Teses / dissertações sobre o tema "Nanostructures et nanocomposites"
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Belchi, Raphaëlle. "Architectures à base de nanostructures de carbone et TiO₂pour le photovoltaïque". Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS329/document.
Texto completo da fontePhotovoltaic is a promising renewable energy to tackle global warming and the depletion of fossil resources. The emerging field of perovskite solar cells (3rd generation photovoltaic) is very attractive because it uses abundant and easy-processing materials (low-cost technology) and provides competitive efficiencies.Still, efforts remain to be performed to develop this technology, especially concerning the improvement of efficient and reliable charge transporting electrodes. Titanium dioxide layer, commonly used for electron extraction, presents defects that limit the performance and lifetime of the perovskite solar cells.This work proposes the use of materials based on TiO₂ and carbon nanostructures to improve the electron transport and collection within the solar cells, in order to enhance the power conversion efficiency. The singular technique of laser pyrolysis, which is a continuous process of nanoparticles synthesis, was adapted to produce TiO₂/graphene nanocomposites with well-controlled properties. These materials have been characterized and integrated into perovskite solar cells that demonstrate an improved efficiency in presence of graphene.Besides, this work presents an innovating architecture based on vertically aligned carbon nanotubes for the electron collection of a perovskite solar cell. We show then the strong potential of carbon materials for optoelectronic, especially 3rd generation photovoltaic
Do, Isabelle. "Nanocomposites nanotubes de carbone/élastomère : Propriétés rhéologiques et électriques". Pau, 2007. http://www.theses.fr/2007PAUU3005.
Texto completo da fonteSince carbon nanotubes (CNT) tend to remain as entangled agglomerates, homogeneous dispersed states within a polymer is not easily obtained, which reduces the interest of nanotubes as reinforcements. Many of the solutions proposed to address this issue rely on the modification of the interface between carbon nanotubes and the polymer matrix. The aim of the study is to establish the relationship between the nature of the CNT/polymethylacrylate (PMA) interface and the spatial organization of the CNTs in the matrix, on the one hand, and rheological and electrical properties of the nanocomposites, on the other hand. The interface is controlled by using polyacrylic acid (PAA), either by grafting it on the nanotubes surface, or by using it as a surfactant. The study of the morphology of the composites by electronic microscopy showed the importance of distinguishing the distribution of CNTs in the matrix (i. E. The repartition of the nanotubes clusters in the whole sample), from their dispersion (i. E. Their individualization within the clusters). This distinction is central as it allows explaining the physical properties of the nanocomposites. The studies of the linear viscoelastic and electrical properties of the composites highlighted the existence of percolation phenomena. We also showed that the electrical properties of the composites are sensitive to the CNTs dispersion, whereas the rheological ones are sensitive to the quality of distribution. The use of PAA, either grafted or adsorbed on nanotubes, allows an increase in electrical conductivity as well as a better dispersion of the nanotubes, thus lowering the electrical percolation thresholds
Mayne-L'Hermite, Martine. "Elaboration, microstructure et comportement au fluage de nanocomposites Si3N4/SiC". Limoges, 1997. http://www.theses.fr/1997LIMO0021.
Texto completo da fonteHoang, Minh Tuan. "Modélisation et simulation multi échelle des effets de taille et des couplages électromécaniques dans les nanostructures". Thesis, Paris Est, 2014. http://www.theses.fr/2014PEST1074/document.
Texto completo da fonteNanostructures, and more specifically semiconductor nanowires, have drawn special attention in recent years for many applications such as energy harvesting systems or sensors of very high precision. Many recent experiments and theoretical ab-initio calculations have evidenced size effects, which can significantly modify the electromechanical properties of nanowires for diameters below 10 nm. The objective of this thesis is to provide multi-scale modeling of electromechanical properties of nanostructures, such as ionic nanowires and laminated nanocomposites, to reproduce the size effects associated with nanoscale in a continuum model, based on ab-initio calculations to identify and validate the models. In a first part, the surface effects in isolated homogeneous piezoelectric nanowires are modeled. A multi-scale approach is developed, including continuous nanowires modeling taking into account an additional surface energy in the piezoelectric laminates where the associated parameters are identified by ab-initio calculations. For this, a procedure based on slabs is developed, allowing through first-principles calculations on successive slabs thicknesses to isolate the surface energy and to deduce the surface elastic and piezoelectric coefficients. The equations of the continuous model are then solved by a finite element method including appropriate surface elements. The continuous multi-scale model is compared with ab-initio calculations involving full atomistic models of nanowires with different diameters (from 0.6 to 3.9 nm) to validate model regarding size effects of electromechanical properties. In the second part, multi-scale models are constructed to describe the size effects for heterogeneous nanostructures. These structures include coated nanowires or laminated nanocomposites. For nanowires with radial heterogeneity, the previously developed approach is extended to the case of coated surfaces, and involves a continuous surface energy incorporating the effects of the coating. For laminated AlN/GaN nanocomposites, size effects observed by ab-initio calculations are caused by the presence of the interfaces and induce size-dependent elastic properties with respect to the layer thickness. A continuum model based on an imperfect interface is proposed to describe the size dependent effective elastic properties of the overall composite, which are identified by ab-initio calculations. In the last part, nanogenerators system based on nanowires are modeled, involving nanowires arrays aligned in polymer substrates with graphene electrode. The previously developed finite element models are used to simulate the electromechanical properties of such systems
Habis, Christelle. "Development of ZnO-FTO nanocomposites for the use in transparent conductive thin films". Electronic Thesis or Diss., Université de Lorraine, 2022. http://www.theses.fr/2022LORR0192.
Texto completo da fonteMy thesis work entitled “Development of ZnO-FTO nanocomposites for the use in transparent conductive thin films” is supervised by Professor Michel Aillerie at University of Lorraine. This work was mainly made at the “Laboratoire des Matériaux Optiques, Photoniques et Systèmes” LMOPS in Centrale Supélec, Metz. Although this work forms a whole in the elaboration of transparent conductive oxides, it is divided into two parts. The first part consists on identifying the properties of bulk materials (ZnO and FTO) deposited in the form of thin film. Whereas, the second part is about the elaboration and characterization of Zinc Oxide (ZnO) and Aluminum doped Zinc Oxide (AZO) nanofibers, then associated to FTO thin films to form nanocomposite. The main objective of this work is to make flexible electrodes using low cost and abundant material, but also improving the optical properties and more specifically the haze factor of the nanocomposite layers.Transparent conductive oxides (TCOs) are technologically significant class of materials extensively used in thin film solar cells due to their ability to transmit light and collect charge carriers. In addition to the fundamental qualities of transparency and conductivity, the TCOs are frequently desired to have a certain degree of surface roughness (i.e., texture) in order to effectively scatter transmitted light into the active materials, therefore lengthen the optical path and, as a result, enhance the performance of the cell and light absorption. This thesis focuses on the development of low-cost fabrication techniques for transparent oxide layers using non-polluting materials to enable the functionalization of operational devices with high efficiency for renewable energy production. The choice was made to study tin-based TCO layers doped with fluorine, F:SnO2, known as FTOs for "Fluor Tin Oxides". FTOs are wide band gap oxides, like ZnO, TiO2, Al2O3, pure or doped. In principle, these layers have a high scattering factor, as defined above, in order to improve the optical path and absorption. In addition, the optical texture of TCOs can be easily controlled by depositing suspensions of nanostructures before the film deposition. Generally, these nanostructures are nanoparticles or even carbon nanowires or metallic nanowires (silver, copper, ...) and more recently nanowires of TiO2 (presenting the disadvantage of the titanium element) or of undoped ZnO which unfortunately decrease the conductivity due to the increase of the interface resistance with the concentration of the nanoparticles.Therefore, we propose the study of FTO thin films, pure and also in the presence of ZnO and AZO nanofibers by electrospinning from a PVA-based solution in order to have a nanostructured layer with improved transparency and electrical conductivity properties to be integrated as transparent electrodes in photovoltaic cells, meeting the performance criteria defined above. With the characterization techniques available in the LMOPS laboratory and the University of Lorraine (SEM, Raman, EDX, DRX, UV-vis Spectro, ATG, AFM, profilometer) the growth will be followed by morphological and structural studies of the layers. Finally, electrical and optical properties, in particular absorption and scattering factor, will also be extensively investigated on selected layers with the best structural and morphological properties and the minimum of interface defects when deposited on a PV structure
Zaitsev, Andrii. "Exploration de la voie plasma pour la synthèse de nanostructures et de nanocomposites à base de polyaniline". Thesis, Le Mans, 2015. http://www.theses.fr/2015LEMA1014/document.
Texto completo da fontePolymer nanostructures are of great interest due to their unique properties such as high shape factor. This property is essential for applications where surface interactions are involved. One example of such an application is the gas detection. Polyaniline (PANi) has been shown as a promising material for ammonia detection. Conventional synthesis (chemical orelectrochemical) of PANi nanofibers has been widely described in the literature but this way has many drawbacks. They include several steps (synthesis, purification, deposition on the substrate) and the use of chemicals (oxidants, acids) which are not environmentally friendly. The polymerization assisted by cold plasma (PECVD) allows overcoming it, as only themonomer is used and is directly polymerized on the substrate. This thesis work aims to develop plasma polyanilinenanostructures while retaining the monomer unit in the polymer. The key parameter that determines thenanostructuring process is the discharge power. At high power, highly structured films are obtained but the monomer molecules are totally fragmented. On the contrary, low power allows conservation of the monomer unit but no surface structuring is observed. We developed a method which combines the advantages of each regime. This "bottom-up" process consists to vary the input power during deposition in two or three stages. Parameters influencing the chemical and morphological structures are determined and the two and three steps methods are compared. Furthermore, the "top-down" synthesis of nanostructures by etching the PANi layer is also studied according to the plasma parameters (power and discharge time, etching gas flow rate and substrate bias). Finally, in plasma phase, we synthesized nanocomposite by combining PANi nanostructures and sputtered Pd particles. The chemical structure of the PANi films is characterized by UV-Vis spectroscopy, FT-IR and XPS. In order to highlight the nanostructuring of thin films, SEM and AFM microscopy areused. The latter one allows also the calculation of the roughness and specific surface of the PANi. EDX spectroscopyis used to bring out the presence of palladium and to quantify it. Finally, the obtained layers are characterized under gas byabsorbance variation measurements in order to determine their sensitivity and response time to ammonia
Dubois, Jean-Baptiste. "Conducteurs nanocomposites métalliques élaborés par déformation plastique sévère : formation et stabilité thermo-mécanique des nanostructures, propriétés induites". Poitiers, 2010. http://theses.univ-poitiers.fr/26782/2010-Dubois-Jean-Baptiste-These.pdf.
Texto completo da fonteThis thesis concerns the study of metallic nanocomposite copper/niobium (Cu/Nb) wires, combining high electrical conductivity and high strength, as required for the design of high magnetic field resistive coils. The reinforced continuous nanocomposite Cu/Nb conductors are fabricated via a severe plastic deformation process (SPD), which consists in repeated extrusion, drawing and bundling cycles (Accumulative Drawing and Bundling : ADB) and leads to the nanostructuration of the Nb reinforcements and a multi-scale Cu matrix. In order to optimize the process, the effect of heat treatments on texture and its development during the process were analysed by means of laboratory X-ray diffraction. Complementary in-situ heat treatments under synchrotron radiation gave a better insight into the elementary annealing mechanisms and enabled defining optimized heat treatments. These experiments also revealed that the thermal stability of Cu/Nb conductors is extremely dependent of the microstructure size: recovery, recrystallization, grain growth and all relaxation processes are frustrated in the case of nanocomposites. From these results, optimized “co-axial” conductors reinforced by Nb nanofilaments and nanotubes were processed. Their microstructure and physical properties have been characterized and compared to those of previous Cu/Nb nanocomposite conductors. With the possibility to produce long wires with improved properties, these new Cu/Nb nanocomposites offer a great alternative to existing conductors for future high magnetic field applications
Aldroe, Hanaya. "Analyse des propriétés physiques et mécaniques des nanocomposites polyamide 12 / cloisite® 30B en lien avec leurs nanostructures". Thesis, Tours, 2014. http://www.theses.fr/2014TOUR4034/document.
Texto completo da fonteNanocomposites are interestingly growing since their development in the 1990s by Toyota Company. Therefore, improving the properties of such materials is a major issue from fundamental and industrial point of view. This improvement can pass through a relevant choice of reinforcing loads added to the matrix particularly regarding the type, geometry, the proportion, and the treatment of these fillers. The processing parameters of the mixture play also a key role. The objective of this work is to contribute to the identification and understanding of the mechanisms at the origin of the reinforcing thermoplastic matrices by nanofillers. This aspect presented through the study of the thermal and mechanical properties of nanocomposites formed by a polyamide 12 matrix (PA12) filled with organically modified clay nanoparticles. More specifically, we analysed the effects of the filler mass fraction and environmental aging on structural, thermal and mechanical properties of these nanocomposites. The mixing conditions on these properties were also examined. A particular attention has been paid to the study of relationships between the macroscopic properties and the structure of nanocomposites. Viscoelastic properties of these materials in both melt and solid states were compared, which represents one of the originalities of this work
Laurent, Christophe. "Contribution à l'étude de nanocomposites à matrice céramique. Alumine-alliages fer-chrome et alumine-zircone-fer et alliages fer-chrome". Toulouse 3, 1994. http://www.theses.fr/1994TOU30017.
Texto completo da fonteSauvage, Xavier. "Transformations de phases induites par déformation plastique intense. Cas des aciers perlitiques tréfilés et des nanocomposites filamentaires Cu/Nb". Rouen, 2001. http://www.theses.fr/2001ROUES032.
Texto completo da fonteThilly, Ludovic. "Exploration theorique et experimentale de fils nanocomposites continus presentant des proprietes extremes de conductivite electrique et de limite elastique : application future : Coilin 100 t". Toulouse, INSA, 2000. http://www.theses.fr/2000ISAT0028.
Texto completo da fonteKintz, Harold. "Réalisation de couches minces nanocomposites par un procédé original couplant la pyrolyse laser et la pulvérisation magnétron : application aux cellules solaires tout silicium de troisième génération". Phd thesis, Université Paris Sud - Paris XI, 2013. http://tel.archives-ouvertes.fr/tel-00958453.
Texto completo da fonteDems, Dounia. "Nanostructuration de particules de silice et élaboration de biomatériaux composites". Electronic Thesis or Diss., Sorbonne université, 2018. http://www.theses.fr/2018SORUS373.
Texto completo da fonteThis work describes the design of tunable biomaterials for tissue engineering. The composite approach provides numerous advantages to enhance cell adhesion and control bioactivity by complying both with structural and functional requirements. The host matrix, made from a natural macromolecule (collagen), or from synthetic supramolecular polymers (peptide amphiphiles), provides a suitable structural environment to the cells and can also display intrinsic biochemical cues to influence cell behavior. Functionalized silica nanoparticles can be added to be used as platforms either to further tune the architecture of the scaffold or display additional bioactive ligands. The combination of peptide amphiphiles with such nanoparticles led to composite biomaterials with high modularity allowing to compare different displays of one bioactive epitope and the simultaneous grafting of two epitopes known to work in a distance-dependent manner. The next step was to achieve the control of the spatial organization of several functions on the surface of a single nanoparticle. We have developed an original and challenging strategy based on the synthesis of self-assembling alkoxysilane precursors that could form pre-organized domains to be transferred at the silica nanoparticle surface to create patches. A large library of mono- and bifunctional particles were prepared that were incorporated in collagen-based threads evaluated in a model of peripheral nerve regeneration. Finally, we have elaborated thin porous scaffolds by electrospinning collagen in non-denaturing conditions that should allow to improve the cells access to the functional nanoparticles
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.
Texto completo da fonteBouakaz, Boubkeur Seddik. "Effets de synergies entre montmorillonites organophiles (OMMT) et graphène dans les nanocomposites à base de polymères biodégradables". Thesis, Lorient, 2017. http://www.theses.fr/2017LORIS430/document.
Texto completo da fonteThe work carried out during this thesis highlights the effect of different kinds of organophilic clays OMMT (Cloisite®15A and Cloisite®30B) and/or epoxy functionalized graphene (Gr) on the functional properties of biodegradable polylactic acid (PLA), poly (ε-caprolactone) (PCL) and their mixture PLA/PCL (70/30 mass%). The first part is devoted to study the binary mixtures (PLA/Cloisite® and PLA/Gr) and ternary materials (PLA/Cloisite®/Gr) prepared via melt blending method. The combination of the two fillers (OMMT and Gr) improves all the rheological parameters of the PLA matrix and contributes to the appearance of a pseudo-solid viscoelastic behavior for PLA/Gr composites in the presence of clays, attributed to the better dispersion confirmed by transmission electron microscopy. The water vapor permeability, thermal and thermomechanical properties of PLA have been significantly improved, especially in the presence of hybrids OMMT/Gr and show the great interest of PLA/Cloisite®/Gr ternary nanobiocomposites in several applications. The second part is related to nanocomposite materials based on the biodegradable PCL matrix. The rheological study confirms the advantage of combining the organomodified clays and graphene nanofillers, and indicates the presence of tridimensional networks in the binary nanocomposites PCL/OMMT and PCL/OMMT/Gr. The good state of dispersion of the hybrids nanofillers (OMMT + Gr) has considerably improved the water vapor permeability and the thermal resistance of the PCL matrix. The dispersability of the nanofillers and their effect on the miscibility were the subject of the last part devoted to the PLA/PCL immiscible blend. Very interesting viscoelastic properties were obtained after the incorporation of the OMMT/Gr mixtures, indicating the existence of good level of distribution of nanofillers in the PLA/PCL matrix. The synergy between the OMMT and epoxy functionalized graphene led to the best improvement in term of barrier properties, thermal stability and compatibility of the matrix
Ngo, Biboum Bimbong Rosa. "Polyoxométallates et chimie verte : molécules et matériaux nanostructurés pour la conversion de l’énergie et l’environnement". Thesis, Paris 11, 2011. http://www.theses.fr/2011PA112095/document.
Texto completo da fonteThis thesis focuses on the synthesis of nanostructured composite materials based on polyoxometalates for energy conversion and applications to environmental problems. To achieve these goals, many new compounds of this family of molecular oxides were synthesized and were associated with different nature friendly matrices, in agreement with the main criteria of Green Chemistry. In the field of energy, the new catalysts have proved very effective in important but difficult to achieve reactions, such as producing hydrogen, oxygen reduction or water oxidation. Similarly, among applications to pollution problems, these nanomaterials have shown a strong electrocatalytic and photocatalytic activity for the reduction of nitrogen oxides, bromate and for the photodegradation of a toxic textile dye, Acid Orange 7. The performances of these new catalysts are comparable to those of the best known systems
Kostadinova, Dessislava. "Préparation et caractérisation de catalyseurs métaux supportés à partir de nanocomposites colloïdes métalliques/HDL". Montpellier 2, 2007. http://www.theses.fr/2007MON20211.
Texto completo da fonteNgo, Biboum Bimbong Rosa. "Polyoxométallates et chimie verte : molécules et matériaux nanostructurés pour la conversion de l'énergie et l'environnement". Phd thesis, Université Paris Sud - Paris XI, 2011. http://tel.archives-ouvertes.fr/tel-00612028.
Texto completo da fonteFraga, Malfatti Célia de. "Elaboration et caractérisation de revêtements nanocomposites NiP/SiC électrodéposés". Toulouse 3, 2004. http://www.theses.fr/2004TOU30287.
Texto completo da fonteIn this work electrodeposited Ni-P/SiC composites coatings had been electrodeposited from a nickel salts solution containing H3PO3 and SiC particles in suspension (600nm and 30nm). Through measures of viscosity and sedimentation speed it was evidenced that the size of particles is a very important characteristic and it influences in the suspension stability. We had shown that organic additives modifies the characteristic of suspensions. Depending on size particles the organic additives can change the number of incorporated particles. It was observed that depending on the particles concentration in suspension, the number of incorporated particles in deposits can be changed. The incorporation rate evaluated as a function of the fraction in volume reaches a plateau, but continues to increase if it´s evaluated as a function of the number of particles. For the suspensions with raised particles concentration, the incorporation process becomes selective, and the particles with small size are preferentially incorporated. Microhardness measurements, thermal analysis and electrochemical analysis, (cyclic voltammetry and electrochemical impedance spectroscopy) were used to evaluate the influence of the amount and distribution of SiC incorporated particles on the microhardness, corrosion and thermal behaviour of Ni-P/SiC composite coating
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.
Texto completo da fonteNanocomposites 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
Peurton, Frédéric. "Nanocomposites à matrice thermoplastique et renforts plaquettaires : relations élaboration-structure-propriétés". Thesis, Lille 1, 2008. http://www.theses.fr/2008LIL10168/document.
Texto completo da fonteNanocomposites 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
Gaudin, Michael. "Ablation laser impulsionnelle : source de nanoparticules en vol et de films minces : Développement de matériaux nanostructurés à base d'argent, de vanadium et de dioxyde de vanadium". Thesis, Limoges, 2017. http://www.theses.fr/2017LIMO0025/document.
Texto completo da fonteThe work presented in this thesis is focused on the development of an experimental setup for the synthesis of nanoparticles (NPs) by a physical route, based on the laser vaporization of a target and followed by the rapid quenching of the plasma plume. Combining such a NP source with conventional laser ablation makes possible to synthesize silver and vanadium NPs in stacks on substrates or embedded in different matrices synthesized by laser ablation. Transmission electron microscopy (TEM) and atomic force microscopy (AFM) analysis revealed crystallized spherical NPs relatively monodisperse in size (~ 3 nm in diameter) depending on the residence time in the nucleation cavity. The synthesis of amorphous Al2O3 nanocomposites doped with metallic silver NPs of different sizes showed the influence of the size on the position and the width of the surface plasmon resonance (SPR) of the nanostructured material. The NPs keep their original shape during impact on the substrate, leading to highly porous NPs stacks (approximately 50%). Vanadium dioxide nanoparticles (VO2 NPs) have been synthesized by annealing vanadium NPs stacks. Due to their individual behaviour, VO2NPs exhibit lower transition temperature (~ 50°C) and larger hysteresis width (~ 10-30°C) than thin films (transition temperature around 68°C and hysteresis width around 3°C). By coupling a PLD thin film and a NPs stack, it is possible to combine their properties and obtain a nanostructured material having a step transition
Yama, Nzoma Evarice. "Elaboration par Déformation Plastique Intense et Caractérisatioin de Composites Multifilamentaires nanostructurés Cuivre-Carbone". Rouen, 2009. http://www.theses.fr/2009ROUES052.
Texto completo da fonteThe nanostructuring by severe plastic deformation has a clear interest in the development of nanomaterials. Our work contributes to the development of bimetallic multifilamentary materials, where structural dimensions are of the order of the micron or nanometer. The production process based on the so-called "Levi process" developed in the sixties, consists in a serie of steps that include a cold drawing, bundling of drawn materials, then re-stacking of these elements, followed by another cold drawing. Two materials : Cu-CGr and Cu-C60, were developed. The result is a material with a multifilamentary and multiscale microstructure with properties that combine a high yield stress, good electrical conductivity and low thermal expansion coefficient. In, this system, the properties of composites do not follow the "linear law of mixtures" due to the microstructure of the composites
Bosq, Nicolas. "Nanocomposites à matrice polymère : influence de silices nanostructurées sur la cristallisation, la transition vitreuse et les propriétés thermomécaniques". Phd thesis, Université Nice Sophia Antipolis, 2013. http://tel.archives-ouvertes.fr/tel-00932853.
Texto completo da fonteLozay, Quentin. "Conception et caractérisations de matériaux composites nanostructurés à hautes propriétés barrières. Etude films multinanocouches de PE et PA6 chargés de montmorillonite". Thesis, Normandie, 2020. http://www.theses.fr/2020NORMR012.
Texto completo da fontePolymers are used in many fields such as packaging, automotive, etc. as they have good mechanical, thermal and barrier properties. Economic and environmental challenges are driving development towards more efficient and lighter materials. The aim of this thesis work was to develop multilayer composite films based on polyethylene (PE) and polyamide (PA6) with high gas and water barrier properties. A coextrusion process with multiplier elements made it possible to carry out 100 μm thick multilayers containing up to 2049 layers. Two series of PE-binder-PA6 films of different compositions were studied. Clays (organo-modified montmorillonites) were incorporated (at 0.5 and 5 wt%) into the alternating layers of PE and PA6. The structural, thermal and mechanical properties of these multilayers have been correlated with the transport properties. We observed confinement effects on nanostratification of films and crystallinity of polymers and the impact on barrier properties. We showed the complexity of the multinanolayer structures involving interphases as well as the complexity of the transfer mechanisms. The serial model for predicting permeability highlighted significant improvements in the gas barrier properties of confined PE layers but in water. The barrier effect on all of the multilayers was, however, limited due to the “on edge” orientation of the crystalline phases and structural defects. The confinement of nanofillers (at 1% v/v) in PA6 layers has made it possible to increase the barrier properties of multilayers
Charlon, Sébastien. "Elaboration et caractérisation de nouveaux systèmes nanocomposites à propriétés de transport contrôlées. Impact d'un nouveau procédé de mise en oeuvre". Rouen, 2015. http://www.theses.fr/2015ROUES011.
Texto completo da fonteDuring the last decades, a waste-reduction program, specifically for plastic packaging, was promoted due to environmental drawbacks with the development of biodegradable polymers. However, barrier properties of these biodegradable materials must be often improved to be competitive with common polyolefins (PE, PP, PET, etc. ). In this objective, the incorporation of nanofillers using industrializable processes seems to be a promising approach. Indeed, the introduction of inorganic nanofillers like clays (montmorillonite) into a polymer matrix often increased barrier properties of the polymer matrix. In this study, composites were prepared from biodegradable matrices such as Poly(Putylene Succinate) (PBS) and Poly(Butylène Succinate-co-butylène Adipate) (PBSA) loaded with Cloisite Na+ or Cloisite 30B. An extrusion process was applied with the use of liquid water injection under high pressure and high temperature into thermo-moulding or extrusion-calandaring processes. Kinetic permeation revealed changes in barrier properties as function of the elaboration process or the polymer matrix used. These results were explained from structural charectirizations (DSC, XRD) and microscopy observations (TEM) in order to correlate barrier peoperties to the dispersion and exfoliationlevels of fillers into the polymer matrices, to the degrees of cristallinity and to the rigid amorphous fractions (RAF) of the bio-polymers
Saitzek, Sébastien. "Systèmes multifonctionnels à base de dioxydes de cérium nanostructurés. Nanocomposites catalytiques CeO2-CuOx et bicouches CeO2-VO2 pour commutation en optoélectronique IR". Toulon, 2005. http://www.theses.fr/2005TOUL0014.
Texto completo da fonteCerium dioxide is known as presenting a large variety of physico-chemical properties: it can be considered as a multifunctional compound. We present two studies linked to two types of applications in which cerium dioxide is involved as a multifunctional phase: catalytic behaviours of nanocomposite systems CeO2- CuOx for gas sensor applications, optical responses and chemical stability of CeO2-VO2 bilayers for infrared applications. This last study is connected with new technologies like bolometric applications (IR camera). The first study consisted in preparing nanostructured systems CeO2-CuOx from low temperature routes (soft chemistry including sol-gel, low temperature processes). This nanocomposites were characterized from X-ray diffraction, electron microscopy techniques, BET analyses. Infrared spectroscopy associated with homemade equipment was then used to follow catalytic reactions in presence of gas mixtures (air-CH4 or air-CO). A modelling approach is presented to interpret the IR analyses and the catalytic site saturation, observed in the case of ceria based systems. The CuOx –ceria samples were then compacted and inserted in a homemade electronic system to analyse the influence of CO or CH4 reducing gases, on surface conduction of CuOx-CeO2 pellets. The results obtained from FTIR analyses and electronic measurements are found to be coherent: the copper additions decrease the durability of catalytic responses of these nanocomposite systems, however they increase the sensibility in the case of low Cu additions. This might be interesting for gas sensor applications. The second study deals with CeO2-VO2 bilayers obtained from sputtering techniques and deposited in Si and SiO2 substrates. RF sputtering parameters were optimised to deposit first VO2 then CeO2 thin layers. The role of CeO2 was to insure a protection of the VO2 layer from aggressive environments, without degrading optical responses. Starting from a low cost target of V2O5 , layers of VO2 were obtained. We show that these bilayers present a good thermochromic optical contrast (insulating-metal transition at 68°C). Ceria is known as being transparent for IR wavelengths and opaque for UV radiation. However, the emissivity depends on ceria layer thickness. These new bilayers present a double interest: they can present increased chemical stability (improvement of lifetimes), and they can be used to modulate infrared emissivity responses in the case of IR detection
Houf, Latifa. "Développement de nanocomposites à propriétés piézoélectriques et optiques non-linéaires". Phd thesis, Université de Grenoble, 2011. http://tel.archives-ouvertes.fr/tel-00686925.
Texto completo da fontePorcher, Marina. "Matériaux nanostructurés polymères conjugués/nanotubes de carbone verticalement alignés pour la réalisation de supercondensateurs". Thesis, Tours, 2016. http://www.theses.fr/2016TOUR4025/document.
Texto completo da fonteThis thesis focused on the elaboration of nanostructured composite materials based on vertically aligned carbon nanotubes (aligned CNT) and π-conjugated polymers and their use as electrode materials in supercapacitor-type energy storage devices. The first part focused on aligned CNT growth by aerosol-assisted CVD on stainless steel substrates and the deposition of a SiOx ceramic sublayer. Thanks to the optimization of this growth process, long, dense, and aligned CNT carpets which can directly act as support for the electrodeposition of π-conjugated polymers were obtained. The second part focused on the electrodeposition of poly (3-methylthiophene) (P3MT) in EMITFSI ionic liquid medium on aligned CNT carpets using a “pulsed” chronopotentiometric method to produce homogeneous deposits in the depth of the carpets. An optimal P3MT mass composition of 70 %, which helped achieve a specific capacitance of 170 F.g-1 of polymer while maintaining high charge-discharge kinetics, compared with NTC/P3MT entangled composites, was determined. NTC/P3MT // P3MT/NTC symmetrical devices and CA // P3MT/NTC hybrid devices were assembled using the optimized composite materials. The hybrid device reached a voltage of 2.7 V and a system capacitance of 26 F.g-1 in EMITFSI at 25 ° C. Furthermore, a maximum energy of 23 Wh.kg-1 and a maximum power of 6.9 kW.kg-1 were obtained with only a 7 % loss after 4000 cycles. Finally, the electrodeposition of polypyrrole (Ppy) was investigated in different protic and aprotic ionic liquids. After quartz crystal microbalance studies in order to better understand the insertion mechanisms of ionic species during conjugated polymer growth and during its reversible positive doping, the electrodeposition of Ppy within the deepness of the aligned CNT carpets was optimized. Aligned CNT/Ppy nanocomposites with specific capacitances ranging between 100 and 130 F.g-1 were obtained
Shen, Yan. "Synthèse de poudres nanocomposites et dépôts de cathodes pour les piles à combustible à température moyenne". Mémoire, Université de Sherbrooke, 2011. http://savoirs.usherbrooke.ca/handle/11143/1620.
Texto completo da fonteAboulaich, Abdelhay. "Synthèse de nanoparticules d'oxydes et d'oxydes métalliques par sol-gel non-hydrolytique". Montpellier 2, 2009. http://www.theses.fr/2009MON20126.
Texto completo da fonteAmorphous and crystalline nanoparticles (SiO2, SiO2-TiO2, TiO2 and SnO2) were prepared by non-hydrolytic sol-gel process. The synthesis is based on non-hydrolytic condensation reactions of metal chlorides MCln with isopropyl ether or tétraisopropoxyde corresponding metal. SiO2 nanoparticles have been used successfully for the preparation of nanocomposite polymer. The synthesized nanoparticles are reactive to nucleophile agent and are successfully used for the preparation of nanostructured layers
Toudert, Johann. "Croissance, nanostructure et réponse optique de films minces d'agrégats d'argent dans des matrices diélectriques". Phd thesis, Université de Poitiers, 2005. http://tel.archives-ouvertes.fr/tel-00502443.
Texto completo da fonteBrasse, Gurvan. "Fibres optiques nanostructurées par voie sol-gel dans le système silice-zircone dopé terre rare : élaboration, caractérisation microstructurale et étude des propriétés de luminescence". Limoges, 2009. http://aurore.unilim.fr/theses/nxfile/default/0062135b-4c89-459a-b1f7-8746d2cce606/blobholder:0/2009LIMO4018.pdf.
Texto completo da fonteThe nanomaterials and the optical fibers are respectively in the center of the scientific and technological revolution of the last years. This thesis suggest to associate these two fields of applications, in order to elaborate new kinds of optical fibers, which present a solid core nanostructured by the sol-gel process in the silica-zirconia system doped with rare earth ions. Based on a rheological study of silica-zirconia sols, as well as thermogravimetric, thermodifferential and microstructural analysis of silica-zirconia xerogels, an elaboration method of such a fiber is defined. The so elaborated fibers are then characterized on a microstructural point of view (XRD, SEM), as well as on an optical point of view (transmission, index profile, chromatic dispersion, losses). The luminescence properties of the erbium and/or ytterbium doped fibers and undoped fibers are studied and the corresponding mechanisms are discussed. Whole of this work leads to the realization of optical fibers which present a solid nanocomposite core, with good waveguiding properties and weak losses, by taking into account the aimed applications. Original luminescence properties are finally highlighted
Banet, Laurent. "Etude des propriétés diélectriques des matériaux nanocomposites innovants : application à l'isolation des alternateurs de puissance du futur". Thesis, Montpellier 2, 2012. http://www.theses.fr/2012MON20189.
Texto completo da fonteThis work aims to access the impact of nanostructuring over the impregnation resin, developed for the electrical insulation of alternator stator bars, on their electrical and thermal properties. The first step of this study concerns the analysis of impregnation resins with improved physical properties with respect to the usual resins. The second part concerns the characterization of prototypes which are manufactured by Alstom and Von Roll companies; these prototypes are composed by a tape (mica paper and glass fabric) impregnated with the innovative resin.In the best case, the modifications of the resins and the prototypes led to respective improvements up to 14 % for the dielectric strength, 30 % for the thermal diffusivity and 100 % for the voltage endurance. A decrease up to 33 % of the space charge levels can be also observed.The results obtained show that it is possible, in some cases, to improve the electrical and the thermal properties of the insulation by modifying the impregnation resin and the prototypes, with the addition of boron nitride (BN) submicron particles and/or silicon dioxide (SiO2) nanoparticles. However, it is shown that these properties can be highly influenced by the manufacture process of the resin and the prototypes, in particular by the curing parameters
Nguyen, Van Son. "Élaboration de films nanocomposites hybrides P(VDF-TrFE)/nanocristaux, et intégration dans des dispositifs microstructurés". Thesis, Université de Lorraine, 2012. http://www.theses.fr/2012LORR0075/document.
Texto completo da fonteThe objective of this work is to develop flexible organic/inorganic hybrid materials for application in microsystems. This study included the preparation and characterization of nanocomposites based on ferroelectric polymer matrix P(VDF-TrFE), potential materials for applications based on thin films on substrates, and different types of nanoparticles: ZnO, LiNbO3 (piezoelectric) and Al2O3 (non-piezoelectric). The protocols of the ultrasonic dispersion of nanoparticles in solvents and polymeric solutions are optimized, allowing dispersing quite homogeneously clusters of nanocrystals in the matrix copolymer. Films of controlled thickness between 0.1 µm and 100 µm were fabricated by spin-coating and doctor blade coating with surface quality suitable for micro-technologies. Morphology and crystallinity of P(VDF-TrFE) are preserved in the presence of up to 10 wt.% of nanoparticles. Thus nanocomposites keep high piezoelectric properties and show an increased up to 30% of the mechanical properties for 10 wt.% ZnO or Al2O3. In addition, the increase in elastic constant with decreasing cluster size of nanoparticles was observed. Nanocomposite films on substrates or free-standing filled up to 10 wt.% were successfully polarized by corona without contact. Specific procedures for preparing microdevices by photolithography on nanocomposite polymer films, while keeping piezoelectric activities of materials, have been developed. The characterization of realized acoustic wave devices is also presented
Escobar, Teran Freddy David. "A new approach towards understanding the ion transfer dynamics in nanostructured carbon-based thin films for energy storage applications". Thesis, Paris 6, 2016. http://www.theses.fr/2016PA066363/document.
Texto completo da fonteCarbon nanotubes (CNTs) and Electrochemically Reduced Graphene Oxide films were prepared on gold electrodes of microbalance and tested in different electrolytes such as LiCl, NaCl and KCl. The capacitive charge storage of carbon-based film electrodes were investigated by ac-electrogravimetry which couples fast quartz crystal microbalance (QCM) and electrochemical impedance spectroscopy (EIS). The chemical nature and the role of each species, anion, cation, solvated cation, free solvent, involved in the charge storage mechanism, have been clearly identified during the cathodic and anodic polarization through ac-electrogravimetry measurements for the very first time. The ac-electrogravimetric results confirm that the cations are predominantly electroadsorbed when the surface is negatively charged while the anions are electroadsorbed when the surface is positively charged. Nanocomposite films, namely SWCNT/Prussian Blue and SWCNT/Polypyrrole were electrochemically examined. The main idea was to emphasize the capacitive and faradic behavior of these different films by combining two materials. The chemical nature and the role of each species involved in the pseudo-capacitive and capacitive processes were highlighted by the ac-electrogravimetry. The methodology adapted to characterize carbon based electrodes can be suggested as a baseline diagnostic tool to study the pore/ion size relationship, the concentration and the solvent effects, the dynamics of the ions interactions at the interfaces (electroadsorption and/or faradaic process) of the electrode materials which may pave the way towards more performant electrode/electrolyte systems in energy storage devices
Chazeau, Laurent. "Etude de nanocomposites à renfort cellulosique et matrice poly(chlorure de vinyle) : mise en oeuvre, étude structurale, comportement mécanique". Université Joseph Fourier (Grenoble), 1998. http://www.theses.fr/1998GRE10001.
Texto completo da fonteBouclé, Johann. "Elaboration et étude des propriétés électro-optiques de matériaux hybrides à base de nanocristaux de carbure de silicium". Phd thesis, Université du Maine, 2004. http://tel.archives-ouvertes.fr/tel-00007825.
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