Tesi sul tema "Dépôt à l'état fondu"
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Le, Anh-Duc. "Modélisation et simulation multiphysique du procédé de fabrication additive par dépôt à l’état fondu". Electronic Thesis or Diss., Ecole nationale supérieure Mines-Télécom Lille Douai, 2021. http://www.theses.fr/2021MTLD0004.
Additive manufacturing of the polymers through Fused Deposition Modeling (FDM) or Fused Filament Fabrication (FFF) process allows the production of complex plastic parts without using tools. This is such an original plastic processing which makes it possible to pass very quickly from the ideas to the products, thus accelerating the time of development, and arousing great industrial interest. In order to optimize the process, numerical simulation is increasingly becoming an economical alternative to replace repeated experiments, which are always costly and time-consuming. The approach is based on a coupling of fluid mechanics and heat transfer by a Level Set method, which allows to simulate of different physical phenomena involved during the process (i.e. flow, coalescence, cooling, consolidation, etc.). The polymer melt flow is treated as a single-phase flow with a free surface. As a first step, an in-house Level Set code was developed to accurately capture the evolution of the free surface. In a second step, the coupling model was implemented in a computational code using the LiveLink for Matlab of COMSOL Multiphysics software. The effect of variations in process parameters on the final printed part was examined. The rheological properties of the material used are measured by a rotary rheometer. The numerical model is validated using optical micrograph measurements of samples printed by a laboratory printer. The numerical model shows great potential for modeling and optimizing the additive manufacturing process
Andriatsarafara, Tiana. "Comportement rhéologique des pmma-choc à l'état fondu". Pau, 1993. http://www.theses.fr/1993PAUU3001.
Meslin, Frédéric. "Propriétés rhéologiques des composites fibres courtes à l'état fondu". Cachan, Ecole normale supérieure, 1997. http://www.theses.fr/1997DENS0020.
Guichard, Sabine. "Modification des alumines par des nitrures à l'état fondu". Orléans, 2007. http://www.theses.fr/2007ORLE2073.
Vallereau, Robin. "Fabrication additive d'aimants liés anisotropes par dépôt de fil fondu". Electronic Thesis or Diss., Université Grenoble Alpes, 2024. http://www.theses.fr/2024GRALI012.
Rare earth-based anisotropic permanent magnets have excellent magnetic properties and are therefore used in many electromechanical devices such as motors, actuators, generators, and even at small dimensions in micro-electromechanical systems. They can be found in sintered or bonded form. Although bonded magnets are less magnetised than sintered ones because they are diluted in a polymer matrix, they have the advantage of being able to be manufactured in very large series by injection moulding and can be complex in shape. However, the production of small series, or of magnets with a complex magnetic texture, is not currently feasible. The technique of additive manufacturing using molten wire deposition provides a solution to some of these problems: unlike moulding, 3D printing is suitable for small production runs, allows more complex shapes and consumes only the necessary volume of material. As for the texture, this thesis describes a print head based on a piston extruder and equipped with a magnetic aligner, which made it possible to obtain substantially anisotropic rare-earth-based bonded magnets. The composites were formulated in PA12 nylon with industrial-grade NdFeB powders, derived from the recycling of sintered magnets; we also used SmFeN already formulated in granulated form.The piston extruder is fed with pellets which, unlike wound filaments, can be highly charged with magnetic powder. The magnetic aligner is a ring of SmCo magnets assembled around the nozzle; it orients the magnetic particles during extrusion to induce axial anisotropy in the strand and improve its remanent magnetisation. It was designed following a study to determine the temperature and field to be applied to obtain optimum alignment under extrusion conditions. This device produces an axial induction of 545 mT in the zone of interest. Unlike conventional printheads, in our extruder the molten composite is extruded by a plunger, overcoming the frictional forces that confine the magnetic particles in the nozzle under the radial forces of the magnetic field gradient.The manufacture of dense, good quality bonded magnets requires optimisation of the printing parameters. However, there is always some porosity generated by the process itself, which helps to reduce remanent magnetisation. As for anisotropy, this is obtained by following a construction strategy for the bonded magnet that consists of depositing all the strands in the same direction and in the same sense. When printing anisotropic magnets, the friction of the nozzle on the freshly deposited layer mechanically misaligns the particles on the surface, again contributing to a degradation of the maximum properties. The composite filled with 63 %vol NdFeB (MF-P15) in PA12 nylon is particularly affected and has a degree of alignment of almost zero (µ0Mr = 0.3 T and Hc = 995 kA/m), while SmFeN/PA12 (60 %vol) has a degree of alignment of 0.3 (µ0Mr = 0.5 T, Hc = 875 kA/m). The SmFeN particles are very fine (d0.5 = 3 µm) compared with those of NdFeB (d0.5 ~75-100 µm) and spheroidal in shape: a printed layer 200 µm thick therefore contains many more SmFeN particles than NdFeB, and the particles on the surface, mechanically misaligned when the nozzle touches them, thus represent a smaller volume fraction.The long-term objective of the 6DMag project is to exploit this strategy of anisotropic deposition by alignment, to print bonded magnets composed of regions with different directions of magnetisation. The next challenge will be to magnetise the different regions of a multipolar magnet without impacting neighbouring regions
Bertin, Marie-Pierre. "Comportement rhéologique des ABS (acrynolytrile-butadiène-styrène) à l'état fondu". Pau, 1991. http://www.theses.fr/1991PAUU3001.
Bente, Marie-Pierre. "Réactivité à l'état fondu de systèmes époxyde/cyanamide-dicyandiamide-mélamine". Pau, 1992. http://www.theses.fr/1992PAUU3020.
Stanescu, Paul. "Architecture et comportement viscoélastique à l'état fondu de polyéthylènes basse densité". Saint-Etienne, 2005. http://www.theses.fr/2005STET4003.
Low density polyethylene (LDPE) is one of the synthetic polymers most used and the prediction of its rheological behavior is an industrial stake. The difficulty lies in the complex architecture of the molecules. The number, the size and the position of the branches are random and these parameters have major effects on the rheological behavior. This work shows that the real structure of LDPE can be sketched by an irregular Cayley tree. The structural parameters can be determined from SEC measurements and from the kinetics of free radical polymerization. Based on this picture of the molecules, a molecular model is proposed to describe the dynamics of the LDPE in the case of a monodisperse samples and polydisperse samples. The linear viscoelastic behavior of our LDPE was correctly predicted. The strong link between structure and rheology enables to solve the inverse problem. Linear viscoelastic data contain all the structural information. The use of the molecular model and an algorithm of minimization leads to an average structural picture of the molecules very close to that obtained by SEC. This average structure was transformed into "pom-pom" structures that were used in an "pom-pom" multimode constitutive equation. The calculated transient viscosity of our LDPE agrees with experimental measurements both in shear and uniaxial elongational flow
Dreux, Xavier. "Comportement viscoélastique à l'état fondu et structure d'acétates de cellulose plastifiés". Thesis, Lyon, 2019. http://www.theses.fr/2019LYSES002/document.
This present work deals with the rheological properties of cellulose acetate which is a biobased polymer manufactured from cellulose. In order to facilitate its forming process, cellulose acetate is usually blended with plasticizers. As the conventional industrial processes need rheological information for different flow conditions, viscoelastic behaviour of a plasticized cellulose acetate with a degree of substitution of 2,45 was investigated by various rheology experiments. Measurements in the linear regime were carried out for various plasticizer contents and some unexpected behaviours have been highlighted. Compared to conventional thermoplastic polymers, the structure and dynamics of the macromolecular chains of cellulose acetate seem to be more complex than that of common synthetic polymers. This was confirmed by measurements in the nonlinear domain. The results suggests that the viscoelastic behaviour of cellulose acetate chains is not controlled by entanglements but rather by another correlation length related to strong interactions between chains, named stickers. These interactions confer to the polymer dynamics an unusual scaling behaviour depending on plasticizer content and temperature
Deplancke, Tiana. "Approche des mécanismes de frittage du UHMWPE : étude du comportement mécanique à l'état solide et à l'état fondu". Phd thesis, INSA de Lyon, 2013. http://tel.archives-ouvertes.fr/tel-01018639.
Dagron-Lartigau, Christine. "Réactivité à l'état fondu de systèmes cyanate-époxyde,non catalysés et catalysés". Pau, 1996. http://www.theses.fr/1996PAUU3001.
Trillaud, Marc. "Poly-imides-amides fonctionnalisés. : Mécanismes et cinétiques de réactions à l'état fondu". Pau, 1993. http://www.theses.fr/1993PAUU3028.
Domenech, Trystan. "Structure et propriétés de nanocomposites polypropylène/argile lamellaire préparés par mélange à l'état fondu". Phd thesis, Ecole Nationale Supérieure des Mines de Paris, 2012. http://pastel.archives-ouvertes.fr/pastel-00684786.
Lacoste, Jean-François. "Élaboration de fibres de poly(éthylène téréphtalate) à propriétés thermomécaniques améliorées par modification chimique à l'état fondu et à l'état solide". Lyon 1, 2004. http://www.theses.fr/2004LYO10045.
The aim of this thesis is to enhance the thermomechanical properties of PET fibers trialkoxysilane end-group crosslinking (hydrolysis-condensation) after the functionalization the alcohol and acid PET end-groups with bifunctional reagents. OH groupes were reacted with anhydride or isocyanate and COOH groups with epoxide. Reaction kinetics were studied by NMR on end-group model compounds. During melt modification many degradation and side reactions were observed and crosslinking occurred after hydrolysis-condensation. Thus we preferred to study the solid-state functionalization by diffusion of reagents at temperatures below 256°C. After solid-state modification, crosslinking finally occured giving maximum gel contents of 70°C. Mechanical properties of partially crosslinked samples were maintained up to 320°C
Chaunier, Laurent. "Matériaux thermoplastiques à base de biopolymère pour leur impression 3D par dépôt de fil fondu". Thesis, Nantes, 2019. http://www.theses.fr/2019NANT4028/document.
Additive Manufacturing (AM) opens new perspectives for the processing and shaping of materials based on natural polymers. Their intrinsic properties such as edibility and bioresorbability could thus be exploited. This thesis focuses on 3D printing by molten Material Extrusion (AM-ME). It is applied to zein, a corn storage protein which is melt processable in presence of plasticizers. After listing the relevant material specifications for the AM-ME process, all the properties concerned were characterized for a formulation plasticized by 20% of glycerol. Its thermomechanical and rheological behaviour can be compatible with an AM-ME process fed by previously extruded filaments : While rigid enough at 20°C, the material can be extruded above 120°C. Its shear thinning behaviour and fusionbonding ability are similar to those of standard polymers such as ABS and PLA. However, a progressive crosslinking due to protein aggregation in the melt was shown by structural characterizations. The processing window is thus limited, but this issue can be addressed either by modifying the feeding system of the process, or by adapting the formulation. Glycerol can be combined with reducing or denaturing agents, or substituted by ionic liquids. The interest of these plasticizers is to allow bringing pharmaceutical functionalities to printed parts. This would open the field of new applications for zein
Magana, Sylvain. "Elaboration de nouveaux polymères réticulés par la réaction thermoréversible de Diels-Alder à l'état fondu". Saint-Etienne, 2009. http://www.theses.fr/2009STET4013.
During the past ten years, a growing interest has appeared with the application of the reversible Diels-Alder reaction to macromolecular chemistry. The scope of this study is to use the Diels-Alder (DA) and retro-Diels-Alder (rDA) reactions to obtain a thermally reversible cross-linked Polyethylene-GMA Lotader® copolymer in molten state. A study on model DA adducts enables us to find out the characteristic time and temperature of the DA and rDA reactions in the solid state. The rDA and melting temperature are equals, and the rDA temperature of the exo stereoisomer is higher than the endo. Synthesis and thermal stability of the diacid adduct between 3-(2-furyl)-propanoic acid (Fac32) and maleimidoundecanoic acid (AMU) are described for the first time. The DA synthesis happens beneath 140°C, and the rDA of the endo isomer is 70°C while 125°C for the exo. Analysis shows an izomerisation temperature between 80 and 113°C. The rDA of the exo isomer is about 20°C higher than the melt temperature of the Polyethylene-GMA. Grafting of the diene and dienophile molecules onto the copolymer is done thanks to epoxy-acid reaction in melt processing. An original way of grafting is employed to graft the two molecules in a one step procedure. The grafting succeeded in functionalizing more than 60% of the epoxy with the AMU and 80% with the Fac32 at 140°C in 15 minutes without catalysts. The DA reaction between diene and dienophile moieties grafted is followed by IR-TF analysis on a film on cooling. The rDA reaction is observed until 100°C during the heating. Eventually, the reversibility of theses reactions is evidenced with 20 cycles with little decline in their yields
Bouajila, Jalloul. "Etudes physico-chimiques et analyses thermiques de précurseurs de polycondensation obtenus par polymérisation à l'état fondu". Lyon 1, 2002. http://www.theses.fr/2002LYO10092.
Ayçaguer, Nathalie. "Mécanismes et cinétiques d'homopolymérisation et de copolymérisation des systèmes maleimide, acétylénique et propargylique à l'état fondu". Pau, 1997. http://www.theses.fr/1997PAUU3039.
Muller, René. "Comportement rhéologique et mesures d'orientation moléculaire de polymères à l'état fondu dans un écoulement élongationnel simple". Université Louis Pasteur (Strasbourg) (1971-2008), 1988. http://www.theses.fr/1988STR13102.
Sarrabi, Salah. "Vers une approche mécanistique du vieillissement thermique du polyprophylène à l'état fondu au cours du rotomoulage". Paris, ENSAM, 2008. https://pastel.archives-ouvertes.fr/pastel-00004925.
Le rotomoulage est une technique de mise en œuvre des polymères thermoplastiques. Le principal inconvénient du procédé est un séjour prolongé aux hautes températures du polymère à l’état fondu. Afin d’éviter une dégradation thermique du polymère, il est nécessaire de définir, au préalable, une fenêtre de mise en œuvre. L’objectif de la thèse est d’élaborer, par une approche mécanistique, un modèle cinétique de dégradation thermique permettant de définir certaines frontières importantes de cette fenêtre, comme le plafond de dégradation thermique. Ce modèle général est composé de deux domaines : i) Le premier domaine est consacré au modèle thermique prédisant, en tout point d’une pièce en polypropylène (PP), l’évolution locale de la température. Ce premier modèle est dérivé des mécanismes de transfert thermique se produisant au cours de la mise en œuvre, les changements de phase, fusion et cristallisation de chaque couche de polymère, étant simulés à l’aide de la méthode enthalpique. Il est validé pour différentes conditions opératoires et au niveau des divers constituants de la rotomouleuse (four, moule, polymère et air interne) à partir de mesures expérimentales. Ii) Le second domaine est consacré au modèle chimique prédisant l’avancement local de la dégradation. Ce modèle est dérivé d’un schéma mécanistique d’oxydation du PP stabilisé à l’état fondu. Il est validé à partir des concentrations des produits d’oxydation, des pertes de masse et des épaisseurs de couche oxydée mesurées expérimentalement sur des films minces et des pièces épaisses exposées en conditions isothermes (entre 170 et 230 °C) et à température variable (conditions réelles de rotomoulage, de 170 jusqu’à 250 °C). Le modèle général, constitué de ces deux modèles couplés, permet de prédire la consommation des antioxydants au cours du rotomoulage pour diverses conditions opératoires. A titre d’exemple, pour une consigne de 300 °C, le modèle prédit une période d’induction de 22 min. A 350 °C, la pièce est stable thermiquement pendant 15 min
Sanglar, Corinne. "Prépolymères à terminaisons propargylique et chromène. : Synthèse, études physicochimiques, mécanismes et cinétique de polymérisation à l'état fondu". Pau, 1995. http://www.theses.fr/1995PAUU3025.
Pesce, Jean-Jacques. "Incidence de l'orientation moléculaire d'un polymère fondu en écoulement sur l'anisotropie induite des propriétés à l'état solide". Université Louis Pasteur (Strasbourg) (1971-2008), 1993. http://www.theses.fr/1993STR13258.
Pernel, Carole. "Comportement électrochimique de l'américium dans l'eutectique LiCl-KCl fondu en vue de sa séparation des lanthanides par électrodéposition". Grenoble INPG, 2002. http://www.theses.fr/2002INPG0008.
Da, Cunha Louis. "Synthèse, mécanisme et cinétique de polymérisation à l'état fondu de prépolymère à réactivité élevée et sélective de type bismaleimide". Pau, 1996. http://www.theses.fr/1996PAUU3036.
Carrot, Christian. "Elaboration er propriétés d'alliages polyamide-ABS : influence d'un compatibilisant obtenu par greffage à l'état fondu d'anhydride maléique sur l'ABS". Saint-Etienne, 1990. http://www.theses.fr/1990STET4012.
Cherqaoui, Bennaceur. "Etude du comportement rhéologique à l'état fondu et du comportement diélectrique du polyfluorure de vinylidène chargé de titanate de baryum". Saint-Etienne, 1986. http://www.theses.fr/1986STET4007.
Kuras, Marta. "Compréhension de la nature de l'état d'un oxyde à structure définie par la connaissance du dépôt carboné". Université Louis Pasteur (Strasbourg) (1971-2008), 2006. http://www.theses.fr/2006STR13193.
This work is initially about the oxides with definite structure synthesis in order to use them as catalyst precursors and in the second time, is about the using of these systems for the controlled formation of MWNT by C. V. D. The final objective is to establish the connections between the morphology of MWNT (TEM and SEM), the texture (SEM) and the structure (XRD, EDS, TPR) of the catalyst precursors. To study the influence of the method of preparation on solid’s texture the catalysts precursors based on Ni and La were prepared by different resin methods (mixed oxides perovskite type: LaNiO3, LaNi0. 95O3, LaNi0. 85O3, LaNi0. 60O3 and K2NiF4 type: La2NiO4). The catalysts (nanoparticles Ni0 deposited on La2O3) were obtained by oxides reduction under H2 or under CH4. The study of the reduction mechanism of these oxides under H2 and CH4 made possible to work out two types of catalytic tests: reduction under H2 followed by a reaction with mix gases CH4-H2 and reduction then reaction only under CH4. The process of tubes formation (with H2, CH4, CO2 and CO quantification) was followed by mass spectrometry, procedure reported exceptionally in the literature. In the presence of H2 all catalysts calcined at 900°C gave selectively MWNT. Without H2 only the structure perovskite LaNiO3 calcined at 900°C gave tubes of a good crystallinity and a great homogeneity (10-15 nm)
Tadlaoui, Khalid. "Synthèse d'oligomères du méthacrylate de méthyle par télomérisation radicalaire et étude de leurs comportements viscoélastique [sic, au singulier] à l'état fondu". Montpellier 2, 1989. http://www.theses.fr/1989MON20178.
Boutahar, Khaled. "Comportement rhéologique de polyoléfines au cours d'une cristallisation isotherme à partir de l'état fondu : relation entre la fraction transformée et les modules dynamiques". Saint-Etienne, 1997. http://www.theses.fr/1997STET4003.
Jaziri, Mohamed. "Etude du greffage à l'état fondu de l'anhydride maléique sur l'ABS : influence du composé obtenu sur l'élaboration et les propriétés des mélanges polycarbonate / ABS". Saint-Etienne, 1992. http://www.theses.fr/1992STET4006.
Franbourg, Alain. "Influence d'un traitement à l'état fondu sur la structure cristalline et les propriétés mécaniques du poly(oxymethylène) et du poly(éther éther cétone) : relations : mise en oeuvre par injection/structure/propriétés". Lille 1, 1990. http://www.theses.fr/1990LIL10091.
Gervais, Emelyne. "Design et optimisation d'une interface fonctionnalisée par des nanoparticules métalliques et des couches organiques électroformées pour la détection de métaux lourds à l'état de traces dans les eaux". Thesis, Toulouse 3, 2017. http://www.theses.fr/2017TOU30258/document.
Mercury is known for its toxicity on human beings, causing neurological and kidney diseases when absorbed in the body. It is rejected in the environment, and especially in surface waters, through natural processes like volcanism and human industrial activities. When present in water, it is ingested by marine plants and wildlife and bioaccumulates all along the food chain. It is then present in high proportions in marine predators, jeopardizing their health and exposing human beings to important mercury quantities in the food supply. The European legislation is very strict regarding to allowed mercury levels in waters, and is based on very low values, from traces to ultra traces. Current techniques able to detect such small doses are efficient but suffer from numerous drawbacks like their cost or the impossibility to use them for in situ measurements. Electrochemical sensors appear to be one of the most interesting alternatives for detection of this heavy metal in aqueous solution. The aim of this work was then to develop an electrochemical sensor based on the functionalization of a glassy carbon electrode with organic layers and gold nanoparticles for mercury detection. Two types of organic layers were used and the interfaces were characterised by using cyclic voltammetry and Scanning Electron Microscopy. Two different gold nanoparticles activation processes were tested. The interfaces performances were evaluated for detection of traces of mercury, as well as their storage stability
Berková, Kristýna. "Processing, structure and properties of composites based on natural fillers and strereoregular polyolefins". Thesis, Clermont-Ferrand 2, 2013. http://www.theses.fr/2013CLF22386/document.
This doctoral thesis is focused on composites based on polypropylene and wood flour. Firstly, the experimental work deals with preparation of composites based on wood flour with various concentrations and isotactic polypropylene with various melt flow indexes. In terms of this study, one polypropylene, which can have also practical use, was chosen. Further, this polypropylene is investigated with various types and concentrations of wood flour. Also, the attention is devoted to the modification of polypropylene by a specific β-Nucleating agent. The differences are compared and described between the composites with neat and nucleated polypropylene. Further, the work is focused on solvent extraction of wood flour. The effect of extraction and solvent of wood flour is also examined in composites with neat and nucleated polypropylene. On prepared composites, the rheological, structural and thermal properties are studied. These properties differ depending on specific type of wood flour, its concentration and specific type of polypropylene
Předložená doktorská práce je zaměřena na kompozity polypropylenu a dřevní moučky. V experimentální části práce jsou připraveny kompozity s různými koncentracemi plniva a izotaktických polypropylenů s různými indexy toku taveniny. Na základě této studie je vybrán jeden konkrétní polypropylen, který může mít v kombinaci s dřevní moučkou i praktické využití. Tento polypropylen je dále zkoumán s různými druhy a koncentracemi dřevní moučky. Pozornost je také kladena na úpravu vlastností izotaktického polypropylenu užitím specifického β-nukleačního činidla. Jsou porovnávány a popisovány rozdíly mezi kompozity s čistým a nukleovaným polypropylenem. Práce se dále zabývá extrakcí dřevní moučky v rozpouštědle. Je studován vliv extrakce a rozpouštědla dřevní moučky na vlastnosti připravených kompozitů. Byly studovány reologické, strukturální a tepelné vlastnosti, které se lišily v závislosti na zvoleném typu plniva, jeho koncentraci a typu polymerní matrice
Liao, Jingjing. "Préparation et modification de composites thermoplastiques/tannins par extrusion réactive". Thesis, Université de Lorraine, 2019. http://www.theses.fr/2019LORR0071.
Condensed tannins are widely distributed and highly abundant in nature. In the past decades, such tannins have played an important role in thermosetting systems (e.g. adhesives for wood bonding, foam material) because of their chemical reactivity. However, they also exhibit great potential as a component of polymeric materials because of their physicochemical properties (e.g. antioxidant, antimicrobial and stabilizing properties), which are promising for material preparation. In order to transform tannins from traditional application to a broaden application in polymeric materials, the main challenge facing tannins are their incompatibility with hydrophobic polymer. For this purpose, three modification pathways were developed to improve the compatibility of tannins with PP or PLA matrix. In the first part, PP/ tannins were modified with hexamine or glyoxal via dynamic vulcanization technique. After vulcanized extrusion, vulcanized tannins present better compatibility and UV protective performance in PP matrix. The second approach is CTs modified with acetic anhydride. With this method, up to 30 wt% acetylated tannin (AT) can be well incorporated with PLA while PLA containing up to 20 wt% AT did not deteriorate the mechanical property and surface morphology. This PLA/AT composites are printable via fused deposition modeling process. In the third part, the efficient reactive compatibilization have been successful used to improve the interfacial adhesion between PLA and CTs by using 3-aminopropytriethoxysilane, methylene diphenyl diisocyanate, and dicumyl peroxide (DCP)
Benrabbah, Rafik. "Développement de procédés plasma pour l'élaboration et la caractérisation du silicium photovoltaïque : dépôt de couches minces épitaxiées de silicium par PECVD : mesure de la pureté du silicium à l'état solide ( 20°C) et liquide (1414°C) par LIBS". Thesis, Paris 6, 2015. http://www.theses.fr/2015PA066110/document.
Today, the main limiting factor of PV is the high price of electricity production by the PV modules. To cope with this difficulty, current researches focus on several ways and alternatives solutions: reducing energy costs including reducing the cost of the raw material, which consists in reducing the thickness of silicon wafers or in the development of cells in thin silicon layers. The latter process is intended to overcome the sawing step of silicon ingots which is necessary for the realization of photovoltaic wafer. It is this very approach that led us to develop a method to prepare thin films by using plasma and heating the substrate. Moreover, whatever the method chosen to achieve the required crystallinity and purity for solar grade, it is necessary to have a multi-elements analytical technique to control the evolution of purity. In our laboratory, we have developed LIBS which can meet these expectations, i-e very low detection limits while allowing online tracking of silicon in solid or liquid state
Ben, Salem Mouna. "Développement d'une capsule de prélèvement de microbiote intestinal utilisant un mécanisme bistable et exploitant la fabrication additive". Thesis, Montpellier, 2020. http://www.theses.fr/2020MONTS002.
The diagnosis and the treatment of gastro-intestinal pathologies have experienced significant development in recent years with the invention of endoscopic capsules which facilitate the access to different sections of the gastro-intestinal tract.Although these capsules can perform several functions such as gastrointestinal tract inspection and drug delivery, microbiota sampling still requires surgery in order to collect intestinal liquid samples.We propose through this work a microbiota sampling device that navigates through the gastro-intestinal tract, takes a sample of the intestinal fluid and protects it from any contamination as the device navigates in the human body. We use a bistable structure to close the capsule after sampling and a sponge for the triggering.The device is safe for the human body, as it does not contain electronic components, batteries and does not require any external intervention.To manufacture the microbiota sampling capsule, we use additive manufacturing. This technology offers the use of biocompatible material at a relatively low cost and allows fast prototyping cycle
Liao, Jingjing. "Préparation et modification de composites thermoplastiques/tannins par extrusion réactive". Electronic Thesis or Diss., Université de Lorraine, 2019. http://www.theses.fr/2019LORR0071.
Condensed tannins are widely distributed and highly abundant in nature. In the past decades, such tannins have played an important role in thermosetting systems (e.g. adhesives for wood bonding, foam material) because of their chemical reactivity. However, they also exhibit great potential as a component of polymeric materials because of their physicochemical properties (e.g. antioxidant, antimicrobial and stabilizing properties), which are promising for material preparation. In order to transform tannins from traditional application to a broaden application in polymeric materials, the main challenge facing tannins are their incompatibility with hydrophobic polymer. For this purpose, three modification pathways were developed to improve the compatibility of tannins with PP or PLA matrix. In the first part, PP/ tannins were modified with hexamine or glyoxal via dynamic vulcanization technique. After vulcanized extrusion, vulcanized tannins present better compatibility and UV protective performance in PP matrix. The second approach is CTs modified with acetic anhydride. With this method, up to 30 wt% acetylated tannin (AT) can be well incorporated with PLA while PLA containing up to 20 wt% AT did not deteriorate the mechanical property and surface morphology. This PLA/AT composites are printable via fused deposition modeling process. In the third part, the efficient reactive compatibilization have been successful used to improve the interfacial adhesion between PLA and CTs by using 3-aminopropytriethoxysilane, methylene diphenyl diisocyanate, and dicumyl peroxide (DCP)
Farano, Vincenzo. "An investigation into different phosphate glass processing routes and the role of phosphate glass in dental collagen-based scaffolds". Thesis, Lyon, 2018. http://www.theses.fr/2018LYSE1192/document.
This thesis concerns the development of a new series of Sr-doped phosphate-based glasses for biomedical applications. Such glasses in powder form are envisaged to have applications in novel composite restorations where the following is achievable: dentin cell-mediated bioremineralization, dental pulp regeneration and as carrier for therapeutics or antibacterial ions.The initial aim was to produce soluble porous phosphate glasses using the sol-gel method (phosphate-alkoxide based sol-gel process). Knowing the effect that the variation of Ca content has on the dissolution properties of the glass, a series of glasses where Ca was progressively increased at the expense of Na was produced. The structure of the prepared samples was probed by XRD, XRF and FTIR to confirm the successful synthesis of the target phosphate-based glass compositions. After that a promising methodology was established, attempts were made to replace Ca with Sr. Different Sr sources were used without success due to the difficulty to fully dissolve those precursors in the sol-gel mixture. Subsequently, the issue of the toxicity of some precursors and solvents used in the sol-gel procedure was recognised. To overcome this obstacle, efforts were made to replace the toxic precursor chemicals with safer ones. Nevertheless, due to the low solubility of some new precursors and the low reactivity of others, the sol-gel process did not proceed in a predictable and reproducible fashion. At this stage, the sol-gel route was put aside, and two alternative soft and water-based chemical approaches were experimented: the precipitation method and the coacervation process. The first one was found to be unsuitable for our needs for two main reasons: 1) the presence of Na in the composition generated a crystalline material (instead of a glassy amorphous one); 2) the Ca/P ratio of our composition fell in the range of crystalline phase by using this method. In addition, the yield was really low. The second method (coacervation process) was a complete success. The glassy nature of the materials obtained was proved by XRD and XRF and the surface features were tested by BET and SEM. The process was retained for a while as the preferred synthesis route and both the scale-up effect and the possibility to add Sr were analysed. The production scale of the material was increased by 5 times and different Sr sources were tested to find the best one. XRD and XRF analysis proved both the success of the scale-up and the incorporation of the Sr in glass composition
Lara, Garcia Alejandra. "Optimisation de l'adhésion interfaciale dans l'impression 3D multi-polymère pour améliorer les propriétés mécaniques des structures spatialement amorties". Electronic Thesis or Diss., Université de Lorraine, 2022. http://www.theses.fr/2022LORR0340.
Solutions for improving multi-polymer FFF interlayer adhesion between PLA and a TPC were studied. Two solutions were proposed: (i) the use of adhesion promoter additives and (ii) the synthesis of copolymers incorporating PLA as building blocks. In the first one, different biosourced additives were individually incorporated into the formulation of the TPC. Filament fabrication conditions were optimized to achieve filaments with no defects and a constant diameter. Evaluation of adhesion was done using a modified version of the T-peel test. Only 2-hydroxyethyl starch presented the highest adhesion enhancement with low variabilities. Findings demonstrate the strategic potential of using modified biosourced additives to boost interfacial adhesion between two incompatible polymers. Furthermore, this formulation did not change the vibration-damping and filtering behavior of the TPC. Therefore, it was possible to print a prototype of protective equipment combining a PLA and the formulated TPC, such as a knee pad, using a multi-polymer FFF. The second solution refers to the synthesis through transesterification reactions of PLA and PBT new multiblock copolymers with a reactive extrusion process. Different experiments were done to optimize the transesterification's conditions. Although FTIR, 1H NMR, DSC and DMA results evidence the presence of the copolymer in small amounts, material had low printability presenting layer delamination. Therefore, the evaluation of adhesion was not achieved with this material
Kimouche, Amina. "Vers de nouveaux matériaux hybrides basés sur le graphène épitaxié : contrôle de la formation de défauts et leur rôle dans l’intercalation". Thesis, Grenoble, 2013. http://www.theses.fr/2013GRENY027/document.
Epitaxial graphene grown on metal substrates is a promising platform for developing new hybrid systems, in which interface effects can be exploited to engineer novel properties. The insertion of foreign species between graphene and its substrate, referred to as “intercalation”, was shown very powerful in this respect. With the help of surface science tools, we have studied three graphene/metal systems, two of which are intercalated hybrid systems, and the other is a candidate for such a system: (i) graphene/Ir(111) intercalated with an ultrathin oxide, (ii) graphene/Ir(111) intercalated with cobalt (sub) atomic layers, and (iii) graphene on Re(0001). We found that some defects, especially wrinkles (linear delaminations of graphene from its substrate) and other curve graphene regions, play a crucial, yet unanticipated role in the intercalation process. We also found that the intercalation proceeds in a markedly different fashion under ultra-high vacuum and under atmospheric pressure. In the first system, oxygen-containing species were found to intercalate via the open end of wrinkles, to diffuse along then, and to form oxide nanoribbons along wrinkles accordingly. These ribbons modify the charge density of graphene, which also translates into substantial changes in the inelastic (Raman) optical response of graphene. In the second system, the efficiency of intercalation proved to be dependent on the graphene-metal interaction, which varies between differently oriented graphene domains on Ir(111). In this systems the entry sites for intercalated species could be identified, thanks to in operando observation of the process, as curved regions in graphene. Finally, graphene growth in a third system, graphene on Re(0001), was addressed in order to enable the future development of graphene/Re superconducting hybrids. In this system, we proposed two growth routes, one being a surface-confined process, on bulk single-crystal Re(0001), and the other being a temperature-induced segregation of carbon dissolved at high temperature in thin Re(0001) films on sapphire
Arialdi, Gianluigi. "Contribution de la simulation sur ordinateur à l'interprétation d'expériences spectroscopiques sondant la dynamique locale de fondus de polymères". Doctoral thesis, Universite Libre de Bruxelles, 2003. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/211289.
Une contribution à l'étude de la dynamique des polymères non enchevêtrés à l'état fondu est apportée, en se focalisant sur les aspects de dynamique locale d'un polymère particulier déjà fort étudié expérimentalement et par simulation, à savoir le polyéthylène.
Néanmoins, plusieurs nouveaux résultats spécifiques à cette macromolécule linéaire ou ayant une portée sur les fondus de polymères en général sont obtenus grâce à une approche présentant plusieurs aspects originaux.
Notre étude par simulation de la phase liquide du polyéthylène est menée sur une large gamme de températures. La nouveauté principale à ce sujet est l'attention particulière portée à la qualité d'équilibration des échantillons à chaque température. A cette fin, des techniques sophistiquées d'échantillonnage Monte Carlo, mises au point récemment, ont été utilisées pour générer des configurations initiales, la phase de polyéthylène à l'état fondu ainsi obtenue pouvant être stable ou métastable. Un programme original de Dynamique Moléculaire a par ailleurs été écrit, en incorporant diverses procédures d'optimisation adaptées au cas du polyéthylène représenté par un modèle atomistique.
Des observables de diffusion quasi-élastique de neutrons et de résonance magnétique nucléaire sont analysées sur base d'une combinaison linéaire continue d'exponentielles, dont les poids sont donnés par une distribution des temps de relaxation. Cette méthode permet de mieux mettre en évidence les différents processus de relaxation sondés, en évitant les biais induits par un choix particulier de forme analytique servant à une procédure d'ajustement.
Ayant participé à une expérience de spectroscopie par temps de vol de neutrons, un schéma commun d'analyse est adopté pour les données expérimentales et de simulation concernant le polyéthylène à 450 K. D'autre part, une étude très fouillée de l'évolution de la fonction de diffusion intermédiaire incohérente vers les températures plus basses, suivie par simulation, a permis de distinguer différents processus dynamiques et de déterminer parfois leur origine moléculaire.
Ces résultats sont combinés à une analyse de la fonction d'auto corrélation d'orientation d'un vecteur C-H en termes d'une description microscopique des processus dynamiques, proposée lors d'une étude récente de fondus de polyéthylène par résonance magnétique nucléaire du 13C. Deux approches complémentaires sont exploitées afin de révéler les caractéristiques essentielles des deux types de relaxation impliqués.
Doctorat en Sciences
info:eu-repo/semantics/nonPublished
D'Ans, Pierre. "Contribution à la mise au point d'une démarche rationnelle de sélection des traitements de surface: illustration dans le cas des dispositifs de fonderie de l'aluminium". Doctoral thesis, Universite Libre de Bruxelles, 2009. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/210366.
- Utiliser des multitraitements de surface peut se faire en scindant les différentes requêtes en sous-ensembles, de manière à ce que chaque traitement réponde à l’un d’eux. Dans quel ordre ces requêtes doivent-elles être introduites par rapport au substrat ?
- Comment sélectionner les traitements de surface répondant à chaque requête individuelle ?
- Comment classer des multitraitements en termes d’adéquation au problème posé ?
Dans ce travail, les première et troisième questions sont abordées, en explorant les requêtes concernant habituellement les dispositifs de moulage de l’aluminium :
- Résistance aux contraintes d’origine thermique.
- Résistance à la corrosion par les métaux fondus.
- Résistance au frottement.
L’analyse de la bibliographie relative aux traitements de surface utilisés dans ces systèmes a été analysée et des « architectures »-types ont été identifiées (chapitre 3). On prévoit, par exemple, un traitement conférant la résistance à la fatigue superficielle, ainsi qu’un revêtement étanche et résistant à l’aluminium fondu. Une barrière thermique est parfois préconisée.
Pour chacune des architectures, des traitements de surface individuels peuvent être sélectionnés. Un « facteur de performance » permettant de classer les solutions par rapport au problème de la fatigue thermique a été construit (chapitre 4) et discuté dans deux situations :
- Lorsqu’un revêtement est présent, et que les contraintes d’origine thermique (différence de dilatation thermique couche-substrat) menacent de le rompre lors de l’immersion dans un milieu corrosif à haute température. Des essais de corrosion dans de l’aluminium fondu ont été réalisés sur un acier revêtu par du nitrure de chrome dopé à l’aluminium, synthétisé par déposition physique en phase vapeur (chapitre 5 – collaboration :Inasmet).
- Lorsque des variations thermiques rapides menacent de rompre le substrat et la (les) couches. Des essais de fatigue thermique ont été réalisés sur de l’acier à outils pour travail à chaud non traité, boruré ou recouvert d’un multitraitements (zircone yttriée / NiCrAlY / boruration / acier). Le revêtement en zircone yttriée a été obtenu par projection par plasma. L’essai de fatigue thermique a été modélisé et le facteur de performance, discuté (chapitre 6).
Au chapitre 7, les architectures-types ont été introduites dans une méthodologie de sélection des multi-traitements de surface, qui a été appliquée dans deux cas :
- Celui des moules de fonderie, devant résister à la fatigue thermique et à la corrosion par l’aluminium fondu. Le facteur de performance a été extrapolé à d’autres situations qu’aux chapitres 5 et 6. Les solutions habituellement proposées pour résoudre ce problème sont retrouvées.
- Celui de deux pièces en acier frottant l’une contre l’autre en présence d’aluminium fondu.
To select surface treatments, one must account for the required functional properties, the substrate features and the solicitations the substrate must endure. Certain combinations of these parameters make it difficult to select a single surface treatment, a reason why several successive treatments are preferred. To select them, one needs to determine:
- How to divide the several requests into groups and how to stack up these groups from the substrate to the outer surface, so that each treatment deals with one specific group of requests/properties.
- How to select individual layers for each group of properties.
- How to rank the multi-treatments in terms of relevance for a given application.
In this work, one tries to answer the first and the third questions, by studying the case of aluminium foundry, in which the industrial devices frequently face the following solicitations:
- Thermal stress (thermal fatigue, thermal expansion mismatch).
- Presence of corrosive molten metal.
- Sliding wear.
In the literature, several “standard” architectures are proposed (chapter 3), like a diffusion layer reducing superficial fatigue plus a corrosion barrier layer. A thermal barrier coating is also sometimes proposed.
For each of these architectures, one can select individual treatments. To rank them, one devised a “performance index” for thermal stress (chap.4), which is discussed for two cases:
- For large differences between layer and substrate thermal expansion coefficients, when both are put into contact with a high temperature corrosive medium, the layer may be damaged. One discusses this case by examining the corrosion caused by molten aluminium for a steel substrate coated by anticorrosive chromium nitride doped with aluminium. The layer is produced by physical vapour deposition (chap. 5 – cooperation: Inasmet).
- Repeated fast surface temperature transients can also damage the substrate and/or the layer by thermal fatigue. One conducted thermal fatigue tests with samples of hot work tool steel, respectively untreated, simply borided and protected by a multilayer. In the last case, top coat is yttria stabilised zirconia, followed by a nickel superalloy and then a borided layer (undercoat). One synthesized the zirconia coating by plasma spray and one modelled the thermal fatigue (chap. 6).
In chap. 7, architectures from chap. 2 are introduced in a multi-treatment selection routine, which is applied in two cases:
- Foundry moulds for molten aluminium, withstanding both thermal fatigue and corrosion. The devised performance index is extrapolated beyond the tests of chap. 5 and 6 to treatments for this industrial application, thereby quantifying their respective merits.
- A foundry device exposed to molten metal and sliding wear.
Doctorat en Sciences de l'ingénieur
info:eu-repo/semantics/nonPublished
Sarrabi, Salah. "Vers une approche mécanistique du vieillissement thermique du polyprophylène à l'état fondu au cours du rotomoulage". Phd thesis, 2009. http://pastel.archives-ouvertes.fr/pastel-00004925.
Palomino, Jean-François. "L'État et l'espace colonial : savoirs géographiques entre la France et la Nouvelle-France aux XVIIe et XVIIIe siècles". Thèse, 2018. http://hdl.handle.net/1866/21137.