Дисертації з теми "Physical additives"

Polymer modified bitumen is a binder obtained by the incorporation of various types of polymers in bitumen using mechanical mixing or chemical reactions. There are several factors affecting the properties of polymer modified bituminous composites such as
chemical composition of bitumen, kind of polymer and filler, compatibility of bitumen and polymer, amount of bitumen, polymer and filler, particle size of filler and process conditions. The main objective of this study is to determine the effects of polymer type and concentration on mechanical, thermal, properties and morphologies of bitumen based composites. It was also aimed to determine the effect of process temperature on mechanical and thermal properties of bituminous composites. Bituminous composites were prepared by using Brabender Plastic Coder, PLV 151. Mixing was made at two different temperatures (150 º
C and 180 º
C) at 60 rpm for 20 minutes. Three different kinds of polymer and four different polymer concentrations were used to understand the effect of polymer type and polymer concentration on bituminous composites properties. Low density polyethylene (LDPE), styrene-butadiene-styrene copolymer (SBS) and ethylene-vinyl-acetate (EVA) were chosen as polymer. The compositions were adjusted as the polymer volumes were equal to 5%, 10%, 20% and 50% of bitumen volume. According to the test results, addition of polymer increases the mechanical properties, reduces the melt flow index and thermal conductivity values of bituminous composites. Morphological analysis results show that, fibrillation occurs at tensile fractured surfaces of composites which contain LDPE and EVA when the polymer concentration reaches 20% of bitumen volume.

Antimony trioxide (Sb203) and halogenated additives are used together in flameretarded formulations due to their synergistic retardant properties. A study has been made to determine the effects of adding different grades of Sb203 (dSD particle sizes 0.11 um, 0.52um and 1.31 um) into ABS polymer either alone or with commercial brominated materials (BTBPE, TBBA, DBDPO) and an experimental bromine grade (sDBDPO). The Sb20 3 was added at 4wt% loadings and the bromines at 20wt% loadings. The results consider the influence of the additives on processing, mechanical, morphological and flame retardant properties. All compounds were produced using a twin-screw co-rotating extruder and then an injection moulder was used to mould notched impact (falling weight testing), flexural, LOI and UL-94 flame test bars. Samples of all the compounded formulations were titrated to determine Sb20 3 and Br contents. Fracture surface, morphology, size and dispersion analysis was carried out using both SEM and TEM equipment. Osmium tetroxide (OS04) staining was used to determine relative locations of filler particles and polybutadiene phase. Additions of the different antimony trioxide grades showed that the 0.52um and 1.31 um grades lowered impact energy absorption (-25 to -30%) when added at 4wt% loading. The use of a sub-micron size grade (0.1 um) did not significantly lower impact properties (-3%) and had similarly small effects on the flexural modulus and flexural strength. Additions of the brominated materials had much greater effects causing large reductions in impact properties (-20 to :70%). The presence of the bromines generally increased flexural modulus and lowered flexural strength with the exception of TB BA, which increased both modulus and strength. Compounds containing both 1.31 um Sb203 and bromines suffered a further reduction in impact energies, with the bromine properties dominating. Using the 0.1 um Sb20 3 grade again improved impact and flexural properties compared to the 1.31 um grade. The 0.1 um grade resulted in improvements in fire resistance as measured by the UL-94 properties when used with all bromine grades.

Lithium-ion batteries (LIBs) are the most commonly used type of rechargeable batteries with a global market estimated at $11 billion, which is predicted to grow to $60 billion by 2020. The global commercialization of Li-ion batteries is impeded by issues such as poor cycle life (5000 cycles achieved in some LIBs) in high energy and power density applications because of the rising internal resistance due to aging and safety concerns such as overcharge which ultimately leads to thermal runaway and explosions. A battery’s performance mainly depends on external factors such as electrode thickness and degree of compacting, and the type of conductive additive and electrolyte mixture used, and internal factors such as its internal temperature and state of charge. The performance suffers due to aging or erroneous mechanisms such as decomposition of the electrode or electrolyte material affecting the lifetime. In this thesis, an attempt is made to improve the lifetimes of the Li-ion batteries by incorporating suitable electrolyte additives, which were incorporated in the battery electrolyte to prevent overcharge. Also, several conductive electrode additives were incorporated as filler materials in an anode to explore the effects on its discharge capacities.

Doutoramento em Engenharia Química - Especialização em Engenharia de Materiais e Produtos Macromoleculares
The ultra-high hydrostatic pressure processing (UHP) is an expanding technology used mostly in food industry for the pasteurization of foods while preserving their organoleptic properties. This technique may be also applied to introduce structural and functional changes in biomolecules including cellulose. Recent studies have demonstrated the potential of UHP towards cellulosic pulps, namely the ability to promote forced fibre hydration thus improving cellulose accessibility and fibrils reorganization. The main purpose of this thesis was the evaluation of UHP potential for the modification of recycled fibres aiming to improve its performance in the production of tissue paper in collaboration with the biggest national producer Renova FPA, S.A. The present study has identified the structural changes that occurred in cellulose of recycled pulp induced by UHP. Thus the crystalline regions demonstrated to some extent the co-crystallization of appropriately oriented crystallites and the recrystallization of paracrystalline regions as demonstrated by XRD and 13C NMR. In addition, UHP have induced fibrils disaggregation upon forced hydration thus enhancing their accessibility towards water and chemical reagents. A substantial reduction of recycled fibres hornification upon UHP has been suggested. UHP-processed recycled fibres also demonstrated the increment of strongly bound water content, as revealed by thermal analysis and by FTIR of deuterated samples. Changes in physical structure of cellulose caused the enhancement of such properties of recycled pulp as accessibility, hydrophilicity, moisture sorption capacity, surface contact angle, capillarity, among others. The effect of beating (B) before (B-HP) or after the UHP (HP-B) or between two beating stages (B1-HP-B2) on the drainability and mechanical properties were evaluated. In these studies, basic papermaking properties and, especially, the capillarity (up to 112%) were improved. The most advantageous from the point of view of strength properties of tissue paper production was suggested to be the B1-HP-B2 sequence suitable both for recycled fibres and softwood fibres. A synergetic effect of UHP on the beating of recycled cellulosic fibres has been detected allowing up to 50% energy savings in refining. At the same time, the UHP effect on the virgin fibres refinability was much more moderated. The enhanced accessibility of recycled pulp upon UHP was also used to improve its ability towards targeted chemicals, enzymes and nano-sized structures. These experiments were carried out also with dried virgin fibres used as the models of recycled pulp. As concerns enzymes, it was suggested that enzymatic modification improves significantly the papermaking properties of recycled pulp. These improvements were related with selective removal of xylan bound to impurities and to aggregated cellulose fibrils on the fibre surface thus favouring the ensuing swelling and inter-fibre bonding in paper. UHP pretreatment and posterior enzymatic treatment revealed a synergetic effect on the mechanical properties of recycled pulp. This fact was assigned to enhanced accessibility of fibres towards xylanase by forced hydration and favourable rearrangement of cellulosic fibrils in fibres after UHP pre-treatment. The increase of basic strength properties after UHP and promoted by xylanase treatment was up to 30%, being the most pronounced for the tensile strength and the burst resistance. The impregnation of dyes in combination with UHP also has demonstrated an enhancement in impregnation/fixation of dye molecules. However, a high dependence was found on the equilibrium between dye, fixative and cellulosic fibres, depending on the dye used, both with and without UHP. This behaviour was assigned to specificity of dyes molecular structure, affinity, substantivity, among others. The impregnation of humectant compounds applying UHP was also evaluated and the improved hygroscopicity of treated pulp was confirmed. This fact was evidenced by capillarity, water absorption capacity and moisture sorption tests. The effect of UHP on the impregnation of antimicrobial agent in fibres has been carried out using polyhexamethylene biguanide (PHMB). Being a cationic polymer, PHMB was readily absorbed in fibres with and without UHP treatment. However, UHP allowed higher PHMB uptake and better retention after leaching when compared to conventional impregnation without UHP. This was attributed to stronger interactions between cationic PHMB and cellulose due to the deeper penetration of the antimicrobial agent under UHP treatment. However, the amount of PHMB to impregnate in fibres is limited because of its negative effect on paper strength properties due to disruptive action of PHMB as debonding agent. Likewise, silica encapsulated PHMB demonstrated fairly high retention upon UHP and high release during the leaching tests. Being encapsulated, PHMB was not directly bound to cellulose (electrostatic interaction) and the final paper showed at the same time fairly high PHMB release rates. The impregnation with encapsulated perfumes (Dovena New) was also carried out and revealed higher impregnation of these nano-sized structures upon UHP than under conventional conditions. This was reflected by a higher release of volatiles from pulp samples impregnated with stuffed nanoparticles under UHP treatment when compared to pulps samples with free adsorbed nanoparticles
O processamento de alta pressão hidrostática (UHP) é uma tecnologia em expansão, bastante utilizada na indústria alimentar para a pasteurização de alimentos, ao mesmo tempo que preserva as suas propriedades organoléticas. Esta técnica pode ainda ser aplicada na modificação estrutural e funcional de biomoléculas, tais como a celulose. Em estudos recentes demonstrou-se o potencial da UHP para com pastas celulósicas, nomeadamente no que diz respeito à sua capacidade de promover a hidratação forçada das fibras e, consequentemente, melhorar a acessibilidade das mesmas e ainda promover a reorganização das suas fibrilas. Posto isto, o principal objetivo desta dissertação consistiu na avaliação do potencial da UHP na modificação de fibras recicladas e virgens, para alcançar a melhoria da sua performance na produção de papéis tissue, em colaboração com uma das maiores empresas nacionais do ramo, a Renova FPA, SA. No presente estudo foram identificadas alterações estruturais na celulose, tanto em fibras recicladas como em virgens, produzidas pelo UHP. Neste sentido, as regiões cristalinas demonstraram, até certa extensão, a cocristalização de cristalitos convenientemente orientados e a recristalização de regiões paracristalinas, tal como evidenciado por XRD e 13C RMN. Para além disso, a UHP induziu ainda a desagregação das fibrilas, aquando o fenómeno de hidratação forçada, originando maior acessibilidade à água e a reagentes químicos. Sugere-se ainda a ocorrência de uma redução significativa da hornificação das fibras. Fibras processadas por UHP também demonstraram um incremento na presença de água fortemente ligada, tal como sugerido por análises térmicas e FTIR de amostras deuteradas. As alterações produzidas na celulose originaram uma melhoria nas propriedades das fibras, nomeadamente da sua hidrofilicidade, sorção de vapor de água, ângulo de contacto de superfície, capilaridade, etc. O efeito da refinação (B) antes (B-HP), ou depois da UHP (HP-B), ou entre refinações (B1-HP-B2), também foi analisado no que diz respeito à drenabilidade e propriedades mecânicas das fibras. Nestes estudos, as propriedades papeleiras e em especial a capilaridade (112%) revelaram melhorias. Com base nos resultados sugere-se que a sequência B1-HP-B2 seria a mais vantajosa para fibras recicladas e fibras virgens longas. Para além disso, o efeito sinergético da UHP com a refinação sugere ainda a possibilidade de uma poupança de 50% de energia na refinação. As melhorias induzidas pela UHP na acessibilidade de fibras celulósicas foram também utilizadas para otimizar a impregnação de químicos, enzimas e nanoestruturas. No que diz respeito às enzimas, verificou-se que a modificação enzimática de fibras celulósicas promoveu melhorias significativas nas propriedades papeleiras destas, em especial das fibras recicladas. Estes resultados foram relacionados com a remoção seletiva de xilana ligada a impurezas e a fibrilas na superfície das fibras, que consequentemente favoreceu o intumescimento e a ligação entre fibras. A utilização de um pré-tratamento de UHP e um posterior tratamento enzimático revelaram um efeito sinergético nas propriedades mecânicas das fibras celulósicas, em especial nas fibras recicladas. Este facto foi relacionado com o aumento de acessibilidade nas fibras para com a xilanase, como consequência da hidratação forçada e rearranjo favorável das fibrilas originado pela UHP. A melhoria registada nas propriedades mecânicas das fibras, como resultado do pré-tratamento UHP e posterior tratamento enzimático, foi até 30%, tendo demonstrado maior impacto nas propriedades de índices de tração e rebentamento. A impregnação de corantes com UHP também foi realizada e demonstrou uma melhor impregnação/fixação das moléculas de corante. No entanto, verificouse uma grande dependência no equilíbrio entre moléculas de corante, fixador e fibras celulósicas, dependendo no corante utilizado, com e sem alta pressão. Estas variações foram atribuídas à especificidade da estrutura molecular da molécula de corante, à sua afinidade, substantividade, etc. A impregnação de agentes humectantes com UHP também foi avaliada e a melhoria nas propriedades hidrofílicas de fibras celulósicas foi confirmada. Este facto foi evidenciado por testes de capilaridade, sorção de vapor de água e testes de capacidade de sorção de água. O efeito da UHP na impregnação de um agente antimicrobiano também foi estudado utilizando polihexametileno biguanide (PHMB). Sendo um polímero catiónico, o PHMB foi facilmente absorvido pelas fibras celulósicas, com e sem alta pressão. A UHP permitiu ainda uma melhor impregnação/retenção do PHMB, após lixiviação, quando comparado com a amostra impregnada sem UHP. Estes resultados foram relacionados com as fortes interações estabelecidas entre o PHMB catiónico e a celulose, devido a uma impregnação mais profunda do agente antimicrobiano durante o tratamento de UHP. No entanto, o teor de PHMB a impregnar nas fibras é limitado pelos efeitos negativos que este originou nas fibras como consequência da sua ação de interrupção das ligações entre fibras como “agente desligante”. Do mesmo modo, cápsulas de sílica com PHMB também demonstraram uma maior retenção nas fibras celulósicas com a utilização da UHP. Encapsulado, o PHMB não está diretamente em contacto com a celulose (interações electroestáticas), exibindo deste modo uma maior libertação de PHMB (limitação por difusão). A impregnação com perfumes (Dovena New) encapsulados também foi realizada e revelou uma maior impregnação destas nanoestrutras, com a utilização da UHP, relativamente à metodologia convencional. Isto foi refletido pela maior libertação de voláteis por parte das amostras impregnadas com cápsulas com perfumes.

Orientador: Gladis Camarini
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo
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Resumo: As novas leis ambientais vem forçando a sociedade e empresas a mudar suas atitudes com relação à geração e destino dos resíduos. A produção indiscriminada desses rejeitos e a deposição incorreta do material vem causando impactos ambientais, apresentando-se como um grave problema de gestão pública, pois precisam ser descartados em aterros especiais. Um número limitado desses aterros especiais foram construídos para receber os resíduos de gesso, o que pode motivar a destinação dos resíduos de gesso para centrais de reciclagem. O gesso reciclado é obtido por meio de um simples processo de moagem e calcinação em temperaturas relativamente baixas. Comprovou-se, em trabalhos anteriores, que o gesso reciclado endurece rapidamente, reduzindo seu tempo de aplicação. Aditivos retardadores de pega do gesso têm sido estudados, contudo os testes são baseados em gesso comercial. A escolha de um aditivo adequado, bem como de sua dosagem, pode melhorar o tempo de pega do gesso reciclado, de modo a permitir a reaplicação do produto em obras e na produção de componentes. O objetivo deste trabalho foi estudar as propriedades do gesso reciclado, tanto no estado fresco como no endurecido, com o uso de aditivos retardadores: ácido cítrico, tânico, tartárico e citrato de sódio. Foram avaliadas a consistência, tempo de pega, cinética da temperatura, resistência à compressão, dureza e microestrutura. Os resultados mostraram que alguns aditivos foram capazes de alterar as propriedades do gesso reciclado. No estado fresco, o gesso reciclado teve seu tempo de pega aumentado por influência do ácido cítrico e do citrato de sódio. No estado endurecido, o ácido cítrico e o citrato de sódio reduziram a resistência à compressão e a dureza do gesso reciclado. O ácido tânico e o ácido tartárico, por outro lado, não alteraram significativamente o comportamento do gesso reciclado
Abstract: The new environmental laws are forcing the society and the enterprises to change their attitudes regarding the generation and the destination of wastes. The indiscriminate production of these wastes is causing environmental impacts, presenting itself as a serious problem of public management because it must be discharged in special landfills. A limited number of cells have been built for receiving sulfate waste, which may encourage this waste transfer to special recycling stations. The recycled gypsum plaster is obtained by a simple process of crushing and heating at relatively low temperatures. Previous works on gypsum recycling show that recycled gypsum plaster has fast setting and lack of workability. Gypsum retarders have been studied intensively, but the emphasis was always laid on commercial gypsum. The selection of suitable retarders and dosage can adjust the setting times of recycled gypsum plaster to a desired level to use this material again in construction works or to make components. The present study investigated the properties of recycled gypsum plaster with added citric, tannic, tartaric acid and sodium citrate to improve the performance in fresh and hardened states. The consistency, the setting times and kinetics of temperature, compressive strength, hardness and microstructure were evaluated. The results show that some admixtures can modify the recycled plaster properties. Setting times of the recycled plaster increased by influence of the citric acid and sodium citrate. Compressive strength and hardness were reduced by using citric acid and sodium citrate. On the other hand, tannic and tartaric acid did not change significantly the recycled plaster behavior
Mestrado
Arquitetura e Construção
Mestra em Engenharia Civil

The long-term outdoor durability of dye-sensitized solar cells (DSSCs) is still a challenging issue for the large-scale commercial application of this promising photovoltaic technique. In order to study the degradation mechanism of DSSCs, ageing tests under selected accelerating conditions were carried out. The electrolyte is a crucial component of the device. The interactions between the electrolyte and other device components were unraveled during the ageing test, and this is the focus of this thesis. The dynamics and the underlying effects of these interactions on the DSSC performance were studied. Co(bpy)32+/3+-mediated solar cells sensitized by triphenylamine-based organic dyes are systems of main interest. The changes with respect to the configuration of both labile Co(bpy)32+ and apparently inert Co(bpy)33+ redox complexes under different ageing conditions have been characterized, emphasizing the ligand exchange problem due to the addition of Lewis-base-type electrolyte additives and the unavoidable presence of oxygen. Both beneficial and adverse effects on the DSSC performance have been separately discussed in the short-term and long-term ageing tests. The stability of dye molecules adsorbed on the TiO2 surface and dissolved in the electrolyte has been studied by monitoring the spectral change of the dye, revealing the crucial effect of cation-based additives and the cation-dependent stability of the device photovoltage. The dye/TiO2 interfacial electron transfer kinetics were compared for the bithiophene-linked dyes before and after ageing in the presence of Lewis base additives; the observed change being related to the light-promoted and Lewis-base-assisted performance enhancement. The effect of electrolyte co-additives on passivating the counter electrode was also observed. The final chapter shows the effect of electrolyte composition on the electrolyte diffusion limitation from the perspectives of cation additive options, cation concentration and solvent additives respectively. Based on a comprehensive analysis, suggestions have been made regarding lithium-ion-free and polymer-in-salt strategies, and also regarding cobalt complex degradation and the crucial role of Lewis base additives. The fundamental studies contribute to the understanding of DSSC chemistry and provide a guideline towards achieving efficient and stable DSSCs.

QC 20160517

Les systèmes d'extinction incendie aujourd'hui employés pour la protection des véhicules militaires terrestres utilisent le gaz FM200, qui répond à une exigence du protocole de Montréal sur les espèces qui réduisent la couche d'ozone. Cependant, le potentiel de réchauffement global important de ce gaz appelle aujourd'hui à un remplacement urgent. En parallèle, la recherche sur le brouillard d'eau s'est intensifiée depuis les années 1990, en tant que dispositif d'extinction sans appauvrissement de la couche d'ozone, ni potentiel de réchauffement global. Dans le cadre de cette thèse, l'objectif est d'étudier la faisabilité d'un brouillard d'eau additivée comme système d'extinction incendie pour la protection des compartiments moteurs de véhicules militaires et civiles. En effet, l'eau pulvérisée sous forme de brouillard peut être additivée de substances qui modifient ses propriétés physico-chimiques et procurent à la solution résultante de meilleures caractéristiques et des performances d'extinction accrues. Une revue exhaustive de la littérature a notamment permis de mettre en évidence l'existence paradoxale des solvants, espèces hautement inflammables, comme additifs pour le brouillard d'eau. Afin de pouvoir quantifier l'ajout de ces espèces sur les performances d'extinction, une première étape a consisté à caractériser l'interaction entre une flamme et un brouillard d'eau, en présence d'une ventilation variable. Des mesures de vélocimétrie par imagerie de particules ont notamment permis d'identifier des valeurs critiques de ventilation et de pression d'injection. Dans un second temps, un brouillard d'eau additivée aux solvants, en concentrations variables, a été étudié au travers de sept alcools primaires linéaires, du méthanol à l'heptanol. Une analyse statistique a permis d'identifier le pentanol et le butanol comme les meilleurs alcools primaires linéaires en tant qu'additifs pour le brouillard d'eau. La diminution du temps d'extinction par rapport à l'eau seule provient du refroidissement accru de la zone de la flamme apporté par les additifs alcoolisés
The fire extinguishing systems currently used to protect military land vehicles use the gas FM200, which meets a requirement of the Montreal Protocol on species that deplete the ozone layer. However, its significant global warming potential means it urgently needs to be replaced. At the same time, research on water mist has intensified since the 1990s, as a fire extinguishing system that neither depletes the ozone layer nor has a global warming potential. The aim of this thesis is to study the feasibility of a water mist with additives as a fire extinguishing system for the protection of the engine compartments of military and civilian vehicles. The finely sprayed water can be added with substances that modify its physical and chemical properties and give the resulting solution improved characteristics and extinguishing performance. An exhaustive review of the literature has highlighted the paradoxical existence of solvents, highly flammable species, as additives for the water mist. In order to quantify the impact of these species on the extinguishing performance, the first step was to characterize the interaction between a flame and a water mist, in the presence of variable ventilation. Particle image velocimetry measurements were used to identify critical values for ventilation and injection pressure. Secondly, a solvent-added water mist in varying concentrations was studied using seven linear primary alcohols, from methanol to heptanol. A statistical analysis identified pentanol and butanol as the best linear primary alcohols as water mist additives. The reduction of the extinguishing time compared with only water is due to the increased cooling of the flame zone provided by the alcohol additives

This thesis proposes a new method for detecting malicious cyber-physical attacks on additive manufacturing (AM) systems. The method makes use of a physical hash, which links digital data to the manufactured part via a disconnected side-channel measurement system. The disconnection ensures that if the network and/or AM system become compromised, the manufacturer can still rely on the measurement system for attack detection. The physical hash takes the form of a QR code that contains a hash string of the nominal process parameters and toolpath. It is manufactured alongside the original geometry for the measurement system to scan and compare to the readings from its sensor suite. By taking measurements in situ, the measurement system can detect in real-time if the part being manufactured matches the designer's specification. A proof-of-concept validation was realized on a material extrusion machine. The implementation was successful and demonstrated the ability of this method to detect the existence (and absence) of malicious attacks on both process parameters and the toolpath. A case study for detecting changes to the toolpath is also presented, which uses a simple measurement of how long each layer takes to build. Given benchmark readings from a 30x30 mm square layer created on a material extrusion system, several modifications were able to be detected. The machine's repeatability and measurement technique's accuracy resulted in the detection of a 1 mm internal void, a 2 mm scaling attack, and a 1 mm skewing attack. Additionally, for a short to moderate length build of an impeller model, it was possible to detect a 0.25 mm change in the fin base thickness. A second case study is also presented wherein dogbone tensile test coupons were manufactured on a material extrusion system at different extrusion temperatures. This process parameter is an example of a setting that can be maliciously modified and have an effect on the final part strength without the operator's knowledge. The performance characteristics (Young's modulus and maximum stress) were determined to be statistically different at different extrusion temperatures (235 and 270 °C).
Master of Science

Fabrication of miniaturized devices is usually time-consuming, costly, and the materials commonly used limit the structures that are possible to create. The techniques most often used to make microsystems involve multiple steps, where each step takes considerable time, and if only a few systems are to be made, the price per device becomes excessive. This thesis describes how a simple syringebased 3D-printer, in combination with an appropriate choice of materials, can reduce the delay between design and prototype and simplify fabrication of microsystems. This thesis suggest two types of materials that we propose be used in combination with 3D-printing to further develop microsystems for biology and biochemistry. Analytical applications in biology and biochemistry often contain electrodes, such as in gel electrophoresis. Faradaic (electrochemical) reactions have to occur at the metal electrodes to allow electron-to-ion transduction through an electrolyte-based system to drive a current when a potential is applied to the electrodes in an electrolyte-based system. These electrochemical reactions at the electrodes, such as water electrolysis, are usually problematic when miniaturizing devices and analytical systems. An alternative to metal electrodes can be electrochemicallyactive conducting polymers, e.g. poly(3,4-ethylenedioxythiophene) (PEDOT), which can be used to reduce electrolysis when driving a current through water-based systems. Paper 1 describes gel electrophoresis where the platinum electrodes were replaced with the conductive polymer PEDOT, without affecting the separation. Manufacturing and prototyping of microsystems can be simplified by using 3Dprinting in combination with a sacrificial material. A sacrificial template material can further simplify bottom-up manufacturing of more complicated forms such as protruding and overhanging structures. We showed in paper 2 that polyethylene glycol (PEG), in combination with a carbonate-based plasticizer, functions well as a 3D-printable sacrificial template material. PEG2000 with between 20 wt% and 30 wt% ethylene carbonate or propylene carbonate has properties advantageous for 3D-printing, such as shear-thinning rheology, mechanical and chemical stability, and easy dissolution in water.

In the printed version the thesis number 1720 on the cover is incorrect. The correct thesis number is 1724 which is corrected in the electronic version.

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Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES
The use of active packaging incorporated with natural antimicrobials as essential oils (EOs) for food preservation is a modern concept for the food industry. The objective of this study was to characterize cellulose acetate film (CA) incorporated with EOs and their combinations and/or added plasticizer, evaluating the influence of additives on the behavior of these materials. It is characterized as the thickness of the films, visual aspect, chemical structure, surface, mechanical strength, water vapor rate of transmission (WVRT) and antimicrobial activity. Through technique "casting" were obtained films incorporated with 50% (w/v) of EOs oregano or cinnamon or sweet fennel or combinations thereof and/or glycerol (5, 10, 20 and 30% (w/v)). Having as controls only films containing 50% (w/v) glycerol, and CA pure film, a total 41 treatments. The incorporation of EOs did not change the thickness and transparency of the films, but it reduced the WVRT. The color parameters L *, a* and b* were affected by the incorporation with EOs and/or glycerol the films exhibited clear with different colors compared with the AC pure film. Incorporating the most EOs cause increased tensile strength (TS) of the modulus of elasticity (ME) and reduced elongation at break (EB), except for the film with fennel EO (FEO) who presented plasticizer power differing from the other for all the evaluated mechanical parameters. The drilling force (DF) has increased to most films EOs incorporated with the exception of the film incorporated with the three EOs. The scanning electron microscopy (SEM) images revealed that most of the EOs and their combinations did not cause changes in the surface and cross-sectional area of the films, except the film with FEO. In the spectra of infrared spectroscopy with Fourier transform (FTIR), it observed that the interactions between the polymer matrix and most EOs were similar except for the film with FEO. As for the antibacterial efficiency in vitro, only the film incorporated with FEO showed no efficacy against Staphylococcus aureus (Gram +) and Escherichia coli (Gram +). It was observed that glycerol causes increased thickness and WVRT the AC films, however, the active films with EOs does not modify the parameter to most treatments. Transparency was not affected for most films. The addition of glycerol for most films incorporated with EOs caused reduction of TS, the ME and increased EB and DF. From the SEM pictures it can be observed that the glycerol promoted the emergence of porous structures, networked or compact, depending on the EO concentration and glycerol. The FTIR spectral showed that glycerol has different interactions, depending on the embedded EOs. The antibacterial efficiency of films with EO oregano or cinnamon or oregano more cinnamon has been improved with the presence of glycerol, while the others were not affected. In the face of changes in functional properties observed, it appears that with the additivation materials it is necessary to characterize them to define their applicability
O emprego de embalagens ativas incorporadas com antimicrobianos naturais, como os ?leos essenciais (OEs) para conserva??o de alimentos, representa um conceito moderno para a ind?stria aliment?cia. Objetivou-se neste trabalho caracterizar filmes de acetato de celulose (AC) incorporados com OEs e suas combina??es e/ou adi??o de plastificante, avaliando as influ?ncias da aditiva??o no comportamento f?sico e mec?nico destes materiais. Caracterizou-se os filmes quanto ? espessura, aspectos visuais, estrutura qu?mica, superf?cie, resist?ncia mec?nica, taxa de transmiss?o ao vapor de ?gua (TTVA) e atividade antimicrobiana. Atrav?s da t?cnica ?casting? foram obtidos filmes incorporados com 50% (p/v) de OEs de or?gano, canela, funcho doce ou suas combina??es e/ou glicerol (5, 10, 20 e 30% (p/v)). Tendo como controles filmes contendo somente 50% (p/v) de glicerol, e filme de AC puro, totalizando 41 tratamentos. A incorpora??o de OEs n?o modificou a espessura e transpar?ncia dos filmes, por?m causou redu??o da TTVA. Os par?metros de cor L*, a* e b* foram afetados pela incorpora??o de OEs e/ou glicerol tendo os filmes apresentado-se claros com diferentes cores em compara??o com o filme de AC puro. A incorpora??o da maioria dos OEs causou aumento da resist?ncia ? tra??o (RT), do m?dulo de elasticidade (ME) e redu??o do alongamento na ruptura (AR), com exce??o para o filme com OE de funcho (OEF) que apresentou poder plastificante diferindo dos demais para todos os par?metros mec?nicos avaliados. A for?a de perfura??o (FP) aumentou para a maioria dos filmes incorporados com OEs, a exce??o do filme incorporado com os tr?s OEs. As imagens de microscopia eletr?nica de varredura (MEV) revelaram que a maioria dos OEs e suas combina??es n?o causaram mudan?as na superf?cie e regi?o transversal dos filmes, a exce??o do filme com OEF. Nos espectros da espectroscopia no infravermelho com transformada de Fourier (FTIR), notou-se que as intera??es entre a matriz polim?rica e a maioria dos OEs foram semelhantes, com exce??o para o filme com OEF. Quanto ? efici?ncia antibacteriana in vitro, somente o filme incorporado com OEF n?o apresentou efetividade contra Staphylococcus aureus (Gram +) e Escherichia coli (Gram -). Foi observado que o glicerol causou aumento da espessura e TTVA nos filmes de AC, por?m, nos filmes ativos com OEs n?o modificou o par?metro para maioria dos tratamentos. A transpar?ncia n?o foi afetada para a maioria dos filmes. A adi??o de glicerol para a maioria dos filmes incorporados com OEs causou redu??o da RT, do ME e aumento do AR e FP. Pelas imagens do MEV observa-se que o glicerol promoveu o surgimento de estruturas porosas, em rede ou compactas, dependendo do OE e concentra??o de glicerol. Os espectros da FTIR demonstraram que o glicerol apresentou diferentes intera??es, dependendo do OE incorporado. A efici?ncia antibacteriana dos filmes com OE de or?gano ou canela ou or?gano mais canela foi melhorada com a presen?a de glicerol, enquanto os demais n?o sofreram influ?ncia. Diante das varia??es nas propriedades funcionais observadas, verifica-se que com a aditiva??o dos materiais ? necess?rio caracteriza??o para definir sua aplicabilidade

Tyrimo tikslas: Įvertinti VU studentų gyvenseną ir mitybą Tyrimo uždaviniai: 1. Įvertinti VU studentų dienos režimą ir fizinį aktyvumą. 2. Įvertinti VU studentų žalingus įpročius. 3. Įvertinti VU studentų mitybos režimą. 4. Įvertinti VU studentų faktinę mitybą. 5. Įvertinti VU studentų maisto papildų vartojimo ypatumus. Tyrimo populiacija: Biomedicinos, tiksliųjų, socialinių ir humanitarinių studijų krypčių, Vilniaus universiteto studentai. Apklausti vienuolikos VU fakultetų atitinkančių aukščiau paminėtas studijų kryptis studentai. Tyrimo imtį sudarė 702 VU studentai, iš jų 400 merginų ir 302 vaikinų. Tyrimo metodai: • Teorinė apžvalga • Anketinė apklausa • Faktinės mitybos tyrimas Anketinė apklausa buvo vykdoma 2010 metų, balandžio – gegužės mėnesį, panaudojant specialiai šiam tyrimui parengtą anketą, kurią sudarė dvi dalys. Pirma apklausos anketos dalis buvo skirta respondentų gyvensenos ypatumams įvertinti. Antroje anketos dalyje buvo surinkti studentų faktinės mitybos duomenys. Statistinė duomenų analizė buvo atlikta SPSS for Windows programos 17 versijos paketo pagalba ir Microsoft Office Excel 2007 programa. Faktinė mityba buvo tiriama 24 valandų apklausos būdu fiksuojant valgymo laiką, suvartojamų produktų, patiekalų ir gėrimų asortimentą bei jų kiekį. Maisto cheminės sudėties analizė atlikta naudojant maisto produktų cheminės sudėties lentelės, rezultatai lyginti su rekomenduojamomis paros maistinių medžiagų ir energijos normomis. Tyrimo rezultatai: Aktyviai fizinei... [toliau žr. visą tekstą]
The goal of the survey: To assess the lifestyle and dietary habits of students of Vilnius University. The tasks of the survey: 1. To assess the day regimen and physical activity of students of Vilnius University. 2. To assess addictions of students of Vilnius University. 3. To assess the dietary regimen of students of Vilnius University. 4. To assess the actual dietary habits of students of Vilnius University. 5. To assess the peculiarities of using food additives by students of Vilnius University. The population of the survey: Students of Vilnius University involved in study branches of Biomedicine, Exact Sciences, Social Sciences and Arts. Students of the said branches were interviewed at eleven faculties of Vilnius University. The sample under the survey included 702 students of Vilnius University - 400 females and 302 males. The methods of the survey: • Theoretical review • Interviewing under a questionnaire • Exploration of the actual dietary habits. The interviewing under a questionnaire was carried out in April - May 2010 using the questionnaire developed for this purpose. The questionnaire included two parts. The first part was used for assessing the peculiarities of the lifestyle of the respondents. In the second part of the questionnaire, the data on actual dietary habits of students were collected. The analysis of the statistical data was carried out using the version 17 of the software package SPSS for Windows and Microsoft Office Excel 2007. The actual dietary... [to full text]

The desktop publishing revolution of the 1980s is currently repeating itself in 3D, referred to as desktop manufacturing. Online services such as Shapeways have become available, making personalized manufacturing on cutting edge additive manufacturing (AM) technologies accessible to a broad audience. Affordable desktop printers will soon take over, enabling people to fabricate
Engineering and Applied Sciences

Thesis (Ph.D.); Submitted to Iowa State Univ., Ames, IA (US); 12 Dec 2003.
Published through the Information Bridge: DOE Scientific and Technical Information. "IS-T 2036" Andrew Michael Chubb. 12/12/2003. Report is also available in paper and microfiche from NTIS.

Este trabalho teve o objetivo de avaliar o efeito da adição da transglutaminase microbiana (MTGase) na fabricação de pão de forma, através do desenvolvimento de formulação ideal, com combinações de aditivos e enzima, e da avaliação do efeito da enzima nas proteínas, na massa crua, na massa após a fermentação e no produto final. Para comparar a qualidade dos pães produzidos com ou sem enzima, foram testadas três formulações: a básica, livre de aditivos (pão Zero); com a adição de emulsificante e ácido ascórbico (pão Controle); e a preparada com a formulação básica adicionada de enzima (pão MTGase). A avaliação da qualidade dos pães foi feita por meio de medidas físicas e instrumentais. A análise de textura foi realizada pelo método TPA (Texture Profíle Analysis), cujas respostas de firmeza, elasticidade, mastigabilidade e gomosidade podem ser correlacionadas com análises sensoriais. Paralelamente, de amostras de farinha, de massa e de pão foram obtidas as frações protéicas de gliadinas, gluteninas e os resíduos de extração. As gliadinas e as gluteninas foram analisadas por cromatografia líquida de alta eficiência em fase reversa e por eletroforese em gel de poliacrilamida contendo SDS. Os resultados de volume e de firmeza dos diferentes pães apresentaram diferenças significativas a nível de 5%, em que as respostas do pão MTGase foram melhores que as do pão Zero, porém ainda inferiores às do Controle. A melhor formulação foi obtida por meio de um planejamento composto central, com variações nas concentrações de emulsificante, ácido ascórbico e enzima, com os resultados avaliados pela metodologia de superfície de resposta. Exceto para a coesividade, todos os outros parâmetros de volume, dureza (TA), firmeza, elasticidade, mastigabilidade e gomosidade (TPA) apresentaram resultados positivos pela ação da transglutaminase a 0,6%, combinada com 0,2 % de emulsificante e 70 ppm de ácido ascórbico. Os resultados sugerem que a enzima foi capaz de modificar as propriedades químicas das proteínas, o comportamento reológico da massa e as propriedades funcionais do pão, melhorando a força da massa, a textura e o volume dos pães. As análises das frações gliadínicas apresentaram cerca de 3% de Nitrogênio total, em base seca, e as frações glutenínicas apresentaram entre 2 e 5% de Nitrogênio total. Os perfis cromatográficos e eletroforéticos dessas frações sugerem que as gliadinas não foram afetadas pela presença da enzima, que envolveram sobretudo as gluteninas. O conjunto de resultados indica que a aplicação de MTGase em associação com aditivos convencionais pode ser uma alternativa à panificação, embora os mecanismos de sua ação na massa não estejam completamente esclarecidos.
The application of microbial transglutaminase on weak gluten flour used in breadmaking was studied over the process. To verify the enzyme effects, three formulations were tested: Base formulation, characterized by the absence of enzyme and emulsifying agents; Control formulation, comprised by the presence of emulsifying agents and ascorbic acid and MTGase formulation, with the enzyme. Samples of flour, dough and bread were analyzed. The effect of enzyme on bread quality was estimated by parameters of Texture Analysis, Texture Profile Analysis and specific volume. The protein contents from those samples were determined by the total nitrogen in glutenin and gliadin fractions, that were also analyzed by RP-HPLC (reversed phase high performance liquid chromatography) and by SDS-PAGE (sodium dodecyl sulfate polyacrylamide gel electrophoresis). Although the MTGase bread did not reach the same quality parameters as those achieved by the Control samples, it showed as an alternative formulation to reduce the quantity of emulsifying agents and ascorbic acid as compared to the Control. The results indicate that the enzyme modified chemical and functional properties of glutenin fraction, improving dough strength and bread volume. Results of total nitrogen content, and electrophoretic and chromatographic profiles of the protein fractions suggest that while glutenin proteins were modified by enzyme, gliadin proteins were not affected.

Ce travail porte sur la caracterisation physico-chimique de suspensions aqueuses de microfibrilles de cellulose (mfc) issues de la transformation des betteraves sucrieres, seules ou en presence d'additifs. La composition chimique des suspensions meres de mfc est determinee : elles sont composees de 86% de cellulose pure, les 14% restant etant des pectines, des hemicelluloses et des sels. Les proprietes ioniques des mfc sont ensuite etudiees par differentes techniques (conductimetrie, potentiel d'ecoulement, potentiel zeta). L'etat de dispersion des suspensions a ete caracterise par des mesures rheologiques en ecoulement et de sedimentation, qui ont mis en evidence l'importance du mode de dispersion et de la concentration en mfc sur la stabilite des suspensions. Nous avons montre l'existence d'une concentration critique c* au-dela de laquelle les suspensions ont un comportement de type gel. Des echantillons de mfc seches sous forme de film ne permettent pas de recuperer les proprietes rheologiques initiales lors de la remise en suspension. L'etude du comportement rheologique dynamique, montre que la remise en suspension est satisfaisante si un additif anionique est ajoute aux mfc avant sechage. L'etude de l'adsorption et de la desorption de ces additifs et des observations en microscopie de fluorescence, montrent que l'adsorption se fait de maniere uniforme sur toute la surface des mfc, mais que les interactions mises en jeu sont faibles, totalement reversibles. L'adsorption depend fortement de la charge et de la structure chimique de l'additif, mais pas de sa masse molaire. Ces resultats conduisent a l'hypothese de la formation d'un film interfacial d'additif anionique parfaitement hydrosoluble autour des mfc lors du sechage, permettant la remise en suspension et la recuperation des proprietes rheologiques de la suspension initiale. Certaines proprietes des suspensions de mfc ont ete comparees a celles de suspensions d'une cellulose bacterienne.

Les pièces multimatériaux à gradient fonctionnel (Functionally Graded Materials - FGM) sont des structures dont la composition et la microstructure du matériau changent graduellement à l'intérieur de la pièce. Cette distribution des matériaux permet de réaliser des gradients de propriétés au niveau mécanique, physique, chimique, etc. Les domaines d'application sont nombreux pour ces pièces, en particulier l'aérospatial et le biomédical mais également l'électronique, l'énergie nucléaire, la production d'outillage, le design, etc. L'utilisation des procédés innovants tels que les procédés de fabrication additive est indispensable pour la réalisation de pièces multimatériaux complexes. Bien que ces procédés aient les caractéristiques attendues pour la réalisation de pièces multimatériaux, on constate qu'aucune pièce fonctionnelle n'a encore été fabriquée à ce jour. Pour permettre la fabrication de pièces fonctionnelles, il est indispensable de proposer une méthodologie de fabrication complète permettant de passer de l'objet imaginé par le concepteur à la fabrication. Cette méthodologie doit comporter les étapes suivantes : description de la pièce à fabriquer, détermination d'une stratégie de fabrication adaptée et génération des instructions de fabrication. Parmi les étapes du processus de fabrication, celle de choix d'une stratégie de fabrication occupe une place importante. En effet, les caractéristiques de pièces - géométrie et répartition des matériaux - sont fortement dépendantes de la stratégie de fabrication choisie. Les travaux de thèse portent principalement sur les méthodes mises en place pour la détermination de trajectoires appropriées à la fabrication des pièces multimatériaux. Ces méthodes reposent sur la modélisation du procédé nécessaire à l'évaluation des stratégies et une optimisation du procédé permettant de diminuer les différences entre la répartition des matériaux souhaitée et celle fabriquée. Une des méthodes proposées permet d'obtenir automatiquement des trajectoires parfaitement adaptées aux pièces multimatériaux et repose sur la modélisation et l'optimisation du procédé. Ces travaux sont intégrés dans une méthodologie de fabrication de pièces multimatériaux. De plus, une maquette informatique a été développée pour mettre en avant les possibilités d'utilisation de cette méthodologie.

A quantitative understanding of thermal field evolution is vital for quality control in additive manufacturing (AM). Because of the unknown material parameters, high computational costs, and imperfect understanding of the underlying science, physically-based approaches alone are insufficient for component-scale thermal field prediction. Here, I present a new framework that integrates physically-based and data-driven approaches with quasi in situ thermal imaging to address this problem. The framework consists of (i) thermal modeling using 3D finite element analysis (FEA), (ii) surrogate modeling using functional Gaussian process, and (iii) Bayesian calibration using the thermal imaging data. Based on heat transfer laws, I first investigate the transient thermal behavior during AM using 3D FEA. A functional Gaussian process-based surrogate model is then constructed to reduce the computational costs from the high-fidelity, physically-based model. I finally employ a Bayesian calibration method, which incorporates the surrogate model and thermal measurements, to enable layer-to-layer thermal field prediction across the whole component. A case study on fused deposition modeling is conducted for components with 7 to 16 layers. The cross-validation results show that the proposed framework allows for accurate and fast thermal field prediction for components with different process settings and geometric designs.
Master of Science
This paper aims to achieve the layer to layer temperature monitoring and consequently predict the temperature distribution for any new freeform geometry. An engineering statistical synergistic model is proposed to integrate the pure statistical methods and finite element modeling (FEM), which is physically meaningful as well as accurate for temperature prediction. Besides, this proposed synergistic model contains geometry information, which can be applied to any freeform geometry. This paper serves to enable a holistic cyber physical systems-based approach for the additive manufacturing (AM) not only restricted in fused deposition modeling (FDM) process but also can be extended to powder-based process like laser engineered net shaping (LENS) and selective laser sintering (SLS). This paper as well as the scheduled future works will make it affordable for customized AM including customized geometries and materials, which will greatly accelerate the transition from rapid prototyping to rapid manufacturing. This article demonstrates a first evaluation of engineering statistical synergistic model in AM technology, which gives a perspective on future researches about online quality monitoring and control of AM based data fusion principles.

Les procédés de fabrication additive (FA) permettent de répondre, aujourd’hui, à des problématiques industrielles majeures. Ces technologies offrent la possibilité de réaliser, pour un temps et un coup raisonnables, des pièces avec des géométriques complexes difficiles, voire impossibles, à réaliser avec des procédés traditionnaux. Parmi les différents procédés de FA, le procédé APF (Arburg Plastic Freeforming) permet la fabrication de pièces 3D à partir de granulés de polymères identiques à ceux employés en injection. Ces granulés peu onéreux constituent une matière première de choix puisque, théoriquement, n’importe quel thermoplastique peut être utilisé. La technologie Freeformer s’appuie sur deux unités d’injection qui permettent de fondre et de plastifier les granulés de polymère et ainsi d’alimenter la tête d’impression. L'unité de décharge dotée d’un système piézo-électrique d’ouverture/fermeture génère, en tête de buse, des gouttelettes de polymère fondu (jusqu'à 200 μm) déposées sur une plaque de fabrication spécifique au matériau employé. Ces gouttes sont déposées selon un fichier CAO défini en amont afin de constituer des pièces 3D, couche par couche, dans une chambre thermorégulée. Même si la réalisation de pièces à partir de matériaux standards (ABS, TPU, …) est relativement simple, il est nécessaire d’optimiser les paramètres de fabrication de l’APF pour obtenir des pièces de bonne qualité avec d’autres matériaux. De la même manière que dans le cas d’un procédé de transformation de matière polymère classique, le choix de grades appropriés et l’optimisation des paramètres de fabrication associés est nécessaire. Ainsi, les différents phénomènes physico-chimiques impliqués dans la réalisation d’une pièce doivent être étudiés pour la réalisation de pièces avec un polymère peu employé en FA : le polypropylène. Une approche classique d’optimisation des paramètres de fabrication consisterait en la réalisation d’une étude paramétrique faisant intervenir, par exemple, un plan d’expérience. Cette méthode chronophage et demandeuse en matière ne permet pas la compréhension fine du procédé et n’est finalement applicable qu’à un polymère donné. L’objectif de ces travaux, cofinancés par la région Hauts de France, est donc de comprendre les corrélations existantes entre les paramètres du procédé et les propriétés du polymère pour comprendre comment le procédé influence la matière
Additive Manufacturing (AM) concerns are growing the last years due to the capabilities brought by the technology. Indeed, the AM processes offer the possibility to simply and rapidly create 3D parts with specific geometries, difficult or impossible to obtain with conventional processes. A new technology called Freeformer supplied by ARBURG (Germany) allows to manufacture high quality 3D parts using standard-commercial pellets. Contrary to the standard FDM processes, feedstock materials are cheap and any thermoplastic polymer can be theoretically employed. The Freeformer technology is based on two injection molding units that enables to melt the standard pellets and to feed the printing head. The discharge unit featuring a pulsed nozzle closure generates small (down to 200 μm) molten polymer droplets to build, layer-by-layer, three-dimensional parts in a thermoregulated chamber. Even if 3D parts are easily fabricated by using standard materials (ABS, TPU, …), the process parameters have to be optimized before getting good-quality parts with all other polymers, which consumes times and materials. In the same way than for a conventional polymer processing technology the choice of appropriate grades and the optimization of the associated processing parameters are needed. Hence, the different phenomenon which occur during a part realisation have to be examined in the case of a non-standard material in AM: polypropylene (PP). To optimize the structure and the mechanical properties of the parts, a common approach is to practice a parametric study. This time-consuming approach is not always efficient. Thus, the aim of this work, cofounded by the Région Hauts de France, is to understand the correlations between materials properties and process parameters

Le comportement en frottement de deux poudres lubrifiantes à base de graphite a été étudié. Afin de mieux appréhender les différentes phases du frottement, un nouvel essai a été mis au point. Il utilise des plots de poudre compactée et une géométrie cylindre/plan. La formation des films de transfert puis leurs propriétés lubrifiantes contre un acier ont été examinées d'un point de vue macroscopique (coefficient de frottement, aspect des films, poids transféré) puis microscopique (diffraction RX sous incidence rasante, ESCA, Microscopie Electronique de Transmission). La spectroscopie Raman s'est révélée être une technique de caractérisation bien adaptée à notre étude. Le recoupement des résultats des approches mécaniques et physico-chimiques permet d'interpréter les différentes étapes du frottement. La phase de latence, accélérée par la présence de vapeur d'eau dans l'atmosphère, est caractérisée par une facturation des cristallites du graphite et un renforcement de la cohésion des plots localisé autour des cristaux d'additifs. Les premiers germes transférés sur la surface métallique ont une structure turbostratique avec des atomes étrangers en position interstitielle. La présence de soufre provoque la formation de liaisons C-S tandis que le molydate entraîne une légère oxydation du graphite. Sur cette première couche de germination se forme alors une couche de croissance à structure graphitique nanocristalline renforcée par la présence de petits précipités d'additif uniformément répartis. Les films ainsi formés ont un comportement en frottement contre un acier similaire à celui de films de MoS2. Contrairement au graphite, leur coefficient de frottement diminue en l'absence de vapeur d'eau et leur durée de vie est accrue.

De nombreuses opérations d'usinage nécessitent la présence d'un fluide de coupe afin d'en assurer le succès du fait de la sévérité des sollicitations que subit l'outil. Le but de l'étude est d'identifier les performances de divers additifs soufrés dans les huiles entières, de sélectionner parmi eux l'additif soufré le plus efficace pour la coupe des métaux, ainsi que de comprendre leurs mécanismes d'action dans les différentes applications d'usinage. L'objectif de l'étude est donc d'analyser les mécanismes tribochimiques de lubrification mis en jeu dans les procédés d'usinage et d'optimiser la formulation du lubrifiant. L'influence des différents paramètres liés à la coupe est également étudiée afin d'apporter plus de connaissances sur l'action générale des lubrifiants dans le cas de l'usinage moderne.

Additive Manufacturing (AM) is a unique method of fabrication that, in contrast to traditional manufacturing methods, builds objects layer by layer. The ability of AM (when partnered with 3D scanning) to clone physical objects has raised concerns in the area of intellectual property (IP). To address this issue, the goal of this dissertation is to characterize and model a method to incorporate unique security features within AM builds. By adding optically detectable nanoparticles into transparent AM media, Physical Unclonable Function (PUFs) can be embedded into AM builds and serve as an anti-counterfeiting measure. The nanoparticle selected for this work is a Quantum Dot (QD), which absorbs UV light and emits light in the visible spectrum. This unique interaction with light makes the QDs ideal for a security system since the challenge (UV light) is a different signal from the response (the visible light emitted by the QDs). PolyJet, the AM process selected for this work, utilizes inkjet to deposit a photopolymer into layers, which are then cured with a UV light. An investigation into the visibility of the QDs within the printed PolyJet media revealed that the QDs produce PUF patterns visible via fluorescent microscopy. Furthermore, rheological data shows that the ink-jetting properties of the printing media are not significantly affected by QDs in sufficient concentrations to produce PUFs. The final objective of this study is to characterize the effects of the QDs on photocuring. The mathematical model to predict the critical exposure of the QD-doped photopolymer utilizes light scattering theory, QD characterization results, and photopolymer-curing characterization results. This mathematical representation will contribute toward the body of knowledge in the area of Additive Manufacturing of nanomaterials in photopolymers. Overall, this work embodies the first investigations of the effects of QDs on rheological characteristics of ink-jetted media, the effects of QDs on curing of AM photopolymer media, visibility of nanoparticles within printed AM media, and the first attempt to incorporate security features within AM builds. Finally, the major scientific contribution of this work is the theoretical model developed to predict the effects of QDs on the curing properties of AM photopolymers.
Ph. D.

La pression du marché dans un monde globalisé, en parallèle d’une conscience environnementale croissante de la société, pousse l'industrie chimique à développer des procédés plus propres et plus efficaces. Aujourd'hui, il s’agit d’être capable de produire davantage, tout en réduisant l’impact environnemental et les coûts. L'Intensification des Procédés (IP) apparaît comme une solution à ces défis, l'IP étant définie comme "le développement de nouvelles voies de synthèse et de technologies modulaires innovantes susceptibles de déboucher sur des progrès décisifs". Il existe plusieurs approches d'IP, depuis l'utilisation de technologies innovantes, telles que les micro-ondes ou les ultrasons, jusqu'au passage de la chimie en batch à la chimie en flux continu. Le passage de la chimie en batch à la chimie en flux continu présente de nombreux avantages, tels que la production à la demande, une plus grande sélectivité et un meilleur contrôle du processus. De plus, l'amélioration des procédés peut aussi être permise par la miniaturisation des réacteurs, dont la réduction des longueurs de diffusion permet d’améliorer les transferts de chaleur et de matière au sein du réacteur. Parmi ces réacteurs miniaturisés, on trouve les « réacteurs structurés » présentant un certain degré de régularité dans leur structure, qui permet notamment la réduction des points chauds et un meilleur mélange des réactifs. Toutefois, la fabrication de ce type de réacteurs peut s’avérer relativement difficile. La Fabrication Additive (FA) est une technologie de rupture dans plusieurs domaines de l'ingénierie, y compris dans l’industrie chimique. La FA permet notamment la réalisation de réacteurs structurés miniaturisés avec des géométries internes impossibles à fabriquer auparavant. Ces types de structures peuvent présenter de nombreux avantages pour l'industrie chimique, à la condition de pouvoir exploiter correctement le nombre important de géométries et de possibilités permises par la FA. Pour cette raison, il est nécessaire de mieux comprendre comment les nombreux paramètres géométriques des réacteurs structurés affectent leur performance. Cette thèse vise à améliorer la compréhension de ces nouveaux réacteurs, leurs avantages, leurs inconvénients et les défis futurs possibles dans le but d’améliorer leurs performances. Par conséquent, l'objectif principal est de développer une méthodologie complète, depuis la conception, la caractérisation et la simulation de réacteurs structurés jusqu'à leur optimisation. Ce travail est divisé en quatre sections, la fabrication des réacteurs (de la conception de la géométrie jusqu'à leur fabrication par FA), leur caractérisation hydrodynamique par l'étude de la Distribution de Temps de Séjour (DTS), l'étude des performances de ce réacteur pour des applications en catalyse hétérogène (solide/liquide) et leur simulation par Mécanique des Fluides Numérique (CFD). Pour la caractérisation hydrodynamique des réacteurs, un système automatisé complet a été développé pour mesurer la DTS par une technique de fluorescence, qui présente l’avantage principal de ne pas être intrusive et permet également une acquisition à haute fréquence. Les réacteurs structurés ont été fabriqués dans une résine polymère qui a permis le greffage de palladium pour l'utilisation des réacteurs dans des réactions catalytiques hétérogènes. Enfin, un premier workflow complet pour la simulation CFD et l'optimisation des réacteurs a été développé. En outre, une présentation des différentes techniques de fabrication additive et des perspectives d'applications futures concernant la fabrication de réacteurs microstructurés ont également été présentées
The market pressure from a globalized world, in conjunction with a growing environmental conscience from society, pushes the chemical industry to develop cleaner and more efficient processes. Today, we should produce more, with reducing our environmental impact and at the same time lowering the costs. The Process Intensification (PI) appears as one solution for this challenge. PI is defined as “the development of new chemical routes and of innovative modular technologies that may lead to some breakthrough progress”. There exist several approaches for PI, from using innovative technologies such as microwaves or ultrasounds, to the transition from the chemistry in batch to flow chemistry. The passage from batch to continuous flow can bring several benefits, such as the production in demand, higher selectivity and better control of the process. The process improvement can be obtained by the miniaturization of the reactors, leading to small diffusion lengths that can improve heat and mass transfer properties. One type of miniaturized reactor are what is called “structured reactors”, with a certain degree of regularity inside their structure which leads to the reduction of hotspots, as well as better mixing among other benefits. Nevertheless, the fabrication of this type of reactors can be ratherchallenging. Additive Manufacturing (AM) has been a disrupting technology in several fields of engineering, including in the chemical industry. AM brings the possibility to fabricate miniaturized structured reactors with internal geometries that were not possible to fabricate. The benefit of this type of structures to the chemistry industry are very promising. Nevertheless, as AM enables a wide range of geometries and possibilities, it is necessary to better understand how the geometrical characteristics of the reactors affect their performance. This thesis aimed to improve the understanding of structured reactors, their advantages, disadvantages and future challenges to improve their performance. Consequently, the main objective was to develop a comprehensive methodology, from the conception, characterization and simulation of structured reactors up to their optimization. The work was divided into four different sections, i.e., the fabrication of the reactors (from the conception of the geometry, to their fabrication by AM), their hydrodynamic characterization by studying the Residence Time Distribution (RTD), the study of their performance for applications in heterogeneous catalysis (solid/liquid) and their simulation by Computational Fluid Dynamics (CFD). For the hydrodynamic characterization of the reactors, a complete automated system was developed to measure the RTD by a fluorescence technique, which had the main benefits of not being intrusive and also offered high frequency acquisition rates. The microstructured reactors were fabricated in a polymeric resin, which enabled the grafting of palladium for the use of the reactors for heterogeneous catalytic reactions. Finally, a first step for the development of a complete workflow for the CFD simulation and optimization of structured reactors was presented. Furthermore, a brief presentation of the different additive manufacturing techniques and the perspectives for future applications regarding the fabrication of microstructured reactors were also presented

La bonne maîtrise de l'opération de laminage passe par le contrôle du frottement d'origine limite ce qui nécessite une meilleure compréhension de la rhéologie des films interfaciaux et donc des mécanismes d'action des additifs de lubrification. La grande complexité des phénomènes physico-chimiques contrôlant le régime limite nous a amenés à développer une démarche originale visant à modéliser expérimentalement la lubrification limite par un tribomètre analytique sous ultra-vide. Cette méthode permet de simplifier le système tribologique et d'étudier in situ les mécanismes de formation de tribofilms au moyen de technique d'analyse de surface (XPS, AES). Nous avons utilisé des conditions mécaniques sévères pour former de la surface métallique nouvelle qui serait fortement impliquée dans la génération des tribofilms. Pour lubrifier le contact, nous avons introduit des molécules de petit poids moléculaire modélisant les différents constituants du lubrifiant par leur fonction chimique. Le contrôle de la pession de ces molécules dans l'enceinte (de 10-9 à 10 mbar) permet d'évaluer la cinétique de formation/destruction des tribofilms et de quantifier l'efficacité de ces molécules en régime de frottement limite. L'ensemble de ces résultats et leur rapprochement avec des expériences conduites avec les mêmes molécules en phase liquide valident la démarche expérimentale. En effet, les comportements tribologiques observés sont très proches des comportements usuels. Cette méthode pourrait donc être utilisée pour prédire le comportement tribologique de nouvelles molécules. Par ailleurs, les techniques d'analyse de surface ont permis de déterminer, pour de nombreuses molécules, les chemins réactionnels conduisant à la formation de tribofilms. Ces résultats nous ont conduit à diviser la formation d'un film protecteur en trois étapes clés (adsorption de la molécule, réactions chimiques et propriétés mécaniques du tribofilm) qui permettent de mieux comprendre la formation des tribofilms et de clarifier les effets des nombreux paramètres influençant leur formation, en particulier l'effet complexe de la température.

Depuis quelques années, une prise de conscience accrue des risques associés aux solvants a abouti à durcir la réglementation et à optimiser leur mise en œuvre. Cette évolution a entrainé un intérêt croissant pour les biosolvants, i.e. les solvants d’origine naturelle et respectueux des critères sanitaires et environnementaux. Dans ce contexte, l’isosorbide, un diol issu de la filière amidon par double déshydratation du sorbitol, constitue un synthon intéressant à partir duquel une grande variété de molécules ou de polymères peuvent être développés. Les diéthers courts d’isosorbide (≤ 5 carbones par chaine alkyle), bio-sourcés et liquides à température ambiante, présentent un intérêt potentiel comme solvants et ont donc été étudiés. Les monométhyle isosorbides (formes -endo et -exo) ont également été évalués puisqu’ils constituent l’impureté principale du Diméthyle Isosorbide commercial (DMI), le candidat le plus prometteur de cette famille de solvants. Les propriétés physicochimiques, fonctionnelles et applicatives nécessaires à la caractérisation et à l’utilisation de nouveaux solvants ont été déterminées : les propriétés thermo-physiques (pression de vapeur,enthalpie de vaporisation), optiques et électriques (indice de réfraction, constante diélectrique, moment dipolaire), fonctionnelles (viscosité, coefficient de partage, paramètres de Kamlet et Taft) ont ainsi été mesurées. Le profil hygiène, sécurité et environnement du DMI a été déterminé et comparé à des solvants usuels, permettant d’évaluer son caractère "vert". Le DMI étant miscible à l’eau en toutes proportions, les propriétés physicochimiques en solutions aqueuses ont également été étudiées et ont permis de mettre en évidence un phénomène d’auto-agrégation du DMI sur une large gamme de concentrations.Une procédure de type "solvent design" a ensuite été développée afin d’estimer le potentiel d’utilisation de ces solvants. Une nouvelle approche pour la classification des solvants a tout d’abord été proposée, basée exclusivement sur la structure moléculaire des solvants et dérivée de l’approche COSMO-RS ("COnductor-like Screening MOdel for Real Solvents") dans laquelle les solvants sont considérés dans leur état liquide. Cette approche a permis la classification de 152 solvants dans 10 classes distinctes sans nécessiter de données expérimentales. A partir de cette classification, la proximité inter-solvants a pu être quantitativement exprimée. La méthode a été appliquée au DMI et a permis de dégager un certain nombre d’applications potentielles qui ont été ensuite évaluées, parmi lesquelles l’utilisation du DMI comme fluxant pour bitumes, agent de coalescence pour peintures hydrodiluables, solvant pour le décapage de peintures, solvant pour le nettoyage d’encres d’imprimerie ou encore agent de couplage pour la formulation de détergents liquides
In the last past years, an increasing awareness of the hazards linked to the use of solvents has strengthened the regulation and forced to optimize their use. This evolution entailed an increasing interest for bio-solvents, i.e. solvents from renewable materials and with good health and environmental properties. In this context, isosorbide, a diol obtained by the double deshydratation of sorbitol, might be valuable synthon for the design of a wide range of molecules and polymers. The short isosorbide diethers (_ 5 carbones per alkyl chain), as they are biosourced and liquid at ambient temperature, are potentialy promising solvents, that is why they have been studied. The monomethyl isosorbides (-endo et -exo forms) have also been evaluated, as they are the main impurities of the commercial dimethyl isosorbide (DMI), the most promising compound of this solvents family. The physicochemical, functional and applicative properties that are necessary to the characterization and the use of new solvents have been assessed : the thermo-physical properties (vapor pressure, vaporization enthalpy), the optical and electrical properties (refractive index, dielectric constant, dipole moment), the functional properties (viscosity, partition coefficient, Kamlet et Taft solvatochromic parameters) have been measured. The environmental, health and safety profile of DMI has been determined and compared to common solvents, allowing the evaluation of its "greenness". As DMI is fully miscible with water, its physicochemical properties in aqueous solutions have been studied as well, and have enlightened a self-aggregation of DMI within a large concentration range.A solvent design process has then been developped in order to estimate the potential use of these new solvents. A novel approach for the classification of solvents has been proposed, based solely on the solvent molecular structure and relying on the "COnductor-like Screening MOdel for Real Solvents" (COSMO-RS) in which solvents are considered in their liquid state. This approach has allowed the classification of 152 solvents into 10 classes without requiring the knowledge of any experimental data. The approach has been applied to DMI and allowed to find some potential applications that have been evaluated, among which the use of DMI as fluxing agent for bitumen composition, coalescing agent for water-borne paints, solvent for paint strippers, solvent for ink removal, or coupling agent for the formulation of liquid detergents

A variety of protected enolic forms of 1, 2-cyclohexanedione was prepared as substrates for conjugate addition studies using organocopper reagents. The sequence involved the enol ether preparation via the enolate, alkylation with an organometalic reagent, and oxidative rearrangement with pyridinium chlorochromate followed by the conjugate addition reactions. Protection of 1, 2-cyclohexanedione was achieved by reacting with chloro tert-butyldimethyl silane and subjected to alkylation. Steric problems were encountered and so an alternative protective group the methoxymethyl acetal was prepared and studied. Alkylation of these derivatives was successful; however, the oxidation was problematic and although evidence for rearrangement was observed in one case, it did not provide the desired ketone.

Depuis quelques années, une prise de conscience accrue des risques associés aux solvants a abouti à durcir la réglementation et à optimiser leur mise en œuvre. Cette évolution a entrainé un intérêt croissant pour les biosolvants, i.e. les solvants d’origine naturelle et respectueux des critères sanitaires et environnementaux. Dans ce contexte, l’isosorbide, un diol issu de la filière amidon par double déshydratation du sorbitol, constitue un synthon intéressant à partir duquel une grande variété de molécules ou de polymères peuvent être développés. Les diéthers courts d’isosorbide (≤ 5 carbones par chaine alkyle), bio-sourcés et liquides à température ambiante, présentent un intérêt potentiel comme solvants et ont donc été étudiés. Les monométhyle isosorbides (formes -endo et -exo) ont également été évalués puisqu’ils constituent l’impureté principale du Diméthyle Isosorbide commercial (DMI), le candidat le plus prometteur de cette famille de solvants. Les propriétés physicochimiques, fonctionnelles et applicatives nécessaires à la caractérisation et à l’utilisation de nouveaux solvants ont été déterminées : les propriétés thermo-physiques (pression de vapeur,enthalpie de vaporisation), optiques et électriques (indice de réfraction, constante diélectrique, moment dipolaire), fonctionnelles (viscosité, coefficient de partage, paramètres de Kamlet et Taft) ont ainsi été mesurées. Le profil hygiène, sécurité et environnement du DMI a été déterminé et comparé à des solvants usuels, permettant d’évaluer son caractère "vert". Le DMI étant miscible à l’eau en toutes proportions, les propriétés physicochimiques en solutions aqueuses ont également été étudiées et ont permis de mettre en évidence un phénomène d’auto-agrégation du DMI sur une large gamme de concentrations.Une procédure de type "solvent design" a ensuite été développée afin d’estimer le potentiel d’utilisation de ces solvants. Une nouvelle approche pour la classification des solvants a tout d’abord été proposée, basée exclusivement sur la structure moléculaire des solvants et dérivée de l’approche COSMO-RS ("COnductor-like Screening MOdel for Real Solvents") dans laquelle les solvants sont considérés dans leur état liquide. Cette approche a permis la classification de 152 solvants dans 10 classes distinctes sans nécessiter de données expérimentales. A partir de cette classification, la proximité inter-solvants a pu être quantitativement exprimée. La méthode a été appliquée au DMI et a permis de dégager un certain nombre d’applications potentielles qui ont été ensuite évaluées, parmi lesquelles l’utilisation du DMI comme fluxant pour bitumes, agent de coalescence pour peintures hydrodiluables, solvant pour le décapage de peintures, solvant pour le nettoyage d’encres d’imprimerie ou encore agent de couplage pour la formulation de détergents liquides
In the last past years, an increasing awareness of the hazards linked to the use of solvents has strengthened the regulation and forced to optimize their use. This evolution entailed an increasing interest for bio-solvents, i.e. solvents from renewable materials and with good health and environmental properties. In this context, isosorbide, a diol obtained by the double deshydratation of sorbitol, might be valuable synthon for the design of a wide range of molecules and polymers. The short isosorbide diethers (_ 5 carbones per alkyl chain), as they are biosourced and liquid at ambient temperature, are potentialy promising solvents, that is why they have been studied. The monomethyl isosorbides (-endo et -exo forms) have also been evaluated, as they are the main impurities of the commercial dimethyl isosorbide (DMI), the most promising compound of this solvents family. The physicochemical, functional and applicative properties that are necessary to the characterization and the use of new solvents have been assessed : the thermo-physical properties (vapor pressure, vaporization enthalpy), the optical and electrical properties (refractive index, dielectric constant, dipole moment), the functional properties (viscosity, partition coefficient, Kamlet et Taft solvatochromic parameters) have been measured. The environmental, health and safety profile of DMI has been determined and compared to common solvents, allowing the evaluation of its "greenness". As DMI is fully miscible with water, its physicochemical properties in aqueous solutions have been studied as well, and have enlightened a self-aggregation of DMI within a large concentration range.A solvent design process has then been developped in order to estimate the potential use of these new solvents. A novel approach for the classification of solvents has been proposed, based solely on the solvent molecular structure and relying on the "COnductor-like Screening MOdel for Real Solvents" (COSMO-RS) in which solvents are considered in their liquid state. This approach has allowed the classification of 152 solvents into 10 classes without requiring the knowledge of any experimental data. The approach has been applied to DMI and allowed to find some potential applications that have been evaluated, among which the use of DMI as fluxing agent for bitumen composition, coalescing agent for water-borne paints, solvent for paint strippers, solvent for ink removal, or coupling agent for the formulation of liquid detergents

Les procédés de fabrication additive permettent, à partir d’un fichier de CAO, la fabrication de pièces complexes sans outillage, dans des délais de développement très courts et avec une grande flexibilité. Parmi les procédés de fabrication additive employés avec les polymères, le frittage laser de poudre est le plus utilisé. Ces travaux de thèse sont consacrés à l’étude et la compréhension des mécanismes fondamentaux impliqués lors du procédé de frittage laser de poudres de polyamide 12. Au cours du procédé de frittage laser de nombreux paramètres interviennent. Ainsi l’énergie fournie à la poudre par l’intermédiaire du rayon laser dépend de la puissance de celui-ci, de la vitesse de balayage et de l’espacement entre deux balayages successifs. De plus, le matériau subit un cycle thermique sévère : avant d’être frittée, la poudre est préchauffée. Puis, dans le bac de fabrication, la poudre non frittée ainsi que les pièces séjournent pendant toute la durée de la fabrication à des températures élevées. Cette histoire thermique entraîne un vieillissement et donc une modification des propriétés de la poudre ce qui complique sa réutilisation. L’influence de ces différents paramètres sur la microstructure et les propriétés mécaniques des pièces finales a été mise en évidence. De plus l’utilisation de différentes poudres de polyamide 12 a permis l’identification des paramètres-clés de la matière.Le frittage laser des polymères semi-cristallins est régi par plusieurs mécanismes fondamentaux : la fusion des particules de poudre, l’interdiffusion des chaînes macromoléculaires aux interfaces, la coalescence des particules fondues, la densification et enfin la cristallisation. L’étude et la modélisation de la cristallisation ont été effectuées pour l’un des polyamides 12 employés au cours de cette thèse. De ce traitement théorique ont pu être déduits les temps de maintien du polymère à l’état fondu au cours du procédé. Dans une seconde phase, des analyses rhéologiques menées dans le cadre de la viscoélasticité linéaires des polymères à l’état fondu ont permis de déduire les temps d’interdiffusion des chaînes macromoléculaires. Par ailleurs, le processus de coalescence des particules de poudres à l’état fondu a été suivi expérimentalement et modélisé pour différentes températures. Ces temps ont été confrontés à la durée de maintien du polymère à l’état fondu, confirmant ainsi la bonne consolidation obtenue lors du frittage du polyamide 12. En conclusion, ce travail contribue à la compréhension des différents mécanismes physico-chimiques intervenant au cours du frittage laser : il permet d’expliciter de façon assez approfondie les relations entre les propriétés des poudres, les paramètres du procédé et les propriétés finales des pièces. De nombreuses préconisations relatives à l’optimisation des propriétés des poudres pourront être déduites de ce travail et aideront au développement de nouveaux matériaux adaptés à ce procédé
Additive processing technologies are aimed at manufacturing parts directly from a computer-aided design (CAD) file, without the need for tooling. Therefore flexibility of production increases and manufacturing of small to mid-size series of very complex or even customized parts becomes possible within reduced development time and expenses. Because of the good mechanical properties obtained in the parts, the most commonly used among additive technologies for polymers is laser sintering (LS). The objective of this work is to contribute to a better understanding of the different physical mechanisms involved during laser sintering of polyamide 12 powders. Many operating variables impact the laser sintering process. Especially, the energy supplied to the powder with the laser beam depends on its power, its displacement velocity and the scan spacing. Moreover, the polymer material undergoes a quite severe thermal treatment : before its sintering, the powder is preheated, then in the build tank the sintered parts and the un-sintered surrounding powder remain until the end of the job at elevated temperatures. This thermal history induces ageing, which modifies some powder features and hinders its future reuse. The influence of the parameters mentioned above on the part microstructure and mechanical properties was investigated. Moreover the use of different polyamide 12 powders enabled to identify the key material characteristics towards the physical processes involved in LS and towards the final properties of parts. The laser sintering of semi-crystalline polymers is governed by several fundamental mechanisms: melting of particles, interdiffusion of macromolecular chains at interfaces, coalescence of molten particles, then densification and finally crystallisation. The study and modelling of crystallisation were carried out with one of the PA12 powders used in the first part of this work. From this modelling, the time during which the polymer remains in the molten state during the process was estimated. Next, a rheological analysis made within the framework of linear viscoelasticity of polymer melts allowed to compute the interdiffusion time of the macromolecular chains. Moreover, the coalescence process of molten particles was observed at different temperatures and modeled. The characteristic times thus estimated for these physical processes were opposed to the time during which the polymer remains in the molten state and confirmed the good consolidation obtained by laser sintering of polyamide 12. In conclusion this work contributes to understand the different physico-chemical mechanisms involved during polymer laser sintering by specifying the relations between powder parameters, process variables and final properties of parts. Many recommendations for the optimisation of powder properties can be derived from this work for the purpose of developing new polymeric materials adapted to this process

Ne nécessitant pas d’outillage dédié ni de brut de matière, les procédés additifs apportent de nouvelles perspectives quant au triptyque Produit-Process-Matériau. D’un autre côté, comme tous les autres procédés, ils ont leurs propres spécificités et contraintes liées aux phénomènes physiques mis en jeu au cours du processus de fabrication. Tirer profit de la rupture techno logique que représente la fabrication additive implique donc de concevoir les produits autrement. Ce travail de thèse consiste en l'élaboration d'une méthodologie de conception orientée fabrication additive. Organisée en quatre étapes, la méthode permet, à partir du cahier des charges fonctionnel et des caractéristiques duprocédé de fabrication utilisé, de définir une géométrie de pièce optimisée, à la fois, vis-à-vis des objectifs fonctionnels et des contraintes de fabricabilité. Un domaine de conception est, dans un premier temps, établie à partir des entités fonctionnelles et d'un choix d'orientations de fabrication. La topologie générale du produit y est alors optimisée vis à vis des critères globaux issus des spécifications fonctionnelles et des règles métier globales. La géométrie locale est ensuite définie à partir d'un choix de trajectoires de fabrication et de la simulation du processus de fabrication. Enfin, chaque choix lié à la stratégie de fabrication débouchant sur une géométrie de pièce différente, la dernière étape consiste à identifier celle répondant le mieux aux spécifications attendues. La méthodologie a l’avantage d’être générique dans sa structure et peut être utilisée pour les différents procédés employés pour la fabrication directe. Les contraintes de fabrications sont cependant spécifiques à chaque procédé car liés aux phénomènes physiques mis en jeu au cours des processus de fabrication. Dans le cadre de nos travaux de thèse, nous nous sommes particulièrement intéressés à la technologie de fabrication par projection de poudres. Ainsi, un modèle du processus de fabrication a été mis en place. Il permet d’évaluer et d’optimiser les stratégies de fabrication vis-à-vis des besoins fonctionnels, en permettant de prédire la géométrie finale des pièces, et des contraintes procédés enpermettant de prédire les variations de paramètres de fabrication. Ce modèle a été particulièrement mis à profit au cours de nos travaux pour alimenter la méthode d'optimisation de trajectoires, par ailleurs proposée, pour la fabrication de pièces à parois minces
Manufacturers are constantly encountering tough international competition. In order to stay competitive they have to developed new products with time and cost constraints always more significant. In this context, as a ‘tool-less’ and digital approach to manufacture, additive manufacturing presents companies with a wide and expanding range of technical and economic benefits. However, the additive manufacturing processes, as the others, have also their own characteristics and limits. Finally, to take advantages of the technological breakthrough which is additive manufacturing, a new way of designing products is needed. This work deals with the development of a new methodology of design for additive manufacturing. Subdivided in four main steps, the proposed method allows from functional specifications and manufacturing process characteristics to define an optimised part geometry regarding both the functional objectives and the manufacturing constraints. In the first step, manufacturing orientations are chosen from the functional entities and allow to propose a design area. The general topology of the part is then optimised in this area regarding the functional specifications and the global manufacturing constraints. In the third step, the accurate part geometry is generated from a choice of manufacturing trajectories and thanks to the manufacturing process simulation. The fourth and last step is to determine and compare each other the different geometries corresponding to all the possible choices of manufacturing strategy. At the end, the best suitable is selected. The proposed method structure is generic and can be applied to all the additive manufacturing processes. However, the physical phenomena involved during the manufacturing processes are different for each one; the manufacturing constraints can be thus also different. This work deals more specifically with the laser claddingtechnology. Indeed, a physical model of this process has been proposed. It allows to estimate and optimise the manufacturing strategies regarding the functional needs and the manufacturing constraints. This model has been particularly used in the optimisation method of manufacturing paths which has also been developed in this work to manufacture thin wall metal parts

Le projet NEOPHIL a pour ambition d'élaborer une membrane d'ultrafiltration (UF) en fibre creuse de poly(fluorure de vinylidène) (PVdF) possédant une résistance au colmatage stable dans le temps. Cette propriété peut être acquise par l'ajout d'un copolymère à blocs nommé GEN dans la solution de préparation des fibres en plus de l'additif poly(vinyl pyrrolidone) (PVP) classiquement utilisé. Dans ce travail, nous nous sommes attachés à la détermination des additifs en surface, dans la masse et à établir des profils de concentration par ATR-FTIR, T%-FTIR et microscopie Raman. Ces analyses ont montré que la moitié de la PVP est lessivée dans le bain de coagulation alors que GEN reste quantitativement ancré dans la matrice. Dans le cas de la PVP, les paramètres d'élaboration comme la présence de solvant ou de PVP dans le bain de coagulation influent fortement sur le profil de concentration au niveau des interfaces. Par la suite, une analyse multicritère entre l'hydrophilie apportée par les additifs et le colmatage a été effectuée. Cette étude a été réalisée par des mesures d'angle de contact à l'eau, de rétention d'eau et de pression d'intrusion d'eau sur fibres sèches en relation avec la taille et la distribution des pores, la rugosité de surface (AFM) et la perméabilité à l'eau pure. La rétention d'eau et la pression d'intrusion d'eau semblent les deux techniques les plus pertinentes pouvant relier les propriétés physico-chimiques et les performances de filtration. Une étude préliminaire sur le comportement au vieillissement a également été effectuée qui montre que GEN est peu extrait alors que la PVP disparait en partie par extraction et/ou dégradation. Ce phénomène affecte fortement les différents paramètres étudiés dans l'analyse multicritère
The project NEOPHIL aims to develop an ultrafiltration (UF) membrane hollow fiber from poly (vinylidene fluoride) (PVdF) that resists to fouling amide time. This property can be achieved by adding a block copolymer called GEN in the fiber preparation solution in addition to the classic additive, poly (vinyl pyrrolidone) (PVP). In this work, we focused on the quantification of additives on the surface, in the bulk and establishing the concentration profile by ATR-FTIR, T% -FTIR and Raman microscopy. These analyzes showed that half of the PVP is washed away into the coagulation bath while GEN quantitatively remains anchored in the matrix. In the case of PVP, the formulation parameters such as the presence of solvent or PVP in the coagulation bath greatly affects the concentration profile at the interfaces. In addition a multi-criteria analysis between hydrophilicity provided by the additives and the fouling was established. This study was carried out by measurement of the water contact angle, water retention and water intrusion pressure of dry fibers in relation to the size and distribution of pores, the surface roughness (AFM) and the permeability to pure water. Water retention and water intrusion pressure seem to be the two most relevant techniques that can connect the physicochemical properties and filtration performance. A preliminary study on the aging behavior was also performed showing that GEN is not extracted while the PVP is lost partly by extraction and/or degradation. This phenomenon strongly affects the different parameters studied in the multi-criteria analysis

Ce travail est centré sur l'étude des suspensions aqueuses de
Laponite à l'équilibre mécanique et sous écoulement. Le premier
objectif de cette étude a été de préciser les conditions de
formation du gel, en faisant varier les interactions, au travers
de la force ionique (NaCl) et de la présence de différents
additifs comme le pyrophosphate de sodium ou des couches de
polymères adsorbées (POE) qui ralentissent l'agrégation des
particules. Nous avons associé pour cela différentes techniques
(observations visuelles, diffusion de lumière statique et
dynamique, rhéologie classique et optique). L'origine de la
gélification, la structure des suspensions de Laponite à
l'équilibre et sous cisaillement en présence ou non d'additifs ont
également été déterminées. L'étude des suspensions, couvrant une
large gamme de forces ioniques et s'étendant dans un régime très
dilué, nous a permis de construire un diagramme de phase à temps
long qui tient mieux compte des cinétiques d'équilibre de la
Laponite et de conclure à la formation d'un gel par agrégation (et
non vitrification par répulsion des particules) dans ces systèmes.

L'adsorption du POE sur les particules puis la cinétique
d'agrégation des suspensions de Laponite en présence du POE ont
été étudiées pour différentes concentrations et masses molaires de
POE. Nous concluons que la couche de polymère adsorbé ne suffit
pas à écranter totalement l'influence des interactions
électrostatiques. De plus, les POE de masses molaires élevées
pontent plusieurs particules de Laponite formant des agrégats
tenus entre eux, même sous écoulement, par l'intermédiaire du POE.