Extruded products with precision shape have been used widely to 3C products, electronic equipment, communicatory installation, precision instrument, automobile industry. The tolerance for this kind of asymmetric products with small size is strictly required. During extrusion, the plastic flow of the billet inside the die cavity is complicated. The temperature distribution of the billet, the elastic deformation of the die, and the design of the flow guide affect the final dimension of the product. This paper uses the finite element code ¡§DEFORM 3D¡¨ to simulate the plastic flow of the billet inside the die cavity and the stress, strain, temperature distributions of the die during extrusion of a 3C product, Clip and Housing. From the simulation results, a die design guideline is proposed and the temperature, stress, strain distributions are discussed systematically. Furthermore, extrusion experiments are conducted. From the comparisons of the temperature at the die exit, the product sizes and the extrusion force, the validity of the die design rule is verified.

La faible stabilité thermique et les problèmes d’agrégations irréversibles limitent l’utilisation de nanocomposites polymères à renfort cellulosique. Dans ce contexte, des CNC thermiquement stable et fortement dispersés ont été préparés par des procédés verts, basés sur des méthodes en milieu aqueux, telle que l'adsorption physique et la modification de surface. Ces deux types de CNC extrudables ont été utilisés comme renfort dans des polymères réputés hydrophobes. Les composites biosourcés à matrice polymère ainsi réalisés sont caractérisés par une amélioration du module visqueux, de la résistance à la traction et du module d’Young. On constate également sur les images de microscopie électronique à balayage, qu’à la différence des observations réalisées avec les CNC non traités, qu’aucun micro-agrégat cellulosique n’est observé dans la matrice polymère. Ces deux méthodes, développées en milieu aqueux, apparaissent ainsi comme des solutions industriellement viables. / The low thermal stability and irreversible agglomeration issues are limiting to process the polymer nanocomposites using CNC as the reinforcing phase. In this context, thermally stable and highly dispersed CNC were prepared by green process (Aqueous based methods) like physical adsorption and surface modification. These two different Extrudable CNC was reinforced in to hydrophobic polymers. Ensuing polymer nanocomposites had a positive impact on the storage modulus, tensile strength, Young’s modulus. Importantly, no evidence of micro aggregates in the matrix was observed in the scanning electron microscopy images contrary to non-treated CNC. Both the surface modification and adsorption are the water based methods and is an industrially viable solution. Also, it can be applicable at industrial level.

Massas de pães são preparadas a partir da mistura de farinha de trigo, água, sal e fermento. Ao entrar em contato com a água e sofrer amassamento mecânico, a farinha de trigo tem a propriedade, quase exclusiva, de produzir uma massa coesa e viscoelástica, por conter proteínas formadoras de glúten. O processo de mistura pela qual passam as massas de pães, seguido de etapas de fermentação é fundamental para o bom desenvolvimento da massa e qualidade final do pão acabado. As análises de textura (back extrusion e extensibilidade) e volume, em massa crua de pão, podem avaliar o desenvolvimento e a qualidade de massas, eficácia de formulações e a eficiência dos ingredientes usados na melhoria do desenvolvimento da massa e do pão acabado. O projeto teve como objetivo elaborar formulações de massas de pães por diferentes processos de fermentação e testá-las através das análises de textura por extensibilidade e back extrusion, e volume sendo esta última sugerida para esse fim. Também foi testada a substituição de parte da farinha de trigo por triticale. As formulações utilizadas incluíram diferentes métodos de preparo de massas, como método direto e indireto, sendo nove formulações propostas. Pelo método direto o fermento seco instantâneo é adicionado diretamente à farinha e em seguida os demais ingredientes da formulação são adicionados, em uma única fase, seguido das etapas de mistura e fermentação. Já para as massas elaboradas de forma indireta, preparou-se uma massa fermentada denominada esponja, que foi feita com parte da farinha e da água e todo fermento seco instantâneo da formulação, deixada fermentar durante uma hora. Em uma segunda fase, a esponja foi adicionada ao restante dos ingredientes, seguido das etapas de mistura e fermentação. Os resultados das análises mostraram as diferenças do comportamento reológico de massas preparadas por diferentes processos fermentativos e a influência dos ingredientes como, o iogurte, adicionado por conter substâncias que são encontradas em pães fermentados naturalmente, resultando no aumento dos parâmetros reológico das massas contendo esse ingrediente. / Dough of bread are prepared from the mixture of flour wheat, water, salt and yeast. By contacting the water and suffer mechanical kneading the flour has property, almost exclusively, to produce a cohesive dough and viscoelasticity, which contain gluten-forming proteins. The mixing process through which runs the dough of bread, followed stages of fermentation is essential for the dough development and final quality of the finished bread. The analysis of texture (back extrusion and extensibility) and the volume dough of raw bread, can measure the development and quality of dough, formulation\'s effectiveness and efficiency of ingredients used in enhancing development of dough and the finished bread. The project had the object to develop formulations of doug for different fermentation processes and test them through the analysis of texture by extensibility and back extrusion, the latter being suggested for this purpose. Also was tested the substitution of part of the flour for triticale. The formulations used included different methods of preparation of dough, as a direct and indirect method, being nine formulations proposed. Through direct method the instant dry yeast is added directly to flour and then other ingredients formulation are added in a single phase, followed by stages of mixing and fermentation. To the dough produced in an indirect way, has been prepared a fermented dough called sponge, which is made with part of the flour and water and all instant dry yeast used in the formulation, and left to ferment for one hour. In a second phase, the sponge was added to the rest of the ingredients, followed the steps of mixing and fermentation. The analysis results showed the differences of rheological behavior of doughs prepared by different fermentation processes and the influence of ingredients as yogurt, added to contain substances that are found in naturally fermented breads, resulting in the increase of rheological parameters of the dough containing this ingredient.

Le tendon est un tissu conjonctif fibreux qui transmet les forces du muscle à l'os. Il a une structure hiérarchique formée de faisceaux et de fibrilles de collagène de type I orientées parallèlement à son axe. Leurs propriétés structurales confèrent aux tendons une flexibilité et une résistance à la traction élevées. Cependant, soumis à des sollicitations répétées, les tendons peuvent se déchirer et même rompre, ce qui peut rendre nécessaire Une intervention chirurgicale. Plusieurs stratégies sont en cours de développement comme les autogreffes, les tendons décellularisés ou les fibres synthétiques tressées. Cependant, aucun de ces matériaux ne répond parfaitement au cahier des charges de l'ingénierie tissulaire (cytocompatibilitité, propriétés mécaniques etc). L'objectif de cette thèse est donc de produire par extrusion et dans des conditions physiologiques une matrice de collagène qui imite le tendon. Tout d'abord, nous avons étudié les instabilités d’extrusion d’un système modèle (alginate de sodium), choisi pour ses propriétés rhéologiques proches du collagène. A partir de cette étude, nous avons ensuite produit des fils de collagène dense ou de mélanges collagène/alginate de diamètre de l’ordre de 500 µm conduisant à l’obtention de structures alignées selon l'axe du fil. Les conditions physico-chimiques ont été sélectionnées afin d'obtenir des fils homogènes avec les meilleures propriétés mécaniques. Enfin, ces fils ont été mis in vitro en contact avec des cellules souches mésenchymateuses. Celles-ci colonisent nos matrices et expriment les différents gènes caractéristiques du tendon, ce qui suggère qu’elles se différencient en cellules tendineuses. / Tendon is a fibrous connective tissue, which transmits forces from muscle to bone. It is mainly composed of collagen I fibrils and fascicles aligned along its axis. Moreover, collagen fascicles exhibit a helical “crimp” which acts as a natural shock-absorber and may play a role in elastic recoil. Due to this hierarchical structure, tendons present both flexibility and a high tensile strength over a wide load range. When an injured tendon is severely ruptured, a heavy surgical procedure is required. To overcome this issue, several strategies have already been developed as autografts, decellularized tendons, braided synthetic fibers. However, none of these materials fully meets chemical, mechanical and cytocompatibility requirements. The aim of this thesis is to produce a collagen matrix which mimics tendon by extrusion under physiological conditions. First, using alginate solutions as a model system for their similar rheological properties, we performed an extensive study of the helical extrusion instability which hinders the formation of regular threads. Based on this work, we then produced micrometric threads of dense collagen or mixtures of collagen and alginate which exhibit structures aligned along the thread axis. The physico-chemical conditions are chosen in order to obtain homogeneous threads with optimized mechanical properties. Finally, mesenchymal stem cells are seeded in vitro on collagen based threads. They colonize our matrices and express characteristic genes which suggests that they differentiate into tendon-like cells.

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