to take into account the crystallization dependence on the polymerization kinetic, allowing to edit Time-Temperature-Transformation (TTT) diagrams of the PA6 synthesis. Simulations of the thermokinetic coupling with a source term have been performed, highlighting the impact of these exothermic phenomena on thermal and kinetic gradient in the thickness of a part. To reproduce the conditions of the composite manufacturing process, kinetics have also been studied in the presence of glass fibers and in a rheometer. The presence of fibers leads to slower kinetics and the rheokinetic behavior revealed gelation. These observations have to be considered to simulate the reactive system flow in a reinforcement.
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Submitted on : Thursday, August 23, 2018 - 5:29:06 PM
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  • HAL Id : tel-01860758, version 1

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Céline Vicard. Étude et modélisation de la synthèse du polyamide 6 pour la mise en œuvre de composites thermoplastiques par voie liquide réactive. Matériaux. Ecole des Mines d'Albi-Carmaux, 2018. Français. ⟨NNT : 2018EMAC0001⟩. ⟨tel-01860758⟩

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