<p>Development of products which can be produced from a country’s natural resources is very important as far as the industrialization of a nation and saving foreign exchange is concerned. Presently, industries in Uganda and the other states in the Lake Victoria region import all refractory-related-consumables, as the demand cannot be met locally. Based on the abundance of ceramic raw materials for high temperature applications in the region and the demand for refractories by industries it is pertinent to develop and manufacture firebricks by exploiting the locally available raw materials.</p><p>This thesis thus, concerns the characterisation of ceramic raw mineral powders from the Lake Victoria region, more particularly, Uganda, with the aim of developing firebrick refractories from the minerals. Two main deposits of kaolin and a ball clay deposit were investigated to assess their potential in the manufacture of refractory bricks. Raw- and processed sample powders were investigated by means of X-ray diffraction (XRD), thermal analysis (DTA-TG) and Scanning Electron Microscopy (SEM). In addition, the chemical composition, particle size distribution, density, and surface area of the powders were determined.</p><p>A comprehensive study on beneficiation of Mutaka kaolin was carried out using mechanical segregation of particles. The aim of the study was to explore other potential applications like in paper filling and coating. The beneficiation process improves the chemical composition of kaolin to almost pure, the major impurity being iron oxide.</p><p>A general production process scheme for manufacturing fireclay bricks starting with raw powder minerals (Mutaka kaolin and Mukono ball clay) was used to make six groups of sample fireclay brick. Experimental results from the characterization of formulated sample bricks indeed revealed the viability of manufacturing fireclay bricks from the raw minerals. Based on these results, industrial samples were formulated and manufactured at Höganäs Bjuf AB, Sweden. Kaolin from the Mutaka deposit was used as the main source of alumina while ball clay from Mukono was the main plasticizer and binder material. The formulated green body was consolidated by wet pressing and fired at 1350°C in a tunnel kiln. Characterization of the sintered articles was done by X-ray diffraction, scanning electron microscopy, and chemical composition (ICP-AES). In addition, technological properties related to thermal conductivity, thermal shock, alkali resistance, water absorption, porosity, shrinkage, permanent linear change (PLC), linear thermal expansion, refractoriness under load (RUL), and cold crushing strength were determined. The properties of the articles manufactured from the selected naturally occurring raw minerals reveal that the produced articles compare favourably with those of parallel types. Thus, the raw materials can be exploited for industrial production.</p>

The requirements of food packages are to ensure food safety and quality, to minimize spoilage, and to provide an easy way to store and handle food. To meet these demands for fibre-based food packages, barrier coatings are generally used to regulate the amount of gases entering a package, as some gases are detrimental to food quality. Oxygen, for example, initiates lipid oxidation in fatty foods. Bakery products may also be sensitive to oxygen. This thesis focused on mass transport of oxygen in order to gain deeper knowledge in the performance of barrier coatings and to develop means to optimize the performance of barrier coatings. This experimental study along with computer modelling characterized the structure of barrier materials with respect to the mass transport process.This project was performed as part of the multidisciplinary industrial graduate school VIPP (www.kau.se/en/vipp) - Values Created in Fibre Based Processes and Products – at Karlstad University, with the financial support from the Knowledge Foundation, Sweden, and Stora Enso. / <p>Artikel 2 "The influence of clay orientation..." ingick som manuskript i avhandlingen, då med titeln: "Influence of clay orientation in dispersion barrier coatings on oxygen permeation". Nu publicerad.</p>

Made available in DSpace on 2014-12-17T15:42:15Z (GMT). No. of bitstreams: 1 SeverinoHSF_DISSERT.pdf: 1697537 bytes, checksum: d7338ec77a9bb83dfa28e39f146cdab3 (MD5) Previous issue date: 2014-01-24 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / Three studies were performed using tailings kaolin for the synthesis of zeolite A. The first synthesis of zeolite A was performed using a kaolin waste generated from the beneficiation of kaolin for paper production process was studied. The kaolin waste was thermally activated at a temperature range of 550-800?C. For comparison was performed a synthesis pattern of Zeolite A(procedure IZA). The prepared materials were characterized by 27Al MAS NMR, X-ray diffraction and scanning electron microscopy with microprobe rays. The pre-tramento proved to be the most appropriate and suitable temperatures are between 600 and 700?C. Observed the formation of zeolite A in all materials, reaching 52% crystallinity, and the presence of phase sodalite and amorphous material. The second study was the use of a highly reactive metakaolin originating from the Jari region in the synthesis of zeolite A by a new method of hydrothermal synthesis. The zeolite is obtained pure and highly crystalline employing the Jari kaolin calcined at 600 ? C for 2h when the transformation to metakaolin occurs. Get to zeolite phase A at 4pm. The best crystallization time was of 24 h afforded a crystallinity of 67.9%. The third study was the evaluation of the NaOH / metakaolin and crystallization time on the synthesis of zeolite NaA from a sample of kaolin waste, named Kaolin Coverage. The experiments were performed using statistical design (axial points) and rejoinder the center point. The samples were characterized by X-ray diffraction (XRD), scanning microscopic analysis and chemical analysis using an EPMA microprobe. The results showed that a relationship exists between the amount of NaOH added and the crystallization time. The experiment performed using the lowest ratio NaOH / metakaolin (0.5) and shorter (4 h) produced an amorphous material. The increase ratio of NaOH / metakaolin and crystallization time leads to formation of a more crystalline NaA phase, but the presence of phase with sodalite as impurities / Tr?s estudos foram realizados empregando rejeitos de caulins para a s?ntese da ze?lita A. O primeiro a s?ntese da Ze?lita A foi realizada utilizando-se um rejeito de caulim, gerado a partir do processo de beneficiamento de caulim para produ??o de papel, foi estudada. O rejeito de caulim foi ativado termicamente em um intervalo de temperatura de 550 a 800?C. Para efeito de compara??o foi realizada uma s?ntese padr?o de Ze?lita A (procedimento da IZA). Os materiais preparados foram caracterizados por RMN-MAS de 27Al, difra??o de raios X e Microscopia eletr?nica de varredura com microsonda. O pr?-tramento mostrou-se necess?rio e as temperaturas mais adequadas foram entre 600 e 700?C. Observou-se a forma??o da ze?lita A em todos os materiais, alcan?ando-se 52% de cristalinidade, al?m da presen?a da fase sodalita e de material amorfo. O segundo estudo foi o emprego de um metacaulim altamente reativo origin?rio da regi?o do Jar? na s?ntese da Ze?lita A atrav?s de um novo m?todo de s?ntese hidrotermal. A zeolita A ? obtida pura e altamente cristalina empregando o caulim da regi?o do Jar? calcinado a 600?C por 2h quando ocorre a transforma??o para metacaulim. Obtem-se a fase zeolita A em 4h. O melhor tempo de cristaliza??o encontrado foi de 24 h que proporcionou uma cristalinidade de 67,9 %. E o terceiro estudo foi a avalia??o da rela??o de NaOH / metacaulim e tempo de cristaliza??o na s?ntese da ze?lita NaA a partir de uma amostra de rejeito de caulim, nomeado como Caulim de Cobertura. Os experimentos foram realizados utilizando planejamento estat?stico (com pontos axiais) e treplica do ponto central. As amostras obtidas foram caracterizadas por difra??o de Raios-X (DRX), an?lises microsc?picas de varredura e an?lise qu?mica utilizando-se uma microssonda EPMA. Os resultados mostraram que existe uma rela??o entre a quantidade de NaOH adicionado e o tempo de cristaliza??o. Os experimento realizados utilizando a mais baixa rela??o NaOH / metacaulim (0,5) e menor tempo (4 h) produziu um material amorfo. J? o aumento da rela??o NaOH /Metacaulim e o tempo de cristaliza??o leva a forma??o de uma fase NaA mais cristalina, mas com a presen?a da fase sodalita como impureza

Development of products which can be produced from a country’s natural resources is very important as far as the industrialization of a nation and saving foreign exchange is concerned. Presently, industries in Uganda and the other states in the Lake Victoria region import all refractory-related-consumables, as the demand cannot be met locally. Based on the abundance of ceramic raw materials for high temperature applications in the region and the demand for refractories by industries it is pertinent to develop and manufacture firebricks by exploiting the locally available raw materials. This thesis thus, concerns the characterisation of ceramic raw mineral powders from the Lake Victoria region, more particularly, Uganda, with the aim of developing firebrick refractories from the minerals. Two main deposits of kaolin and a ball clay deposit were investigated to assess their potential in the manufacture of refractory bricks. Raw- and processed sample powders were investigated by means of X-ray diffraction (XRD), thermal analysis (DTA-TG) and Scanning Electron Microscopy (SEM). In addition, the chemical composition, particle size distribution, density, and surface area of the powders were determined. A comprehensive study on beneficiation of Mutaka kaolin was carried out using mechanical segregation of particles. The aim of the study was to explore other potential applications like in paper filling and coating. The beneficiation process improves the chemical composition of kaolin to almost pure, the major impurity being iron oxide. A general production process scheme for manufacturing fireclay bricks starting with raw powder minerals (Mutaka kaolin and Mukono ball clay) was used to make six groups of sample fireclay brick. Experimental results from the characterization of formulated sample bricks indeed revealed the viability of manufacturing fireclay bricks from the raw minerals. Based on these results, industrial samples were formulated and manufactured at Höganäs Bjuf AB, Sweden. Kaolin from the Mutaka deposit was used as the main source of alumina while ball clay from Mukono was the main plasticizer and binder material. The formulated green body was consolidated by wet pressing and fired at 1350°C in a tunnel kiln. Characterization of the sintered articles was done by X-ray diffraction, scanning electron microscopy, and chemical composition (ICP-AES). In addition, technological properties related to thermal conductivity, thermal shock, alkali resistance, water absorption, porosity, shrinkage, permanent linear change (PLC), linear thermal expansion, refractoriness under load (RUL), and cold crushing strength were determined. The properties of the articles manufactured from the selected naturally occurring raw minerals reveal that the produced articles compare favourably with those of parallel types. Thus, the raw materials can be exploited for industrial production. / QC 20101029

The effects of coating formulation on thermal characteristics of coating layers were systematically studied for xerographic toner fusion on coated papers. Model coatings were formulated using three types of ground calcium carbonate and one kaolin pigments, each mixed with 6, 10, 18, and 25 pph of styrene butadiene latex binder. Porosity was found to be a key parameter for coating thermal conductivity adjustment, and was determined by the latex concentration. The particle size distribution and morphology of pigments also affect the overall thermal characteristics of coating layers. Print qualities on model coated papers were evaluated by print gloss measurement, toner adhesion test, and pair-wise visual ranking, and it was proved that print gloss is reduced with increasing bulk thermal conductivity of coating layers. The coating layer consisted of Covercarb HP pigment and 10 pph of latex was found to have the best performance in the three print quality evaluation tests.

The effects of coating formulation on thermal characteristics of coating layers were systematically studied for xerographic toner fusion on coated papers. Model coatings were formulated using three types of ground calcium carbonate and one kaolin pigments, each mixed with 6, 10, 18, and 25 pph of styrene butadiene latex binder. Porosity was found to be a key parameter for coating thermal conductivity adjustment, and was determined by the latex concentration. The particle size distribution and morphology of pigments also affect the overall thermal characteristics of coating layers. Print qualities on model coated papers were evaluated by print gloss measurement, toner adhesion test, and pair-wise visual ranking, and it was proved that print gloss is reduced with increasing bulk thermal conductivity of coating layers. The coating layer consisted of Covercarb HP pigment and 10 pph of latex was found to have the best performance in the three print quality evaluation tests.

La caolinita, constituyente principal del caolín, es una arcilla de fórmula 2SiO(2) Al(2).O(3).2H(2)O que da lugar a un producto de calcinación denominado metacaolinita, muy utilizado como materia prima en la síntesis de zeolitas de bajo contenido en SiO(2), como por ejemplo las zeolitas del grupo de la faujasita NaA, NaX y NaY (Breck, 1974). Aunque la producción de zeolita A para detergencia a partir de la metacaolinita ha sido ampliamente descrita en numerosas patentes y trabajos de investigación, el mecanismo de esta reacción se conoce desde hace muy pocos años. La síntesis de zeolitas del tipo X o Y ha sido también descrita, aunque con menos profusión, y su obtención a partir de la caolinita requiere una técnica más elaborada que ha sido escasamente descrita. La adición de una fuente externa de SiO(2) es la vía mejor conocida (Covián, 1991), aunque el proceso presenta una conversión baja y da lugar a productos de baja calidad con la consiguiente pérdida de valor en el mercado que ello supone. El ajuste de la razón SiO(2)/Al(2)O(3) por extracción de aluminio es un proceso concebible pero poco estudiado hasta la fecha. En otro orden de cosas, se han realizado numerosos esfuerzos por desarrollar procesos de obtención de aluminio a partir de fuentes diferentes de la bauxita como consecuencia de que su distribución en el mundo ha originado situaciones de potencial escasez. El caolín, por el contrario, se halla extensamente distribuido y es un mineral rico en aluminio por lo que se constituye en el sustituto por excelencia de la bauxita. Los procesos de obtención de aluminio a partir de caolín desarrollados han tenido como objetivo, consecuentemente, la maximización del rendimiento de las reacciones químicas implicadas, así como una optimización tecnológica y económica de los procesos que diera lugar a un producto con un coste competitivo. Los procesos de obtención de aluminio a partir de caolín mencionados arriba han sido analizados en el presente trabajo desde una perspectiva diferente: la de acondicionar el caolín a base de ajustar su razón SiO(2)/Al(2)O(3) en vez de agotar el aluminio presente en el mismo. Se han estudiado tres procesos diferentes no tan sólo en cuanto a la naturaleza de los reactivos empleados, sino también en las operaciones unitarias que comportan. Por orden de novedad creciente, se ha estudiado el ajuste empleando ácido clorhídrico en disolución acuosa, hidrógenosulfato de sodio y ácido sulfúrico. Los resultados obtenidos muestran que, si bien los tres métodos resultan viables, existen diferencias que es necesario tener en cuenta a la hora de escoger uno de ellos: mientras que la cinética de la reacción con HCl puede explicarse en base al modelo de nucleación de Hulbert y Huff (1970), modelo cinético de orden uno, las cinéticas de las reacciones con NaHSO(4) y H2SO(4) se explican adecuadamente mediante un modelo de núcleo decreciente (MND), un modelo cinético de orden cero. Esto, unido a las bajas energías de activación halladas, redunda en un mejor o peor control del punto final de la reacción: mientras que con el ácido clorhídrico se alcanzan valores elevados de la razón SiO(2)/Al(2)O(3), el punto final de la reacción es difícil de determinar. El hidrógenosulfato de sodio da lugar a valores inferiores de la razón SiO(2)/Al(2)O(3), pero muestra un comportamiento más favorable al apreciarse una detención paulatina de la reacción por resistencia a la difusión en la capa de cenizas. Este es también el caso del ácido sulfúrico, aunque en este reactivo juega un papel relevante la posibilidad de forzar su agotamiento corno método de detener la reacción. La calidad de los productos obtenidos mediante los tres reactivos varía sensiblemente obteniéndose productos de diferente composición química y diferentes características texturales dependiendo no sólo del proceso escogido sino también de las condiciones de operación. Es interesante hacer aquí mención a los contenidos en hierro y titanio, que dan coloración al producto final, pues existen diferencias notables en los productos obtenidos mediante un procedimiento u otro. Aunque existen numerosos procesos descritos para la separación de los minerales de hierro y titanio presentes en el caolín, poca cosa se puede hacer cuando hierro y titanio se hallan constituyendo la estructura cristalina de la caolinita misma. El proceso de ajuste de la razón SiO(2)/Al(2)O(3) brinda una oportunidad de rebajar los contenidos en estas especies dando lugar a productos de mayor valor final. Con el fin de comprender mejor las reacciones del caolín con hidrógenosulfato de sodio y con ácido sulfúrico se presenta un estudio acerca del mecanismo de reacción por el cual cursan las reacciones con cada uno de estos reactivos. Los resultados obtenidos se comparan con los hallados para la reacción con ácido clorhídrico. Una vez conseguido el ajuste de la razón SiO(2)/Al(2)O(3) por reacción con los tres agentes mencionados, se muestra que su reacción con hidróxido de sodio manifiesta diferencias importantes que cabrá analizar con el objeto de conocer en profundidad el proceso de obtención de zeolita X a partir de caolines con razón SiO(2)/Al(2)O(3) ajustada. La característica más relevante de estos materiales consiste en que dan lugar a una curva concentración - tiempo para Si y Al que es muy similar a la obtenida para caolines a los que se les ha añadido una fuente de silicio altamente soluble y también a la que presenta el caolín calcinado a temperaturas iguales o superiores a 900ºC. Los análisis por difracción de rayos X muestran, asimismo, que los sólidos en suspensión presentan un aspecto amorfo durante tiempos prolongados sin que se aprecien fases zeolíticas de ninguna clase, hecho que sugiere la viabilidad del empleo de caolines con razón SiO(2)/Al(2)O(3) ajustada mediante ácidos o sales inorgánicas en la obtención de zeolita X. Así lo muestran los ensayos realizados en este sentido, en los que se ha obtenido una zeolita X a partir de caolines tratados con ácido clorhídrico. Finalmente se proponen sendos esquemas de proceso para la obtención de zeolita X a partir de caolines tratados con los reactivos estudiados y se efectúan diversas consideraciones acerca de los mismos.

Cette thèse se propose de développer de nouvelles stratégies d'amélioration du comportement au feu du PolyEthylène Téréphtalate (PET) recyclé. L'objectif de ce travail est d'engendrer de nouveaux domaines d'application du PET recyclé en tant que plastique technique. Trois stratégies complémentaires ont été mises en place. La première a été de mélanger le PET avec du PolyCarbonate (PC) afin de créer un composite plus résistant au feu. Ces mélanges PET/PC ont été compatibilisés, par extrusion réactive, par ajout de catalyseur qui accélére la réaction de transestérification et forme alors des copolymères PET-PC stabilisant le mélange. La seconde stratégie a été d'augmenter la viscosité du PET grâce à des réactions d'allongement de chaînes. Le composé choisi est le TriPhenylPhosphite (TPP) car il peut jouer le rôle à la fois d'allongeur de chaînes mais aussi de retardateur de flamme grâce à sa teneur en phosphore. Une synergie importante entre les copolymères et le TPP a été mise en évidence. Enfin, la troisième stratégie a été d'utiliser des nanocharges modifiées par du phosphore. Les deux nanocharges qui ont été utilisées sont la montmorillonite et le kaolin. Grâce à ces trois stratégies, les performances mécaniques et thermiques des composites deviennent très intéressantes.

Vertical and inclined soil nails under footings as settlement &ndash / reducing elements is investigated using a physical 1g model in the laboratory. Nails are not connected to footing, they are not so long and vertical settlement of nails is very large compared to usual limits encountered for piles or micropiles. Following the settlement of footing, they share the load together with the footing. The skin friction is mostly mobilized and end-bearing failure occurs continuously during the settlement. The system of footing- soil nail is studied by model square footings of 30 mm x 30 mm and 50 mm x 50 mm breadth dimensions and remoulded kaolin clay consolidated under constant controlled stress of 50 kPa in 200 mm cube boxes. In the first section of the testing series 4, 5, 9 and 12 nails were inserted into soil in 3B, 2.4B, 1.33B and B lengths, respectively. In the second section, 4 and 6 nails in 1.5B and 2B lengths were tested for vertical and 15 degrees and 30 degrees inclined cases. Settlements of footings were measured under constant footing pressure for all groups. Several tests were repeated in each group of testing series. It is concluded that keeping the total nail length constant, decreasing the nail number thus using longer individual nails is more effective in decreasing the footing settlements. 15 degrees inclined nails decrease total settlements more.

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