Добірка наукової літератури з теми "Acide polylactique – Propriétés mécaniques – Rupture"
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Дисертації з теми "Acide polylactique – Propriétés mécaniques – Rupture":
Khalifa, Anissa. "Etude des propriétés mécaniques et de rupture d'un biocomposite à base de particules de coquillages de mer élaboré par fabrication additive." Electronic Thesis or Diss., Université de Lille (2022-....), 2023. https://pepite-depot.univ-lille.fr/ToutIDP/EDENGSYS/2023/2023ULILN050.pdf.
Filaments of PLA biocomposites loaded with seashell particles (Oyster and Mussel) were produced by extrusion with four mass fraction rates of particles (5%, 10%, 15%, 20%) with particle sizes less than 160 microns. These filaments were used for additive manufacturing (AM) in Fused Deposition Modeling (FDM) of test specimens. Thermal and mechanical characterization tests were conducted to understand the behavior of the filaments before their use in printing. X-ray tomographic observations highlight the distribution of seashell particles in the PLA matrix. Microscope observations of fracture surfaces are presented. Finally, thermogravimetric analyses are performed and analyzed.A printing strategy was developed to study the effect of printing parameters such as infill angle, layer thickness, printing temperature, and printing speed on the mechanical properties of the biocomposites. The objective was to identify the optimal parameters for obtaining the best mechanical properties on printed dumbbell-shaped specimens (ASTM D638 standard). The results obtained reveal significant dispersion, especially in terms of elongation at break. A fracture study on SENT (Single Edge Notched Tension) specimens printed with two different infill angles (+45/-45°, 0°/90°) was conducted to determine the toughness of the biocomposites by coupling monotonic tensile tests with Digital Image Correlation (DIC) method. This approach provided a better understanding of the mechanical behaviors of the biocomposites and characterized their fracture resistance
Réti, Christelle. "Procédés d’élaboration de matériaux biosourcés à propriétés retard au feu améliorées : application à l’acide polylactique." Thesis, Lille 1, 2009. http://www.theses.fr/2009LIL10088/document.
The aim of this study is to evaluate the efficiency of different intumescent formulations to flame retard polylactic acid (PLA) by the incorporation of a phosphorous flame retardant compound (APP) and products coming from renewable resources. PLA/APP/starch composite shows the best fire retardant properties. Upon heating, the material forms a foamed cellular charred layer which protects the underlying material from the action of heat flux and flame and slows down heat and mass transfer between the gas and the condensed phase. The efficiency of intumescent structure can be explained by the viscosity of the formulation. Moreover, the explanation of the improvement of the fire properties is because of chemical reactions between the components of the formulation leading to thermally stable species like phosphocarbonaceous compound. Several solutions have been studied to improve mechanical properties of intumescent formulation
Peurton, Frédéric. "Nanocomposites à matrice thermoplastique et renforts plaquettaires : relations élaboration-structure-propriétés." Electronic Thesis or Diss., Lille 1, 2008. http://www.theses.fr/2008LIL10168.
Nanocomposites based on polymerie matrix and clay reinforcements have created a huge effort from academic and industrial researches. This investments are recompensed by the significant amelioration of several properties in comparison to conventional composites. The present work is devoted to a key parameter which is the elaboration conditions, in relation to structural organizations and mechanical properties. The first part deals with the clarification, in case of Nylon 6 nanocomposites, of the relationship existing between thermo-mechanical history and crystalline organization. Those elements are then used in properties optimization of blown films. The second part of the work tackles the elaboration of nanocomposites with a biodegradable polymerie matrix (Polylactide) and an unmodified clay using an original process of water injection, in collaboration with the university of Louvain La Neuve (High Polymer Unit). The obtained films exhibit a dispersion of fine clay aggregates intercalated by PLA (tactoïdes). The presence of this dispersion gives raise to a remarkable mechanical behavior, especially in term of ultimate properties
Bouzouita, Amani. "Élaboration des matériaux à base de l'acide polylactique pour application automobile : étude des interactions entre structure-process-propriétés." Thesis, Valenciennes, 2016. http://www.theses.fr/2016VALE0027/document.
The interest to use polymeric materials derived from renewable resources increases continuously due to considerably improved environmental awareness and the expected depletion of petrochemical ressources. In this regard, Poly(lactic acid), PLA, is a biopolymer that can respond to the demand for such materials for a wide range of applications, thanks to interesting mechanical properties such as high tensile/flexural strength and rigidity, in particular. However, in many cases, durable applications of PLA have been significantly limited by its inherent brittleness and limited thermal stability. In this dissertation, we focused on the design of new biobased PLA materials for automotive parts subjected to severe loading and environmental conditions, by improving thermal and mechanical properties, including under high strain rate loadings. Thus, the most promising compound is selected as the one that offers the best balance between different properties (ductility, strength and stiffness, impact toughness, good thermal stability…) with a content of bio-sourced polymer in the blend at least equal to 50%. Other strategies to improve crystallinity of PLA-based compounds are also studied. In all those developments, a particular attention is paid to the study of structure-process-properties interactions
Peurton, Frédéric. "Nanocomposites à matrice thermoplastique et renforts plaquettaires : relations élaboration-structure-propriétés." Thesis, Lille 1, 2008. http://www.theses.fr/2008LIL10168/document.
Nanocomposites based on polymerie matrix and clay reinforcements have created a huge effort from academic and industrial researches. This investments are recompensed by the significant amelioration of several properties in comparison to conventional composites. The present work is devoted to a key parameter which is the elaboration conditions, in relation to structural organizations and mechanical properties. The first part deals with the clarification, in case of Nylon 6 nanocomposites, of the relationship existing between thermo-mechanical history and crystalline organization. Those elements are then used in properties optimization of blown films. The second part of the work tackles the elaboration of nanocomposites with a biodegradable polymerie matrix (Polylactide) and an unmodified clay using an original process of water injection, in collaboration with the university of Louvain La Neuve (High Polymer Unit). The obtained films exhibit a dispersion of fine clay aggregates intercalated by PLA (tactoïdes). The presence of this dispersion gives raise to a remarkable mechanical behavior, especially in term of ultimate properties
Raj, Gijo. "Interfacial interactions in Flax fibre / PLA biocomposite : from model surfaces to real fibres." Lorient, 2010. http://www.theses.fr/2010LORIS197.
Abdillahi, Houssein. "Propriétes barrière et mécaniques d'agromatériaux thermoplastiques à base de farine de blé et de polyesters biosources et biodégradables." Thesis, Toulouse, INPT, 2014. http://www.theses.fr/2014INPT0027.
From basic and essential to unnecessary and optional consumer products, packaging, particularly plastic, is today an indispensable part of our daily life. Its extensive use in the food industry for a single use and for a short shelf-life encourages us today to move towards new renewable and biodegradable materials with similar characteristics than their counterparts from fossil resources. Biopolymers and biopolyesters blends can be a good alternative. Within the framework of this present work, wheat flour, thermoplasticised by glycerol and water, and biobased and biodegradable polyesters such as PLA and/or PHB, were blended using an industrial twin screw extruder and were injection-molded into thermoplastic materials. Thermal, dynamic thermomechanical, morphological, mechanical and barriers properties of these new materials were studied. Citric acid was used as a compatibilizer to improve the interface starch/PLA. The different investigations have allowed us to develop various types of formulations, with mechanical characteristics and barrier properties to water vapor, very attractive for manufacturing plastic food packaging which can be used for meats or cheeses. Food contact suitability and biodegradability of thermoplasticised wheat flour/polyester materials have also studied
Chomat, Dimitri. "Élaboration et mise en forme de composites micro-fibrillaires par fibrillation in-situ : optimisation de la microstructure et des propriétés mécaniques résultantes." Thesis, Lille 1, 2013. http://www.theses.fr/2013LIL10127.
Elaboration of microfibrillar composites based on immiscible polymer blends was performed by means of in-situ fibrillation. First, a polypropylene / polyamide 6 blend (PP/PA6) was used as a reference in order to develop an extrusion - drawing process. Upon variation of rheological parameters, it appeared that fibrillation requests a viscosity ratio less than 4 and an elastic ratio less than 1. Experiences about influence of processing temperature demonstrated that the injection step must be proceed at a temperature lower than the melting temperature of the dispersed phase in order to preserve the morphology. In a second part, this study dealt with the incorporation of organically modified montmorillonite with the aim of compatibilizing PP/PA6 blends. Several ways of nanoclay addition have been tested. Among them, nanoclay pre-dispersion in the PP matrix lead to the migration of clay platelets from PP to PP/PA6 interface during the in-situ fibrillation process. Hence, fibrils refinement was observed, inducing an improvement of impact resistance. Finally, one last part was dedicated to the development of a poly(lactic acid) / polyamide 11 bio-based micro-fibrillar composite. Whereas a partially fibrillar morphology was formed upon drawing, injection of the composite involved fibrils destruction due to overheating and subsequent relaxation
Raj, Amulya. "Development of Biobased Poly(L-Lactide)/Polyamide Blends with Improved Interfaces and Thermo-Mechanical Properties for High-Performance Applications." Electronic Thesis or Diss., Ecole nationale supérieure Mines-Télécom Lille Douai, 2019. http://www.theses.fr/2019MTLD0011.
The major objective of this thesis is to enhance the (thermo)mechanical properties of biobased poly(lactic acid) (PLA) to reach high performance/durable applications. Polymer blending with engineering polymers is an effective approach to improve these properties and polyamides (PA) were selected for blending with PLA due to their inherent high ductilities, high impact toughnesses, high thermal resistances coupled with a potential production from renewable feedstocks. Various biobased polyamides such as polyamide10-10, polyamide10-12, polyamide11 and polyamide12 were blended with PLA in a twin-screw extruder. Thorough characterizations such as morphology, rheology, surface tension, mechanical testing and thermal properties of PLA/PA blends were performed to assess the apt polyamide for PLA. Polyamide12 (PA12) was found to be the ideal candidate for PLA with a low PLA/PA12 interfacial tension, very good PA12 dispersion into PLA and enhanced (thermo)mechanical properties for PLA/PA12 blends compared to other PLA/PA blends (higher ductility and impact strength with significant increase in thermal resistance). To further enhance (thermo)mechanical properties, two different strategies were attempted namely compatibilization with a reactive PLA-graft-maleic anhydride (PLA-g-MA) and optimization of the extrusion processing parameters. In the former classical compatibilization strategy, PLA-g-MA was incorporated as a compatibilizer in PLA/PA12 blends and PLA-g-MA content was optimized with respect to various properties such as morphology and (thermo)mechanical. It was observed that 1 – 2 wt.% PLA-g-MA could induce significant improvements of the PLA/PA12 ductility, impact strength and thermal resistance. The latter strategy involved the optimization of extrusion parameters such as screw speed and feed rate. PLA/PA12 blends were extruded at various screw speeds (200 - 1100rpm) and feed rate (2 - 5kg/hr) on a pilot twin-screw extrusion line. The screw speed has a profound impact on the blend properties. The best (thermo)mechanical properties were archieved for an optimal screw speed of 800 rpm followed by a dramatic deterioration of the blend properties at extreme screw speed. Such effects are discussed based on the generation of fibrillary PA12 structures and PLA macromolecular degradation during high shear extrusion. In conclusion, remarkable improvements in (thermo)mechanical properties were achieved by blending PLA with PA12. Amongst the strategies employed to further enhance the properties, the optimization of extrusion parameters represent a cost-effective approach compared to classical compatibilization. PLA/PA12 blends could be a potential candidate for the replacement of petrosourced counterparts used in high-performance applications, in particular electronic casing applications
Ouchiar, Saadia. "Étude des relations structure – propriétés physiques de composites verts biopolymère/argile : effet de la nature et de la teneur en renfort." Thesis, Lille 1, 2016. http://www.theses.fr/2016LIL10023.
Although in constant development, the use of biobased polymers for industrial applications is still limited mainly because of their intrinsically limited physical properties. Adding clay is one solution to outclass these limitations. The main goal of this thesis, with an applied nature, was to elaborate and characterize new composite materials based on biopolymers and clays for applications in the packaging field. More especially, the influence of the clay nature was assessed. One of the distinctive features of this PhD work is the use of a high clay contents (≥ 30 wt%). Moreover, a particular attention was paid to study the role of the interface between the polymer matrix and the mineral filler on the structure as well as on the thermomechanical and barrier properties of the elaborated biocomposite.A screening of different biopolymer/clay compound elaborated at the laboratory scale was firstly studied in terms of structure, morphology and physical properties. Then the most promising formulations were selected and elaborated at a larger scale using industrially processes. The results obtained on Polylactide (PLA)/clay compounds showed that rather than the content of clay or its dispersion degree, it is the nature of the clay, i.e. its chemistry and its crystallography, that mainly govern the thermomechanical properties. Furthermore it was highlighted that applying a biaxial stretching on this kind of materials offsets the PLA brittleness and increases its barrier properties. Finally, regarding the alginate based composites, plasticization leads to a heterogeneous material and adding clay involves an increase of the material rigidity without any decrease of stretchability