The objective of this work is development of a new adsorbent on the base of an organoclay with a chelating ligand covalently attached to the clay mineral surface. The presence of a chelating ligand in the clay structure significantly improves its ability to immobilize heavy metal ions from contaminated sludge of wastewater. Montmorillonite and kaolinite were chosen as typical examples of expandable and non-expandable clay minerals. A two-step modification procedure comprised of sequential modification with oxides and grafting of a chelating agent to the modified clay minerals was used. Modifications with silica and ferric oxide were conducted by reacting the dispersed raw clay minerals with tetraethoxysilane and ferric nitrate solution. A chelating ligand, N-[3-(trimethoxysilyl)propyl]ethylenediamine triacetic acid trisodium salt, was introduced into interlayer space of raw and modified clay minerals in aqueous solutions. Laboratory tests of the organoclay efficiency for purification of wastewater were conducted with the most promising sample, i.e., organoclay with the highest specific loading of chelating agent. Experiments were conducted with model wastewater containing either individual or mixed heavy metal ions. The modified organoclay displayed high adsorption capacity for heavy metal cations even in acidic media. The method of modification presented in this work can be used for synthesis of efficient adsorbents for applications in contaminated areas.

No description available.

Apesar dos vários avanços que levaram à expansão do uso de compósitos dentários, ainda há deficiências que limitam suas aplicações. A resistência inadequada ao desgaste mastigatório é constantemente citada como problema das resinas e que acaba tornando-se responsável parcialmente pela redução de sua vida útil. O desgaste do material ocorre pela perda ou degradação da matriz orgânica permitindo a exposição da matriz inorgânica e consequentemente levando a perda desta. Sendo assim, o presente trabalho tem como objetivo principal avaliar o efeito das diferentes concentrações de argila organofílica nas propriedades de uma resina dentária modelo. Primeiramente, foi realizada a purificação da argila e sua posterior troca iônica, o preparo das resinas experimentais e posterior adição de argila em diferentes concentrações, e finalmente a confecção dos corpos de prova. Então, as resinas foram avaliadas através de técnicas como o DMA, TGA, PCA, FTIR, DRX e por testes de inchamento para avaliar a absorção de água. Por FTIR e por PCA foi possível realizar o acompanhamento da cinética de reação das resinas preparadas, obtendo-se assim o seu grau de conversão e também uma análise da sua cinética de polimerização, sendo observado que em concentrações maiores de argila, o grau de conversão e a taxa de polimerização diminuíram. Por TGA foi possível observar dois picos no segundo processo de degradação térmica da amostra sem adição de argila, indicando uma polimerização não homogênea; conforme aumenta-se a quantidade de argila presente na mistura, os picos duplos tornam-se um. DMA mostrou discreto aumento da Tg e aumento de E\' e E\", indicando um reforço destes compósitos. DRX mostrou que não houve exfoliação da argila no polímero, podendo ter a formação de um compósito convencional ou de um compósito intercalado sem expansão do espaço interlamelar. Já os testes de inchamento mostraram que quanto maior o teor de argila maior a absorção de água das resinas. / In spite of the developments that led to the use of dental composites, there are still some shortcomings that limit their use. Inadequate resistance due to the mastigatory wearing is often cited as an issue in resins, which is partially responsible for reducing its lifetime. Wearing out of the material occurs by the loss or degradation of the organic matrix, thus allowing the inorganic matrix to become exposed and consequently leading to its loss. Therefore, the present work has as main goal the evaluation of the effect of different organoclay filler content in the properties of a experimental dental resin. For such, the clay was first purified and then underwent through cationic exchange, following preparation of the resins and later addition of the organoclay obtained and preparing the specimens. The, the resins were evaluated by techniques such as DMA, TGA, PCA, DRX and swelling tests to observe water sorption. By FTIR and PCA it was possible to follow the reaction kinectics of the prepared resins, thus obtaining the degree of convertion and polymerization rate, allowing to observe that the higher the organoclay loadings the lower was both the polymerization rate and the degree of convertion. TGA allowed us to observe two peaks on the second process of thermal degradation on the sample with no clay, thus indicating a non-homogeneous polymerization; and with higher clay loadings the double peaks become one single peak. DMA showed a slight increase of Tg and also an increase in E\' and E\", indicating a reinforcement of the obtained composites. DRX showed no exfoliation of the polymer, thus forming either a conventional composite or maybe a interlacated composite with no expansion of the interlamelar space. Swelling tests showed that the higher the amount of organoclay added the higher was the amount of water absorbed by the specimens.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Nanocompósitos de poliamida 6 (PA6) e montmorilonita modificada com sal de amônio quaternário têm sido estudados, visando melhorar as propriedades térmicas e mecânicas. De fato os efeitos da nano-escala e da interação carga-matriz resultam em maior módulo de elasticidade e resistência à tração, porém a deformação é reduzida. Assim, nesse trabalho, optou-se por adicionar elastômeros, terpolímero de etileno-propileno-dieno (EPDM) e terpolímero de etileno-propileno-dieno modificado com anidrido maleico (EPDM-MA), ao sistema PA 6/argila organofílica para recuperar os valores de deformação. Foi utilizada montmorilonita modificada com cloreto de dimetildioctadecil amônio. A intercalação por fusão foi realizada em câmara interna de mistura. Além das propriedades mecânicas, térmicas e reológicas, foram investigadas as modificações na cristalinidade da fase PA-6 em função da adição da argila modificada, EPDM e EPDM-MA, detectando-se as variações no grau de cristalinidade e nas temperaturas de fusão e cristalização. Os difratogramas de raios-x revelaram ocorrência de intercalação/esfoliação e também modificação da forma cristalina da PA 6, indicando a formação do cristal gama / Nanocomposites of polyamide 6 and montmorillonite modified with alquil-ammonium salts have been studied, searching for the improvement of mechanical and thermal properties. In fact the effects of the nano-scale and the interaction matrix-filler result in larger module of elasticity and tensile strength. However, the elongation at break was greatly reduced. Therefore, in this work, it has been decided to add elastomers, ethylene-proplene-diene terpolymer (EPDM) and ethylene-proplene-diene terpolymer funcionalized with maleic anhydride (EPDM-MA), to the system PA6/organoclay, using modified montmorillonite with ditallowdimethylammonium chloride. The nanocomposites were prepared by melt intercalation technique in a mix internal chamber. Besides the mechanical, thermal and rheological properties, the modifications in the crystallinity of PA6 phase were investigated, being detected the variations in the degree of crystallinity and in the melt temperature and crystallization. The diffractograms of x-ray (XRD) revealed occurrence of intercalation/exfoliation as well as modification of the crystalline form of PA 6, indicating the formation of  crystals

Made available in DSpace on 2014-12-17T15:41:46Z (GMT). No. of bitstreams: 1 MaryelzyFDOpdf.pdf: 2807390 bytes, checksum: 8f6874eb0deb6349d074ce9c9fbbe71e (MD5) Previous issue date: 2009-09-03 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / This study evaluates the inclusion of quaternary ammonium salt, bromide hexadecyl trimethyl ammonium (HDTMA-Br) on sodium bentonite to evaluate their performance on the adsorption of phenol present in produced water. It was observed an increase in d001 samples modified with HDTMA-Br by diffraction of X-rays, showing the intercalation of quaternary ammonium cations in the interlamellar layers of clay. Through the adsorption isotherms could be abserver adsorption behavior of sodium bentonite and organophilic bentonite produced in three different concentrations of HDTMA-Br for adsorption of phenol, which is the main phenolic compound found in the product water. Different concentrations of synthetic solutions of phenol were placed in contact with these adsorbents under the same conditions of agitation and temperature. The adsorbent showed adsorptive favorable, especially the clay modified with the highest concentration of HDTMA-Br, 150% CEC of clay, BEN30-14, with higher amounts of phenol adsorbed per gram of adsorbent (mg.g-1) / Este trabalho objetiva avaliar a inser??o do sal de am?nio quatern?rio, brometo de hexadecil trimetil am?nio (HDTMA-Br) em bentonita s?dica para avaliar seu desempenho na adsor??o de fenol presente em ?gua produzida. P?de-se observar o aumento na d001 das amostras modificadas com HDTMABr por meio de difra??o de raios-X, o que evidencia a intercala??o dos c?tions quatern?rios de am?nio nas camadas interlamelares da argila. Atrav?s das isotermas de adsor??o p?de-se abservar os comportamentos adsortivos da bentonita s?dica e da bentonita organof?lica produzida em tr?s concentra??es de HDTMA-Br para adsor??o do fenol, o qual ? o principal composto fen?lico encontrado na ?gua produzida. Diferentes concentra??es de solu??es sint?ticas de fenol foram colocadas em contato com estes adsorventes sob mesmas condi??es de agita??o e de temperatura. Os adsorventes apresentaram comportamento adsortivo favor?vel, destacando-se a argila modificada com a maior concentra??o de HDTMA-Br, 150% da CTC da argila, BEN30-14, com maiores quantidades de fenol adsorvida por grama de adsorvente (mg.g-1)

Apesar dos vários avanços que levaram à expansão do uso de compósitos dentários, ainda há deficiências que limitam suas aplicações. A resistência inadequada ao desgaste mastigatório é constantemente citada como problema das resinas e que acaba tornando-se responsável parcialmente pela redução de sua vida útil. O desgaste do material ocorre pela perda ou degradação da matriz orgânica permitindo a exposição da matriz inorgânica e consequentemente levando a perda desta. Sendo assim, o presente trabalho tem como objetivo principal avaliar o efeito das diferentes concentrações de argila organofílica nas propriedades de uma resina dentária modelo. Primeiramente, foi realizada a purificação da argila e sua posterior troca iônica, o preparo das resinas experimentais e posterior adição de argila em diferentes concentrações, e finalmente a confecção dos corpos de prova. Então, as resinas foram avaliadas através de técnicas como o DMA, TGA, PCA, FTIR, DRX e por testes de inchamento para avaliar a absorção de água. Por FTIR e por PCA foi possível realizar o acompanhamento da cinética de reação das resinas preparadas, obtendo-se assim o seu grau de conversão e também uma análise da sua cinética de polimerização, sendo observado que em concentrações maiores de argila, o grau de conversão e a taxa de polimerização diminuíram. Por TGA foi possível observar dois picos no segundo processo de degradação térmica da amostra sem adição de argila, indicando uma polimerização não homogênea; conforme aumenta-se a quantidade de argila presente na mistura, os picos duplos tornam-se um. DMA mostrou discreto aumento da Tg e aumento de E\' e E\", indicando um reforço destes compósitos. DRX mostrou que não houve exfoliação da argila no polímero, podendo ter a formação de um compósito convencional ou de um compósito intercalado sem expansão do espaço interlamelar. Já os testes de inchamento mostraram que quanto maior o teor de argila maior a absorção de água das resinas. / In spite of the developments that led to the use of dental composites, there are still some shortcomings that limit their use. Inadequate resistance due to the mastigatory wearing is often cited as an issue in resins, which is partially responsible for reducing its lifetime. Wearing out of the material occurs by the loss or degradation of the organic matrix, thus allowing the inorganic matrix to become exposed and consequently leading to its loss. Therefore, the present work has as main goal the evaluation of the effect of different organoclay filler content in the properties of a experimental dental resin. For such, the clay was first purified and then underwent through cationic exchange, following preparation of the resins and later addition of the organoclay obtained and preparing the specimens. The, the resins were evaluated by techniques such as DMA, TGA, PCA, DRX and swelling tests to observe water sorption. By FTIR and PCA it was possible to follow the reaction kinectics of the prepared resins, thus obtaining the degree of convertion and polymerization rate, allowing to observe that the higher the organoclay loadings the lower was both the polymerization rate and the degree of convertion. TGA allowed us to observe two peaks on the second process of thermal degradation on the sample with no clay, thus indicating a non-homogeneous polymerization; and with higher clay loadings the double peaks become one single peak. DMA showed a slight increase of Tg and also an increase in E\' and E\", indicating a reinforcement of the obtained composites. DRX showed no exfoliation of the polymer, thus forming either a conventional composite or maybe a interlacated composite with no expansion of the interlamelar space. Swelling tests showed that the higher the amount of organoclay added the higher was the amount of water absorbed by the specimens.

The synthesis, characterization and application of dendrimers on solid supports are described. Melamine-based dendrimers are incorporated on clay minerals and silica gel. The hybrid materials are characterized using a variety of analytical techniques including thermal gravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR) and mass spectrometry (MS). The first chapter gives an overview of the two main methods, convergent and divergent, for the synthesis of dendrimers. It also describes the synthesis of melamine-based dendrimers and their advantages over conventional dendrimers. Synthetic strategies and applications of dendrimers at surfaces are discussed. The preparation of organoclay materials containing dendritic surfactants is presented in the second chapter. The morphology of these organoclays is studied by X-ray powder diffraction (XPD). A new type of morphology is observed when large dendritic surfactants are incorporated onto the clay. This new morphology is described as frustrated intercalation. The ability of the dendritic organoclay composites to recognize small organic molecules in water is presented in the third chapter. Atrazine, a commonly used herbicide, is used as a model compound. Structure-activity relationship studies were conducted in order to gain some insight on the recognition and sequestration mechanisms. In the fourth chapter, reactive resins are evaluated for the covalent sequestration of monochlorotriazines from organic and aqueous solutions. The sequestration is monitored spectrophotometrically and using liquid chromatography coupled to a mass spectrometer (LC-MS). 1H NMR spectroscopy and MS are used to identify the covalent adducts formed between the monochlorotriazines and the resins. The efficiency of the resin is compared to several types of charcoal using aqueous solutions of atrazine. The final chapter describes the attachment of melamine-based dendrimers onto silica gels. Dendrimers are incorporated to the silica gel surface using two synthetic strategies, the stepwise growth strategy (SGS) and the "attach-to" strategy (ATS). These composites are also evaluated for their ability to remove atrazine from aqueous solutions.

PA 66 nanocomposites and PA 66 blends were prepared using Cloisite 15A, Cloisite 25A and Cloisite 30B as organoclays and Lotader 2210 (E-BA-MAH), Lotader AX8840 (E-GMA) and Lotader AX8900 (E-MA-GMA) as impact modifiers. The effects of the composition, types of the components and the addition order of the nanocomposites on the morphology, mechanical, flow and thermal properties were investigated. Melt compounding step was carried out twice in a co-rotating twin-screw extruder. This was called as All-S mixing sequence when all the components were melt mixed, simultaneously. The concentration of the elastomer was determined as 5 wt% and the organoclay as 2 wt% to minimize agglomeration of the organoclay and decrease in the mechanical properties. The components which exhibited the best mechanical results and organoclay delamination in All-S mixing sequences were compounded by using different addition orders. Substantial increases were not observed in the tensile, impact, flexural and hardness test results of the nanocomposites compared to the polymer matrix that was twice extruded. Addition order of the components affected the properties of the nanocomposites and dispersion of the elastomeric domains and the organoclay. The best mechanical test results were obtained for All-S mixing sequence of (PA 66-15A-2210). The degree of organoclay dispersion is better in Cloisite 15A and Cloisite 25A containing nanocomposites than the ones which have Cloisite 30B. Low melt flow index values aided dispersion of the organoclay whereas the slight changes in the crystallinity did not significantly contribute to the changes in the mechanical properties of the nanocomposites or the blends.

The objective of this study is to process and characterize the compatibilized blends of acrylonitrile-butadiene-styrene (ABS) and polyamide-6 (PA6) using olefin based reactive copolymers and subsequently to utilize this blend as a matrix material in short glass fiber (SGF) reinforced composites and organoclay based nanocomposites by applying melt processing technique. In this context, commercially available epoxydized and maleated olefinic copolymers, ethylene-methyl acrylate-glycidyl methacrylate (EMA-GMA) and ethylene-n butyl acrylate-carbon monoxide-maleic anhydride (EnBACO-MAH) were used as compatibilizers at different ratios. Compatibilizing performance of these two olefinic polymers was investigated through blend morphologies, thermal and mechanical properties as a function of blend composition and compatibilizer loading level. Incorporation of compatibilizer resulted in a fine morphology with reduced dispersed particle size. At 5 % EnBACO-MAH, the toughness was observed to be the highest among the blends produced. SGF reinforced ABS and ABS/PA6 blends were prepared with twin screw extrusion. The effects of SGF concentration and extrusion process conditions on the fiber length distribution, mechanical properties and morphologies of the composites were examined. The most compatible organosilane type was designated from interfacial tension and short beam flexural tests, to promote adhesion of SGF to both ABS and PA6. Increasing amount of PA6 in the polymer matrix improved the strength, stiffness and also toughness of the composites. Effects of compatibilizer content and ABS/PA6 ratio on the morphology and mechanical properties of 30% SGF reinforced ABS/PA6 blends were investigated. The most striking result of the study was the improvement in the impact strength of the SGF/ABS/PA6 composite with the additions of compatibilizer. Melt intercalation method was applied to produce ABS/PA6 blends based organoclay nanocomposites. The effects of process conditions and material parameters on the morphology of blends, dispersibility of nanoparticles and mechanical properties were investigated. To improve mixing, the screws of the extruder were modified. Processing with co-rotation yielded finer blend morphology than processing with counter-rotation. Clays were selectively exfoliated in PA6 phase and agglomerated at the interface of ABS/PA6. High level of exfoliation was obtained with increasing PA6 content and with screw speed in co-rotation mode. Screw modification improved the dispersion of clay platelets in the matrix.

Polypropylene, PP, based nanocomposites were produced via melt blending method by using twin-screw extrusion in this study. The effects of organoclay type, compatibilizer type, and mixing order of components on the morphology, thermal, mechanical and flow properties of ternary nanocomposites were investigated. Terpolymer of ethylene/butyl acrylate/maleic anhydride, ethylene/methyl acrylate/glycidyl methacrylate, and copolymer of ethylene/glycidyl methacrylate elastomers were used as compatibilizer, whereas Cloisite&reg / 30B, Cloisite&reg / 15A, and Cloisite&reg / 25A were used as organoclay. iv In order to determine the optimum amount of compatibilizer, PP/compatibilizer blends were produced with different compositions. The content of compatibilizer was determined as 5 wt % based on the mechanical tests. Then, ternary nanocomposites were prepared with 5 wt % compatibilizer and 2 wt % organoclay contents. In addition, neat PP and PP/organoclay composites were prepared in order to make comparison. After that, the samples were characterized. According to the XRD analysis, the highest increase in the interlayer spacings of organoclays were observed in the PP/E-MA-GMA/Cloisite&reg / 15A (23%) and PP/E-MA-GMA/ Cloisite&reg / 25A (88.3%) ternary systems. SEM micrograms revealed that compatibilizer E-MA-GMA is the most compatible elastomer with PP. Thus, it was decided to investigate the effect of mixing order on the properties of these nanocomposites with E-MA-GMA. DSC analysis showed that the melting behavior of the nanocomposites does not change significantly with the presence of organoclay and compatibilizer. In addition, compatibilizers and organoclays have no significant nucleation activity in PP. The systems PP/E-MA-GMA/Cloisite&reg / 15A and PP/E-MA-GMA/Cloisite&reg / 25A have the highest improvements according to the results of mechanical tests. The results of mechanical tests showed that the mixing sequence (PEC), in which PP, organoclay and compatibilizer were compounded simultaneously in the first extrusion run, is the best sequence.