Orientador: Fernando Galembeck / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-25T09:34:27Z (GMT). No. of bitstreams: 1 Silva_LucimaraLopes_D.pdf: 8828120 bytes, checksum: 3631493bce3c7f33cbc0007290af3e16 (MD5) Previous issue date: 2013 / Resumo: Neste trabalho, examinou-se o comportamento de dispersões aquosas de látex e seus nanocompósitos com argila, quando submetidos aos processos de moldagem por liofilização (freeze-casting) e eletrofiação (electrospinning). Os sólidos resultantes foram caracterizados principalmente por microscopia eletrônica de varredura (MEV). Através do freeze-casting do látex poli(estireno-co-acrilato de butila-co-ácido acrílico (P(S-BA-AA)) foi obtido um monolito de baixa densidade com variadas morfologias de poros (colunares, alongados e lamelares) e predominância de poros com morfologia do tipo espinha de peixe, semelhantes a "shish-kebabs" encontrados em polímeros semicristalinos. A moldagem por liofilização de espumas líquidas de látex com e sem argila originou espumas sólidas que apresentaram hierarquia de poros, com poros menores orientados sobre cavidades maiores, derivadas de bolhas de ar. As diferentes morfologias obtidas são modeladas pelo gelo, cujo hábito cristalino experimenta diversas transições morfológicas durante o processo de congelamento, devido às instabilidades térmicas na interface sólido-líquido (S/L). A técnica de eletrofiação permitiu obter fibras de blendas poliméricas imiscíveis e fibras nanocompósitas a partir de uma dispersão aquosa de látex poli(estireno-acrilato de butila) (P(S-BA)) misturada com soluções aquosas de poli(óxido de etileno) (PEO) de diferentes massas molares e argila. As fibras poliméricas apresentaram morfologia coaxial, com o polímero hidrofílico alojado preferencialmente na região interna, quanto menor for sua massa molar. As técnicas de espectroscopia de absorção no infravermelho (FTIR) e calorimetria diferencial de varredura (DSC) mostraram que o PEO é removido das fibras após o tratamento destas com água. Medidas de decaimento do potencial eletrostático de superfícies de polietileno de baixa densidade (PEBD), submetidas a tratamento corona, mostraram que a deposição das nanofibras de látex e PEO aceleraram a dissipação da carga elétrica da superfície deste dielétrico. Ensaios de adsorção mostraram que os nanocompósitos obtidos por ambas as técnicas são interessantes adsorventes do corante azul de metileno (AM), com eficiência de remoção comparável à da dispersão aquosa de argila / Abstract: In this work, we examined the behavior of latex aqueous dispersions and their nanocomposites with clay, when subjected to two polymer processing techniques: freeze-casting and electrospinning. The resulting solids were examined mainly by using scanning electron microscopy (SEM). By freeze-casting poly(styrene-co-butyl acrylate-co-acrylic acid) (P(S-BA-AA)) latex aqueous dispersion, a low density monolith was obtained with pores of varying morphologies (columnar, elongated and lamellar) and predominance of fishbone morphology resembling "shish-kebabs" found in semi-crystalline polymers. The freeze-casting of liquid latex foams with and without clay originated solid foams which contain small pores distributed along larger cavities derived from air bubbles. The different morphologies obtained was template by the frozen liquid precursor, which experiences several morphological transitions during the freezing process, due to thermal instabilities in the solid-liquid (S/L) interface. The electrospinning process afforded to obtain polymeric and composite nanofibers using poly (styrene-butyl acrylate) (P-S-BA) aqueous latex blended with poly(ethylene oxide) (PEO) solutions with different molecular weights and clay. Fibers show coaxial morphology, in which hydrophilic polymer and clay are in the inner of the fibers and latex is localized in the shell, as the molar mass of PEO decreases. Infrared (IR) and differential scanning calorimetry (DSC) techniques have shown that PEO is removed from fibers after water treatment. Measurements of the electrostatic potential decay on low-density polyethylene (LDPE) surfaces, charged with corona, showed faster electrostatic potential dissipation when polymeric nanofibers are deposited on LDPE. Sorbent tests of methylene blue (MB) dye revealed that nanocomposites prepared by both techniques show interesting dye sorbent properties, presenting same efficiency as the aqueous clay dispersion / Doutorado / Físico-Química / Doutora em Ciências

Orientador: Liliane Maria Ferrareso Lona / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-19T09:07:05Z (GMT). No. of bitstreams: 1 Silva_RodrigoDuarte_M.pdf: 10171342 bytes, checksum: d8c5c116297d9e1edee32a935dfb816c (MD5) Previous issue date: 2011 / Resumo: O objetivo deste trabalho foi sintetizar nanocompósitos poliméricos (NCPs) contendo Hidróxidos Duplos Lamelares (HDLs) por meio da técnica de polimerização em miniemulsão. O copolímero poli(acrilato de n-butila-co-metacrilato de metila) P(BA-co- MMA) foi escolhido como matriz dos NCPs devido à sua importância comercial na formulação de adesivos sensíveis à pressão (PSA). Os HDLs organicamente modificados disponíveis comercialmente Perkalite F100S, Perkalite A100 e Perkalite AF50 foram usados como agentes de reforço dos nanocompósitos. A metodologia utilizada foi semelhante a metodologia utilizada para produção de NCPs contendo argilas catiônicas pela polimerização em miniemulsão, na qual a carga mineral é adicionada à fase orgânica antes da produção das miniemulsões. Os látices obtidos foram caracterizados por: Difração de Raios-X (DRX), Espalhamento Dinâmico de Luz (DLS), Calorimetria Exploratória Diferencial (DSC), Análise Termogravimétrica (TG) e Microscopia Eletrônica de Transmissão (MET) / Abstract: The aim of this work was the synthesis of polymeric nanocomposites (PNCs) filled with Layered Double Hydroxides (LDHs) through miniemulsion polymerization. The copolymer poli(n-butyl acrylate-co-methyl methacrylate) P(BA-co-MMA) was chosen to form the matrix because it is a commercially important component in the formulation of pressure sensitive adhesives (PSA). The commercial available organically modified LDHs Perkalite F100S, Perkalite A100 and Perkalite AF50 were used as fillers. The methodology used was similar to the one used to produce PNCs filled with cationic clays through miniemulsion polymerization, where the inorganic charge is added to the organic phase before the preparation of the miniemulsion. The latexes prepared were characterized by: X-Ray Diffraction (XDR), Dynamic Light Scattering (DLS), Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TG) and Transmission Electron Microscopy (TEM) / Mestrado / Desenvolvimento de Processos Químicos / Mestre em Engenharia Química

Orientador: Liliane Maria Ferrareso Lona / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-19T15:02:05Z (GMT). No. of bitstreams: 1 MacedoNeto_JoseCostade_D.pdf: 15337503 bytes, checksum: 2d35593a90de41c2e7333e60488e1bf0 (MD5) Previous issue date: 2011 / Resumo: Materiais nanocompósitos poliméricos utilizando argilas naturais como reforço tem sido bastante estudados por apresentar propriedades melhoradas em relação ao polímero sem reforço. Este trabalho tem como objetivo produzir e caracterizar materiais nanocompósitos polimérico com matriz de poliestireno por meio da polimerização in situ em emulsão utilizando com nanopartícula a caulinita amazônica. Os resultados obtidos mostraram que a caulinita utilizada como reforço neste trabalho apresentou alta razão de aspecto, foi possível ser intercalada por moléculas orgânicas de dimetilsulfóxido (DMSO) e acetato de potássio (AcK). Nesta tese foram produzidos nanocompósitos com 1, 3 e 5% de caulinita modificada com DMSO e outros com 1, 3 e 5% de argila modificada com AcK. A estabilidade do látex produzido pela polimerização foi medida por dynamic light scattering (DLS). O látex com 3% de argila modificada com DMSO apresentou melhor estabilidade em relação ao com 1% de argila e ao do poliestireno puro. As análises por difração de raios X (DRX) e microscopia eletrônica de varredura de alta resolução (HRSEM) revelaram que a utilização das quantidades 1 e 3% de argila modificada com DMSO são as ideais para a obtenção de nanocompósitos. A análise termogravimétrica (TGA) dos nanocompósitos com 1 e 3% apresentou melhores propriedades térmicas em relação ao polímero sem reforço. A análise por calorimetria exploratória diferencial (DSC) mostrou que a adição de 1 e 3% de argila não alterou a temperatura de transição vítrea em relação ao polímero sem reforço. A análise térmica dinâmico-mecânica (TDMA) mostrou que o módulo de armazenamento (E') foi maior para o poliestireno puro em relação aos nanocompósitos com 1 e 3% de argila durante o aquecimento. A TDMA também mostrou que a adição de 1 e 3% de argila não influenciou a temperatura de transição vítrea (Tg). O ensaio de inflamabilidade horizontal mostrou que a taxa de queima foi menor para o nanocompósito com 3% de argila em relação ao PS e 1%. Sendo assim, foi possível produzir nanocompósitos com a caulinita. O látex obtido com 3% de argila foi o mais estável. Os nanocompósitos com quantidades de1 e 3% de argila obtiveram melhores propriedades térmicas em relação ao poliestireno sem argila. O PS puro apresentou maior E' as quantidades de 1 e 3% de argila não influenciou a Tg. O nanocompósito com 3% de argila obteve menor taxa de queima / Abstract: Polymer nanocomposites materials using natural clays as reinforcement has been extensively studied by presenting improved properties compared to unreinforced polymer. The goal of This work is to produce and characterize a polymer nanocomposites materials with matrix od polystyrene and nanoparticle by kaolinite through in situ emulsion polymerization. The kaolinite used as reinforcement in this study had a high aspect ratio, could be intercalated by organic molecules of dimethylsulfoxide (DMSO) and potassium acetate (ACK). In this thesis were produced nanocomposites with 1, 3 and 5% kaolinite modified with DMSO and others with 1, 3 and 5% clay modified with AcK. The stability of the latex produced by polymerization was measured by dynamic light scattering (DLS). Latex with 3% clay modified with DMSO showed better stability compared with the 1% clay and the pure polystyrene. Analyses by X-ray diffraction (XRD) and scanning electron microscopy, high resolution (HRSEM) revealed that use of the quantities 1 and 3% clay modified with DMSO are ideal for obtaining nanocomposites. The thermogravimetric analysis (TGA) of the nanocomposites with 1 and 3% showed better thermal properties compared to unreinforced polymer. Analysis by differential scanning calorimetry (DSC) showed that the addition of 1 and 3% clay did not change the glass transition temperature compared to the unreinforced polymer. The dynamic mechanical thermal analysis (TDMA) showed that the storage modulus (E') was higher for the pure polystyrene compared to nanocomposites with 1 and 3% clay during heating. TDMA also showed that the addition of 1 and 3% clay did not influence the glass transition temperature (Tg). The horizontal flammability test showed that the burn rate was lower for the nanocomposite with 3% clay compared to PS and 1%. Therefore, it was possible to produce nanocomposites with kaolinite. The latex obtained with 3% clay was the most stable. Nanocomposites with quantities of 1 and 3% clay had better thermal properties compared to polystyrene clay. The pure PS had a higher E' quantities of 1 and 3% clay did not affect the Tg. The nanocomposite with 3% clay had lower burn rate / Doutorado / Desenvolvimento de Processos Químicos / Doutor em Engenharia Química

Orientadores: Rubens Maciel Filho, Maria Carolina Burgos Costa / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-20T08:40:01Z (GMT). No. of bitstreams: 1 Pattaro_AnaFlavia_M.pdf: 11480434 bytes, checksum: e73b5f91ac734cab17a6d1dd1e142174 (MD5) Previous issue date: 2012 / Resumo: Este projeto envolve o estudo e desenvolvimento de materiais compósitos (polímero/carga) nanoestruturados (nanocompósitos), produzidos em uma unidade experimental de polimerização, destinada ao desenvolvimento de Nylon -6 (Poliamida-6 ou PA-6) para novas aplicações como plástico de engenharia. O estudo envolve o processo de polimerização de PA-6 e nanocompósitos de PA-6/argila organofílica a partir do monômero 'ÉPSILON '-Caprolactama, como também a produção das argilas organofílicas. A mistura é feita em um reator de bancada em batelada no qual argilas bentoníticas sódica e organofilizada são adicionadas à massa reacional (matriz polimérica) durante o processo de polimerização. Os estudos para o desenvolvimento de PA-6 e de seus nanocompósitos com diferentes características pretendem correlacionar os parâmetros reacionais e operacionais às propriedades finais do polímero obtido. Para isto, estudos de simulação do processo de polimerização foram desenvolvidos, juntamente com análises experimentais do produto. Dessa forma, a PA-6 e os nanocompósitos produzidos por meio do processo de polimerização in situ foram avaliados levando em consideração a eficiência da incorporação ou grau de esfoliação da argila no polímero, a massa molecular dos polímeros/nanocompósitos obtidos e suas características térmicas, determinadas por análises de DSC e TGA. Com base nos resultados obtidos, conclui-se que a polimerização in situ de nanocompósitos de PA-6/Argila Organofílica, utilizando o processo de polimerização hidrolítica da PA-6, é um processo viável de produção de nanocompósitos, uma vez que foi observada, através da técnica de DRX, uma possível formação de nanocompósitos esfoliados e/ou intercalados. Além disso, as simulações do processo de polimerização da PA-6, com ou sem a adição de argilas, apresentaram boa concordância com os valores obtidos experimentalmente / Abstract: This project involves the study and development of composite materials (polymer / filler) nanostructured (nanocomposites), produced in an experimental polymerization unit, for the development of Nylon-6 (Polyamide-6 or PA-6) for new applications such as engineering plastics. The study involves the PA-6 and PA-6/organoclay nanocomposites polymerization process using 'ÉPSILON '-caprolactam monomer, as well as the production of organoclays. The blend is done in a batch reactor in which organophilizated and sodic bentonite are added to the reaction mass (polymeric matrix) during the polymerization process. The studies on the development of PA-6 and its nanocomposites with different characteristics intend to correlate the reaction and operational parameters to the final properties of the obtained polymer. Thus, simulation studies of the polymerization process were developed, along with experimental analysis of the product. In this sense, PA-6 and nanocomposites produced by the in situ polymerization process were evaluated taking into account the incorporation efficiency or the exfoliation rate of the clay in the polymer, the molecular weight of polymers / nanocomposites obtained and their thermal characteristics, determined by DSC and TGA analysis. Based on these results, the conclusion is that the in situ polymerization of PA-6 and PA-6/organoclay nanocomposites using the PA-6 hidrolitic polymerization process, is a viable process for the production of nano-composites, since it was observed through the DRX technique a possible formation of exfoliated and/or intercalary nanocomposites. In addition, the PA-6 polymerization process simulations, with or without the addition of clays, presented a good fit with the experimental values / Mestrado / Desenvolvimento de Processos Químicos / Mestre em Engenharia Química

Orientadores: Júlio Roberto Bartoli, Marcos Akira D'Ávila / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-20T09:53:53Z (GMT). No. of bitstreams: 1 Galvan_Danieli_M.pdf: 5419216 bytes, checksum: 3bbb69d4a9a4e73278d7ed9781b01c43 (MD5) Previous issue date: 2012 / Resumo: O presente trabalho estudou a preparação e caracterização de híbridos de polímero-argila, tendo a poli(acrilonitrila-butadieno-estireno) (ABS) como matriz polimérica e duas argilas montmorilonitas organofílicas (MMTO) distintas e sua mistura binária 1:1 como fases dispersas. O objetivo foi avaliar os efeitos das variáveis: tipo de argila e processo nas propriedades físicas dos híbridos de ABS/MMTO. A seleção das argilas MMTO comerciais (Cloisite 30B e Cloisite 20A) baseou-se nas possíveis afinidades químicas de cada uma delas com as distintas fases do terpolímero ABS. Na preparação dos híbridos através do processo de intercalação no estado fundido, em extrusora com rosca-dupla co-rotacional, foi investigado o efeito do torque da rosca (ou tempo de residência na extrusora), na dispersão das argilas na matriz ABS. Os compostos obtidos foram caracterizados através de análises de difração de raios-X, termogravimetria, ensaios de tração uniaxial e resistência ao impacto, flamabilidade e análises reológicas do fundido em regime permanente e oscilatório em altas e baixas taxas de cisalhamento. A difração de raios-X indicou que os híbridos obtidos apresentavam estruturas intercaladas, que proporcionaram aumento nos módulos de elasticidade por tração e por cisalhamento (armazenamento e perda). As análises reológicas dos híbridos ABS mostram o surgimento de um caráter pseudo-sólido, em especial para os híbridos contendo a MMTO com maior afinidade química (Cloisite 30B) à fase SAN do terpolímero. Este comportamento indicaria uma provável dispersão em escala nanométrica da Cloisite 30B nos híbridos ABS, seja como único componente na fase dispersa ou na sua mistura binária com a Cloisite 20A. Este resultado caracterizaria os materiais obtidos como nanocompósitos. Melhorias significativas nas propriedades mecânicas de tração também foram verificadas nos híbridos a base de Cloisite 30B. Já os ensaios de rigidez ao impacto e as análises de estabilidade térmica não apresentaram resultados satisfatórios. Entretanto a adição de MMTO eliminou o gotejamento de material incandescente apresentado pelo ABS durante a queima (norma UL 94 HB). A utilização de um menor torque na rosca, ou seja, maior tempo de residência dos híbridos na extrusora, parece favorecer a dispersão/intercalação das argilas na matriz de ABS. Entretanto, o efeito deste fator foi confundido com variações na concentração nominal de argila / Abstract: This work studied the preparation and characterization of hybrids of polymer-clay, where the polymeric matrix was the poly(acrylonitrile-butadiene-styrene) (ABS) and two different organically modified montmorillonite (OMMT) and their mixture (1:1) were used as dispersed phase. The aim was evaluate the effect of kind of clay and process parameters on physical properties of ABS/OMMT hybrids. Two grades of commercial OMMT organoclay (Cloisite 20A and Cloisite 30B) were investigated, with distinct chemical affinities according to terpolymer phases, and a binary mixture of these clays. The hybrids were prepared by melt intercalation process, on a co-rotating twin-screw extruder, the effect of screw torque (or residence time on extruder) on clay dispersion in the polymeric matrix was investigated. The hybrids were characterized by analysis of X-ray diffraction, thermogravimetry, mechanical properties (uniaxial tensile and impact strength), flammability, and rheological analysis in steady and oscillatory states, at high and low shear rates. The X-ray diffractions indicated that the ABS hybrids present an intercalated structure, which improved the tensile elastic modulus and shear modulus (storage and loss). The rheological analysis of ABS hybrids shows the emergence of a pseudo-solid character, especially to the hybrids containing the OMMT with higher chemical affinity (Cloisite 30B) to SAN phase of the terpolymer. This behavior would indicate a probable nanometric scale dispersion of the Cloisite 30B on the hybrids of ABS, even in the single form or in a binary mixture, likely characterizing them as nanocomposites. Significant improvements in the tensile mechanical properties were also verified on the hybrids based on Cloisite 30B. Nevertheless the impact strength and thermal stability analysis did not show satisfactory results. The flammability test (UL 94 HB standard) of ABS hybrids showed a non-dripping effect of incandescent material during burning. The use of a lower screw torque, higher residence time of the hybrids on extruder, seems to favor clay dispersion/intercalation on the ABS matrix, however, the effect of this factor was confounded with some variations in the organoclay nominal content / Mestrado / Ciencia e Tecnologia de Materiais / Mestre em Engenharia Química

Orientadores: Julio Roberto Bartoli, Humberto Gracher Riella / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-20T23:19:45Z (GMT). No. of bitstreams: 1 Mazzucco_MateusDeLorenziCancelier_M.pdf: 25131087 bytes, checksum: 9d983cb4726735834e67d038fd3a6235 (MD5) Previous issue date: 2012 / Resumo: Este trabalho apresenta um estudo sobre a relação entre estrutura e propriedades de híbridos de montmorilonitas organicamente modificadas (MMTO) e terpolímero de acrilonitrila-butadieno-estireno (ABS), compatibilizados com o copolímero de estirenoetileno- butadieno-estireno (SEBS) ou de estireno-butadieno-estireno (SBS) preparados via intercalação no estado fundido em extrusora de rosca-dupla. Quatro formulações de híbridos foram propostas segundo um planejamento fatorial de experimentos 22 para estudar o efeito dos fatores compatibilizante (SEBS e SBS) e composição da MMTO (Cloisite 30B e mistura Cloisite 30B+Cloisite 20A (1:1)). A mistura binária de argilas foi proposta para verificar a viabilidade em balancear o caráter hidrofílico e hidrofóbico dos surfactantes destes dois tipos de argilas. As etapas de processamento foram: 1) Preparação de quatro concentrados na proporção mássica de 49,5: 40: 10: 0,5 de ABS/argila/compatibilizante/antioxidante em misturador interno; 2) Diluição para 4% em massa de MMTO; 3) extrusão do composto; 4) Granulação em moinho e moldagem por injeção dos corpos de prova. O efeito destes fatores e suas interações foram avaliados através de análises de difração de raios-X (DRX), microscopia eletrônica de varredura (MEV), microscopia eletrônica de transmissão (MET), termogravimetria (TGA), calorimetria diferencial de varredura (DSC), ensaios de tração uniaxial, resistência ao impacto, flamabilidade e análises reológicas do fundido em regime permanente e oscilatório em altas e baixas taxas de cisalhamento. As análises de DRX e de MET indicaram que os híbridos apresentaram estruturas intercaladas (ABS/20A30B/SEBS) e parcialmente esfoliadas (ABS/30B/SBS), essencialmente na fase SAN dos híbridos. As análises por MEV mostraram morfologias distintas da superfície de fratura na tração para os híbridos com SBS e SEBS sendo o SEBS caracterizado por uma fratura dúctil. As análises reológicas dos híbridos mostraram o surgimento de um caráter pseudo-sólido, com aumento significativo nos módulos de armazenamento e na viscosidade complexa, em especial para os híbridos com SBS. Este comportamento revela uma provável dispersão em escala nanométrica das argilas nos híbridos ABS, seja na forma simples ou mistura binária de MMTO. A resistência ao impacto, de todos os híbridos, foi significativamente reduzida devido às micro ou nano partículas de argila que podem atuar como defeitos aumentando aconcentração das tensões localizadas. Melhorias significativas nas propriedades mecânicas de tração quanto ao módulo de elasticidade foram verificadas nos híbridos com SBS em relação ao ABS de referência, por sua vez os híbridos com SEBS mostraram um expressivo comportamento dúctil. No ensaio de flamabilidade na horizontal (norma UL 94 HB) verificou-se uma supressão do gotejamento de material incandescente durante a queima dos híbridos contendo SBS, gotejamento observado nos híbridos com SEBS e no ABS de referência, este comportamento favorável é provavelmente devido à viscosidade do híbrido fundido SBS ser o dobro do SEBS. O estudo da cinética de degradação termo-oxidativa dos híbridos mostrou que a energia de ativação dos híbridos compatibilizados com SEBS é significativamente maior do que os híbridos com SBS, provavelmente devido à hidrogenação do butadieno no SEBS que melhora a sua estabilidade térmica. O grau de dispersão obtido pelas argilas permite designar estes híbridos como nanocompósitos de ABS / Abstract: The present work, shows a study about the relationship between structure and properties of hybrids of organically modified montmorillonites (MMTO) and terpolymer of acrylonitrile-butadiene-styrene (ABS), compatibilized with styrene-ethylene-butadienestyrene (SEBS) or styrene-butadiene-styrene (SBS) prepared by melt blending process. Four formulations of hybrids were proposed in a 22 factorial design of experiments to study the effect of factors compatibilizer (SEBS and SBS) and composition of OMMT (Cloisite 30B and Cloisite 30B + Cloisite 20A mixture (1:1)). The binary mixture of clay was proposed to verify the feasibility of balancing the hydrophobic and hydrophilic character of surfactants these two types of clays. The processing steps were: 1) Preparation of four masterbatches in mass ratio of 49,5: 40: 10:0,5 of ABS/clay/compatibilizer/antioxidant in an internal mixer; 2) Dilution to 4% by weight of OMMT; 3) Extrusion of the compound; 4) Granulation in mill and injection molding of test specimens. The effect of these factors and their interactions were evaluated through analysis of X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetry (TGA), differential scanning calorimetry (DSC), uniaxial tensile tests, impact strength, flammability and rheological analysis at high and low shear rates. The analyses of XRD and TEM showed that hybrids had structures intercaled (ABS/20A30B/SEBS) and partially exfoliated (ABS/30B/SBS) essentially in the SAN phase of the hybrids. The analyses by SEM showed different morphologies of the fracture surface in tensile for hybrids with SBS and SEBS, being the SEBS characterized by a ductile fracture. The analyses rheological of hybrids showed the appearance of a pseudo-solid behavior, with a significant increase in storage modulus and complex viscosity, in particular for hybrids with SBS. This behavior reveals a probable dispersion in nano scale of clays in hybrids ABS, either as single or binary mixture of MMTO. The impact strength of all hybrids were significantly reduced due to micro or nano clay particles that can act as defects increasing the concentration of localized stresses. The mechanical properties showed positive results of tensile as so elastic modulus observed in hybrids with SBS in relation to pristine ABS, while hybrids with SEBS showed a significant ductile behavior. In horizontal flammability test (UL 94 HB) verified a suppression of dripping of incandescent material during the burning of hybrids containing SBS, drip observed in hybrids with SEBS and pristine ABS reference, this behavior is probably due to the viscosity of hybrid melted SBS be the double of SEBS. The study of the kinetics of thermo-oxidative degradation of hybrids showed that the activation energy of the hybrid compatibilized with SEBS is significantly greater than the hybrids with SBS, probably due to hydrogenation of the butadiene on SEBS which improves their thermal stability. The degree of dispersion obtained by clays allows to designate these hybrids how nanocomposites ABS / Mestrado / Ciencia e Tecnologia de Materiais / Mestre em Engenharia Química

Ph.D. (Chemistry) / This study focuses on the morphology and crystal-growth behaviour of polyactide (PLA)-based blends and blends modified with organoclay thin films. The study further examined the effect of blending and the incorporation of organoclays on the enzymatic degradation behaviour. Thin films of unmodified and nanoclay-modified PLA/poly(butylene succinate) (PBS) blends were cast on a glass substrate by a spin coater, while thin films of biodegradable PLA/poly[(butylene succinate)-coadipate] PBSA blends and blends containing organoclays were cast on a silicon (100) wafer substrate. The morphology and crystal growth behaviour of the thin films crystallized at different temperatures were examined with an atomic force microscopy (AFM) equipped with a hot-stage scanner. In PLA/PBS blend thin films, AFM images showed that the size of the dispersed PBS phase was influenced by C30B clay loading on the blends. The dispersed size reduced on the addition of C30B clay up to 2 wt%, beyond which, dispersed size began to increase. Transmission electron microscopy studies indicated that this behaviour was due to the preferential location of silicates in the PBS phase than in the PLA phase. For thin films annealed at 60 °C, the additi on of organoclays to the blend quenched the growth of edge-on lamellae. The crystalline morphologies at 120 °C were dominated by edge-on lamellae grown, around the PBS phase to form spherulites. Morphologies of thin films crystallized at 120 °C from melt were dominated by the flat-on lamellae, while those crystallized at 70 °C from melt were dominated by the edge-on lamellae. In the case of PLA/PBSA blend thin films, the results indicated that the size and distribution of the dispersed phase were directly related to the blend composition. The crystal growth behaviours indicated the presence of homogeneous and heterogeneous nucleations, and the nature of nucleation was directly related to the blend ratio and the temperature at which crystallization occurred. Therefore, this study will facilitate the understanding of crystal growth behaviour in a confined environment and will enable the modulation of the blend properties.

When a permanent magnet is considered for an application, the quantity that quantifies the usability of that material is the magnetic energy product (BH)max. In today’s world, rare earth transition metal permanent magnets like Nd-Fe-B, Sm-Co possesses the maximum magnetic energy product. But still for the industrial application, the ferrite permanent magnets are the primary choice over these rare transition metal magnets. Thus, in the present context, the magnetic energy product of the low cost ferrite system makes it unsuitable for the high magnetic energy application. In this regard, exchange spring magnets which combine the magnetization of the soft phase and coercivity of the hard magnetic phases become important in enhancing the magnetic energy product of the system. In this thesis, the exchange spring behaviour is reported for the first time in hard/soft oxide nanocomposites by microstructural tailoring of hard Barium Ferrite and soft Nickel Zinc Ferrite particles. We have analyzed the magnetization reversal and its correlation with the coercivity mechanism in the Ni0.8Zn0.2Fe2O4/BaFe12O19 exchange spring systems. Using this exchange spring concept, we could enhance the magnetic energy product in Iron Oxide/ Barium Calcium Ferrite nanocomposites compared to the bare hard ferrite by ~13%. The presence of the exchange interaction in this nanocomposite is confirmed by the Henkel plot. Moreover, a detailed Reitveld study, magnetization loop and corresponding variation of the magnetic energy product, Henkel plot analysis and First Order Reversal Curve analysis are performed on nanocomposites of hard Strontium Ferrite and soft Cobalt Ferrite. We have proved the exchange spring behaviour in this composite. In addition, we could successfully tailor the magnetization behaviour of the soft Cobalt Ferrite- hard Strontium Ferrite nanocomposite from non exchange spring behaviour to exchange spring behaviour, by tuning the size of the soft Cobalt Ferrite in the Cobalt Ferrite/Strontium Ferrite nanocomposite. The relative strength of the interaction governing the magnetization process in the composites has been studied using Henkel plot and First Order Reversal Curve method. The FORC method has been utilized to understand the magnetization reversal behaviour as well as the extent of the irreversible magnetization present in both the nanocomposites, having smaller and larger particle size of the Cobalt Ferrite. It has been found that for the all the studied composites, the pinning is the dominant process for magnetization reversal. The detailed structural analysis using thin film XRD, angle dependent magnetic hysteresis and remanent coercivity measurement, coercivity mechanism by micromagnetic analysis and First Order Reversal Curve analysis are performed for thin films of Strontium Ferrite which are grown on c-plane alumina using Pulsed Laser Deposition (PLD) at two different oxygen partial pressures. The magnetic easy directions of both the films lie in the out of plane direction where as the in plane direction corresponds to the magnetic hard direction. Depending on the oxygen partial pressure during deposition, the magnetization reversal changes from S-W type reversal to Kondorsky kind of reversal. Thus, the growth parameter for the Strontium Ferrite single layer which will be used further as a hard layer for realizing oxide exchange spring in oxide multilayer, is optimized. The details of the magnetic and structural properties are analyzed for Nickel Zinc Ferrite thin film grown on (100) MgAl2O4. We have obtained an epitaxial growth of Nickel Zinc Ferrite by tuning the growth parameters of PLD deposition. The ferromagnetic resonance and the angle dependent hysteresis loop suggest that, the magnetic easy direction for the soft Nickel Zinc Ferrite lie in the film plane whereas the out of plane direction is the magnetic hard direction. Using the growth condition of respective Nickel Zinc Ferrite and Strontium Ferrite, we have realized the exchange spring behaviour for the first time in the trilayer structure of SrFe12O19 (20 nm)/Ni0.8Zn0.2Fe2O4(20 nm)/ SrFe12O19 (20 nm) grown on c-plane alumina (Al2O3) using PLD. The FORC distribution for this trilayer structure shows the single switching behaviour, corresponding to the exchange spring behaviour. The reversible ridge measurement shows that the reversible and the irreversible part of the magnetizations are not coupled with each other.

Les nanostructures de polymères suscitent un grand intérêt grâce à leurs propriétés uniques comme le facteur de forme important. Cette propriété est essentielle pour l’utilisation dans des domaines où les interactions de surface sont mises en jeu. Un exemple d’une telle application est la détection de gaz. La polyaniline (PANi) s’est montrée prometteuse pour l’utilisation dans les capteurs d’ammoniac. La synthèse conventionnelle (chimique ou électrochimique) de nanofibres de PANi a été largement décrite dans la littérature mais cette voie possède de nombreux inconvénients. Parmi eux, figurent plusieurs étapes de synthèse (la synthèse, la purification, le dépôt sur le substrat) et l’utilisation de produits chimiques (oxydants, acides) peu respectueux de l’environnement. La polymérisation assistée par plasma froid (PECVD) permet de s’en affranchir car seul le monomère est utilisé qui se polymérise directement sur le substrat. Ainsi, ce travail de thèse a pour objectif d’élaborer des nanostructures de polyaniline plasma tout en conservant au mieux l’unité monomère dans le polymère. Le paramètre essentiel qui détermine le processus de nanostructuration est la puissance de décharge. A forte puissance, des films fortement structurés sont obtenus mais les molécules de monomère sont totalement fragmentées. En revanche, une faible puissance conduit à des films avec conservation de l’entité monomère mais sans structure morphologique particulière. Nous avons développé une méthode permettant de combiner les avantages de chaque régime : ce procédé dit « bottom-up » est réalisé en variant la puissance au cours du dépôt selon deux ou trois étapes. Les paramètres qui influencent les structures chimique et morphologique sont déterminés et les procédés à deux et trois étapes sont comparés. Par ailleurs, la synthèse « top-down » de nanostructures par gravure de la couche mince de PANi est également étudiée en fonction des paramètres du plasma (puissance et temps de décharge, débit du gaz de gravure et polarisation du substrat). Finalement, nous avons synthétisé, en phase plasma, des nanocomposites associant les nanostructures de PANi et des particules métalliques de Pd déposées par pulvérisation. La structure chimique des films de PANi est caractérisée par les spectroscopies UV-Vis, IR-TF et XPS. Pour mettre en évidence la nanostructuration des couches minces, les microscopies MEB et AFM sont utilisées. Cette dernière permet également de calculer la valeur de rugosité ainsi que la surface spécifique de la PANi. La spectroscopie EDX est utilisée pour mettre en évidence et pour quantifier le palladium dans les films synthétisés. Les couches obtenues sont finalement caractérisées sous gaz par mesures de variation d’absorbance afin de déterminer leur sensibilité et leur temps de réponse à l’ammoniac. / Polymer nanostructures are of great interest due to their unique properties such as high shape factor. This property is essential for applications where surface interactions are involved. One example of such an application is the gas detection. Polyaniline (PANi) has been shown as a promising material for ammonia detection. Conventional synthesis (chemical orelectrochemical) of PANi nanofibers has been widely described in the literature but this way has many drawbacks. They include several steps (synthesis, purification, deposition on the substrate) and the use of chemicals (oxidants, acids) which are not environmentally friendly. The polymerization assisted by cold plasma (PECVD) allows overcoming it, as only themonomer is used and is directly polymerized on the substrate. This thesis work aims to develop plasma polyanilinenanostructures while retaining the monomer unit in the polymer. The key parameter that determines thenanostructuring process is the discharge power. At high power, highly structured films are obtained but the monomer molecules are totally fragmented. On the contrary, low power allows conservation of the monomer unit but no surface structuring is observed. We developed a method which combines the advantages of each regime. This "bottom-up" process consists to vary the input power during deposition in two or three stages. Parameters influencing the chemical and morphological structures are determined and the two and three steps methods are compared. Furthermore, the "top-down" synthesis of nanostructures by etching the PANi layer is also studied according to the plasma parameters (power and discharge time, etching gas flow rate and substrate bias). Finally, in plasma phase, we synthesized nanocomposite by combining PANi nanostructures and sputtered Pd particles. The chemical structure of the PANi films is characterized by UV-Vis spectroscopy, FT-IR and XPS. In order to highlight the nanostructuring of thin films, SEM and AFM microscopy areused. The latter one allows also the calculation of the roughness and specific surface of the PANi. EDX spectroscopyis used to bring out the presence of palladium and to quantify it. Finally, the obtained layers are characterized under gas byabsorbance variation measurements in order to determine their sensitivity and response time to ammonia.

Ce travail concerne l’évaluation de nanoparticules de silice associées à la poly-ethylèneimine (PEI) comme vecteurs de délivrance de gène pour le traitement des plaies chroniques de la peau. Des matériaux nanocomposites associant des complexes formés par l’association de ces particules hybrides et d’ADN avec des hydrogels de collagène colonisés par des fibroblastes 3T3 ont été élaborés. Grâce à la modulation de la taille de la particule et de la masse moléculaire du polymère, il a été possible de réaliser la transfection des fibroblastes au sein du gel, permettant l’expression génique pendant une semaine. Ces études montrent le rôle clé joué par la prolifération et la migration cellulaire sur l’efficacité de la transfection. L’efficacité de la transfection a ensuite été modulée en modifiant les interactions silice-PEI. Les résultats obtenus suggèrent que le détachement du complexe de la particule dans les endosomes est une étape clé de ce processus. La transfection de cellules humaines primaires a aussi été étudiée en vue d’applications in vivo. La transfection a été observée avec des fibroblastes et des keratinocytes humains en culture et avec les fibroblastes au sein des gels, mais avec des efficacités moindres que pour les cellules 3T3. Ceci est attribué au plus faible taux de prolifération des cellules primaires. Enfin la capacité des nanocomposites à moduler l’inflammation a été testée sur des macrophages humains activés. Ces systèmes permettent la synthèse soutenue d’IL-10 par les fibroblastes et l’inhibition de l’expression de TNF-alpha chez les macrophages. / This work is devoted to the evaluation of silica nanoparticles associated to poly-ethyleneimine (PEI) as vectors for gene therapy in the context of skin chronic wounds repair. Nanocomposite materials associating complexes formed by the association of these hybrid particles and DNA with collagen hydrogels cellularized with 3T3 fibroblasts have been prepared. Thanks to the modulation of particle size and polymer molecular weight, it has been possible to achieve fibroblast transfection within the gel, allowing for sustained protein expression over one week. These studies evidence the key role of cell proliferation and migration on transfection efficiency. The transfection process has been further modulated by modification of the silica-PEI interactions. The results suggest that the complex detachment from the particles within the endosomes is a key step in this process. The transfection of human primary cells has also been studied foreseeing in vivo applications. Human fibroblasts and keratinocytes have been successfully transfected in culture and, in the case of fibroblasts, within collagen hydrogels, but with lower efficiency than with 3T3 cells. This has been attributed to the lower proliferation rate of primary cells. Finally the ability of nanocomposites to modulate inflammation has been evaluated on activated human macrophages. These systems have allowed for the sustained production of IL-10 by fibroblasts and the inhibition of TNF-alpha expression by macrophages.