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Structure de matériaux à base de polylactide obtenus par extrusion réactive : formation et transformation thermomécaniques

Abstract : Polylactide (PLA), a biodegradable and bio-based polymer, raised researchers’ attention to replace conventional plastics. At room temperature, PLA is brittle and requires physical plasticization that increases its ductility but at the same time drastically decreases its stiffness. As an alternative, plasticization by reactive extrusion was recently developed. The reactive extrusion of PLA with acrylated poly(ethylene glycol) (acrylPEG) as plasticizer yields a plasticized PLA named pPLA. This thesis aims at identifying the structure of this pPLA and studying its evolution engendered by thermomechanical transformations as drawing and recycling. First, pPLA’s structural features are analyzed by a multi-scale and multi-disciplinary approach. pPLA is characterized by partially grafted and partially free inclusions of the polymerized plasticizer and a slightly crosslinked PLA matrix. These plasticizer inclusions lead to a material with a good stiffness-ductility balance. Second, the deformation mechanisms of pPLA upon drawing indicate that chain orientation mechanisms are predominant compared to damage, the latter dominating deformation in PLA. Third, the thermomechanical recycling of pPLA shows that degradation is dependent on the type of processing step. Compression-molding is detrimental to pPLA inducing after recycling a higher degradation compared to PLA. This thesis releases new characterization methodologies enabling a better identification of biopolymer structural features
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Submitted on : Tuesday, December 12, 2017 - 1:05:49 AM
Last modification on : Thursday, January 11, 2018 - 6:27:33 AM

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  • HAL Id : tel-01661553, version 1

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Berit Brüster. Structure de matériaux à base de polylactide obtenus par extrusion réactive : formation et transformation thermomécaniques. Mechanics of materials [physics.class-ph]. Université de Lorraine, 2017. English. ⟨NNT : 2017LORR0156⟩. ⟨tel-01661553⟩

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