Ces travaux de recherche portent sur le développement d’un procédé permettant de mélanger, directement en sortie de polycondensation, du polyamide fondu avec d’autres polymères immiscibles en tant qu’additifs. Ce procédé se distingue ainsi des méthodes d’élaboration conventionnelles pour lesquelles une fusion préalable des polymères est nécessaire. L’étude concerne le mélange de polymères de viscosités très différentes (polyamide 66 et polyéthylène glycol) et le mélange de polymères de viscosités similaires (polyamide 66 et copolymère d’éthylène propylène, en présence ou non d’un agent d’interface : polypropylène greffé par de l’anhydride maléique).Une première partie de ce travail a consisté à caractériser la dispersion de ces mélanges élaborés selon des procédés conventionnels. Ce travail a conduit à développer un modèle reliant la taille de la phase dispersée aux principaux paramètres opératoires de chaque procédé, pour le cas rarement recensé dans la littérature, des mélanges de polymères de viscosités très différentes.La seconde partie a été consacrée à la conception et à la réalisation d’une installation constituée d’un pilote de polycondensation équipé, en sortie de réacteurs, d’un dispositif de mélange reposant sur la technologie des mélangeurs statiques. Son fonctionnement a ensuite été éprouvé pour les deux mélanges considérés, grâce des expériences qui ont permis d’analyser l’influence de différentes conditions opératoires sur la morphologie des mélanges générés. La comparaison des résultats obtenus à ceux issus des procédés conventionnels, a alors permis de préciser les performances et les limites du procédé développé dans cette étude / The aim of this work is to develop a process, which enables to blend polyamide in molten state with others polymers, directly at the outlet of a polycondensation reactor. Contrary to currently industrial processes, no remelting stage is needed in this one. The study has been carried out with polyamide 66 / polyethylene glycol blends (products with very different viscosities) and with polyamide 66 / ethylene propylene blends (products with similar viscosities), with or without polypropylene-graft-maleic-anhydride as interfacial agent. The first part of this work deals with the characterization of the dispersions obtained for these blends when their elaborations are carried out using conventional processes. Only few studies are available on blends, which exhibit a large difference between components viscosity. This work led us to develop a model to correlate, in this case, the dispersed phase size to the main operating conditions of each processes.The second part is dedicated to the design and the realization of an experimental installation, which is composed of polycondensation plant equipped, at the outlet of reactors, with a blending device based on static mixers technology. Its operation has been tested and experiments have been carried out in order to study the influence of the different processing parameters on blends morphology. The comparison of the results with those previously obtained using conventional processes allowed then to precise the performances and the limits of the process developed in this study

Les polyamides sont des thermoplastiques techniques qui entrent dans la conception de pièces destinées à remplacer certains composants métalliques des moteurs automobiles. En dépit de propriétés mécaniques initiales satisfaisantes, leur tenue à long terme est limitée par leur sensibilité à l'oxygène conduisant à des réactions de thermo-oxydation. Ces réactions ont été largement étudiées dans le cas des polyoléfines mais peu dans le cas des polyamides, rendant nécessaire l'élaboration d'un modèle cinétique susceptible de prédire la fragilisation donc la durée de vie des polyamides. Cette thèse est une contribution à la compréhension du processus d'oxydation dans le cas des polyamides aliphatiques et à la construction d'un modèle cinétique. La démarche cinétique réside tout d'abord dans la caractérisation physico-chimique multi-échelle de films de PA11 oxydés dans différentes conditions de températures (90 à 165 °C sous air) et sous différentes pressions partielles d'oxygène. Un modèle cinétique couplant oxydation et post-polycondensation est proposé ici : il permet de simuler les données expérimentales (hydroperoxydes, carbonyles et masse molaires) quelles que soient les conditions d'exposition. Parallèlement, un critère intrinsèque gouvernant la fragilisation du PA11 est identifié afin de prédire cette dernière à partir du modèle cinétique. Enfin, l'influence de l'ajout d'antioxydants phénoliques et des sels de cuivre sur la cinétique d'oxydation est caractérisée. Un premier modèle cinétique prenant en compte la stabilisation du PA11 décrit les tendances spécifiques de la stabilisation du PA11 comme l'apparition de la pseudo-période d'induction contribuant à une augmentation significative de la durée de vie du PA11. / Some metal components of automotive engine are bound to be replaced by polyamide parts. However, despite their thermal resistance polyamides are sensitive to oxygen leading to thermal oxidation chain reactions responsible for their long-term properties. While durability is critical for polyamide users, only a few studies deal with the elaboration of a kinetic model capable of predicting polyamide lifetime (time to embrittlement) in contrary to polyolefins (especially polyethylene). This PhD thesis is a contribution to the understanding of aliphatic polyamide thermal degradation by considering chemical and physical aspects of oxidation process in order to build a kinetic model. Our approach is based on a multi-scale physicochemical characterization of oxidized PA11 film samples under air between 90 and 165 °C but also under oxygen pressure. The proposed kinetic model coupling oxidation and solid state polymerization is able to simulate the whole experimental data (hydroperoxides, carbonyls and molar mass changes). In a same time, an intrinsic criterion for embrittlement is assessed to predict lifetime whatever the exposure conditions. Finally, the influence of phenols and copper salts on the oxidation kinetic is investigated. A first kinetic model including the phenol stabilizing effect is capable of simulating the main observed trends for stabilized PA11 such as the appearance of the pseudo induction period which contributes to the significant improvement of PA11 durability.

Thesis (MScEng (Process Engineering))--University of Stellenbosch, 2009. / ENGLISH ABSTRACT: The aim of this study was to modify the surface of polyethersulfone (PES) ultrafiltration (UF) membranes to produce a more hydrophilic membrane by cross-linking poly(vinyl alcohol) (PVA) with sodium tetraborate (Na2B4O7.10H2O) (SB) on the surface. Key preparation factors were identified as PVA molecular weight, concentrations of the PVA and SB, cross-linking reaction time, number of coatings and the mode of coating. The effect of these factors on the membrane performance (salt retention and permeate flux) is discussed. These PVA-SB membranes typically had 11.46% retention and 413.30 L/m2.h flux for a feed containing 2000 ppm NaCl (0.45 MPa, 20°C, 45 – 50 L/h). The coating was shown to be uniform and stable by Fourier transform infrared spectroscopy (FT-IR) analyses. Coating significantly increased hydrophilicity and a maximum flux increase of 500 L/m2.h was reached. Measurements showed a reduced water contact angle and this confirmed the obvious enhancement of surface hydrophilicity. As a control, the role of the PVA base layer without cross-linking and the effects of its drying and heating on the water permeability of the PES-UF membrane were also studied, in order to ascertain maximum treatment conditions. Retention and permeate flux were determined (feed solution: 2000 ppm NaCl, applied pressure 0.45 MPa, 25°C, 45 – 50 L/h). It was found that the heating had the largest effect on the reduction of water permeability and therefore 50°C was the limit for treatment of this specific PES-UF membrane. Thin-film composite (TFC) membranes were prepared by an interfacial polymerization (IP) reaction between a polyfunctional amine and tri- or di-functional carboxylic chloride and then evaluated for their reverse osmosis (RO) performance. The salt retention of the PVA-SB membranes was improved when covering the cross-linked PVA gel sub-layer with a polyamide (PA) layer. However, the permeate flux decreased to below 30 L/m2.h (2000 ppm NaCl, 1 – 2 MPa, 20°C, 45 – 50 L/h). Two TFC membranes made from trimesoyl chloride (TMC) with m-phenylenediamine (MPD) or 2,6-diaminopyridine (DAP) exhibited retentions of 96.71% to 89.65% and fluxes of 10.93 to 27.91 L/m2.h, depending on the type of diamine used, when tested with a 2000 ppm NaCl solution (2 MPa, 25°C, 45 – 50 L/h). Two TFC membranes made from a n ew 2,5-furanoyl chloride (FC) with MPD or DAP exhibited retentions of 34.22% to 58.54% and fluxes of 49.21 to 25.80 L/m2.h, depending on the type of diamine used, when tested with a 2000 ppm NaCl solution (1 MPa, 25°C, 45 – 50 L/h). Novel PVA-SB-DAP-FC membranes made from the DAP with FC had the highest hydrophilicity value and exhibited >58.54% NaCl retention and 25.80 L/m2.h flux, and 75.08% MgSO4 retention and 34.75 L/m2.h flux, when tested with (2000 ppm feed, 1 MPa, 25°C, 45 – 50 L/h). The effect of the chemical structures of the different amines and carboxylic chlorides used on the RO performances of the TFC membranes prepared by two amines reacting with TMC or FC, on the surfaces of the modified asymmetric PES-UF membranes, was investigated. FT-IR and water contact angle determination were used to characterize the chemical structure, morphology and hydrophilicity of the PA layers of the composite membranes. The response surface methodology (RSM) was used to optimize the preparation conditions that had the largest effects on the RO performance of the PVA-SB-DAP-FC membranes. Good membrane performance could be realized particularly by manipulating three variables: DAP concentration, FC concentration and polymerization time (PT). The regression equation between the preparation variables and the performance of the composite membranes was established. Main effects, quadratic effects and interactions of these variables on the composite membrane performance were investigated. The membranes were characterized in terms of pure water permeation (PWP) rate, molecular weight cut off (MWCO), solute separation and flux. Mean pore size (μp) and standard deviation (σp) of the membranes were determined using solute transport data. The results revealed that PVA-SB membranes have almost the same pure water permeation that PES-UF membranes have. The MWCO of the PES-UF membranes decreased from 19,000 to 13,000 Daltons when the membrane was coated with PVA. / AFRIKAANSE OPSOMMING: Die doel van hierdie studie is die modifikasie van die oppervlakte van poliëtersulfoon ultrafiltrasie (PES-UF) membrane om meer hidrofiliese membrane te berei deur die kruisbinding van polivinielalkohol (PVA) met natriumtetraboraat ((Na2B4O7.10H2O) (NaB) op die membraanoppervlakte. Sleutelfaktore in die bereidingsproses is geïdentifiseer, naamlik: PVA molekulêre massa, PVA en NaB konsentrasies, kruisbindingsreaksietyd, die aantal bestrykingslae, en die manier waarop die bestrykingslae aangewend is. Die invloed van hierdie faktore op die membraanontsouting en vloed is ondersoek, en word hier bespreek. Hierdie PVA-NaB membrane het die volgende tipiese resultate getoon: 11.46% ontsouting en 413.30 L/m2.h vloed (Kondisies: 2000 dpm NaCl oplossing, 0.45 MPa toegepaste druk, 20 °C, vloeitempo 45–50 L/h). Die deklaag was uniform en stabiel, soos bepaal d.m.v. FTIR. Die aanwesigheid van die deklaag het die hidrofilisiteit verhoog en 'n maksimum vloed van 500 L/m2.h is behaal. Die waterkontakhoek is ook gemeet; 'n laer waarde het 'n verbetering in die hidrofilisiteit van die oppervlakte bevestig. Die rol van die PVA basislaag, sonder kruisbinding (kontrole), en die effek van uitdroging en verhitting hiervan, is ook bestudeer, om sodoende optimale behandelingskondisies te bepaal. Membraanontsouting en vloed is bepaal (Kondisies: 2000 dpm NaCl oplossing, 0.45 MPa toegepaste druk, 25 °C, vloeitempo 45–50 L/h). Verhitting het die grootste effek gehad op die afname in vloed. Daar is bevind dat 'n maksimum temperatuur van 50°C geskik is vir die behandeling van hierdie spesifieke PES-UF membraan. Dunfilmsaamgestelde (DFS) membrane is berei d.m.v. 'n tussenvlakpolimerisasiereaksie tussen 'n polifunksionele amien en 'n di- of tri-funksionele karbonielchloried, en daarna is die tru-osmose (TO) gedrag bepaal. Die ontsouting van die PVA-NaB membrane was hoër nadat die kruisgebinde PVA jel sub-laag met 'n poliamied (PA) laag bedek is. Die vloed het egter afgeneem, tot onder 30 L/m2.h (Kondisies: 2000 dpm NaCl oplossing, 1–2 MPa toegepaste druk, 20 °C, vloeitempo 45–50 L/h). Twee DFS membrane is berei met trimesoïelchloried (TMC), naamlik met m-fenieldiamien (MFD) of 2,6-diaminopiridien (DAP). Afhangend van die diamien wat gebruik is, is die volgende ontsoutingsresultate en vloede verkry: 96.71% tot 89.65% en 10.93 to 27.91 L/m2.h (Kondisies: 2 000 dpm NaCl oplossing, 2 MPa toegepaste druk, 25 °C, v loeitempo 45–50 L/h). Twee DFS membrane is ook berei met 'n nuwe verbinding, 2,5-furanoïelchloride (FC), en MFD of DAP. Afhangend van die diamien wat gebruik is is die volgende ontsoutingsresultate en vloede behaal: 34.22% tot 58.54% en 49.21 tot 25.80 L/m2.h (Kondisies: 2000 dpm NaCl oplossing, 1 MPa toegepaste druk, 25 °C, vloeitempo 45–50 L/h). Die PVA-NaB-DAP-FC membrane het die hoogste hidrofilisiteit getoon: 58.54% NaCl ontsouting en 25.80 L/m2.h vloed, en 75.08% MgSO4 ontsouting en 34.75 L/m2.h vloed (2000 ppm NaCl oplossing, 1 MPa toegepaste druk, 25 °C, vloeitempo 5–50 L/h). Die invloed van die chemiese struktuur van die verskillende diamiene en karboksielsuurchloriedes wat gebruik is in die bereiding van die DFC membrane op die oppervlakte van die gewysigde PES-UF membrane is in terme van TO ondersoek. FTIR en kontakhoekbepalings is gebruik om die chemiese struktuur, morfologie en hidrofilisiteit van die PA lae van die saamgestelde membrane te bepaal. Die eksperimentele oppervlakte ontwerp metode is gebruik om die bereidingskondisies vir die TO aanwending van die PVA-NaB-DAP-FC membrane te optimiseer. Goeie resultate is verkry deur die volgende veranderlikes te manipuleer: DAP en FC konsentrasies en die tydsduur van die polimerisasie. 'n Regressie-vergelyking tussen die bereidingsverandelikes en die funksionering van die saamgestelde membrane is bepaal. Die volgende is ook ondersoek vir hul effek op die funksionering van die saamgestelde membrane: hoof-effekte, vierkantseffekte, en interaksie tussen veranderlikes. Die eienskappe van die membrane wat bepaal is, is: deurlatingstempo van suiwer water (DSW), molekulêre massa-afsnypunt (MMAP), skeiding van opgeloste sout en vloed. Deurlating van opgeloste sout data is gebruik om gemiddelde poriegrootte (μp) en standaard afwyking (σp) van die membrane te bepaal. Resultate het getoon dat die PVA-NaB membrane amper dieselfde DSW gehad het as die PES-UF membrane. Die MMAP van die PES-UF membrane het afgeneem van 19,000 tot 13,000 Daltons na behandeling met PVA.

Reproduction de : Thèse de doctorat : Instrumentation et analyses avancées : Lille 1 : 2004. / N° d'ordre (Lille 1) : 3438. Résumé en français et en anglais. Titre provenant de la page de titre du document numérisé. Bibliogr. à la suite de chaque chapitre.

Reproduction de : Thèse de doctorat : Structure et dynamique des systèmes réactifs : Lille 1 : 2005. / N° d'ordre (Lille 1) : 3630. Résumé en français et en anglais. Titre provenant de la page de titre du document numérisé. Bibliogr. à la suite de chaque chapitre.

Thesis (Ph.D.)--University of Western Sydney, 2008. / A thesis presented to the University of Western Sydney, College of Health and Science, School of Biomedical and Health Sciences, in fulfilment of the requirements for the degree of Doctor of Philosophy. Includes bibliographies.

Thesis (Ph.D.)--University of Western Sydney, 2008. / "A thesis presented to the University of Western Sydney, College of Health and Science, School of Biomedical and Health Sciences in fulfilment of the requirements for the degree of Doctor of Philosophy." Includes bibliography.

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Orientador: Cecília Amélia de Carvalho Zavaglia / Dissertação (mestrado profissional) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-17T10:45:04Z (GMT). No. of bitstreams: 1 Oliveira_SimoneGoncalvesde_M.pdf: 3805652 bytes, checksum: 8b1a4cc53b1b8005bdadd9b629bab628 (MD5) Previous issue date: 2010 / Resumo: No mundo moderno em que vivemos, devido à acirrada competição no mercado automotivo, surge à necessidade de um motor cada vez mais econômico, necessidade esta agravada pela competição internacional com os mercados asiáticos. Assim, acelera-se não apenas a corrida pelo aumento de qualidade e redução de custo dos produtos, mas também para as questões ambientais, como a redução das emissões de gás carbônico e de consumo de combustível. Sabe-se que, quanto maior o veículo, maior é o seu impacto sobre o consumo de combustível. O peso, por exemplo, é o fator mais importante nas emissões de CO2. Considerando que os metais são mais pesados que os plásticos, existe um grande interesse na substituição de peças metálicas por poliméricas. O objetivo geral deste trabalho foi selecionar plásticos de engenharia ou compósitos de matriz polimérica para aplicação em coletores de admissão de gases de motores a diesel. Para tanto, foi elaborada uma matriz de decisão, onde foram avaliadas as principais características necessárias para essa peça específica, que atualmente é constituída pela liga de alumínio fundida. As seguintes características foram consideradas importantes na montagem da matriz de decisão: resistência mecânica à tração e ao impacto; densidade; resistência ao calor; resistência química aos combustíveis; processabilidade por injeção; custo e disponibilidade. Como substitutos ao alumínio fundido foram escolhidos os seguintes materiais: Poliamida 66 sem reforço (PA 66); Poliamida 66 com reforço de 30% fibras de vidro e sem termoestabilizante (PA 66 30 FV - ST); Poliamida 66 com reforço de 30% fibras de vidro com termoestabilizante (PA 66 30 FV - CT); Poliftalamida com 33% de fibras de vidro (PPA 33 FV) e Acetal (PPO). Uma primeira seleção foi feita com dados obtidos na literatura, restando como candidatos mais promissores o PA 66 30FV ST, PA 66 30 FV com CT e o PPA 33 FV. Para esses três plásticos de engenharia foram realizados ensaios de caracterização como: avaliação das propriedades mecânicas; térmicas; resistência ao calor. Chegou-se à conclusão que o PA66 30FV CT é o material mais adequado para a substituição proposta. Finalmente, foi obtido um modelo da peça estudada (coletor de admissão) por prototipagem rápida, para auxiliar nas etapas posteriores deste trabalho, que será o desenvolvimento da matriz de injeção / Abstract: In the modem world where we live, due to incited competition in the automobilist market, emerges the necessity an engine much more economic and il is worsen by the international competition with the Asian markets. Thus, accelerate not only the race for the raise of the quality and cost reduction of products, but also for the environment topics, such as the reduction of the carbonic gas emissions and fuel consumption. It is known that, as bigger the vehicle is, bigger will be the impact of the fuel consumption. The weight, for example, is the most important factor in the CO2 emissions. Concerning that the metals are heavier than plastics, a great interest in the replacing the metallic parts for polymers exists. The general objective of this work was to select of engineering plastics or composites of polymeries matrix for application in the intake manifold of diesel engines. For this reason, a decision matrix was elaborated where the main necessary characteristics for this specific part had been evaluated, currently is the casting aluminum alloy. The following characteristics had been considered important in the decision matrix: mechanical resistance to the tensile and the impact, density, thermal resistance, chemical resistance to the fuels, injection process, cost and availability. As substitute to casting aluminum the following plastics or composites had been chosen: Polyamide 66 without reinforcement (PA66J, Polyamide 66 with 30% glass fiber reinforcement and without heat stabilizer (PA66 30 GF - CT), Polyamide 66 with 30% glass fiber reinforcement with heat stabilizer (PA 66 30 FV - ST), Poliftalamide with 33% of glass fiber (PPA 33 FV) and Acetal (PPO). A first stage was made with data gotten in literature, remaining as three more promising candidates PA 66 30FV without heat stabilizer, PA 66 30 FV with heat stabilizer and PPA 33 FV. For these three engineering plastics had been carried through characterization tests: evaluation of the mechanical and thermal properties, resistance to the heat. As conclusion, the PA66 30FV with heat stabilizer is the material that more adjusted for the replacement proposal. Finally a model of the studied part (Intake Manifold of Diesel Engine) for rapid prototyping was gotten, to assist the next stage of this work, whit will be the development of the injection matrix / Mestrado / Materiais / Mestre em Engenharia Automobilistica