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Trautmann, Radoslav. "Effect of Composition on Adhesion Strength Between Particle Filled Composite and Fiber Reinforced Composite." Doctoral thesis, Vysoké učení technické v Brně. Fakulta chemická, 2010. http://www.nusl.cz/ntk/nusl-233308.
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Disertační práce se zabývala vlivem adheze mezi vláknovým (FRC) a částicovým (PFC) kompozitem a složením obou komponent na mechanické vlastnosti a způsob porušování modelových bi-materiálových kompozitních těles při statickém namáhání. Zkoumán byl také vliv způsobu přípravy bi-materiálového kompozitního tělesa na pevnost adheze mezi jeho kompozitními komponentami. K hodnocení mechanických vlastností bi-materiálových PFC/FRC těles byl použit jak 3 tak 4-bodový ohybový test za pokojové teploty a relativní vlhkosti 70%. Modifikovaný vytrhávací test byl použit k měření smykové pevnosti adheze mezi vláknovým a částicovým kompozitem. Tyto výsledky byly korelovány s výsledky ze strukturní a fraktografické analýzy (TGA, SEM). Experimentální data byla poté analyzována pomocí existujících mikromechanických modelů a byl nalezen vztah mezi tuhostí modelových bi-materiálových těles, složením a geometrií uspořádání jejich komponent a pevností adheze mezi těmito komponentami. Na základě těchto výsledků byl navržen optimální způsob vrstvení a přípravy PFC/FRC bimateriálových těles. Navržené postupy byly použity k přípravě a pre-klinickým testům nosných konstrukcí zubních můstků.
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Marquina, Edgar Alberto. "Use of Dynamic Mechanical Testing, WAXD and SEM Image Analysis to Study the Properties of Polypropylene/Calcium Carbonate Nanocomposites." University of Akron / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=akron1269363578.
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Gentieu, Timothée. "Development of filled polymers for the replacement of ceramics used as ballistic protection layer." Thesis, Bordeaux, 2018. http://www.theses.fr/2018BORD0419.
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Les matériaux céramiques présentent généralement des propriétés mécaniques très intéressantes pour la réalisation de blindages. Ce sont des matériaux très durs et pourtant légers. Les plaques de blindages en céramique sont classiquement mises en forme par pressage à haute température de poudres, ce qui limite la taille et la forme des réalisations tout en impliquant un coût élevé. Une alternative pour produire ces pièces est le moulage d’un composite constitué de particules de céramiques dans une matrice époxy. Ce procédé permet de réduire le coût des pièces tout en autorisant des géométries plus complexes et des dimensions plus importantes.Le comportement mécanique de ce type de matériau dépend de multiples paramètres de conception : propriétés mécaniques des constituants (matrice polymère et particules céramiques), proportion volumique des deux phases, taille et distribution spatiale des particules ou encore l’adhésion entre les constituants. L’objectif de la thèse est d’évaluer l’influence de ces paramètres sur les propriétés d’usage du matériau. Pour ce faire, une analyse multi-échelle du matériau sous sollicitations quasi-statique et dynamique est réalisée.Plus précisément, les propriétés statiques et dynamiques du composite à renforts particulaires ont été déterminées pour différentes combinaisons de ces paramètres de conception. En particulier, le mécanisme de décohésion particule/matrice a été spécifiquement étudié. Les approches de Modèles de Zone Cohésive (CZM) et de Mécanique de la Rupture Finie (FFM) ont été utilisées pour modéliser ce phénomène et un fort effet de taille des particules a été observéCeramics have extensively been used for ballistic protection in the last decades. The combination of their mechanical properties makes them very interesting for armouring. Indeed, they exhibit a high hardness, large compression strength, high stiffness and low density. Ceramic armouring plates are commonly manufactured through a sintering process, where ceramic powders are pressed at high temperatures. This manufacturing process tends to limit the size and shape of components and imparts high costs. On the other hand, moulding using a polymer matrix composite provides an alternative process for developing lower cost parts whilst accommodating increased complexity of geometry and size.However, the mechanical behaviour of such a material is not completely known and depends on multiple design parameters: the mechanical properties of the phases, their volume fraction, the size and spatial distributions of the particles, and the adhesion between the components. The objective of the thesis is to evaluate the influence of the main morphological parameters on the overall mechanical properties, emphasising the influence of the particle/matrix adhesion. To do so, both numerical and experimental multiscale analyses of the material under quasi-static and dynamic loadings were carried out.More precisely, static and dynamic properties of the particle-reinforced composite have been determined for different combinations of the design variables. In particular, attention has been dedicated to the particle/matrix decohesion mechanism. Cohesive zone models (CZM) and Finite Fracture Mechanics (FFM) approaches were used to model this phenomenon and a strong effect of the particle size on debonding was observed
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Ibarra, Jonatanh José. "Vliv složení mezivrstvy na pevnost adhezního spoje mezi vláknovým a částicovým kompozitem." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2010. http://www.nusl.cz/ntk/nusl-216635.
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Hlavním cílem této práce je studium aktuálního problému adheze mezi kompozitními materiály, a určení vlivu složení mezivrstvy v pevnosti adhezivního spoje mezi vláknové (FRC) a částicové (PFC) kompozity, používané ve stomatologii. FRC tyčinky byly vytvořené na bázi komerční dimetakrylatové pryskyřice a skleněných S vláken. PFC byl vytvořen ze směsi pryskyřic (bis-GMA a PEGDMA), plněných drceným barnatým sklem. Celkově bylo připraveno a vyzkoušeno 84 vzorků. Vzorky byly rozdělené do pěti hlavních skupin. První skupina byla vytvořena ze série vzorků bez mezivrstvy. Zbylé čtyři skupiny byly rozděleny dle složení mezivrstvy (tloušťky a druhu pryskyřic). Částicové kompozity vzorků se lišily obsahem plniva (0, 10, 40 hm %). FRC tyčinky byly stejné pro všechny vzorky. Univerzální testovací přístroj ZWICK Z010 byl použit k zjištění smykové pevnosti adhezivního spoje všech vzorků. Rastrovací elektronový mikroskop byl použít k pozorování místa porušení. Ze získaných výsledků vyplívá, že s přidáváním mezivrstvy mezi vláknovým a částicovým narůstá smyková pevnost spoje. Důležitost těchto výsledků je způsobená tím, že v posledních letech použití těchto materiálů ve stomatologii narůstá a adheze zůstává jeden z hlavních problémů při klinické praxi.
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Šedivý, Zbyněk. "Pokročilé vrstevnaté kompozity pro stomatologické aplikace." Doctoral thesis, Vysoké učení technické v Brně. Fakulta chemická, 2013. http://www.nusl.cz/ntk/nusl-233372.
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Disertační práce se zabývá mechanickou odezvou vrstevnatých kompozitů pro stomatologické aplikace. Různé skladby vrstev a různé částicové a vláknové kompozity jsou studovány v tříbodovém ohybu za pokojové teploty. Tyto výsledky jsou korelovány s výstupy dynamické termomechanické analýzy (DMTA) a optické analýzy (vysokorychlostní video záznam, SEM). Exeprimentální data byla použita pro srovnání s výsledky analytických a numerických modelů s cílem určit nejvhodnější model pro predikci základních mechanických vlastností vrstevnatých kompozitů. Na základě těchto analýz jsou navržena základní pravidla pro klinické použití vrstevnatých kompozitů ve stomatologických aplikacích jako jsou minimálně invazivní můstky nebo stabilizační dlahy.
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Ferranti, Louis Jr. "Mechanochemical Reactions and Strengthening in Epoxy-Cast Aluminum Iron-Oxide Mixtures." Diss., Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/19722.
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This investigation is focused on the understanding of mechanical and chemical reaction behaviors of stoichiometric mixtures of nano- and micro-scale aluminum and hematite (Fe2O3) powders dispersed in epoxy. Epoxy-cast Al+Fe2O3 thermite composites are an example of a structural energetic material that can simultaneously release energy while providing structural strength. The structural and energetic response of this material system is investigated by characterizing the mechanical behavior under high-strain rate and shock loading conditions. The mechanical response and reaction behavior are closely interlinked through deformation characteristics. It is, therefore, desirable to understand the deformation behavior up to and beyond failure and establish the necessary stress and strain states required for initiating chemical reactions.
The composite s behavior has been altered by changing two main processing parameters; the reactants particle size and the relative volume fraction of the epoxy matrix. This study also establishes processing techniques necessary for incorporating nanometric-scale reactants into energetic material systems. The mechanochemical behavior of epoxy-cast Al+Fe2O3 composites and the influence of epoxy volume fraction have been evaluated for a variety of loading conditions over a broad range of strain rates, which include low-strain rate or quasistatic loading experiments (10-4 to 10-2 1/s), medium-strain rate Charpy and Taylor impacts (103 to 104 1/s), and high-strain rate parallel-plate impacts (105 to 106 1/s). In general, structural strength and toughness have been observed to improve as the volume fraction of epoxy decreases, regardless of the loading strain rate regime explored. Hugoniot experiments show damage occurring at approximately the same critical impact stress for compositions prepared with significantly different volume fractions of the epoxy binder phase. Additionally, Taylor impact experiments have indicated evidence for strain-induced chemical reactions, which subject the composite to large shear accompanied by temperature increase and associated softening, preceding these reactions.
Overall, the work aims to establish an understanding of the microstructural influence on mechanical behavior and chemical reactivity exhibited by epoxy-cast Al+Fe2O3 materials when exposed to high stress and high-strain loading conditions. The understanding of fundamental aspects and the results of impact experiment measurements provide information needed for the design of structural energetic materials.
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Brunetti, Lucia. "Electrospinning of PHAs composites filled with bioactive glass particles." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019. http://amslaurea.unibo.it/17525/.
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The use of composite materials, especially for the development of scaffolds, is having a great impact
in the biomedical field. Every day thousands of surgical procedures are performed to replace or repair
tissue that has been damaged through disease or trauma.
The developing field of tissue engineering (TE) aims to regenerate damaged tissues by combining
cells from the body with highly porous biomaterials scaffold, which act as templates for tissue
regeneration, to guide the growth of new tissue.
Consequently, there are a lot of researches focused on the development of new materials that must
fulfill mandatory requirements such as biocompatibility, biodegradability, bioresorbability and
adequate mechanical features. Scaffolds play a key role in the field of TE, thus they provide a
healthy environment for cells attachment, differentiation, proliferation, and migration. Therefore,
according to the native tissue, the mechanical and physiological characteristics of the biomaterials
used for scaffolding are expected to be similar. In this work, electrospun fibers will be realized by
investigating an innovative composition of the homopolymer Poly(3-hydroxybutyrate) (PHB) and
the copolymer Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) for what regards the
polymeric matrix, and the latter will be filled with bioactive glasses, in order to realize a composite
material suitable for biomedical applications.
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Huang, Huan Yao, and barbar0324@gmail com. "The preparation and characterization of polypropylene-compatibilizer-filler composites." RMIT University. Applied Sciences, 2010. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20100218.101808.
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Polypropylene (PP) composites includ a mineral filler, though they can be enhanced by blending with an elastomer. Blending rigid fillers with PP increased strength while decreasing toughness. Blending soft elastomers with PP decreased strength while increasing toughness. PP-elastomer-filler ternary composites offer synergism because the increase of strength due to filler may compensate the loss of strength due to the elastomer. Two morphologies were identified, separated elastomer and filler particles in PP, and filler particles encapsulated by elastomer in PP. Interaction between filler and PP matrix are proposed to increase with the addition of polar elastomers when encapsulated morphology is formed, leading to enhanced mechanical properties. PP-elastomer-filler blended tapes were prepared via single-screw extrusion. Annealing was performed after cooling the tapes, and this combination proved to increase the modulus. Characterization of the composites was carri ed out using thermogravimetry, dynamic-force thermomechanometry, modulated-force thermomechanometry, and Fourier transform infrared imaging. Incorporation of polysiloxane elastomer increased the mobility of PP during extrusion. Elongation at break increased with increasing polysiloxane content, while the tensile modulus was slightly decreased. The silica core within the polysiloxane particles provided an additional strength enhancement. Polar elastomers aided binding between PP and fillers, while enhancing strength and toughness. Glass transition temperature and segmental motion activation energy was shifted to higher temperature with addition of elastomer and filler, including kaolin and talc.
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Aronow, Roger Lockwood. "Toughening mechanisms in composites of miscible polymer blends with rigid filler particles." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/35520.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 2006.Vita.
Includes bibliographical references (leaves 97-98).
Fillers are often added to polymers improve stiffness at the cost of reduced toughness, but this tradeoff is not universal. Well-dispersed microscopic particles have been shown to improve toughness and stiffness simultaneously in some cases. The effect depends on interparticle distance as well as interfacial adhesion. This type of toughening has been more successful in semicrystalline than in amorphous systems. An amorphous polymer blend was chosen to elucidate the effect of matrix properties on the toughening mechanism. The ternary blend of PMMA, PVC, and DOP (a common plasticizer) was characterized using TEM, and was found to be miscible over much of the PVC-rich domain. The blend Tg's fit well to an empirical model, which was used to predict a constant-Tg ([approx.] 40°C) blend series. Mechanical testing showed a wide, systematic variation in properties among these blends, although all were brittle in tension. The blend 90% PVC / 10% DOP was mixed with barium sulfate filler and evaluated for toughness in slow tension. In general, the composites showed decreasing toughness with increasing filler content. However, several specimens at 5 vol% filler exhibited a large increase in ductility and toughness ([approx.] 19-fold).
(cont.) SEM examination of tough specimens revealed several important findings: (1) Filler is present both as micron-scale agglomerates and as well dispersed particles. (2) Well-dispersed particles remain bonded to the matrix even for large deformations. (3) Filler agglomerates are prone to debonding and internal fracture, creating void space and enabling deformation. Base blend properties significantly affect the response to filler. The blend 8% PMMA / 80% PVC / 12% DOP showed small increases in ductility for 5 and 10 vol% filler, with the best result being a 10 vol% specimen showing a 6-fold toughness increase over the neat-blend average. This specimen showed similar microscopic behavior to the 90/10 blend, i.e. agglomerate debonding and fracture, but to a lesser degree. The blend 16% PMMA / 70% PVC / 14% DOP, showed no significant toughening. Also investigated were high-Tg ([approx.] 70°C) blends, which were brittle and became weaker with filler, and low-Tg ([approx.] 30°C) blends, which were intrinsically ductile and were not toughened by filler.
by Roger Lockwood Aronow.
Ph.D.
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MURUGESAN, SURESH. "IN SITU PREPARATION AND STRUCTURE - PROPERTY STUDIES OF FILLER PARTICLES IN POLY(DIMETHYLSILOXANE) ELASTOMERS." University of Cincinnati / OhioLINK, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1059393661.
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Huet, Alexis. "Méthodes particulaires et vraisemblances pour l'inférence de modèles d'évolution avec dépendance au contexte." Phd thesis, Université Claude Bernard - Lyon I, 2014. http://tel.archives-ouvertes.fr/tel-01058827.
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Cette thèse est consacrée à l'inférence de modèles stochastiques d'évolution de l'ADN avec dépendance au contexte, l'étude portant spécifiquement sur la classe de modèles stochastiques RN95+YpR. Cette classe de modèles repose sur un renforcement des taux d'occurrence de certaines substitutions en fonction du contexte local, ce qui introduit des phénomènes de dépendance dans l'évolution des différents sites de la séquence d'ADN. Du fait de cette dépendance, le calcul direct de la vraisemblance des séquences observées met en jeu des matrices de dimensions importantes, et est en général impraticable. Au moyen d'encodages spécifiques à la classe RN95+YpR, nous mettons en évidence de nouvelles structures de dépendance spatiales pour ces modèles, qui sont associées à l'évolution des séquences d'ADN sur toute leur histoire évolutive. Ceci rend notamment possible l'utilisation de méthodes numériques particulaires, développées dans le cadre des modèles de Markov cachés, afin d'obtenir des approximations consistantes de la vraisemblance recherchée. Un autre type d'approximation de la vraisemblance, basé sur des vraisemblances composites, est également introduit. Ces méthodes d'approximation de la vraisemblance sont implémentées au moyen d'un code en C++. Elles sont mises en œuvre sur des données simulées afin d'étudier empiriquement certaines de leurs propriétés, et sur des données génomiques, notamment à des fins de comparaison de modèles d'évolution
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De, Rancourt Yoann. "Dispersion de charges d'oxydes de terres rares, Er2O3 et Pr6O11, dans une matrice polymère." Thesis, Montpellier 2, 2013. http://www.theses.fr/2013MON20202.
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Ce travail de thèse porte sur l'incorporation de charges minérales d'oxyde d'erbium, Er2O3, et d'oxyde de praséodyme, Pr6O11, dans une matrice polymère de type élastomère, ceci dans le cadre d'un projet industriel de remplacement du plomb dans des équipements de radioprotection. L'objet de cette thèse était d'améliorer la dispersion des charges au sein de la matrice par le biais de procédés de traitements chimiques de ces particules. Divers types de fonctionnalisations de surface ont été employés afin de compatibiliser celles-ci avec une matrice organique, notamment par greffage de composés de type acides phosphoniques. Plusieurs acides phosphoniques ont ainsi pu être utilisés avec succès pour la fonctionnalisation des deux types de charges. La caractérisation de ces différentes fonctionnalisations représente une part importante de ce projet. Des techniques d'analyse innovantes, aussi bien directes qu'indirectes ont été employées dans ce but, à savoir de la Py-GC/MS pour la détection des composés ancrés à la surface des charges, de la fluorescence X et de la spectroscopie infrarouge dans un objectif de quantification, mais aussi des études cinétiques de sédimentation des charges dans un milieu liquide organique. Finalement, des composites ont pu être obtenus par mélange des charges, traitées et non traitées, avec une matrice polyuréthane. Des essais de traction ont permis de montrer clairement une amélioration des propriétés mécaniques de certains des composites, grâce à la fonctionnalisation des charges par les acides phosphoniquesThis thesis focuses on the incorporation of mineral fillers of erbium oxide, Er2O3, and praseodymium oxide, Pr6O11, in an elastomeric polymer matrix, in the context of an industrial project to replace the lead in radiation protection equipment. The actual purpose of this thesis was to improve the dispersion of the fillers in the matrix through chemical treatment processes of these particles. Various types of surface functionalization were used to compatibilize them with an organic matrix, in particular by grafting compounds such as phosphonic acids. Hence, several phosphonic acids have been successfully used for the functionalization of both types of fillers. The characterization of these functionalizations is an important part of this project. Innovative analysis techniques, both direct and indirect have been used for this purpose, namely Py-GC/MS to detect the chemical compounds anchored to the surface of the fillers, X-ray fluorescence and FTIR spectroscopy with a quantification target, but also a study of sedimentation kinetics of the fillers in an organic medium. Finally, composites were obtained by mixing the fillers, untreated and treated, with a polyurethane matrix. Tensile tests have clearly shown an improvement of mechanical properties for some of the composites, due to the functionalization of the fillers by phosphonic acids
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Weis, Sebastian. "Beitrag zur Entwicklung partikelverstärkter Weich- und Weichaktivlote zum Fügen temperaturempfindlicher Aluminiummatrix-Verbundwerkstoffe." Doctoral thesis, Universitätsbibliothek Chemnitz, 2012. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-85829.
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Die vorliegende Arbeit beschäftigt sich mit der Entwicklung, Herstellung und Charakterisierung partikelverstärkter Weich- und Weichaktivlote mit dem Ziel der Eigenschaftsverbesserung der Lötverbindungen. Ausgehend vom Stand der Wissenschaft und Technik wird ein Konzept zur Einbringung von keramischen Verstärkungspartikeln in eine Sn-Basis-Lotmatrix erarbeitet und umgesetzt. Im Falle partikelverstärkter Weichaktivlote wird durch das zusätzliche Legieren der Lotmatrix mit dem reaktiven Element Titan die Ausbildung von zwei Reaktionszonen erreicht, welche die Haftung zwischen Partikel und Matrix steigern. Die mechanischen Eigenschaften dieser Verbindungen werden gegenüber der Partikelverstärkung ohne Aktivelement weiter verbessert. Zum Fügen der Aluminium- und Alumi-niummatrix-Verbundwerkstoffe (AMC) findet ein ultraschallunterstütztes Lötverfahren Anwendung, das eine Benetzung ohne den Einsatz von Flussmitteln ermöglicht. Die hergestellten Lötverbindungen zeichnen sich durch gesteigerte Verbindungsfestigkeiten, vor allem bei erhöhten Temperaturen, sowie eine verbesserte Kriechbeständigkeit aus. Aufgezeigt wird das Potenzial der Lote anhand von Zug- und Scherzugversuchen sowie Kriechuntersuchungen, die mit den Ergebnissen der Mikrostrukturanalyse und der fraktografischen Bewertung korreliert werden. Die Arbeit schließt mit einer Diskussion und sich daraus ergebenden Folgerung. Weiterhin liefert sie Ansätze für weitere Forschungstätigkeiten auf diesem GebietThis thesis deals with the development, manufacturing and characterisation of particle-reinforced solders and active solders to improve the mechanical properties of soldered joints. Based on the state of the art, a concept for embedding of ceramic particles in a Sn-based filler matrix is planed and realised. In the case of particle-reinforced active solders two interfacial reaction layers which increase the bonding between the particles and the filler matrix are formed due to the alloying by the reactive element Ti. The mechanical properties of these joints are improved in comparison to particle-reinforced solders without surface-active elements. For joining of aluminium and aluminium matrix composites (AMC), an ultrasound-supported soldering process was used, that accomplishes a fluxless wetting. The produced joints are featured by an improved joining strength, mainly at elevated temperatures, and an increased creep resistance. The potential of the developed solders is performed by tensile and shear as well as creep tests that are correlated with the results of the micro-structural and fractographical analysis. The Discussion and the drawn conclusions summarise the work and give new approaches for following investigations
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Robbes, Anne-sophie. "Nanocomposites à base de particules magnétiques : synthèse et contribution de la dispersion des charges et de la conformation des chaines sur les propriétés de renforcement." Thesis, Paris 11, 2011. http://www.theses.fr/2011PA112201/document.
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Les propriétés mécaniques de films polymériques peuvent être considérablement améliorées par l'inclusion de nanoparticules au sein de la matrice du fait de deux effets majeurs : (i) la structure locale de la dispersion des charges et (ii) la modification potentielle de la dynamique et de la conformation des chaînes à l'interface charge/polymère. Néanmoins, les mécanismes précis qui permettent de relier ces contributions à l’échelle nanométrique aux propriétés macroscopiques des matériaux, et en particulier aux propriétés mécaniques, sont actuellement mal décrits. Dans ce contexte, nous avons synthétisé des nanocomposites modèles à base de nanoparticules magnétiques de maghémite γ-Fe2O3 (nues ou greffées d'une couronne de polystyrène (PS) par polymérisation radicalaire contrôlée) dispersées dans une matrice de PS, que nous avons caractérisé en couplant la diffusion de rayonnement (Rayons X et neutrons) et la microscopie électronique à transmission. En jouant sur différents paramètres tels que la taille des particules, la concentration, ou le rapport de taille entre les chaînes greffées et celles de la matrice pour les charges greffées, nous avons obtenu des nanocomposites présentant un éventail de dispersions de charges variées, contrôlées, parfaitement reproductibles, allant de particules individuelles ou d’agrégats ramifiés jusqu’à la formation d’un réseau de charges connecté. En appliquant un champ magnétique externe durant la synthèse des nanocomposites, nous sommes parvenus à aligner les différentes structures le long de la direction du champ et ainsi former des matériaux présentant des propriétés remarquables de renforcement anisotropes. La conformation des chaînes au sein des nanocomposites, déterminée expérimentalement grâce aux propriétés spécifiques de contraste neutronique du système, n'est pas affectée par la présence des charges, quels que soient le degré de confinement des chaînes, l’orientation, la dispersion ou l'état de surface des charges. L’alignement des charges sous champ magnétique a permis de décrire précisément l’évolution du module de renforcement des matériaux avec la réorganisation structurale locale des charges et des chaînes sous étirement, et de finalement mettre en évidence le rôle majeur joué par la réorganisation des charges sous déformation dans les mécanismes de renforcementThe mechanical properties of polymeric nanocomposite films can be considerably enhanced by the inclusion of inorganic nanoparticles due to two main effects: (i) the local structure of fillers dispersion and (ii) the potential modification of the chains conformation and dynamics in the vicinity of the filler/polymer interface. However, the precise mechanisms which permit to correlate these contributions at nanometric scale to the macroscopic mechanical properties of the materials are actually poorly described. In such a context, we have synthesized model nanocomposites based on magnetic nanoparticles of maghemite γ-Fe2O3 (naked or grafted with a polystyrene (PS) corona by radical controlled polymerization) dispersed in a PS matrix, that we have characterized by combining small angle scattering (X-Ray and neutron) and transmission electronic microscopy. By playing on different parameters such as the particle size, the concentration, or the size ratio between the grafted chains and the ones of the matrix in the case of the grafted fillers, we have obtained nanocomposite films a large panel of controlled and reproducible controlled filler structures, going from individual nanoparticles or fractal aggregates up to the formation of a connected network of fillers. By applying an external magnetic field during the film processing, we succeeded in aligning the different structures along the direction of the field and we obtained materials with remarkable anisotropic reinforcement properties. The conformation of the chains of the matrix, experimentally determined thanks to the specific properties of neutron contrast of the system, is not affected by the presence of the fillers, whatever their confinement, the dispersion the fillers or their chemical state surface. The alignment of the fillers along the magnetic field has allowed us to describe precisely the evolution of the reinforcement modulus of the materials with the structural reorganization of the fillers and the chains at the local scale under stretching, and thus to highlight the key role played by the fillers reorganization under stretching on the nanocomposite reinforcement mechanisms
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Yang, Chen-Hau, and 楊程皓. "Role of mPE based compatibilizer on reinforcing particles filled eco-composites." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/27231677733175488138.
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碩士中國文化大學
材料科學與奈米科技研究所
98
This thesis consists of two different parts to investigate mPE based compatibilizer on the effect of different composite systems. The first part is the preparation of mPE8003/mPE8100-g-silane/clay. Metallocene polyethylene-octene elastomer (mPE8003)/clay nanocomposites were prepared and investigated by using a mPE8100-g-silane as a compatibilizer. Metallocene polyethylene(mPE8100) was grafted with vinyl triethoxy silane at first, and then followed by the mixing with mPE8003 and clay. The crosslinking reaction was conducted in water at 70℃. Two different clays, chemically modified clay Closite 20A and Closite 30B, have been used in this study. The result of FT-IR revealed silane was essentially grafted on mPE8100. The gel content measurement revealed the compatibilizer efficiently reacted with clay 20A, but not for clay 30B system. From the result of XRD analysis, mPE8003/mPE8100-g-silane/clay 20A showed a better dispersion than mPE8003/mPE8100-g-silane/clay 30B. Transmission Electron Microscope (TEM) revealed a similar result with XRD analysis. In the mPE8003/mPE8100-g-silane/clay 20A system, the clay was dispersed within the polymer matrix in delaminated threads shape, but was observed as lumps for clay 30B system. DSC results revealed the melting temperature was not obviously changed with the amount of clay. But the crystallization temperature of mPE8003/mPE8100-g-silane/clay 20A is higher than that of mPE8003/mPE8100-g-silane/clay 30B. From the result of TGA analysis, the decomposition temperature was obviously increased with increasing the amount of clay, and clay 20A system is much higher than clay 30B system. DMA analysis showed the storage modulus at the room temperature was increased with increasing the clay contents. From the tensile test, Young’s modulus was increased with increasing clay 20A content, but for clay 30B cases. This was attributed to the high surface area between the polymer and the clay 20A. The result of tear test revealed the tear strength was obviously increased with increasing the amount of clay for both clay 20A and clay 30B systems. The second part is the study on PA6(Polyamide 6)/mPE-g-MA(Maleic anhydride) binary composites. mPE and mPE-g-MA were pre-mixed with 10 phr NIR(Near infrared reflective pigment), manufactured by Tokan Material Technology, at 165 ℃ to form NmPE and NmPE-g-MA master batches, respectively. Then, variable amounts of NmPE and NmPE-g-MA were mixed with PA6 100 phr at 230 ℃ to prepare PA6/NmPE and PA6/NmPE-g-MA composites, respectively, which were investigated on their micro-structure, thermo properties and mechanical properties. The result of FT-IR (Fourier transform spectroscopy) revealed MA was essentially grafted on mPE. FE-SEM(Field emission scanning electron microscope) photos showed the compatibility of PA6/NmPE-g-MA(samples were all essentially etched by p-xylene) is better than PA6/NmPE. From XRD(X-ray diffraction) analysis, results of two series samples, α-crystal peaks appeared at 20° and 24°, and γ-crystal rarely appeared at 22°. The results of TGA(Thermo gravimetric analyzer) showed limited difference between PA6/NmPE and PA6/NmPE-g-MA at 5 %and 50 % weight loss, and ash content varied with NIR proportion. DSC results revealed that both PA6/NmPE and PA6/NmPE-g-MA composites all showed three melting temperatures(Tm), including Tm of mPE, α-crystal and γ-crystal for PA6. The Tm peak of α-crystal is bigger than γ-crystal, this result was confirmed by XRD. From tensile test, elongation of two systems were increased with elastomer content, but Young’ s modulus showed an opposite trend to elongation. On comparing of two systems, Elongation and Young’ s modulus were higher for PA6/NmPE-g-MA than PA6/NmPE. From impact test, the impact strength was increased with increasing elastomer content for both systems. And, impact strength of PA6/NmPE-g-MA is higher than PA6/NmPE.
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Gentieu, Timothee. "Development of filled polymers for the replacement of ceramics used as ballistic protection layer." Thesis, 2018. http://www.theses.fr/2018BORD0419/document.
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Les matériaux céramiques présentent généralement des propriétés mécaniques très intéressantes pour la réalisation de blindages. Ce sont des matériaux très durs et pourtant légers. Les plaques de blindages en céramique sont classiquement mises en forme par pressage à haute température de poudres, ce qui limite la taille et la forme des réalisations tout en impliquant un coût élevé. Une alternative pour produire ces pièces est le moulage d’un composite constitué de particules de céramiques dans une matrice époxy. Ce procédé permet de réduire le coût des pièces tout en autorisant des géométries plus complexes et des dimensions plus importantes.Le comportement mécanique de ce type de matériau dépend de multiples paramètres de conception : propriétés mécaniques des constituants (matrice polymère et particules céramiques), proportion volumique des deux phases, taille et distribution spatiale des particules ou encore l’adhésion entre les constituants. L’objectif de la thèse est d’évaluer l’influence de ces paramètres sur les propriétés d’usage du matériau. Pour ce faire, une analyse multi-échelle du matériau sous sollicitations quasi-statique et dynamique est réalisée.Plus précisément, les propriétés statiques et dynamiques du composite à renforts particulaires ont été déterminées pour différentes combinaisons de ces paramètres de conception. En particulier, le mécanisme de décohésion particule/matrice a été spécifiquement étudié. Les approches de Modèles de Zone Cohésive (CZM) et de Mécanique de la Rupture Finie (FFM) ont été utilisées pour modéliser ce phénomène et un fort effet de taille des particules a été observéCeramics have extensively been used for ballistic protection in the last decades. The combination of their mechanical properties makes them very interesting for armouring. Indeed, they exhibit a high hardness, large compression strength, high stiffness and low density. Ceramic armouring plates are commonly manufactured through a sintering process, where ceramic powders are pressed at high temperatures. This manufacturing process tends to limit the size and shape of components and imparts high costs. On the other hand, moulding using a polymer matrix composite provides an alternative process for developing lower cost parts whilst accommodating increased complexity of geometry and size.However, the mechanical behaviour of such a material is not completely known and depends on multiple design parameters: the mechanical properties of the phases, their volume fraction, the size and spatial distributions of the particles, and the adhesion between the components. The objective of the thesis is to evaluate the influence of the main morphological parameters on the overall mechanical properties, emphasising the influence of the particle/matrix adhesion. To do so, both numerical and experimental multiscale analyses of the material under quasi-static and dynamic loadings were carried out.More precisely, static and dynamic properties of the particle-reinforced composite have been determined for different combinations of the design variables. In particular, attention has been dedicated to the particle/matrix decohesion mechanism. Cohesive zone models (CZM) and Finite Fracture Mechanics (FFM) approaches were used to model this phenomenon and a strong effect of the particle size on debonding was observed
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Lin, Yi-Hsiang, and 林意翔. "Preparation and antibacterial properties of poly(lactic acid) composites filled with ionic-crosslinked chitosan particles." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/44862458806549936240.
Full textAbstract:
碩士淡江大學
化學工程與材料工程學系碩士班
102
Biodegradable polymers, also known as green plastics, can completely decompose into water and carbon dioxide under appropriate environmental conditions which consequently reduces the harm to the environment. Among many biodegradable polymers in the market, the most widely used is poly(lactic acid) (PLA), which has good mechanical rigidity and thus can be used in the cutlery, packaging materials and biomedical materials. On the other hand, chitosan (CS) is a natural polysaccharide polymer and is recognized as a non-toxic, antibacterial, biocompatible and biodegradable material. It can be used in food engineering and biomaterials. In this study, chitosan ionic-crosslinking particles (CS-TPP) was added into PLA films to render antibacterial properties for the use in food packaging materials. The CS-TPP particles in submicron size were prepared by ionic crosslinking the CS with tripolyphosphate (TPP) and added into the PLA to prepare antimicrobial and biodegradable films. In addition to the mechanical properties measured by tensile test, the initial modulus between 1.65 to 1.73 GPa. It not evident. Thermodynamics measured by DSC and TGA. Distribution of CS-TPP particles in the PLA matrix was evaluated by scanning electron microscopy. It can observe that there had no cluster in PLA matrix. The antibacterial properties of the prepared PLA composite films on two bacteria, Escherichia coli and Staphylococcus aureus, were also tested. When CS-TPP content 4 wt%, the antibacterial properties of Escherichia coli and Staphylococcus aureus were 39% and 13%. When CS-TPP content 8 wt%, the antibacterial properties of Escherichia coli and Staphylococcus aureus were 43% and 29%. Although emulsified PLA can degradable by enzyme, the degradability of PLA films by enzyme is not good.
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Yu, Chieh-Chen, and 游傑丞. "Dental composite resin with TTCP as filler: effect of filler particle size and pretreatment on diametral tensile strength and color matching." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/nrs6rq.
Full textAbstract:
碩士高雄醫學大學
牙醫學研究所
100
Objectives: The objective of this study was to observe the properties of dental composite resins, which was composed of micron-to-nano scale of tetracalcium phosphate (TTCP) under different surface pretreatment conditions as reinforced filler. The different mass fraction ratio of fillers within composite resin was prepared and the influences on diametral tensile strength (DTS) and resin color were also investigated. Materials & Methods: The resin matrix of testing specimens was composed of bisphenol A glycidyl methacrylate (Bis‐GMA) and triethylene glycol dimethacrylate (TEGDMA), with a light-curing initiator of camphoroquinone (CQ). The particle distributions of TTCP filler were set at 10 μm, 1 μm, 370 nm, and 100 nm. The surfaces pretreat method was adapted from patented TTCP pretreatment thereof and observed under transmission electron microscope (TEM). After pretreatment, TTCP particle was mixed within resin matrix to form test specimens. The ratios of the filler mass fraction to dental composite resin were differed from 30%, 40%, 50%, and 60 wt% (six duplicate specimens were prepared and analyzed for each group, n=6). For mechanical measurements, the diametral tensile tests and recordings of stress versus strain of the specimens were measured immediately after sample curing were reached using a universal testing machine at a crosshead speed of 1.0 mm/min. Color matching test on the sample was recorded using color measuring machine at the different times through the sample being immediate cured, 24 hrs, 48hrs, 72 hrs, and 7 days after light curing. The Commission Internationale de l''Eclairage L*, a* and b* (CIELAB) values and the differences in color (ΔE) were measured. Statistic analysis (JMP 8.0) was done by using one-way ANOVA, two-way ANOVA, Tukey’s HSD post hoc test, or Student’s t-test. (α=0.05). Results: TEM observation of pretreated TTCP was showed that nano-scale whisker crystallites were grown on the surface of micron-scale particle. The analysis reported that the DTS was found significantly influenced by the process surface pretreatment on fillers, and different filler mass fractions in 100nm and 370nm group without pretreatment (p <0.0001). In the modulus of elasticity analysis, statistically significant differences were found between the process of surface pretreatment, different filler mass fractions, and particle size distributions (p <0.0001). The color of resins could be distinguished easily between the 10μm and the other groups. The color of resin would change with time after the sample being cured. The color difference ΔE was found statistically significant influenced by pretreatment and filler mass in group comparisons (p <0.0001). Conclusion: 1. The process of TTCP surface pretreatment not only had an affected by phase changes on the surfaces of crystallites through TEM observation, but also had statistically significant effects in DTS and modulus of elasticity. 2. The color of resin would be influenced by filler particle size distributions, filler mass fraction, and changing with time. The higher the filler mass fraction of resin, the more stablie the resin’s color.
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Chia-HaoLin and 林家豪. "Nanohydroxyapatite particles as the reinforcing fillers of dental composites: effects of shape and silanization." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/4b5g2m.
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CHANG, CHIA-CHI, and 張佳奇. "Thermal Conductivity of Epoxy Composites With Ag Particles Doped Al2O3 Micro/nano Fibrous Fillers." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/60210962430892487244.
Full textAbstract:
碩士國立高雄應用科技大學
化學工程與材料工程系博碩士班
104
As the development of electronic components in the direction of miniaturization, high-power, and high integration, it requires more and higher performance, so the waste heat generated by the operation of components, need to be ruled out quickly, otherwise it will reduce the performance of electronic components. High thermal conductivity polymer composite materials with high thermal conductivity and high-performance are the most widely used in electronic components. This study is using electrospinning method to prepare high thermal conductivity micron network Al2O3-Ag fillers, and applied to enhance thermal conductivity of Al2O3-Ag/epoxy composites. Commonly, to enhance thermal conductivity of polymer matrix composite via a large amount of thermal conductivity powders loading in matrix (ex: AlN). From the images of SEM, indicated the Al2O3-Ag fillers with 1-D micron network structure and high aspect ratio (> 50), and identified as cubic system Ag and rhombohedral system Al2O3 by XRD and TEM. From the spectra of FT-IR, confirmed the material surface grafted with siloxane. By a four-point probe tester detected the volume resistivity value, confirmed the Al2O3-Ag/epoxy composites is non-conductive material. The Al2O3-Ag/epoxy composites using a thermal conductivity meter (Hot-Disk) to detect the heat transfer coefficient, was prepared the Al2O3-Ag fiber and modified Al2O3-Ag fibrous fillers, as 50 wt% addition amount of epoxy composite, the thermal conductivity were 0.77, 0.60 W/mK, respectively. And had 285% and 200% enhancement in thermal conductivity, respectively. This conclusion can be observed the filler which were modified has the better thermal conductivity, by using SEM observe the surface morphology of cross section can be found within the composites material is modified through the addition of materials and organic substrates interface significantly reduced, which can be attributed to the additional material bonded with an epoxy resin. DMA detects storage modulus and glass transition temperature, in addition to silane internal substrate material can effectively inhibit crack growth and storage modulus increases, but because of this situation hinders the crosslinked epoxy resin.
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Sardashti, Amirpouyan. "Wheat Straw-Clay-Polypropylene Hybrid Composites." Thesis, 2009. http://hdl.handle.net/10012/4712.
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The preparation of polymeric hybrid composite consisting of organic and inorganic fillers is of interest for industries like automotive, construction and packaging. In order to understand and predict the physical and chemical properties of these hybrid composites, it is necessary to fully understand the nature and properties of the employed fillers. In this study, the preparation of polypropylene hybrid composite consisting of wheat straw and clay was investigated. A detailed study was performed on wheat straw from South Western Ontario region. The effect of grinding the straw and compounding it with polypropylene was investigated. Experiments were carried out to identify the thermal stability of the ground wheat straw with respect to their size and composition. It was important to identify a correlation between these properties in order to minimize the straw degradation by processing and also to improve the final properties of the hybrid composite. The composite samples were prepared through melt blending method using a co-rotating twin-screw extruder. Sample test bars were prepared by injection moulding. The composition of the constituents of the hybrid composite; percentages of wheat straw, clay and coupling agent, were varied in order to investigate their influence on thermal stability, water resistance and mechanical properties.
The results of the study indicated that grinding the wheat straw with a hammer mill produced particles with different sizes and shapes. It was found that through the grinding system all particles, regardless of their size, had a multi-layered structure similar to the plant structure. Further hammer milling did not produce plant particles with long aspect ratios that would be expected in a defibrillation process. Analysis of the chemical composition of wheat straw particles of different sizes and shapes was used to measure the ratio of hemicelluloses: lignin and the ash content. It was found that the large particles contained more amount of lignin whereas smaller particles had larger amount of ash content. The thermal stability of the particles was found to be a function of particle size rather than the lignin content. Particle size analysis on the wheat straw particles after the extrusion process indicated a reduction in the particle length and aspect ratio.
The thermal stability of the composites was found to be enhanced by the addition of clay particles at higher temperature and the addition of coupling agent at lower temperatures. Increasing the amount of wheat straw and clay content increased the flexural modulus and reduced the resistance for water absorption. Increasing the amount of coupling agent also increased the flexural modulus and resistance for water absorption. The morphological study by scanning electron microscopy revealed that coupling agent increased the interfacial interaction between the particles and the polymer matrix.
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Huang, Lu-kai, and 黃律凱. "Ultradrawing and Ultimate Tenacity Properties of Novel Ultra-high Molecular Weight Polyethylene Composite Fibers Filled with Nanosilica Particles with varying specific surface areas." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/77665818151392068361.
Full textAbstract:
碩士國立臺灣科技大學
材料科學與工程系
101
Systemic investigation of the influence of the original and modified nanosilica contents on the ultradrawing properties of ultrahigh molecular weight polyethylene(UHMWPE)/nanosilica (F100Sy) and UHMWPE/ modified nanosilica (F100Smx-y) as-prepared fibers are reported. In a way similar to those found for the orientation factor values, the achievable draw ratios (Dra) of F100Sy and F100Smx-y as-prepared fibers approached a maximum value as their nanosilica and/or modified nanosilica contents reached their corresponding optimum values at 0.0625 and 0.0375 phr, respectively. The maximum Dra values obtained for F100Smx-0.0375 as-prepared fiber specimens prepared at varying maleic anhydride grafted polyethylene (PE-g-MAH)/nanosilica weight ratios were significantly higher that of the F100S0.0625 as-prepared fiber specimen prepared at the optimum nanosilica content. Tensile property analyses further suggested that excellent orientation and tensile properties of the drawn F100Sy and F100Smx-y fibers can be obtained by ultradrawing the fibers prepared at their optimum original nanosilica and/or modified nanosilica contents, respectively. To understand the interesting orientation, ultradrawing and tensile properties of F100Sy and F100Smx-y fiber specimens, FTIR and specific surface area analyses of the original and modified nanosilica particles were performed in this study.