Neste trabalho foram obtidos nanocompósitos contendo 0, 1, 2, 5 e 10% (m/m) de argila organofílica montmorilonita cloisite 30B, contendo terminações hidroxila, por processamento reativo entre um pré-polímero com terminações isocianato e o 1,4-butanodiol, utilizando-se um misturador fechado. Os resultados mostraram que os poliuretanos termoplásticos sintetizados foram obtidos com sucesso. A adição de montmorilonita nos TPUs ocasionou a formação de folhas de argila dispersas de maneira intercalada, parcialmente esfoliada, esfoliada e aglomerados na matriz do TPU. Com a adição da argila houve modificações nos comportamentos de cristalização, estabilidade térmcica e mecanismo de degradação, assim como um aumento nos valores de energia aparente de ativação deste processo. A mobilidade de alguns segmentos poliméricos também foi alterada com a adição da argila. Portanto modificações morfológicas e viscoelásticas foram observadas para os nanocompósitos em dependência da quantidade de argila organofílica empregada, assim como a adição da organoargila alterou o comportamento térmico do poliuretano termoplástico, tornando os nanocompósitos mais suscetíveis a mudanças nos processos de fusão e cristalização em função da exposição a temperaturas elevadas. / In this study, were obtained nanocomposites containing 0, 1, 2, 5 and 10% (w/w) of organophilic clay montmorillonite Cloisite 30B, containing hydroxyl terminations, by reactive processing between a prepolymer with isocyanate terminations and 1,4-butanediol, using a closed mixer. The analysis showed that the obtained thermoplastic polyurethanes were synthesized successfully. The addition of the montmorillonite in the TPUs resulted in the formation of sheets of clay dispersed in order intercalated, partially exfoliated, exfoliated and agglomerate in the TPU matrix. With the addition of clay there were changes in the behavior of crystallization, thermal stability and degradation mechanism, as well as an increase in the values of the apparent activation energy of this process. The mobility of certain polymer segments was also changed with the addition of the clay. Therefore viscoelastic and morphological changes were observed in the nanocomposites in dependence on the amount of organophilic clay used, as well as the addition of the organophilic decreased the thermal stability of the thermoplastic polyurethane, making nanocomposites more susceptible to changes in the melting and crystallization processes due to exposure to elevated temperatures.

Nos dias atuais a busca pela utilização de cargas de reforço aos materiais poliméricos tem sido o grande alvo dos pesquisadores e da indústria. Neste trabalho nanocompósitos de PVC foram obtidos através de duas rotas de preparação, mediante a mistura no estado fundido, utilizando-se uma extrusora monorosca. Empregaram-se diferentes concentrações de montmorilonita e velocidades de injeção nos nanocompósitos. Estes foram caracterizados por suas morfologias, propriedades termomecânicas e termo-dinâmico-mecânicas. O grau de intercalação e esfoliação dos nanocompósitos foi caracterizado por difração de raios X, MET e MEV. O inchamento da argila em plastificante, anterior ao processamento, parece ter induzido um maior grau de intercalação e uma esfoliação parcial em todos os sistemas. As análises termogravimétricas demonstraram pouca influência da carga sobre a estabilidade térmica dos nanocompósitos. / Nowadays the search for the use of reinforcement fillers into polymeric materials has been the great objective of researchers and industry. In this work PVC nanocomposites were obtained through two routes of preparation, by melt blending in a single-screw extruder. Additionally different montimorillonite concentrations and injection speeds were applied to nanocomposites preparation. These were characterized by morphological, thermo-mechanical and thermo-dynamic-mechanical properties. The degree of intercalated and exfoliated of nanocomposites was characterized by x ray diffraction, MET e MEV. The swelled clay in plasticizer, prior of the processing, seems to have induced a higher degree of intercalation and partial exfoliation in all systems. Thermogravimetric analysis demonstrated small influence of the nanofillers on the nanocomposites thermal stability.

Neste trabalho foram obtidos nanocompósitos contendo 0, 1, 2, 5 e 10% (m/m) de argila organofílica montmorilonita cloisite 30B, contendo terminações hidroxila, por processamento reativo entre um pré-polímero com terminações isocianato e o 1,4-butanodiol, utilizando-se um misturador fechado. Os resultados mostraram que os poliuretanos termoplásticos sintetizados foram obtidos com sucesso. A adição de montmorilonita nos TPUs ocasionou a formação de folhas de argila dispersas de maneira intercalada, parcialmente esfoliada, esfoliada e aglomerados na matriz do TPU. Com a adição da argila houve modificações nos comportamentos de cristalização, estabilidade térmcica e mecanismo de degradação, assim como um aumento nos valores de energia aparente de ativação deste processo. A mobilidade de alguns segmentos poliméricos também foi alterada com a adição da argila. Portanto modificações morfológicas e viscoelásticas foram observadas para os nanocompósitos em dependência da quantidade de argila organofílica empregada, assim como a adição da organoargila alterou o comportamento térmico do poliuretano termoplástico, tornando os nanocompósitos mais suscetíveis a mudanças nos processos de fusão e cristalização em função da exposição a temperaturas elevadas. / In this study, were obtained nanocomposites containing 0, 1, 2, 5 and 10% (w/w) of organophilic clay montmorillonite Cloisite 30B, containing hydroxyl terminations, by reactive processing between a prepolymer with isocyanate terminations and 1,4-butanediol, using a closed mixer. The analysis showed that the obtained thermoplastic polyurethanes were synthesized successfully. The addition of the montmorillonite in the TPUs resulted in the formation of sheets of clay dispersed in order intercalated, partially exfoliated, exfoliated and agglomerate in the TPU matrix. With the addition of clay there were changes in the behavior of crystallization, thermal stability and degradation mechanism, as well as an increase in the values of the apparent activation energy of this process. The mobility of certain polymer segments was also changed with the addition of the clay. Therefore viscoelastic and morphological changes were observed in the nanocomposites in dependence on the amount of organophilic clay used, as well as the addition of the organophilic decreased the thermal stability of the thermoplastic polyurethane, making nanocomposites more susceptible to changes in the melting and crystallization processes due to exposure to elevated temperatures.

Orientadores: Florencia Cecília Menegalli, Paulo José do Amaral Sobral / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-17T09:34:33Z (GMT). No. of bitstreams: 1 VillamanDieguez_MariaCristina_M.pdf: 3299521 bytes, checksum: b5bf8aa7ece9693c382d364d2a207cb4 (MD5) Previous issue date: 2011 / Resumo: A aplicação da nanotecnologia na elaboração de filmes nanocompósitos, tem sido muito utilizada nos últimos anos na área de desenvolvimento de materiais biodegradáveis. Os nanocompósitos são misturas de polímeros orgânicos e partículas nanométricas, entre as mais estudadas para esta aplicação está a montmorillonita (MMT), uma argila mineral composta por capas de aluminatos e silicatos hidratados. Neste projeto foram elaborados filmes nanocompósitos (F.NC) baseados em farinha de amaranto (FA) e MMT, utilizandose o método de intercalação por solução. Foram realizados estudos preliminares para escolher o processo mais indicado para a inclusão da MMT na solução filmogênica (SF). Experimentaram-se quatro processos, que compreenderam diferentes tipos e velocidades de agitação e distintos tempos onde era adicionada a MMT (antes ou depois do processo térmico). As análises de microscopia óptica revelaram que o processo em que se utilizou uma agitação forte (7.000 rpm) e que a gelatinização do amido ocorreu na presença da MMT, foi o único que conseguiu obter uma matriz filmogênica homogênea. Por meio deste processo elaboraram-se filmes e analisaram-se por microscopia eletrônica de varredura (MEV), onde se confirmou a formação de uma matriz homogênea, na superfície e na secção transversal dos filmes. Para o desenho experimental foi utilizado um delineamento composto central rotacional DCCR 22, para se estudar o efeito da concentração da argila [CMMT] e da temperatura do processo (TP), nas propriedades dos filmes. Trabalhou-se numa faixa de [CMMT] entre 0% a 9,4% (m/m), com uma concentração fixa de glicerol de 25%, na qual os filmes obtidos eram facilmente manipuláveis. Como resultado observouse que o aumento simultâneo da [CMMT] (m/m) e da TP, produz um aumento na tensão e, conseqüentemente uma diminuição da elongação destes filmes. A propriedade de solubilidade também foi afetada por ambos os fatores. Realizaram-se análises estatísticas para maximizar o valor de tensão e minimizar a solubilidade destes filmes. Encontraramse que as condições ótimas para conseguir esse propósito foram: [CMMT] = 9,4% e TP = 83°C. Nessa T P, quando a CMMT foi aumentada de 0 a 9,4% a tensão aumentou de 1.20 MPa para 1.61 MPa e a solubilidade diminuiu de 48.2% a 44.98%. Interessante foi o resultado obtido para a permeabilidade ao vapor de água (PVA), que decresceu em 96% ao ser adicionada a MMT / Abstract: The application of nanotechnology in the development of nanocomposite films has been the most widely used in recent years in the development of biodegradable materials. Nanocomposites are mixtures of organic polymers and nano-sized particles, among the most studied for this application, is montmorillonite (MMT), a mineral clay composed of layers of hydrated silicates and aluminates. Were carried out preliminary studies to determine what would be the most appropriate process for the production of amaranth flour films (FA) and montmorillonite (MMT) by the method of intercalation by solution. We compared different types of agitation and the differences in the addition of the nanoclay before or after the heat treatment. Optical microscopy analysis revealed that process with vigorous shaking (7.000 rpm) and where gelatinization of the starch occurred in the presence of montmorillonite, was the only one forming a homogeneous matrix. Using Scanning Electron Microscopy (SEM) we were able to corroborate the production of a homogeneous matrix in both, the surface and cross sections. Then the study of the effect of clay content [CMMT] and process temperature (TP) on the production of amaranth flour/clay nanocomposite films was investigated. Since easily manageable films were obtained at concentrations ranging from 0% to 9,4 % (w/w) of MMT and 25% glycerol, these conditions were chosen in the DCCR 22 experimental design. The simultaneous rise on [CMMT] (w/w) and TP, resulted on increased tensile strength and, consequently, decreased elongation at break values. Solubility was also affected by both factors. Statistical analysis was performed to maximize the tensile strength and to minimize the solubility of these films. A concentration of 9,4% at a temperature of 83°C was found to be optimal for this purpose. At that TP, when CMMT was increased from 0 to 9,4% the tensile strength was increased from 1.20 MPa to 1.61 MPa and the solubility (%) was decreased from 48.2% to 44.98%. Interestingly, the water vapor permeability (WVP) values were decreased by 96% upon addition of MMT / Mestrado / Mestre em Engenharia de Alimentos

Orientadores: Ulf F. Schuchardt, Heloise de Oliveira Pastore / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Quimica / Made available in DSpace on 2018-08-05T04:44:02Z (GMT). No. of bitstreams: 1 Gallo_JeanMarcelRibeiro_M.pdf: 5237424 bytes, checksum: 618c52e79b92842d0ef0d9e910c1ebc8 (MD5) Previous issue date: 2005 / Resumo: Otimizamos a síntese da Nb-MCM-41 à temperatura ambiente, variando a base, as fontes de sílica e nióbio e a ordem de adição da fonte de nióbio. Os materiais, antes e após a calcínação, foram caracterizados por difração de raios-X e reflectância difusa na região do UV-Vis. A Nb-MCM-41 com o melhor resultado foi silanizada e caracterizada por espectroscopia de emissão atômica por plasma indutivamente acoplado (ICP-OES), análise termogravimétrica (TGA), adsorção-dessorção de nitrogênio, ressonância magnética nuclear no ângulo mágico (RMN-MAS) de Si, análise elementar de carbono, hidrogênio e nitrogênio (CHN) e espectroscopia na região do infravermelho (IV). As Nb-MCM-41 calcinada e a silanizada foram testadas na epoxidação de cis-cicloocteno com terc-butilhidroperóxido (TBHP) 69,4 % em cicloexano obtendo após 48 h, 46,6 e 62,2 % de conversão e 77 e 94 % de seletividade, respectivamente. Usando peróxido de hidrogênio 70 % em água obtivemos após 5 h, 8 % de conversão e 80% de seletividade para a amostra calcinada e 13 % de conversão e 70 % de seletividade para a silanizada. Nas reações usando peróxido de hidrogênio aquoso. este foi todo consumido nas 10 primeiras horas. mostrando que o nióbio decompõe facilmente o peróxido de hidrogênio. Montmorilonita K-10 foi trocada com polihidroxi-nióbio e caracterizada por difração de raios-X, TGA, adsorção-desorção de nitrogênio e ICP-OES. O material foi então calcinado a 300. 500 e 900°C para se obter a montmorilonita pilarizada com nióbio que foi caracterizada por difração de raios-X. Observando que mesmo quando a argila é calcinada a 900°C mantém-se a microporosidade, o que é surpreendente, pois a maioria das argilas pilarizadas com óxidos metálicos perde sua microporosidade a cerca de 600°C. A montmorilonita K10 pura, a trocada com nióbio e a pilarizada foram testadas como catalisadores ácidos nas reações de abertura do anel oxirano do oleato de metila epoxidado, usando metanol como nucleófilo, para se obter o b-hidroxiéter correspondente. A argila trocada com nióbio foi mais ativa que as demais. mostrando que a incorporação de nióbio realmente aumenta a acidez de Bronsted. As amostras calcinadas eram menos ativas quanto maior a temperatura de calcinação / Abstract: Nb-MCM-41 synthesis was optimized at room temperature varying the hydroxide, the silica and niobium sources and the order of addition of the niobium source. The materials, before and after the calcinations, were characterized by XRD and UV-Vis diffuse reflectance. The Nb-MCM-41 with best results was silylated and characterized by inductively coupled plasma optical emission spectroscopy (ICP-OES) to quantify the niobium, thermogravimetric analysis (TGA) , adsorption-desorption of nitrogen, magic angle spinning nuclear magnetic resonance (RMN-MAS) of Si, elementary analysis of carbon, hydrogen and nitrogen (CHN) and infrared spectroscopy (FTIR). The calcined and the silylated Nb-MCM-41 were used in the epoxidation of ciclooctene with feributylhydroperoxide (TBHP) 69,4 % in ciclohexane obtaining after 48 h, 46,6 and 62,2 % of conversion and 77 and 94 % of selectivity, respectively. Using hydrogen peroxide 70 % in water it was obtained after 5 h, 8% of conversion and 80 % of selectivity for the calcinated sample and 13 % of conversion and 70 % of selectivity for the silylated. When using hydrogen peroxide all the peroxide was decomposed after 10 h, showing that niobium decompose easily hydrogen peroxide Montmorillonite K10 was ion-exchanged with polyhydroxyniobium characterized by XRD, TGA, adsorption-desorption of nitrogen and ICP. Then the material was calcined at 300, 500 e 900°C to obtain the Nb-pillared montmorillonite. These materials were characterized by XRD, and even when calcined at 900°C the microporosity is maintained, which is surprising since most of metal oxide pillared clays lose the microporosity at temperatures around 600°C. The montmorillonite K10 pure, niobium exchanged and Nb-pillared were used as acid catalysts in the oxirane ring-oppening reactions of the epoxidazed methyl oleate with methanol as nucleophile, to obtain the correspondent b-hydroxyether. The ion-exchanged clay was more active that the pure clay, proving than niobium incorporation improves Bronsted acidity. The calcined samples were less active the higher was the calcination temperature / Mestrado / Quimica Inorganica / Mestre em Química

Orientador: Maria do Carmo Gonçalves / Tese (doutorado) - Universadade Estadual de Campinas, Instituto de Quimica / Made available in DSpace on 2018-08-13T18:47:11Z (GMT). No. of bitstreams: 1 Romero_RafaelleBonzanini_D.pdf: 28876791 bytes, checksum: 2296e157df643bcd91224ad26360f6ce (MD5) Previous issue date: 2009 / Resumo: Nanocompósitos de biopolímeros com silicatos lamelares podem ser desenvolvidos para criar uma nova classe de materiais eco-friendly, podendo contribuir para aplicações inovadoras de polímeros. Esses materiais têm despertado grande interesse, devido principalmente à facilidade de obtenção, bem como às suas propriedades químicas, físicas e mecânicas. Neste trabalho foram preparados nanocompósitos de acetato de celulose pelos métodos de intercalação em solução e no estado fundido, onde os efeitos de diferentes solventes, de agentes modificadores da argila e de condições de processamento foram investigados nas suas propriedades estruturais, morfológicas, térmicas e mecânicas. No método de intercalação em solução, os resultados obtidos indicaram que a dispersão e delaminação da argila são alcançadas somente quando ocorreram interações favoráveis entre o solvente, a argila e o polímero. Neste caso, os nanocompósitos apresentaram melhores propriedades térmicas e dinâmico-mecânicas em relação ao acetato de celulose puro. No método de intercalação no estado fundido, os resultados obtidos evidenciaram a intercalação do acetato de celulose entre as lamelas da argila, promovida pela afinidade química favorável entre o polímero, o plastificante e a argila. Além disso, as estruturas intercaladas foram parcialmente delaminadas sob ação do cisalhamento imposto durante o processo de extrusão, resultando em nanocompósitos com partículas intercaladas e também esfoliadas. Devido a estas características, os nanocompósitos obtidos apresentaram propriedades mecânicas e de barreira superiores às apresentadas pelo acetato de celulose puro. Baseado nos dois métodos investigados neste trabalho, pode-se concluir que a escolha apropriada dos aditivos e das condições de preparação é extremamente importante para promover interações favoráveis entre as partículas de argila e o polímero, que por sua vez são necessárias para a desejada melhora nas propriedades finais desses materiais / Abstract: Nanocomposites of bio-based polymers with layered silicates can be used to create new eco-friendly materials, and can open ways towards the innovative applications of polymers. These materials are interesting, mainly due to their easy preparation, as well as their chemical, physical and mechanical properties. Cellulose acetate nanocomposites was prepared in this work by using solution and melt intercalation methods, where the effect of the different solvents, clay modified agents and processing conditions were investigated in terms of their structural, morphological, thermal and mechanical properties. The obtained results, in the solution intercalation method, showed that the dispersion and delamination of the clay were reached only when favorable interactions were promoted between the solvent, clay and polymer. In this case, the nanocomposites presented enhanced thermal and dynamic-mechanical properties in relation to the pure cellulose acetate. The results obtained in the melt intercalation method showed the intercalation of the cellulose acetate chains into the silicate platelets, which was promoted by the favorable chemical affinity between the polymer, plasticizer and clay. Apart from this, the intercalated structures were partially delaminated by the shearing imposed during the extrusion process, resulting in nanocomposites formed by intercalated as well as exfoliated clay particles. Due to these characteristics, the nanocomposites presented enhanced mechanical and barrier properties compared to pure cellulose acetate. Based on the two methods investigated in this work, it can be concluded that the appropriate choice of additives and preparation conditions of preparation is extremely important to promote favorable interactions between the clay particles and the polymer, that in turn are necessary for the desired enhancement in the final properties for these materials / Doutorado / Físico-Química / Doutor em Ciencias Quimicas

Les travaux réalisés au cours de cette thèse traitent et misent en avant l’effet d’associer différents types d’argiles organophiles OMMT (Cloisite®15A et Cloisite®30B) avec le graphène fonctionnalisé époxy (Gr) sur l’ensemble des propriétés fonctionnelles des matrices biodégradables polyacide lactique (PLA), poly (ε-caprolactone) (PCL) et leur mélange PLA/PCL de composition 70/30. Le premier volet est consacré à l’étude des mélanges binaires (PLA/Cloisite® et PLA/Gr) et ternaires (PLA/Cloisite®/Gr) préparés à l’état fondu. L’association des deux renforts OMMT/Gr a amélioré l’ensemble des paramètres rhéologiques de la matrice PLA et contribue à l’apparition d’un comportement viscoélastique pseudo-solide pour les mélanges PLA/Gr en présence des argiles, attribué à un meilleur état de dispersion des couples confirmé par la microscopie électronique à transmission. Les propriétés barrières à la vapeur d’eau, thermiques et thermomécaniques du PLA ont été sensiblement améliorées, particulièrement en présence des couples de nanocharges OMMT/Gr et montrent le grand intérêt des nanobiocomposites PLA/Cloisite®/Gr dans plusieurs applications. La seconde partie est liée aux matériaux nanocomposites à base de la matrice PCL. L’étude rhéologique a confirmé l’intérêt de combiner les nanocharges OMMT et graphène et indique la présence de réseaux 3D dans les nanocomposites PCL/OMMT et PCL/OMMT/Gr. La bonne dispersion des nanocharges a nettement amélioré les propriétés barrières à la vapeur d’eau et la tenue thermique de la PCL. La dispersion des nanocharges et leurs effets sur la miscibilité a fait l’objet de la dernière partie consacrée aux matériaux à base du mélange immiscible PLA/PCL. Des propriétés viscoélastiques très intéressantes ont été obtenues après l’incorporation des mélanges OMMT/Gr, indiquant l’existence d’un bon niveau de distribution des renforts dans la matrice PLA/PCL. La synergie existante entre les nanocharges OMMT et graphène fonctionnalisé époxy a conduit à l’amélioration des propriétés barrières, de la stabilité thermique et de la miscibilité de la matrice. / The work carried out during this thesis highlights the effect of different kinds of organophilic clays OMMT (Cloisite®15A and Cloisite®30B) and/or epoxy functionalized graphene (Gr) on the functional properties of biodegradable polylactic acid (PLA), poly (ε-caprolactone) (PCL) and their mixture PLA/PCL (70/30 mass%). The first part is devoted to study the binary mixtures (PLA/Cloisite® and PLA/Gr) and ternary materials (PLA/Cloisite®/Gr) prepared via melt blending method. The combination of the two fillers (OMMT and Gr) improves all the rheological parameters of the PLA matrix and contributes to the appearance of a pseudo-solid viscoelastic behavior for PLA/Gr composites in the presence of clays, attributed to the better dispersion confirmed by transmission electron microscopy. The water vapor permeability, thermal and thermomechanical properties of PLA have been significantly improved, especially in the presence of hybrids OMMT/Gr and show the great interest of PLA/Cloisite®/Gr ternary nanobiocomposites in several applications. The second part is related to nanocomposite materials based on the biodegradable PCL matrix. The rheological study confirms the advantage of combining the organomodified clays and graphene nanofillers, and indicates the presence of tridimensional networks in the binary nanocomposites PCL/OMMT and PCL/OMMT/Gr. The good state of dispersion of the hybrids nanofillers (OMMT + Gr) has considerably improved the water vapor permeability and the thermal resistance of the PCL matrix. The dispersability of the nanofillers and their effect on the miscibility were the subject of the last part devoted to the PLA/PCL immiscible blend. Very interesting viscoelastic properties were obtained after the incorporation of the OMMT/Gr mixtures, indicating the existence of good level of distribution of nanofillers in the PLA/PCL matrix. The synergy between the OMMT and epoxy functionalized graphene led to the best improvement in term of barrier properties, thermal stability and compatibility of the matrix.

Clays are ubiquitous near the Earth’s surface. Medicinal properties of these nontoxic minerals have been intuitively recognized since ancient times. Up till now, clays have been used in pharmaceutical formulations as active agents and excipients. Currently, there is an urgent need to seek advanced, functional materials with low environmental impact. Answering to that trend, clay-biopolymer nanocomposites were synthesized in this thesis and applied in a drug delivery system. In the first part of the thesis, Portuguese clay from a bentonite deposit in Benavila (Portugal) was collected from six sampling sites and characterized. The highest content of clay fraction, approximately 30%, was found in two of the sampling sites. After purification, the smectite-rich samples were analyzed with respect to clay content, mineralogical and chemical composition, physicochemical and mechanical properties. SEM-EDS revealed that the smectite present in the ore is montmorillonite with varying Fe content. This was also indicated by the means of XRD, XRF and FTIR. The Benavila sample, which was richest in smectite, as well as the sodium Wyoming montmorillonite from the Source Clay Repository (SWy-2) were successfully used to synthesize clay-biopolymer nanocomposites. The chosen biopolymers were the plant-extracted polysaccharides – neutral guar gum and its cationic form. The obtained materials were thoroughly characterized by XRD, TGA and NMR, and the intercalated structure was reported. The prepared nanocomposites were loaded with an anti-inflammatory drug ibuprofen and tested in an in-vitro release system. The drug-loaded materials were characterized with XRD, TGA and NMR. A membrane diffusion method was chosen as a dissolution testing strategy and the drug was quantified by UV-Vis spectroscopy. The materials exhibited improved properties as a noticeable reduction of release rate was achieved.

A series of experiments were performed to study the sorption of humic acid and Eu3+ ion (at trace concentrations) on the minerals: montmorillonite, bentonite, diatomite and kaolinite in ternary systems. Humic acid and europium sorption were investigated as a function of humic acid concentration, ionic strength and pH. There was a strong uptake of humic acid on to the minerals with sorption increasing as humic acid concentration decreases. For montmorillonite, the uptake of discrete size fractions was also studied. It was found that the larger fractions were more strongly sorbing and were better able to retain Eu in solution.The ionic strength has an impact on Eu behaviour: in the absence of humic acid, sorption strength decreases, whilst in the presence of high concentrations of humic it increases. The sorption of Eu3+ increases from pH 2 to 5 in both the presence and absence of humic acid. Above pH 5, the Eu3+ showed different behaviour with and without humic acid, and as humic concentration became high (100 ppm), the Eu behaves in the same way as the humic. Bentonite is able to sorb humic acid and Eu3+ at any concentration expected in the environment, and shows the strongest sorption of any of the materials tested. Experiments confirmed that Eu is an excellent analogue for Am in these systems.The sorption of selected divalent and trivalent metal ions: Ni2+, Co2+, Zn2+, Cd2+, Eu3+ and Cr3+ on montmorillonite has been investigated in the micro-molar concentration range. In all cases, sorption strength increased with pH, and was consistently stronger for the tri-valent ions. In the presence of humic acid, there was some evidence for the enhancement of sorption. Uptake of metal ions (Co2+, Ni2+, Cd2+, Cr3+, Eu3+ and La3+) by natural and modified kaolinite was studied, and for all except Cr3+, it was found that kaolinite modified by manganese hydrothermal treatment gave the strongest sorption.A simple kinetic model was developed to simulate the experimental data for the sorption of humic acid and Eu3+ on the minerals. The model allows two humic binding sites on the mineral surface and two types of humic in solution, which can have different Eu3+ binding strengths. Metal ion surface complexation is modelled with a single kinetic equation. Ternary complexes are included in the model. The interaction of humic acid on the minerals can be fitted reasonably well. However, for the Eu3+ ion behaviour, although the model was able to give a reasonable fit to data for montmorillonite and bentonite, it could not reproduce the behaviour for kaolinite and diatomite.

Les nanocomposites à matrice polymère et à renforts d’argile ont pris une grande importance au cours de ces deux dernières décennies. Ceci trouve son explication d’une part, dans la grande disponibilité et le faible coût de production de la phase renforçante, et d’autre part dans les remarquables améliorations de propriétés physiques et mécaniques. Ces améliorations sont observées même à de très faibles quantités de renforts comparées à celles de leurs homologues microcomposites. Le développement de ces nouveaux matériaux suscite un fort engouement tant au niveau de la recherche académique qu’industrielle. Cependant, les mécanismes responsables de ces améliorations de propriétés demeurent mal compris et restent l’une des principales préoccupations des chercheurs. Il s’agit dans ce travail de thèse, d’apporter une contribution à la compréhension et à la mise au point d’outils prédictifs du comportement mécanique de nanocomposites polymères à renforts d’argile de type montmorillonite. Pour y parvenir, deux approches de modélisation sont utilisées : la micromécanique des matériaux hétérogènes et la simulation de dynamique moléculaire. Du point de vue analytique, un modèle micromécanique basé sur l’approche auto-cohérente est développé. Le modèle proposé est validé par nos données expérimentales et celles issues de la littérature. Un protocole de simulation de dynamique moléculaire est proposé pour la modélisation à l’échelle atomique de ces nanomatériaux. Cette approche nous a permis, entre autres, de faire la lumière sur les interactions moléculaires entre les différents constituants, et de déterminer les propriétés élastiques effectives du nanocomposite. / Polymer nanocomposites reinforced with clay minerals have attracted a great consideration during the last two decades. That can be explained, firstly, by the availability and the reduced production cost of the reinforcing phase, and secondly, by the remarkable improvements in physical and mechanical properties. These improvements are observed even at very low amounts of reinforcements compared to their microcomposite counterparts. The development of these new materials creates a keen interest both in academic and industrial research. However, the mechanisms responsible of these property improvements are still poorly understood and remain a major concern of researchers. This work contributes to the understanding and to the development of predictive tools of the mechanical behavior of polymer nanocomposites reinforced with montmorillonite clay using two modeling approaches: the micromechanics of heterogeneous materials and the molecular dynamics simulation. An analytical micromechanical model based on the self-consistent approach is developed. The proposed model is validated by our experimental data and those from the literature. A new molecular dynamics simulation protocol is proposed for the modeling of these nanomaterials at the nanometric scale. This approach has allowed us, inter alia, to get insight into the molecular interactions between the different components and to determine the effective elastic properties of the nanocomposite.