This work studied the rheological and mechanical properties of polyamide 12 modified montmorillonite clays and bentonita (the organo-modified commercial montmorillonite and a bentonite modified by various routes. Two polyamides 12 were used for the polyamide matrix, a virgin and another reprocessed. The polyamide 12 reprocessed was derived from tailings lines of fluid transport in automotive vehicles. Ten different compositions were prepared in single-screw extruder, and subsequently molded test specimens by injection. For formulations reprocessed polyamide 12, were added 5 to 7 wt.% of a commercial organo-modified montmorillonite ( I44P ) and the virgin polyamide 12 , 3 and 5 wt.%. For virgin polyamide matrix, also formulations were studied with 3 and 5% by weight of bentonite treated with Agent Titanate. The nanocomposite structure formation was evaluated by X-ray diffraction. For all developed formulations, mechanical and rheological tests, and their results were correlated performed: polyamide matrices, the content and the treatments of the clays. Clay dispersion and morphology of the fracture surface were analyzed by SEM. The analysis results showed distinct mechanical and rheological behaviors depending on the type of matrix, the degree of dispersion of clay, content and type of treatment of clays. There was formation of nanocomposites for polyamide 12 modified with I44P clay and composites for polyamide 12 modified bentonite. The rheological properties confirm the increase of the elastic properties of the nanocomposites due to the restriction to macromolecular mobility. The addition of organophilic commercial montmorillonite (I44P) promoted the increased stiffness of the nanocomposites without significant loss of toughness. / Este trabalho estudou as propriedades reológicas e mecânicas de poliamida 12 modificadas com montmorilonitas, sendo uma montmorilonita organofilica comercial (I44P) e montmorilonita sódica (bentonita) modificada por diversas rotas. Para a matriz de poliamida, foram utilizadas duas poliamidas 12, sendo uma virgem e a outra reprocessada oriunda de rejeito de linhas de transporte de fluídos em veículos automotores. Foram preparadas dez composições diferentes em extrusora monorrosca e, posteriormente, moldados corpos de prova por injeção. Para as formulações de poliamida 12 reprocessada, foram adicionados 5 e 7% em massa de montmorilonita organofílica comercial e para a poliamida 12 virgem, 3 e 5%. Para esta mesma matriz de poliamida virgem, também foram estudadas formulações com 3 e 5% em massa das bentonitas tratadas com agente titanato. A formação de estrutura de nanocompósitos foi avaliada por difração de raios-X. Para todas as formulações desenvolvidas, foram realizados ensaios mecânicos e reológicos, e seus resultados correlacionados com: as matrizes de poliamida, o teor e os tratamentos das argilas. A dispersão da argila e a morfologia da superfície de fratura foram avaliadas por MEV. Os resultados das análises mostraram comportamentos mecânicos e reológicos distintos em função do tipo de matriz, grau de dispersão das argilas, o teor e o tipo de tratamento das argilas. Houve formação de nanocompósitos para poliamida 12 modificada com a argila I44P e de compósitos para poliamida 12 modificada com bentonitas. As propriedades reológicas confirmam o aumento das propriedades elásticas dos nanocompósitos devido à restrição a mobilidade macromolecular. A adição da montmorilonita organofilica comercial (I44P) promoveu o aumento da rigidez dos nanocompósitos sem perdas significativas da tenacidade.

Made available in DSpace on 2016-03-15T19:36:56Z (GMT). No. of bitstreams: 1 Thiago Ramos Stellin Malagrino.pdf: 4441654 bytes, checksum: 6ca4cb745da024c77c96b57a51ae6f04 (MD5) Previous issue date: 2016-01-26 / Polycarbonate, an amorphous engineering polymer, has excellent mechanical strength and although it s good chemical resistance, its interaction with some types of alkali and some organic solvents is weak. The main objective of this work was to study the effect of the inclusion of nanometric particle size of natural sodium clay (named Nanolite) and sodium clay treated with quaternary ammonium salt (named Cloisite 15A) in resin processing in order to investigate the variations in chemical properties, transparency and molecular structure. The characterization of nanocomposite was performed using methods of Scanning Electron Microscopy (SEM), Molar Mass Characterization by Mark-Houwink-Sakurada equation, Differential Scanning Calorimetry (DSC), Melt Flow Rate (MFR), Differential Thermal Analysis (DTA), Fourier Transform Infrared Spectroscopy (FTIR), X-Ray Diffraction (XRD) and Chemical Resistance obtained by the contact angle technique / Fowkes method. Optical, thermal, physical and chemical testing indicated that the molecular structure of PC after the inclusion of clays remained unchanged showing no irreversible degradation. The analysis of chemical resistance through the contact angle method showed significant improvement in the surface free energy of the nanocomposites when using the organoclay (Cloisite 15A) and partial improvement when used natural sodium clay (Nanolite). The decrease in surface free energy, indicates a likely improvement in the chemical resistance of the nanocomposites. / O Policarbonato, polímero de engenharia de estrutura amorfa, possui excelente resistência mecânica, e embora possua boa resistência química, deixa a desejar no que se refere ao contato com alguns tipos de álcalis e solventes orgânicos. O objetivo principal deste trabalho foi de estudar comparativamente o efeito da inclusão de partículas nanométricas de argila sódica natural (Nanolite) e argila sódica tratada com sal quaternário de amônio (Cloisite 15A), no processamento da resina a fim de investigar as variações ocorridas nas propriedades químicas e consequentemente, na transparência e estrutura molecular. A caracterização do nanocompósito foi realizada por meio de métodos de Microscopia Eletrônica de Varredura (MEV), massa molar calculada pela equação de Mark-Houwink-Sakurada, Calorimetria Diferencial por Varredura (DSC), Índice de Fluidez (IF), Análise Térmica Diferencial (DTA), Espectroscopia no Infravermelho por Transformada de Fourier (FTIR), Difração de Raios X (DRX) e Resistência Química calculada através da técnica de ângulo de contato / método de Fowkes. Os ensaios óticos, térmicos, físicos e químicos indicaram que a estrutura molecular do PC após a inclusão das argilas permaneceu inalterada, sem degradação irreversível. A análise da resistência química através do método de ângulo de contato apresentou significativa melhora na energia livre superficial dos nanocompósitos quando utilizada a argila organofílica (Cloisite 15A) e, melhora parcial quando utilizada a argila sódica natural (Nanolite). A queda da energia livre superficial, indica que existe uma provável melhora na resistência química dos nanocompósitos.

Les Déchets d'Equipement Electriques et Electroniques (DEEE) constituent un volume important de déchets dont le constituant majoritaire est l’ABS. C’est pour cela que nous avons travaillé principalement avec des polymères provenant d’un gisement réel (carters d’ordinateurs). Puis, des mélanges ABS/PC ont été élaborés (le PC étant un des constituants d’un gisement de carters), dans le but d’obtenir un matériau avec une résilience au moins équivalente à celle d’un ABS neuf. Même si l’ABS a montré une bonne aptitude à être recyclé seul, après vieillissement et recyclage, sa résilience connaît une chute due à la dégradation de la phase élastomère et à la présence d’ignifugeants. Il est important pour le recyclage de l’ABS et de ses mélanges de séparer les polymères ignifugés de ceux qui ne le sont pas. La voie mélange pour le recyclage de l’ABS par l’ajout de PC a l’avantage de simplifier le tri et de recycler un maximum des polymères présents dans les DEEE. Nous avons tout d’abord réalisé des mélanges ABS/PC neufs pour bénéficier d’une mise en œuvre et d’une composition optimales. L’influence des paramètres du procédé de recyclage (température et vis d’extrusion) et des propriétés des matériaux (taux et viscosité du PC, retardateurs de flamme de l’ABS) sur les propriétés du mélange a été étudiée. Nous avons effectué essentiellement des essais de résistance au choc Charpy et des études morphologiques. Les résultats ont montré qu’une morphologie fibrillaire ou co-continue est favorable à la meilleure résilience des mélanges ABS/PC. Nous avons obtenu pour des mélanges neufs ABS neuf FR/PC neuf réalisés avec 70% d’ABS une résilience supérieure à celle de l’ABS neuf. Mais, à composition égale, ce résultat n’a pas été atteint pour les mélanges majoritaires en ABS recyclé. Souhaitant réaliser des mélanges performants majoritaires en ABS recyclé, la compatibilisation semble nécessaire. Un mélange recyclé majoritaire en ABS, compatibilisé avec du PP-g-MA, est montré plus résilient que l’ABS neuf seul. Toutefois, les compatibilisants ont une efficacité limitée lorsqu’ils sont en présence de retardateurs de flamme ou soumis à un temps de séjour élevé dans la presse à injecter. Nous avons voulu utiliser des nanocharges minérales (montmorillonites), ajoutées en faible quantité, en tant qu'ignifugeants et compatibilisants. Elles se sont avérées inefficaces dans les études préliminaires réalisées. Le choix des nanoargiles minérales doit être optimisé. / WEEE constitute a huge waste volume in which ABS is the major component. So, we focused on polymers from a real deposit (casing of computers); such a deposit contains ABS, PC, PS, ABS-PC. In a first step, recycling of aged ABS was studied. The decrease in the C=C content induces an impact strength drop. Nevertheless, ABS proved to be recyclable given that optimized processing conditions are found. The role of flame retardants was shown to be crucial on the recyclability. Separating polymers with or without flame retardants is the key point of the ABS recycling. However, recycled aged ABS do not recover the impact strength of neat virgin ABS. Then, ABS/PC blends were elaborated in order to obtain a material with an impact strength at least equivalent to the neat ABS. The use of ABS/PC blends for this recycling facilitates the sorting and the utilization of most of WEEE polymers. We first made ABS/PC blends from virgin polymers to have optimal processability and composition. Performing Charpy impact strength tests and morphological studies allowed to evaluate the influence of recycling process parameters (temperature and screw extrusion) and material properties (rate and viscosity of PC and ABS flame retardants). Experimental results indicate that the impact strength of the ABS/PC blends is higher when the morphology is fibrillar or co-continuous. We obtained ABS virgin FR/PC virgin blends (70/30) with an impact strength greater than the neat ABS. But, with equal composition, this result was not reached for the blends. So to achieve reliable blends rich in recycled ABS, compatibilisation is necessary. Recycled ABS/PC blends compatibilised with PP-g-MA is more resilient than the ABS. However, the compatibilising agents have a limited efficiency when they are used in the presence of flame retardants or subjected to a high residence time. Finally, nanoclays were attemptively used as both FR and compatibiliser. Tough they proved uneffective in the very first experiments carried out (the choice of clay need to be optimized).

No description available.

No description available.

The objective of this project was to study the influence of increased salinities on interaction processes in the system radionuclide – organics – clay – aquifer. For this purpose, complexation, redox, sorption, and diffusion studies were performed under variation of the ionic strength (up to 4 mol/kg) and the background electrolyte. The U(VI) complexation by propionate was studied in dependence on ionic strength (up to 4 mol/kg NaClO4) by TRLFS, ATR FT-IR spectroscopy, and DFT calculations. An influence of ionic strength on stability constants was detected, depending on the charge of the respective complexes. The conditional stability constants, determined for 1:1, 1:2, and 1:3 complexes at specific ionic strengths, were extrapolated to zero ionic strength. The interaction of the bacteria Sporomusa sp. MT-2.99 and Paenibacillus sp. MT-2.2 cells, isolated from Opalinus Clay, with Pu was studied. The experiments can be divided into such without an electron donor where biosorption is favored and such with addition of Na-pyruvate as an electron donor stimulating also bioreduction processes. Moreover, experiments were performed to study the interactions of the halophilic archaeon Halobacterium noricense DSM-15987 with U(VI), Eu(III), and Cm(III) in 3 M NaCl solutions. Research for improving process understanding with respect to the mobility of multivalent metals in systems containing humic matter was focused on the reversibility of elementary processes and on their interaction. Kinetic stabilization processes in the dynamics of humate complexation equilibria were quantified in isotope exchange studies. The influence of high salinity on the mobilizing potential of humic-like clay organics was systematically investigated and was described by modeling. The sorption of Tc(VII)/Tc(IV) onto the iron(II)-containing minerals magnetite and siderite was studied by means of batch sorption experiments, ATR FT-IR and X-ray absorption spectroscopy. The strong Tc retention at these minerals could be attributed to surface-mediated reduction of Tc(VII) to Tc(IV). An influence of ionic strength was not observed. The influence of ionic strength (up to 3 mol/kg) and background electrolyte (NaCl, CaCl2, MgCl2) on U(VI) sorption onto montmorillonite was studied. The U(VI) sorption is influenced by the background electrolyte, the influence of ionic strength is small. Surface complexation modeling was performed applying the 2SPNE SC/CE model. Surface complexation constants were determined for the NaCl and CaCl2 system and were extrapolated to zero ionic strength. Surface complexation in mixed electrolytes can be modeled applying surface complexation constants derived for pure electrolytes. The influence of citrate on U(VI) diffusion in Opalinus Clay was studied using Opalinus Clay pore water as background electrolyte. The diffusion parameter values obtained for the HTO through-diffusion and the U(VI) in-diffusion in the absence of citric acid were in agreement with literature data. In the presence of citric acid, U(VI) diffusion was significantly retarded, which was attributed to a change in speciation, probably U(VI) was reduced to U(IV). Larger-scale heterogeneous material effects on diffusive transport were investigated with PET. Diffusion parameters were derived by optimum fit of a FEM-model to the measurement. These parameters are in accordance with the results from 1D-through-diffusion experiments. Deviations from the simple transversal-isotropic behavior, which are identified as residuals from the model, are indications for heterogeneous transport on the mm-scale. PET measurements were also conducted in order to display the improvement of the EDZ with waterglass injections. These experiments enable to draw conclusions on the complex reactive transport process and thus an estimation of the achieved improvement of the barrier function. The image reconstruction procedure was largely improved, mainly with the aid of Monte-Carlo simulations, and now allows quantitative analysis and error estimation.

Isolated granitic rock bodies (granites, granodiorites, quartz monzonites) in the vicinity of Benson in southeastern Arizona were studied to trace the behavior of rock weathering. Thin sections of fresh granites were examined to characterize the original mineralogy which consisted mainly of quartz, feldspars, and micas. The weathering products show up on the granites as grus and soil profiles as well as down slope in the basin deposits. X -ray diffraction studies of the < 2 micrometers fraction of the weathering products proved illite, smectite, illite-smectite mixed layer, and kaolinite to be the dominant clays; quartz and feldspar also persisted into this size fraction. Silt sized material produced similar results. The quartz monzonite of Texas Canyon afforded a special study of the initial weathering stages of feldspars and micas. In the < 2 micrometers fraction obtained from granitic material placed in an ultra sonic bath, the feldspars weathered to a Na-montmorillinite while biotite weathered to vermiculite.

Diese Dissertation beschreibt die Synthese der vier Flavanone Lonchocarpol A, 6-Dimethylallylnaringenin, Glabrol und Euchrenon A7. Des weiteren konnten drei dieser Naturstoffe enantiomerenrein mit Hilfe einer kinetischen Racematspaltung hergestellt werden. Dabei wurden die Carboxylkohlenstoffe selektiv mit einer asymmetrischen Transferhydrierung nach Noyori reduziert.

This thesis focuses on the synthesis and characterisation of organoclays. X-ray diffraction has been used to study the changes in the basal spacings of montmorillonite clay and surfactant-intercalated organoclays. Variation in the d-spacing was found to be a step function of the surfactant concentration. Three different molecular environments for surfactant octadecyltrimethylammonium bromide (ODTMA) within the surface-modified montmorillonite are proposed upon the basis of their different decomposition temperatures. High-resolution thermogravimetric analysis (HRTG) shows that the thermal decomposition of montmorillonite modified with ODTMA takes place in four steps attributing to dehydration of adsorbed water, dehydration of water hydrating metal cations, loss of surfactant and the loss of OH units respectively. In addition, it has shown that the decomposition procedure of DODMA and TOMA modified clays are very different from that of ODTMA modified ones. The surfactant decomposition takes place in several steps in the DODMA and TOMA modified clays while for ODTMA modified clays, it shows only one step for the decomposition of surfactant. Also TG was proved to be a useful tool to estimate the amount of surfactant within the organoclays. A model is proposed in which, up to 0.4 CEC, a surfactant monolayer is formed between the montmorillonite clay layers; up to 0.8 CEC, a lateral-bilayer arrangement is formed; and above 1.5 CEC, a pseudotrimolecular layer is formed, with excess surfactant adsorbed on the clay surface. While for dimethyldioctadecylammonium bromide (DODMA) and trioctadecylmethylammonium bromide (TOMA) modified clays, since the larger sizes of the surfactants, some layers of montmorillonite are kept unaltered because of steric effects. The configurations of surfactant within these organoclays usually take paraffin type layers. Thermal analysis also provides an indication of the thermal stability of the organoclay as shown by different starting decomposition temperatures. FTIR was used as a guide to determine the phase state of the organoclay interlayers as determined from the CH asymmetric stretching vibration of the surfactants to provide more information on surfactant configurations. It was used to study the changes in the spectra of the surfactant ODTMA upon intercalation into a sodium montmorillonite. Surfaces of montmorillonites were modified using ultrasonic and hydrothermal methods through the intercalation and adsorption of the cationic surfactant ODTMA. Changes in the surfaces and structure were characterized using electron microscopy. The ultrasonic preparation method results in a higher surfactant concentration within the montmorillonite interlayer when compared with that from the hydrothermal method. Both XRD patterns and TEM images demonstrate that SWy-2-Namontmorillonite contains superlayers. TEM images of organoclays prepared at high surfactant concentrations show alternate basal spacings between neighboring layers. SEM images show that modification with surfactant will reduce the clay particle aggregation. Organoclays prepared at low surfactant concentration display curved flakes, whereas they become flat with increasing intercalated surfactant. Fundamentally this thesis has increased the knowledge base of the structural and morphological properties of organo-montmorillonite clays. The configurations of surfactant in the organoclays have been further investigated and three different molecular environments for surfactant ODTMA within the surface-modified montmorillonite are proposed upon the basis of their different decomposition temperatures. Changes in the spectra of the surfactant upon intercalation into clay have been investigated in details. Novel surfactant-modified montmorillonite results in the formation of new nanophases with the potential for the removal of organic contaminants from aqueous media and for the removal of hydrocarbon spills on roads.

The objective of my work was to develop HDPE clay nanocomposites for packaging with superior barrier (gas and water) properties by economical processing technique. This work also represents a comparative study of thermoplastic nanocomposites for packaging based on linear low density polyethylene (LLDPE), high density polyethylene (HDPE) and Nylon12. In this study properties and processing of a series of linear low density polyethylene (LLDPE), high density polyethylene (HDPE) and Nylon 12 nanocomposites based on Na-MMT clay and two different aspect ratio grades of kaolinite clay are discussed.