Cette thèse a pour objet de développer une nouvelle méthodologie pour valoriser les poudrettes de pneus usagés (PPU). Celles-ci résultent du broyage de la partie caoutchoutique des pneus usagés qui conserve l’excellente élasticité. L’idée est de profiter de leur élasticité pour renforcer la résistance au choc des polymères fragiles tels que le polystyrène (PS) en y incorporant les PPU. Cependant, la réalisation de cette idée a besoin de relever deux défis majeurs : (1) les PPU commerciales ont typiquement des diamètres de l’ordre de plusieurs centaines de micromètres. Or elles doivent être deux ordres de grandeur plus petits en taille pour pouvoir améliorer la résistance au choc des polymères fragiles. (2) L’adhésion interfaciale entre les polymères et les PPU est mauvaise et constitue donc des défauts mécaniques du matériau. Ces deux défis sont liés à la nature même des PPU qui sont intrinsèquement des réseaux réticulés chimiquement. Cette thèse choisit le PS pour représenter les polymères fragiles. La méthodologie visant à renforcer sa résistance au choc est de polymériser le styrène par voie radicalaire au sein des PPU. Cette polymérisation forme à la fois des chaines en PS libres et des greffons en PS liés chimiquement aux mailles du réseau des PPU. Les inclusions des chaines en PS libres facilitent la dispersion des PPU en taille plus petite lorsqu’une action mécanique leur est appliquée lors de l’extrusion par exemple. La formation des greffons en PS sur les mailles du réseau des PPU renforce l’adhésion interfaciale entre le PS et les PPU. Cette thèse a développé un modèle complet permettant de décrire la cinétique de polymérisation radicalaire du PS libre et celle des greffons en PS liés aux mailles du réseau des PPU. Elle l’a validé par un plan d’expériences judicieux / This thesis aims to develop a novel approach to value ground tire rubber (GTR). The latter results from grounding of the rubber part of used tires which retains excellent elasticity. The idea is to take the advantage of its elasticity to toughen brittle polymers such as polystyrene (PS) upon incorporating GTR into them. However, two challenges have to be overcome to realize this idea. (1) Commercial GTR is typically in the form of particles of a few hundreds of micrometers in diameter. However, it has to be at least one to two orders of magnitude smaller when incorporated in a brittle polymer so as to be able to improve its impact resistance. (2) The interfacial adhesion between the polymer and GTR is weak. These two challenges are related to the intrinsic nature of the GTR which is chemically cross-linked. This thesis chooses PS to represent brittle polymers. The approach aiming at toughening it is to polymerize styrene in a free radical manner inside cross-linked GTR particles. This leads to the formation of both free PS and PS that is grafted onto the GTR, denoted as grafted PS. The inclusions of the free PS inside the GTR particles help break them down by mechanical shear in a screw extruder for example and the formation of grafted PS improves the interfacial adhesion between the PS and the GTR. This thesis has developed a comprehensive kinetic model for the polymerization of free PS and that of grafted PS. This model is validated by experimental designs

Asphalt binder modification is a common method of improving Hot-mix Asphalt (HMA) performance by enhancing mix properties and reducing or delaying three general HMA distress types: deformation (rutting and shoving), cracking (from repeated loads and low temperatures) and general deterioration (raveling and stripping). Since the early 1960’s, a common modified asphalt alternative has employed reclaimed rubber as an economical and environmental friendly method of recycling waste tires while improving asphalt physical and mechanical properties. Pavement network deterioration combined with increasing material costs makes polymer modification of asphalt binder desirable, with reclaimed rubber from waste tires being an attractive alternative which addresses performance, economics and environmental issues. The primary objective of this dissertation is to demonstrate the importance of proper processing of all types of modified bituminous binders, whether they be virgin (e.g. styrene-butadiene-styrene (SBS) or styrene-butadiene rubber (SBR)), post-consumer polymers (e.g. ground tire rubber (GTR)) or a combination (GTR plus SBS). To achieve this four secondary objectives were identified: 1) characterize GTR using thermo-gravimetric analysis (TGA), 2) improve processing of GTR modified binders, 3) improve testing and specifications of GTR modified binders and 4) evaluate mixes containing GTR modified binders. A simple efficient instrumental, TGA, method to analyze polymers in binary rubber compounds was developed to quantify the functional polymer content available in GTR. TGA analysis provides a better understanding of the general chemical characteristics of GTR used in modification of asphalt binders for production of asphalt paving mixtures. Results are presented from efforts to optimize GTR modified binder formulations with respect to how GTR loading, GTR particle size, processing temperature and asphalt cement source affect modified binder properties and ability to meet performance graded binder specifications. These results are the basis to establish recommended processing parameters for formulation and preparation of GTR modified asphalt binders. GTR modified binders were used in: dense graded asphalt (DGA), stone matrix asphalt (SMA) and open graded friction courses (OGFC) and compared to conventional asphalt cement and styrene-butadiene-styrene (SBS) modified asphalt binders. Mixture performance evaluation with respect to binder effectiveness as it relates to the three general HMA distress types.

No description available.

La difficulté de recyclage des pneus usagés en raison de la réticulation de la gomme représente un enjeu environnemental important. Une solution envisagée dans cette étude est la mise en œuvre de poudrettes de pneumatique recyclées (GTR) dans la conception de produits de plasturgie visant un bon amortissement choc, acoustique et vibratoire. Notre travail s’est orienté vers la conception et la caractérisation de deux types de matériaux : 1) Des composites Thermoplastique/GTR, sur 2 matrices thermoplastiques (TP) différentes (Acétate de vinyle (EVA) et polypropylène (PP) mis en œuvre par extrusion/injection, 2) Des plaques composées à 100% de poudrettes GTR élaborées par compaction/chauffage. La qualité de l’interface TP/GTR a été estimée par analyse micrographie électronique à balayage MEB. L’influence des charges GTR sur la cristallinité des matrices a été évaluée par DSC. Une étude en traction a permis de déterminer le module de Young en traction, le seuil d’écoulement ainsi que l’allongement à rupture. L’amortissement vibratoire a été caractérisé par analyse mécanique dynamique (DMA) avec la détermination du facteur de perte η sur une large gamme de températures permettant la construction des courbes maîtresses en fréquence (équivalence fréquence/température WLF). L’amortissement choc a été déterminé par impact de chute de masse instrumenté. Le coefficient d’absorption acoustique a été mesuré au moyen d’un tube de Kundt par la méthode des deux microphones. Ces différents moyens de caractérisation ont montré que l’amortissement de vibrations et d’impacts était augmenté par l’incorporation de charges GTR dans une matrice TP. L’étude de la résilience des mélanges PP/GTR a mis en évidence l’influence de la structure interne des éprouvettes moulées sur les mécanismes d’amortissement des chocs. Les plaques constituées à 100% de poudrettes compactées/chauffées ont démontré une bonne cohésion et d’excellentes propriétés d’amortissement aux chocs. Le coefficient d’absorption acoustique n’est intéressant qu’au voisinage de la résonance des différentes plaques testées. / The difficulty of recycling used tires due to the crosslinking of the gum is an important environmental issue. One solution proposed in this study consists in the integration of recycled tire crumb (GTR) in the design of plastic products aiming for a good impact, sound and vibration damping. Our work focused on the design and characterization of two types of materials : 1) Thermoplastic/GTR composites with two different thermoplastic matrix (TP) : vinyl acetate (EVA) and polypropylene (PP)processed by extrusion/injection, 2) plates made from 100 % GTR crumb processed by sintering. The quality of the TP/GTR interface was estimated with a Scanning Electron Microscope SEM. The influence of the GTR fillers on the TP matrix crystallinity was evaluated by DSC. Tensile test determined the Young’s modulus in tension, the yield point and the elongation at break. The vibration damping has been characterized by Dynamic Mechanical Analysis (DMA) with the determination of loss factor η on a wide range of temperatures to allow the construction of master curves frequency (frequency/temperature equivalence WLF). The shock damping was determined by an intrumentad drop test. The sound absorption coefficient was measured using a Kundt tube using the two microphones method. These different means of characterization showed that the vibration damping and impact energy absorption was increased by the incorporation of GTR fillers in a TP matrix. The study of PP/GTR blends revealed the influence of the internal damages of the molded specimens on the shock absorption mechanisms. Plates consisting of sintered GTR showed good cohesion and excellent shock absorption properties. The sound absorption coefficient only proved interesting in the vicinity of the resonance of various plates being tested.

Ces dernières années, la recherche de solutions au problème de l'élimination de déchets polymères, notamment les déchets issus de pneumatiques qui posent de graves problèmes environnementaux, connait un développement croissant. Dans ce contexte, ce projet de recherche a pour objectif de contribuer au développement et à la promotion de solutions innovantes qui font appel aux connaissances développées dans les domaines des nanotechnologies, de la science et l’ingénierie des matériaux nouveaux et du génie des procédés et des produits. Il s’agit plus particulièrement de d’étudier la possibilité de valoriser les déchets issus de pneumatiques en les utilisant comme matière première (en tant que agents de renfort ou agents de modification de la résistance aux chocs) pour l'élaboration de matériaux nanostructurés. Ce travail met l'accent sur l'étude des mélanges de polyéthylène haute densité (PEHD) contenant des particules d’argile (dispersées à l'échelle du nanomètre) et des déchets de caoutchouc issus de pneumatiques usagés (ou Ground Rubber Tire ou GRT). Il est attendu que ce matériau présente des propriétés typiques des mélanges de polymères appelés Vulcanisats Thermoplastiques (TPVs), résultant de la vulcanisation dynamique de la phase de caoutchouc pendant le traitement à l'état de fondu (extrusion). Dans le système étudié, la matrice est le PEHD et la phase dispersée de la poudrette de pneu, préalablement dévulcanisée par micro-ondes. L'argile dispersée dans la phase de la matrice, agit comme un agent compatibilisant entre les phases du mélange et comme agent de renforcement, apportant une amélioration des propriétés mécaniques des matériaux préparés. La caractérisation des mélanges met l'accent sur leur morphologie et leur structure ainsi que sur leurs propriétés rhéologiques, thermiques et mécaniques. Une étude approfondie de l'évolution de la morphologie du mélange au cours de l’extrusion a été effectuée car ce paramètre est la clé pour optimiser le procédé et obtenir les meilleures propriétés pour le matériau final. Ceci représente la contribution plus importante de ces travaux de recherche. / 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.

Made available in DSpace on 2016-06-02T19:56:35Z (GMT). No. of bitstreams: 1 2404.pdf: 4034212 bytes, checksum: 2913adf06c11c92402ccb17ed7a97fa8 (MD5) Previous issue date: 2009-02-27 / Universidade Federal de Sao Carlos / Hydrogen is a clean and renewable source of energy and it is considered the "fuel of the future", because it produces only water during combustion and when it is used as fuel and hydrogen has a high energy yield of 122 kJ/g, which is 2.75 times greater than hydrocarbon fuels. The hydrogen production using microorganisms is a promising area of technological development from a wide variety of renewable and a alternative for this production is to use the anaerobic fluidized bed reactor (AFBR), a promising reactor for hydrogen production. One of the factors that most influence the performance of AFBR is the support material, which should provide resistance to abrasion, porous surface conducive to colonization by microorganisms, easy fluidization to reach and ability to facilitate the transfer of mass between the middle and biofilm. Thus, the objective of this study was to evaluate the influence of different support materials (polystyrene - R1, ground tire - R2 and PET - R3) for the hydrogen production, using three AFBR. Each reactor had a total volume of 4192 cm3, which was used as carbon source 4000 mg.L-1 of glucose, with pH influent around 7.0 and pH effluent of around 5.5, with hydraulic retention time (HRT) between 8 and 0.5 h, with temperature of 30 o C } 1, with heat treatment of the inoculum. The best performance was R2, giving better hydrogen yield production (HY) (2.15 mol-H2.mol-1-glucose), best H2 content in the biogas (52.97%) and showed a higher glucose conversion (90%). However, the R3 was better in the hydrogen production rate (HPR), 1.07 lh-1.L-1, a secondary parameter in the analysis of performance of the reactors. In all reactors, the production volume of hydrogen and H2 content in biogas increased with the reduction of the TDH, 8 pm to 1 HEO yield of hydrogen production increased with the reduction of the TDH, 8 h for 2 h. The major soluble metabolites during H2 fermentation were acetic acid (HAc), butyric acid (HBu), lactic acid (HLa) and ethanol (EtOH), and a small production of propionic acid and R2 was the reactor that more produced HAc and HBu (42.0% e 36.5%, respectively) . The better performance of R2 can be explained by the roughness of ground tire is larger than the other materials used, accumulating a large quantity of attached biomass, and a greater quantity of bacteria hydrogen producing. There was a predominance of bacilli like Clostridium sp. in the biofilm of all support materials. / O hidrogenio e uma fonte de energia limpa e renovavel e e considerado o combustivel do futuro , pois gera somente agua durante sua combustao e apresenta calor de combustao de 122 kJ.g-1, o que representa 2,75 vezes mais conteudo de energia do que qualquer hidrocarboneto. A producao de hidrogenio usando microrganismos e uma promissora area de desenvolvimento tecnologico a partir de uma ampla variedade de fontes renovaveis e uma das alternativas para esta producao e a utilizacao do reator anaerobio de leito fluidizado (RALF). Um dos fatores que mais influenciam o desempenho do RALF e o material suporte, que deve apresentar resistencia a abrasao, superficie porosa favoravel a colonizacao de microrganismos, facilidade para alcancar a fluidizacao e capacidade de favorecer a transferencia de massa entre o meio e o biofilme. Desta maneira, o objetivo deste trabalho foi avaliar a influencia de diferentes materiais suporte (poliestireno - R1, pneu inservivel triturado - R2 e PET - R3) na producao de hidrogenio utilizando tres reatores anaerobios de leito fluidizado. Cada reator possuia um volume total de 4192 cm3, alimentado com meio contendo glicose como fonte de carbono (4000 mg.L-1), com pH afluente em torno de 7,0 e efluente em torno de 5,5, com tempo de detencao hidraulica (TDH) entre 8 e 0,5 h a uma temperatura de 30oC } 1oC, com tratamento termico do inoculo. O melhor desempenho foi do R2, apresentando melhor rendimento de H2 (2,15 mol-H2.mol-1-glicose), melhor conteudo de H2 no biogas (52,97%) e maior conversao de glicose (90%). Entretanto, o R3 foi melhor na producao volumetrica de H2, 1,07 L.h-1.L-1, um parametro secundario na analise de desempenho dos reatores. Em todos os reatores, a producao volumetrica de hidrogenio e o conteudo de H2 no biogas aumentaram com a reducao do TDH de 8 h para 1 h e o rendimento de producao de hidrogenio aumentou com a reducao do TDH de 8 h para 2 h. Os metabolitos soluveis predominantes em todos os reatores foram acidos acetico, butirico, latico e etanol, havendo uma pequena producao de acido propionico, sendo o R2 o que mais produziu acidos acetico e butirico (42,0% e 36,5%, respectivamente). O melhor desempenho do R2 pode ser explicado pela rugosidade do pneu triturado ser maior do que a dos demais materiais empregados, acumulando uma maior quantidade de biomassa aderida e uma maior quantidade de bacterias acidogenicas produtoras de hidrogenio. Houve predominancia de bacilos semelhantes a Clostridium sp. no biofilme de todos os materiais suporte.

No description available.