WorldCat Identities

Hoppe, Sandrine (19..-....).

Overview
Works: 18 works in 23 publications in 2 languages and 23 library holdings
Roles: Thesis advisor, Opponent, Author, Other
Publication Timeline
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Most widely held works by Sandrine Hoppe
Contribution à l'étude de deux procédés d'élaboration de matériaux composites présentant des propriétés d'absorption aux ondes hyperfréquences by Sandrine Hoppe( Book )

3 editions published in 1995 in French and held by 3 WorldCat member libraries worldwide

L'objet de cette thèse est l'étude de procédés d'élaboration de matériaux composites présentant des propriétés d'absorption aux ondes hyperfréquences. Ces matériaux sont constitués d'une matrice polymère au sein de laquelle sont dispersées des particules conductrices. Leurs propriétés d'absorption sont fonction de la fraction volumique, de la taille, de la forme et de la répartition spatiale des inclusions. Cette répartition, qui dépend des conditions expérimentales d'élaboration de ces matériaux, est le paramètre déterminant de la qualité de la réponse électromagnétique. Deux procédés d'élaboration ont fait l'objet d'une analyse approfondie: (1) le malaxage par extrusion d'un polymère thermoplastique et de particules de noir de carbone (2) l'encapsulation de particules de noir de carbone au cours de deux polymérisations radicalaires conduites en suspension. Dans une première partie, la modélisation du mélange des deux constituants dans l'extrudeuse est effectuée. Elle repose sur une approche systémique utilisant le couplage entre un modèle d'écoulement du polymère en l'absence du noir de carbone et un modèle de dispersion des particules de noir de carbone. La deuxième partie concerne la mise au point et l'optimisation des principaux paramètres du procédé d'encapsulation. L'observation par microscopie optique et électronique à transmission, couplée à l'analyse quantitative d'images, est une méthode performante pour caractériser la dispersion du noir de carbone. La détermination des caractéristiques électromagnétiques des matériaux permet de juger la qualité du mélange vis-à-vis de la propriété recherchée
Conception, modélisation et optimisation d'un procédé continu d'élaboration d'une dispersion stabilisée de particules de polystyrène dans un polyéther polyol by Georges Kanaan( Book )

2 editions published in 2007 in French and held by 2 WorldCat member libraries worldwide

This study dealt with the development and the optimization of a new continuous process for making stable dispersions of polystyrene particles in a polyether polyol. The objective was to maximize the solid mass fraction in the mixture and to minimize the mean particles diameter, by maintaining stable dispersion. The bibliographical research showed the importance of the stabilizer and the operating conditions choices. Preliminary studies carried out in a batch reactor with different stabilizers led to select a polystyrene grafted polyol. A complete study of the synthesis of this stabilizer was carried out and transposed on a pilot scale.For to the continuous process, a complete pilot unit was built around a twin screw extruder. Once the operating conditions were optimized, two influencing parameters were identified (rate of stabilizer and concentration of polystyrene), thus an experimental design was developed. A simple model was created in order to determine the relationships between operating conditions and dispersion's quality. The use of multicriteria optimization process allowed determining the best compromises for making stable dispersions
Synthèse par extrusion réactive de polycondensats de polyamides by Jean-Marie Boissière( Book )

2 editions published in 2008 in French and held by 2 WorldCat member libraries worldwide

The aim of this work is to study the feasibility of addition of nylon salt to polyamide (PA) by a reactive extrusion process. As example, the addition of 6T salt, which includes aromatic monomers, to PA 66 is performed in order to synthesize PA 66/6T. This latter replies to demand of high resistance temperature polymer. Consequently, the progress rate of the reaction and the rate of 6T motifs insertion have to be maximized.This work includes the synthesis and the analysis of 6T salt, PA 6T and PA 66/6T. 6T salt synthesis is performed since it is not commercialised. PA 6T is synthesized in order to identify aromatic hydrogen in PA 66/6T molecule. About this latter, it is necessary to adjust and to study the extrusion process. So, the influences of few process parameters are studied as, for example, pressure level on vent gas of the extruder.With the best process parameters, the progress rate is 93 mol% and the rate of 6T motifs insertion is 15,3 mol%. Yet, PA 66/6T presents a significant excess of acidic end group
Elaboration et caractérisation de mélanges de polymères à base de polypropylène et de polycarbonate à propriétés optimisées by Shann-Shan Dai( Book )

2 editions published in 2010 in French and held by 2 WorldCat member libraries worldwide

Polymer blending provides a practical and economic way of preparing new materials with combinations of properties not available in a single polymer. In order to improve the toughness of polypropylene while retaining its rigidity as much as possible, a new concept “rigid-rigid polymer toughening” was developed. Polycarbonate (PC) was selected to blend with PP in this study because of the advantages it provides over many other conventional engineering polymers in terms of high strength and toughness. The key to obtaining materials with high toughness and balanced rigidity relies on effectively compatibilizing this polymer pair and reducing the viscosity ratio. In this study, novel compatibilizers for the PP/PC blend were prepared or chosen to promote interactions between PP and PC and control the morphology of the blend. Some of the compatibilizers took the role of both compatibilizer and toughener. The performance of compatibilizers and toughening mechanism of blends were studied in detail. The morphology evolution of PP/PC blends and the relationship between the composition and microstructure were simulated based on molecular dynamics and mesodyn theories
Étude du comportement mécanique et de l'endommagement de composites thermoplastiques renforcés de fibres courtes de chanvre : approche expérimentale et modélisation by Florian Gehring( )

1 edition published in 2013 in French and held by 1 WorldCat member library worldwide

Natural fibres are expected to have the ability to replace synthetics fibres as reinforcement for thermoplastics. A short plant fibres reinforced thermoplastics (polypropylene/hemp) is therefore studied in this PhD thesis. The processing temperature of PP allows the use of natural fibres. Moreover the hemp growing is easy in Lorraine. The testing specimens were made by compounding and injection moulding. Experimental characterization of the quasi-static thermomechanical behaviour of hemp composite was carried out with particular emphasis on the effect on strain rate, fibre loading and temperature. The damage is pointed out by load-unload-holding tests and in-situ infrared thermography recorder and revealed a « quasi-brittle » failure by matrix cracking regardless the hemp fibre loading. A complete statistical study in terms of spatial and orientation distribution of fibre was conducted by X-ray tomography and enables the development of an algorithm which generate a finite element model including the spatial reinforcement distribution and orientation distribution as well as geometrical features of fibres (L,Ø) Through this algorithm, the complicated interactions between isotropic elastic fibres are taken into account in the finite element modelling. Finally, finite element modelling of composite behaviour is intended. The elastic - progressive damage behaviour of the matrix is obtained in accordance to the micromechanism frame, in which PP is considered as a solid isotropic body weakened by penny-shaped cracks. This behaviour was implemented through a Fortran routine in abaqus software. This approach shows good prediction capabilities and gives opportunities to optimize this composite material
Étude des mélanges de polyéthylène renforcé avec des nanocharges et résidus de pneus régénérés par micro-ondes by Fabiula de Sousa( )

1 edition published in 2016 in English and held by 1 WorldCat member library worldwide

The main objective of this work was the production of dynamically revulcanized blends containing HDPE and GTR devulcanized by microwaves. It comes against a big global problem which is the waste disposal of vulcanized elastomers, especially tires, which bring with them serious environmental and public health problems, since these materials require long periods of time to degrade naturally due to their structure of cross-linkings, and the presence of stabilizers and other additives in its formulation. A way of using the GTR that has been widely studied by researchers is as polymer blends in which one of the phases is a thermoplastic polymer. In this context, the role of elastomers devulcanization is to increase the interaction between raw and recycled material, reducing the degradation of properties of the finished product with its incorporation and making it possible the increase of the recycled rubber amount in the compound recycled rubber/thermoplastic. The devulcanization transformes devulcanized elastomer into a fluid material, allowing a better control of the particle size during the mixing process of the blend by breaking processes in the application of high shear rates. In addition, by becoming a fluid material, it is possible the incorporation of a higher amount of elastomer to the thermoplastic without great damage to its processability. However, the literature does not have works in which the study of the processing parameters of dynamically revulcanized blends containing devulcanized elastomer, as well as the influence of addition of clays from different shapes (lamellar and tubular) on their final properties, especially on rheological properties, which sets out the present work. Summarizing, this work aims to propose a possible solution to the problem of solid waste disposing by producing a dynamically revulcanized blend containing HDPE and GTR devulcanized by microwaves, in addition to decrease some gaps observed currently in the literature from the obtained results
Suivi multi-échelle in situ des réactions de polymérisation en macroémulsion par spectrométrie Raman by Elise Dropsit( )

1 edition published in 2017 in French and held by 1 WorldCat member library worldwide

Le développement de techniques de suivi in situ de réactions de polymérisation en émulsion est un véritable enjeu, motivé par le désir d'établir des relations entre structure, propriétés physico-chimiques et propriétés d'usage du latex final. Par ailleurs, ces techniques fournissent des informations sur les phénomènes chimiques et physico-chimiques mis en jeu qui contribuent à une meilleure compréhension. Des études récentes montrent que la spectroscopie Raman peut être une technique adaptée à cette problématique, de par sa simplicité de mise en œuvre (transportabilité, adaptabilité de l'appareillage, etc.), la performance de la mesure (temps d'acquisition de l'ordre de la seconde) et la richesse des informations fournies (de l'échelle moléculaire à celle du matériau). L'objectif de notre travail a été de déterminer le potentiel de la spectroscopie Raman quant au contrôle de la polymérisation en macroémulsion du styrène tant au niveau du bon déroulement de la réaction (conversion...) qu'au niveau des propriétés du latex formé (stabilité...). Pour réaliser ce travail expérimental, un pilote de polymérisation a été installé pour la première fois au sein du laboratoire des Matériaux Optiques, Photonique et Systèmes (LMOPS). La particularité de notre système est qu'il a été conçu pour conserver le maximum de liberté pour la réalisation de l'étude spectroscopique (montages optiques). La première partie de notre projet a donc été de déterminer un protocole adapté à ce pilote, tant au niveau de la réalisation de la synthèse de latex de polystyrène stabilisé qu'au niveau de l'acquisition de données spectroscopiques. Par la suite, nous avons démontré que la spectroscopie Raman était une technique adaptée au suivi in situ de la cinétique de polymérisation du styrène en macroémulsion. Le suivi du taux de conversion du styrène en polystyrène a été réalisé selon deux méthodes qui reposent sur des principes différents : la première basée sur la variation de l'aire de bandes spécifiques est une approche classique de la quantification de cette grandeur alors que la deuxième, basée sur la modification de la position d'une bande commune au monomère et à son polymère est une méthode innovante. A partir de ces données expérimentales et grâce à une méthode de filtrage adaptée, la quantification de la vitesse de polymérisation a été proposée pour la première fois. Ces données expérimentales ont été comparées à la théorie mécanistique et cinétique de référence de ce procédé, ainsi qu'à de précédents résultats expérimentaux, obtenus par d'autres techniques. Alors que les résultats expérimentaux s'accordent, ils montrent tous une déviation par rapport à la théorie. Enfin, par l'étude approfondie de la variation de l'aire d'une bande de référence, commune au monomère et au polymère, nous avons démontré que la spectroscopie Raman était sensible au phénomène de diffusion élastique, diffusion du faisceau laser par les éléments dispersés dans le milieu réactionnel. Cela se traduit par une modification de l'intensité du signal collecté et permet donc de détecter une transition caractéristique du procédé de polymérisation étudié : la disparition des gouttelettes réservoir de monomère, qui apparaît vers 40% de conversion dans le cas du styrène
Reactive extrusion of Silicone-modified polyolefine Mechanical and Surface Properties by Adrián Artigas Martínez( )

1 edition published in 2011 in English and held by 1 WorldCat member library worldwide

The influence of four silica additives into surface properties of a polyolefine has been studied via reactive extrusion. Particular focus has been made in scratch resistance and the reactive behavior of the four silicon products blend. First results have showed no particular improvement in surface properties on the studied blends. Further experiments have determined that residence time at the extruder was insufficient for the reaction to occur, so investigation on the interactions and reactions between the four products has followed
Étude d'élaboration des mélanges de matériaux bio-sourcés à base d'amidon plastifié et de poly (acide lactique) et de leur compatibilisation by Sara Ronasi( )

1 edition published in 2012 in French and held by 1 WorldCat member library worldwide

This study dealt with the development and the compatibilization of the blends of plasticized starch and polylactic acid. The transformation of native to plasticized starch is possible by extrusion in the presence of plasticizers. In this work, the final properties of plasticized starch are controlled by changing process parameters (temperature, extrusion time, screw's rotation speed) and nature and quantity of plasticizers. Plasticization of starch by water, glycerol, sorbitol and citric acid is studied. The blends of plasticized starch and poly (lactic acid) (PLA) are prepared and characterized in the second part of this work. To improve the compatibility of the blend, one way is the addition of a copolymer to the mixture to stabilize the dispersed phase in the matrix. The copolymer used in this work (Amylose-g-PLA) is constituted of amylose backbone and poly (lactic acid) (PLA) grafts. The number and the size of the grafted chains of PLA have been controlled by a three step process polymerization. Two copolymer structures have been prepared: type1, containing high numbers of low molar weight PLA grafts and type 2, lower numbers of high molar weight PLA grafts. In the final part, efficiency of these copolymers (Amylose-g-PLA) in these blends is studied. The comparison between morphology and mechanical properties of blends prepared with these copolymers, demonstrate the higher efficiency of type1 copolymer
Préparation et modification de composites thermoplastiques/tannins par extrusion réactive by Jingjing Liao( )

1 edition published in 2019 in English and held by 1 WorldCat member library worldwide

Les tanins condensés sont largement répandus et très abondants dans la nature. Au cours des dernières décennies, ces tanins ont été abondamment utilisés pour la production de formulations thermodurcissables (par exemple, les adhésifs pour le collage du bois, les matériaux en mousse) en raison de leur réactivité chimique. Cependant, ils présentent également un grand potentiel en tant que composants pour la conception de matériaux polymères innovants en raison de leurs propriétés physico-chimiques (p. ex. antioxydantes, antimicrobiennes et stabilisantes). Afin d'étendre les domaines d'utilisation des tanins aux matériaux polymères, le principal verrou scientifique et technique réside dans leur incompatibilité avec les polymères hydrophobes. À cette fin, trois voies de modification ont été mises au point pour améliorer la compatibilité des tanins avec les matrices PP ou PLA. Dans la première partie, les PP/ tanins ont été modifiés avec du glyoxal par vulcanisation dynamique. Après extrusion réactive, les tanins vulcanisés présentent une meilleure compatibilité avec la matrice PP et des propriétés anti-UV. La deuxième approche consiste en une modification par estérification à l'aide d'anhydride acétique. Avec cette méthode, des teneurs élevées en AT ont pu être incorporées au PLA, jusqu'à 30 % en poids et jusqu'à 20 % sans diminution notable des propriétés mécaniques ni impact sur la morphologie de surface. Ces composites PLA/AT sont imprimables en impression 3D par dépôt de matière fondue. Dans la troisième partie, une compatibilisation réactive a été réalisée avec succès pour améliorer l'adhésion interfaciale entre PLA et les tanins condensés en utilisant du 3-aminopropytriéthoxysilane, du diisocyanate de méthylène diphényle et du peroxyde de dicumyle (DCP)
Films composites amidon de manioc-kaolinite : influence de la dispersion de l'argile et des interactions argile-amidon sur les propriétés des films by Jean Aimé Mbey( )

1 edition published in 2013 in French and held by 1 WorldCat member library worldwide

Cette étude porte sur des films composites à base d'amidon de manioc plastifié au glycérol et d'une argile kaolinique, comme charge minérale. L'origine et les mécanismes des interactions argile-amidon et leur rôle sur les propriétés des films ont été examinés. Pour vaincre le caractère non-expansible de la kaolinite, l'analyse du mécanisme de son exfoliation a été effectuée par insertion du diméthylsulfoxyde suivi d'un échange en milieux acétate d'éthyle et acétate d'ammonium. Une forte déstructuration de l'édifice cristallin de la kaolinite suite à l'échange est observée. La réassociation des feuillets après échange est désordonnée et permet d'escompter une meilleure dispersion de la kaolinite intercalée au sein d'un polymère. Ceci est confirmé par les analyses comparées de microscopies et de diffraction des rayons X sur des films incorporant diverses doses d'argile brute ou intercalée. L'abaissement de la température de transition vitreuse et du module élastique, ainsi que l'accroissement des effets de barrières à la décomposition thermique, à la diffusion de vapeur d'eau et à la transmission des UV visibles confirme la dispersion meilleure de la kaolinite intercalée. L'orientation des chaînes d'amidon et la diffusion du plastifiant transporté à l'interface par l'argile sont les mécanismes qui justifient l'effet plastifiant apporté par l'argile. L'interférence des interactions amidon-argile sur les interactions chaîne-chaîne au sein de l'amidon participe à la plasticité des films en diminuant la cristallinité. Les interactions amidon-argile se sont avérées faibles du fait des répulsions électrostatiques associées à des interactions associatives de type pont hydrogène
Methodological proposition to evaluate polymer recycling in open-source additive manufacturing contexts by Fabio Alberto Cruz Sanchez( )

1 edition published in 2016 in English and held by 1 WorldCat member library worldwide

Since the beginning of the XXI century, we can recognize that several technical (r)evolutions have changed the way we conceived our world. New realities have appeared thanks to the information and communication technologies (e.g. Internet), peer-to-peer dynamics (e.g. open software/hardware, collaborative economy), new means of production (fablabs, hackerspaces), among others. One of the impacts of this technical ecosystem is the individual's empowerment that changes the relationship between consumer and producer. For instance, we observe an evolution of role passing from a passive consumer towards an active prosumer, where this latter considers not only economic aspects, but also social and environmental issues.This thesis is integrated in this global issue; indeed, throughout the manuscript we analyze about the impact of open-source (OS) Additive Manufacturing (AM) (also as known as open-source 3D printing or just 3D printing) in the light of the sustainability issues. The democratization of OS AM and the creation of spaces for co-creation (e.g. FabLabs) proved the interest for changes in the established roles. Therefore, we are interested in how this OS technology could develop sustainable waste management options through a polymer recycling process. In a first phase, we present the concept of additive manufacturing (AM) and its importance on sustainability issues. A systematic literature review related to the material recycling advances in the commercial and open-source (OS) AM is developed with a focus on thermoplastic polymer recycling.In a second phase, our aim is to validate open-source AM systems as a reliable manufacturing tool. We develop and test an experimental protocol in order to evaluate the dimensional performance using as case study a representative OS 3D printer: called FoldaRap. It was found that the International Standard Tolerance Grade of this machine is situated between IT14 and IT16. We conclude that the dimensional performance of this case study is comparable to the commercial AM systems, taking into account the important different in terms of machine cost. In a third phase, we center our attention on the recycling process and we propose a systematic methodology to evaluate the feasibility of the use of recycled thermoplastic polymer in OS 3D printers. A case study is developed with the evaluation of the recycling process using polylactid acid (PLA). The results allow us to conclude that the use of recycled PLA is technically feasible. Nevertheless, the degradation of the material is more important than in other traditional manufacturing systems (e.g. injection). Finally, we concludes and propose as perspectives, the study of a distributed recycling process for other type of polymers
Characterization of lignin thermal processing in a biorefinery perspective by Binod Shrestha( )

1 edition published in 2016 in English and held by 1 WorldCat member library worldwide

The thermo-chemical conversion of lignin is an important aspect of lignocellulosic biorefinery in order to produce carbon fibers, polymer additives, green aromatics or biofuels. Protobind 1000 lignin was characterized by thermogravimetry, calorimetry, in-situ rheology, in-situ 1H NMR, solution state 13C and 31P NMR. A multiple techniques including elemental analysis, GPC-UV, FTIR, solid-state NMR and LDI-FTICRMS, were performed to understand the softening and pyrolysis of lignin. An overall physical and chemical mechanism of thermo-chemical conversion of lignin has been proposed. A twin screw extrusion of lignin was carried out using Process 11, following the in-situ high temperature rheology and rheomix internal mixing. The operating window was derived from torque evolution at varying throughputs of 0.1-0.3kg.h-1 and rotation speed of 300-600 rpm at barrel temperature of 150°C for two screw configurations. The lignin extrudates obtained at key extrusion conditions were characterized by FTIR, GPC-UV/ELSD, solution state 1H-13C HSQC NMR. The analysis of lignin melts shows no major structural changes concluding twin screw extruder as a hot melt feeder. The lignin characterization in a liquid media i.e. H2O, ethanol and aq. NaOH, were studied by wet rheology, DLS, zeta potential measurement, SAXS and real-time visual analysis. The lignin liquefaction was carried out in ethanol and the liquefaction products were analysed by UV resonance Raman spectroscopy, GPC-UV and UV-Visible absorption and fluorescence spectroscopy. The structural changes undergone by lignin during liquefaction was accounted
Controlling the structure and properties of toughened and reinforced isotactic polypropylene by Shi-Wei Wang( )

1 edition published in 2012 in English and held by 1 WorldCat member library worldwide

En tant que polymère de grande diffusion, les applications du polypropylène isotactique (PP) sont limitées par sa faible resistance au choc. D'après la relation structure - propriétés, sa résistance au choc peut être améliorée en contrôlant sa structure. Dans ces travaux, différents types d'agents nucléants ont été utilsés pour promouvoir la formation des cristaux de type bêta et de mélanges de deux PP de masses molaires différentes. Les propriétés mécaniques, le comportement à la rupture, et la morphologie cristalline ont été étudiés. Les influences du type et de la teneur en peroxyde et agent nucléant sur la morphologie cristalline et les propriétés mécaniques ont aussi été explorées. Un agent nucléant suporté sur des nanotubes de carbone multi-parois (MWCNT) a été utilisé pour modifier la structure cristalline du PP, ce qui a permis d'augumeter sa résistance au choc 7 fois comparée à celle du PP vierge et 3 fois comparée à celle du PP cristallisé en phase bêta. Cette importante augmentation en resistance au choc peut être attribuée à la formation des trans-cristaux de type bêta qui est favorisée par l?agent nucléant supporté sur les MWCNT
Intensification des procédés de polymérisation : passage du batch au continu by Marie-Claire Chevrel( )

1 edition published in 2014 in French and held by 1 WorldCat member library worldwide

Water soluble polymers are typically produced batchwise in multi-product plants, providing the ability to produce a wide range of products. However, some limitations due to the use of batch reactor remain which are the variation of the quality of a synthetic polymer from one run to another run, a non-obvious scale-up step from the laboratory scale to the industrial production, and a technology with limited heat exchange . Dilute conditions are required which implies long cycle production times. A transition from discontinuous to continuous production could be a good alternative if it can accelerate the reaction time but also to ensure a consistent quality of polymer over time. This means in our case a polymer with a high molecular weight and a low polydispersity index. In the frame of the European project F3Factory, a continuous laboratory-scale pilot of 1 to 2kg.hr-1 flowrate for the production of water soluble polymers was designed. The chosen intensified reactor was a tubular reactor containing static mixers. Providing excellent heat transfer, a good mixing with a piston flow character, this technology was also flexible thanks to the presence of standardized flanges and well instrumented for data acquisition in terms of temperature, pressure but also conversion with in-line Raman analysis. Free radical polymerization of acrylic acid was carried out in a continuous way. Two main challenges were faced: an exothermic reaction coupled to a high viscosity. A methodology relative to the transposition from bath to continuous process was developed. A preliminary study coupling rheology and Raman spectroscopy allowed us to acquire relevant data at small-scale (rheokinetic study). This work demonstrates the feasibility of the continuous production of acrylic acid polymer. The impact of various parameters such as the concentrations of monomer and initiator and the temperature was investigated. Finally, our work has focused on characterizing the polymers produced in batch and continuous and to determine the advantages and limitations offered by the continuous process
Polymérisation in-situ en milieu fondu et sous écoulement élongationnel pour l'élaboration de nouveaux matériaux by François Pierrot( )

1 edition published in 2018 in French and held by 1 WorldCat member library worldwide

In this work, binary and ternary reactive blends based on immiscible thermoplastic polymers PMMA,PE and PS were realized. The in-situ polymerization of the styrene, precursor of PS, was led by thermal self-polymerization or still thanks to radical initiator. Blends were realized in a mixer named RMX who generates mainly extensional flows known for their distributive and dispersive skill even if components have an important viscosity difference. Various methods of preparation and parameters of mixtures were tested. Morphology was evaluated by the analysis of electronic microscopy images.The average radiuses of the dispersed PS phase were compared with those observed in the literature. The smallest that we obtained have an average radius of 50 nm. Binary mixtures 90/10 %m with PS or PE and with a thermodur polyepoxide (MDEA/DGEBA) were also realized. The smallest spherical nodules that we obtained have an average radius of the order of 65 nm
Synthèse et mise en oeuvre de nanocomposites à base d'oxyde de zinc utilisés pour le traitement photocatalytique de l'eau contaminée par des disrupteurs endocriniens by Alma Berenice Jasso Salcedo( )

1 edition published in 2014 in English and held by 1 WorldCat member library worldwide

The present work concerns photodegradation of water contaminants using ZnO-based catalysts. The first step consisted in designing a new catalytic system by functionalizing ZnO with silver nanoparticles. Two methods were used: photodeposition and impregnation of silver nanoparticles (AgNPs) on ZnO. The photocatalytic activity of the resulting catalyst towards the degradation of bisphenol-A, triclosan and rhodamine-B was studied. The effect of pH, photocatalyst and contaminant concentrations and wavelength, on bisphenol-A degradation was studied and the kinetic rate constant was determined. The optimization showed that a low silver content and an alkaline pH, during both functionalization of ZnO and photodegradation, maximized the kinetic rate constant of bisphenol-A degradation. A model also predicted that Ag/ZnO obtained by photodeposition showed higher photocatalytic activity that of Ag/ZnO obtained by impregnation.On the other hand, to overcome aggregation problems, Ag/ZnO were immobilized owing to their incorporation in a cross-linked poly(acrylic acid) matrix . The surface of Ag/ZnO was previously modified, using a silane coupling agentwhich allowed (i) dispersing and anchoring NPs on the polyacrylic matrix by formation ester bonds (ii) promoting crystallization of the polymer. The composites were successfully tested under UV light with an efficiency comparable to that of non-immobilized NPs. The immobilization provides additional advantages e.g. hindrance of catalyst photocorrosion and possible use of the composite in continuous mode
Compréhension des phénomènes interfaciaux dans les composites à base de charges carbonate de calcium précipité : influence du traitement de surface et du procédé de mise en œuvre by Floriane Morel( )

1 edition published in 2010 in French and held by 1 WorldCat member library worldwide

Ce travail a eu pour objectif la création de matériaux composites à base de nanocharges de carbonate de calcium. L'étude des phénomènes interfaciaux qui régissent ces systèmes, ainsi que leurs impacts sur les propriétés fonctionnelles du matériau et plus particulièrement des propriétés de transport, ont été réalisées. Pour ce faire, nous avons considéré deux matrices polymères de nature chimique différente : le polylactide et le polyfluore de vinylidène. Les nanocomposites ont été élaborés par deux voies de mise en œuvre : la voie fondu et la voix solvant. Une analyse fine des relations structure/morphologie/propriétés des composites a été réalisée. Nous avons mis en évidence, quelle que soit la matrice polymère choisie, l'importance du traitement de surface des charges afin d'améliorer leurs états de dispersion dans le matériau et d'augmenter la qualité de l'interface charge/polymère. Ces paramètres ont été corrélés aux propriétés de transport de ces matériaux composites
 
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