L’objectif de ces travaux est de développer une nouvelle voie de valorisation de différents coproduits agricoles et forestiers. L’étude s’est focalisée sur l’étape de séparation entre les hémicelluloses et les lignines contenues dans des extraits aqueux obtenus par extrusion bi-vis. La technologie bi-vis du fait de sa modularité a été choisie pour évaluer différentes conditions d’extraction. Les essais ont été menés afin de mettre en évidence l’influence des effets mécanique, thermique et chimique sur l’extraction des hémicelluloses à partir des différentes matrices végétales étudiées. Les travaux ont été conduits soit en conditions hydrothermales, eau sous pression et haute température, soit en conditions faiblement alcalines pour extraire des molécules les plus natives possibles. Ceci a permis d’identifier les conditions d’extraction les plus favorables en fonction des caractéristiques de chacune des biomasses. Dans un second temps, les extraits obtenus, contenants des hémicelluloses et des composés phénoliques, ont été purifiés au moyen de méthode de fixation sur résines d’échange d’ions et d’adsorption. Les travaux se sont focalisés sur la compréhension des mécanismes de fixation des molécules avec des solutions modèles contenant un ou plusieurs solutés. La cinétique et les isothermes d’échanges ont été évaluées pour l’acide férulique, l’acide coumarique et la lignine. Les résultats ont ensuite été comparés à ceux obtenus avec les extraits alcalins. Cette étude a permis d’identifier les mécanismes d’échanges qui interviennent lors de la séparation des complexes lignine-polysaccharides.

Orientador: Marcia Carneiro Valera / Coorientador: Carlos Henrique Ribeiro Camargo / Banca: Cláudio Antonio Talge Carvalho / Banca: Marco Antônio Húngaro Duarte / Resumo: Os objetivos deste estudo foram: Artigo 1 - Analisar a extrusão apical de hipoclorito de sódio (NaOCl), debris e sua citotoxicidade após o preparo dos canais radiculares utilizando NaOCl líquido ou gel. Artigo 2- avaliar a dissolução de matéria orgânica do NaOCl líquido e gel, e a limpeza das paredes dentinárias após a instrumentação; Métodos: Artigo 1 - A avaliação da extrusão apical de NaOCl e debris foi feita pela espectrofotometria do conteúdo extruído após o preparo biomecânico. A citotoxicidade foi avaliada pela resposta de culturas celulares de fibroblastos de ligamento periodontal (PDFL) frente as soluções irrigadoras extruídas, pelo teste XTT para análise da viabilidade celular. Para isso, oitenta dentes foram instrumentados com limas Reciproc #25 e #40 (VDW Munique, Alemanha) e utilizado NaOCl gel e líquido ativados por ultrassom. Os dados foram analisados estatisticamente pelo teste de ANOVA e as diferenças estatísticas pelo teste de Tukey e Dunn (p<0,05). Artigo 2 - A dissolução de matéria orgânica foi realizada usando cubos de carne com tamanho e peso determinado, os quais foram deixados em contato com 1 mL das amostras dos seguintes grupos: NaOCl gel 3% (ChlorCid V); NaOCl gel 3%(VIM); NaOCl líquido 2,5%; NaOCl líquido 5,25%; Solução fisiológica estéril (SF) (controle) por um período de 3 min, os fragmentos foram removidos e pesados novamente para quantificar a matéria orgânica não dissolvida. A comprovação da limpeza das paredes dos canais foi avaliada através ... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The objectives of this study were: Article 1 - Analyze the apical sodium hypochlorite (NaOCl) extrusion, debris and it's cytotoxicity after the root canals preparation using liquid or gel NaOCl. Article 2 - Evaluate the tissue dissolution of NaOCl liquid and gel, and it's cleaning efficiency of dentin walls after instrumentation; Methods: Article 1 - The evaluation of the apical extrusion of NaOCl and debris was done by the spectrophotometry of the extruded contents after the biomechanical preparation. Cytotoxicity was evaluated by the cell cultures response of periodontal ligament fibroblasts (PDFL) against extruded irrigation solutions by the XTT test for cell viability analysis. For this, eight teeth were instrumented with Reciproc # 25 and # 40 files (VDW Munich, Germany) and used NaOCl gel and liquid activated by ultrasound. Data were analyzed statistically by the ANOVA test and the statistical differences by the Tukey and Dunn test (p <0.05). Article 2 - The dissolution of organic matter was carried out using meat cubes of determined size and weight, which were left in contact with 1 mL of samples from the following groups: NaOCl gel 3% (ChlorCid V); NaOCL gel 3% (VIM); NaOCl liquid 2.5%; NaOCl liquid 5.25%; Sterile physiological solution (SP) (control) for a period of 3 min, the fragments were removed and weighed again to quantify the undissolved organic matter. The verification of the cleansing of the canal walls was evaluated through the SEM and the stereomicroscopy ... (Complete abstract click electronic access below) / Mestre

Increased interest in and use of additive manufacturing has made it an important component of advanced manufacturing in the last decade. Material Extrusion Additive Manufacturing (MatEx) has seen a shift from a rapid prototyping method harnessed only in parts of industry due to machine costs, to something widely available and employed at the consumer level, for hobbyists and craftspeople, and industrial level, because falling machine costs have simplified investment decisions. At the same time MatEx systems have been scaled up in size from desktop scale Fused Filament Fabrication (FFF) systems to room scale Big Area Additive Manufacturing (BAAM). Today MatEx is still used for rapid prototyping, but it has also found application in molds for fiber layup processes up to the scale of wind turbine blades. Despite this expansion in interest and use, MatEx continues to be held back by poor part performance, relative to more traditional methods such as injection molding, and lack of reliability and user expertise. In this dissertation, a previously unreported phenomenon, irreversible thermal strain (ITε), is described and explored. Understanding ITε improves our understanding of MatEx and allows for tighter dimensional control of parts over time (each of which speaks to extant challenges in MatEx adoption). It was found that ITε occurs in multiple materials: ABS, an amorphous polymer, and PLA, a semi-crystalline one, suggesting a number of polymers may exhibit it. Control over ITε was achieved by tying its magnitude back to part layer thickness and its directionality to the direction of roads within parts. This was explained in a detail by a micromechanical model for MatEx described in this document. The model also allows for better description of stress-strain response in MatEx parts broadly. Expanding MatEx into new areas, one-way shape memory in a commodity thermoplastic, ABS, was shown. Thermal history of polymers heavily influences their performance and MatEx thermal histories are difficult to measure experimentally. To this end, a finite element model of heat transfer in the part during a MatEx build was developed and validated against experimental data for a simple geometry. The application of the model to more complex geometries was also shown. Print speed was predicted to have little impact on bonds within parts, consistent with work in the literature. Thermal diffusivity was also predicted to have a small impact, though larger than print speed. Comparisons of FFF and BAAM demonstrated that, while the processes are similar, the size scale difference changes how they respond to process parameter and material property changes, such as print speed or thermal diffusivity, with FFF having a larger response to thermal diffusivity and a smaller response to print speed. From this experimental and simulation work, understanding of MatEx has been improved. New applications have been shown and rational design of both MatEx processes and materials for MatEx has been enabled.

The thesis presents a manufacturing technology proposition for a terminal pin made of copper according to ČSN 42 3001.1 located in combution engine distributor in a series of 320 000 pcs. Based on a literature study, 3 versions of operation sequence were proposed, 2 of them with concern for lowest number of operations possible and the third, chosen one, was designed so the strain and therefore mechanical properties were equal in whole volume of final part. Forming force and work were calculated, utilizing the Johnson-Cook material model. Overall calculated forming force was 64,5 kN and total work for one part 189 J. Subsequently technical drawings of die and punch for the second operation of forward extrusion of shaft were processed along with workspace assembly drawing for the Šmeral TPM 5 machine, which was chosen for the fabrication. Economic evaluation set the costs for one part manufactured 0,09 Eur and equilibrium point, after which the production generates profit, located at 170 000 pcs produced.

Diploma thesis deals with preparation of polypropylene functionalized by maleimides, based on the reaction between maleic anhydride and amine. The overview of functionalization of polypropylene by maleic anhydride by reactive extrusion and routes for the synthesis and utilization of maleimides are contained in the theoretical part. Samples of maleimide-functionalized polypropylene were prepared by reactive extrusion using low molecular weight amines (aniline and 4-aminophenol) and hight molecular weight polyether monoamines. Functionalized polypropylene samples were prepared by several methods differing in the composition of the reaction mixture and performing a grafting reaction. Appropriate maleamic acids and maleimides were synthesized from low molecular weight amines and further used to functionalize the polypropylene. To characterize the samples, the degree of monomer conversion and melt flow index were determined and further analyses were performed by Fourier transform infrared spectroscopy, differential scanning calorimetry and thermogravimetric analysis. The synthesis of low molecular weight products was further monitored by thin layer chromatography and thermogravimetric analysis with evolved gas analysis.

The thesis deals with the design of a suitable technology for serial production of a pin. The component material is structural steel 11,320 5R. Due to the series production and material savings, the molding technology was chosen to be cold. For production, the CM 4-5 ECO HATEBUR process press was designed with a nominal force of 1 700 kN. Progressive tool and drawing documentation of tools for the final operation were also designed. The tool load was verified by manual calculation, and the finite element method was calculated to heat the formed blank due to molding.

Increased interest in and use of additive manufacturing has made it an important component of advanced manufacturing in the last decade. Material Extrusion Additive Manufacturing (MatEx) has seen a shift from a rapid prototyping method harnessed only in parts of industry due to machine costs, to something widely available and employed at the consumer level, for hobbyists and craftspeople, and industrial level, because falling machine costs have simplified investment decisions. At the same time MatEx systems have been scaled up in size from desktop scale Fused Filament Fabrication (FFF) systems to room scale Big Area Additive Manufacturing (BAAM). Today MatEx is still used for rapid prototyping, but it has also found application in molds for fiber layup processes up to the scale of wind turbine blades. Despite this expansion in interest and use, MatEx continues to be held back by poor part performance, relative to more traditional methods such as injection molding, and lack of reliability and user expertise. In this dissertation, a previously unreported phenomenon, irreversible thermal strain (ITε), is described and explored. Understanding ITε improves our understanding of MatEx and allows for tighter dimensional control of parts over time (each of which speaks to extant challenges in MatEx adoption). It was found that ITε occurs in multiple materials: ABS, an amorphous polymer, and PLA, a semi-crystalline one, suggesting a number of polymers may exhibit it. Control over ITε was achieved by tying its magnitude back to part layer thickness and its directionality to the direction of roads within parts. This was explained in a detail by a micromechanical model for MatEx described in this document. The model also allows for better description of stress-strain response in MatEx parts broadly. Expanding MatEx into new areas, one-way shape memory in a commodity thermoplastic, ABS, was shown. Thermal history of polymers heavily influences their performance and MatEx thermal histories are difficult to measure experimentally. To this end, a finite element model of heat transfer in the part during a MatEx build was developed and validated against experimental data for a simple geometry. The application of the model to more complex geometries was also shown. Print speed was predicted to have little impact on bonds within parts, consistent with work in the literature. Thermal diffusivity was also predicted to have a small impact, though larger than print speed. Comparisons of FFF and BAAM demonstrated that, while the processes are similar, the size scale difference changes how they respond to process parameter and material property changes, such as print speed or thermal diffusivity, with FFF having a larger response to thermal diffusivity and a smaller response to print speed. From this experimental and simulation work, understanding of MatEx has been improved. New applications have been shown and rational design of both MatEx processes and materials for MatEx has been enabled.

<p>    </p> <p>To meet the needs of the high-end electronics and energy industry, it is important to operate these devices in elevated temperatures and under high voltage. The dielectric materials for advanced capacitors must have high temperature tolerance (Tg>80C) high dielectric constant, low loss and high breakdown strength to meet the demands of the future. In order to understand fundamental relationships between the processing, structural hierarchy and electrical properties, in this dissertation we focus on slow crystallizing PET/PEI polymer blends, crystallizable Nylon 12 and noncrystallizable Polyetherimide and its chemical variants. </p>

El texto completo de este trabajo no está disponible en el Repositorio Académico UPC por restricciones de la casa editorial donde ha sido publicado. / At present, companies in the Peruvian plastic sector have an average capacity utilization indicator of 71.45%. However, in Peru many SMEs are with 50% well below this indicator. After a study performed in a representative company of the Peruvian plastic sector, the causes of low efficiency in resource utilization were determined through a problems tree and a Pareto analysis. These causes are failures, reprocesses and Setup times in the extrusion machines, taking around 1008 h a year to solve these problems. This article proposes a model to improve efficiency, integrating Lean Manufacturing tools such as 5s, SMED, and autonomous maintenance. The first one was used as a support tool, while SMED was used to reduce the configuration time and autonomous maintenance to reduce the failures number and the reprocesses number. The model was validated through a case study, obtaining as results the reduction of the setup time by 50%, breakdowns by 50% and reprocesses by 60%.

Thesis: M.S., Massachusetts Institute of Technology, Department of Nutrition and Food Science, 1979 / Bibliography: leaves 95-99. / by Herman Hiu-Lam Sze. / M.S. / M.S. Massachusetts Institute of Technology, Department of Nutrition and Food Science