<p>U disertaciji je ispitana mogucnost kori&scaron;cenja<br />izluženih rezanaca &scaron;ecerne repe za adsorpciju<br />jona bakra u koloni sa nepokretnim<br />slojem. Eksperimenti su izvedeni primenom<br />Boks-Benkenovog eksperimentalnog dizajna<br />na tri nivoa sa tri promenljive: koncentracija<br />napojnog rastvora (50-150 mgL^-1), masa<br />adsorbenta (8-12 g) i pH napojnog rastvora<br />(4,0-5,0). Dobijene prevojne krive su<br />fitovane uobicajenim empirijskim modelima,<br />Boart-Adamsovim i modelom doza-odziv.<br />Na osnovu uocene asimetrije prevojne<br />krive, predložen je novi matematicki model.<br />Novi model predlaže prevojnu krivu koja<br />se sastoji od dva dela, koji u zbiru daju<br />kumulativnu krivu koja dosledno pokriva<br />uocenu asimetriju. Uzimajuci u obzir najnižu<br />prosecnu sumu kvadrata odstupanja, SSer<br />(3,610^-3) i najvi&scaron;u prosecnu vrednost<br />koeficijenta determinacije, R² (0,9989),<br />novi model je pokazao najbolje fitovanje<br />eksperimentalnih podataka, u poreenju sa<br />uobicajeno kori&scaron;cenim modelima adsorpcije<br />u koloni. RSM i ANN modelovanje je dalje<br />kori&scaron;ceno za evaluaciju procesnih parametara<br />i optimizaciju procesa. Najznacajnija<br />nezavisno promenljiva velicina, koja ispoljava<br />negativan uticaj na odabrani odziv (kriticno<br />vreme), bila je koncentracija napojnog<br />rastvora, dok je masa adsorbenta ispoljila<br />slabiji i pozitivan uticaj na odziv. Optimizacijom procesa metodom ANN je<br />utvreno da se najveca vrednost kriticnog<br />vremena (341,4 min) postiže pri sledecim<br />uslovima: C0=50 mgL^-1, ma=12 g and pH<br />4,53, dok metoda RSM smatra pH vrednost<br />faktorom koji nema znacaja po odziv u<br />ispitivanom opsegu, i postiže maksimalno<br />kriticno vreme od 314,8 min, pri istim ostalim<br />uslovima kao i ANN.<br />Iskori&scaron;ceni adsorbent, zasicen jonima bakra,<br />je zatim spaljen i dobijeni pepeo je iskori&scaron;cen<br />kao punilo u proizvodnji gume. Proizvedena<br />su cetiri uzorka gume sa razlicitim sadržajem<br />pepela. Pracen je proces vulkanizacije<br />gume, odreena su mehanicka svojstva<br />gotovog proizvoda i izvreno je poreenje<br />dobijenih rezultata izmeu uzoraka sa i<br />bez dodatka pepela. Rezultati su pokazali<br />da dodatak pepela u strukturu gume ne<br />utice znacajno na njene mehanicke osobine.<br />Meutim, povecanje sadržaja pepela u gumi<br />dovodi do povecanja energije aktivacije<br />procesa vulkanizacije, &scaron;to se može smatrati<br />unapreenjem procesa proizvodnje gume u<br />slucaju proizvoda velikih dimenzija. Na<br />kraju, ispitano je izluživanje bakra iz gotovih<br />proizvoda od gume. Rezultti su pokazali da je<br />kolicina bakra izluženog u vodu veoma niska,<br />reda velicine 0,001%, &scaron;to se može smatrati<br />zanemarljivim.</p> / <p>The potential use of sugar beet shreds for<br />copper ions removal from aqueous solution<br />in a fixed-bed column was investigated.<br />Experiments were performed using<br />Box-Behnken experimental design on three<br />levels and three variables: concentration of<br />the inlet solution (50-150 mgL^-1), adsorbent<br />dosage (8-12 g) and pH of the inlet solution<br />(4.0-5.0). The obtained breakthrough curves<br />were fitted with two common empirical<br />models, Bohart-Adams and dose-response.<br />Observing the asymmetric shape of the<br />breakthrough curves, the new mathematical<br />model was proposed. The new model<br />proposes the breakthrough curve composed<br />of two parts, sum of which gives the<br />asymmetrical S-shaped curve, accurately<br />matching experimental data. Regarding the<br />lowest average SSer (3.610^-3) and highest<br />average R² (0.9989), new model exhibited<br />the best fit comparing to the commonly used<br />models. RSM and ANN modelling were<br />employed for process variables evaluation and<br />optimization. The most influential parameter<br />exhibiting negative influence on target<br />response (critical time) was concentration of<br />the inlet solution, while the adsorbent dosage<br />exhibited positive influence. Optimization procedure revealed that the<br />highest critical time (341.4 min) was achieved<br />at following conditions: C0=50 mgL^-1,<br />ma=12 g and pH 4.53 by ANN, while<br />RSM considered pH as insignificant factor<br />and obtained 314.8 min as the highest<br />response. Discarded adsorbent, saturated<br />with copper ions, was then incinerated and<br />the obtained ash was used as a rubber filler.<br />Four rubber samples containing different<br />amounts of added ash were produced. The<br />vulcanization process was monitored and<br />mechanical properties was measured and<br />compared with the samples with no ash<br />added. The results revealed that addition of<br />ash has no significant effect on the rubber<br />mechanical properties. However, as the<br />ash content increases, the activation energy<br />of the vulcanization process increases too,<br />which can be considered as an improvement<br />in the cases of large-dimensioned rubber<br />products production. Finally, the leaching<br />of the copper from rubber products was<br />investigated. Results showed that very small<br />amount of copper, order of magnitude 0,001%,<br />were leached from the rubber into the water,<br />which can be considered as insignificant.</p>

Submitted by JOSIANE SANTOS DE OLIVEIRA (josianeso) on 2018-07-09T16:18:43Z No. of bitstreams: 1 Paôla Valentini_.pdf: 16360357 bytes, checksum: 11cfed092ec8572550d478091c843fbc (MD5) / Made available in DSpace on 2018-07-09T16:18:43Z (GMT). No. of bitstreams: 1 Paôla Valentini_.pdf: 16360357 bytes, checksum: 11cfed092ec8572550d478091c843fbc (MD5) Previous issue date: 2018-03-23 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Diversos fatores influenciam a durabilidade de argamassas de revestimento, sendo alguns deles: a absorção de água, porosidade e rugosidade da superfície do substrato; a execução, com o preparo ou não do substrato, a forma de aplicação e as condições de cura da argamassa; as condições climáticas, decorrentes da ação do vento, umidade e temperatura; e a própria argamassa com seus componentes. Partindo deste contexto, esta pesquisa tem como objetivo avaliar fatores relacionados ao substrato e à argamassa que influenciam na resistência de aderência à tração de sistemas de revestimento. O programa experimental buscou avaliar a influência da absorção de água total, da absorção por capilaridade e da rugosidade de três substratos cerâmicos e também da adição de fíler na argamassa, na resistência de aderência à tração de sistemas de revestimento. Os substratos cerâmicos foram queimados nas temperaturas de 800°C, 900°C e 1000°C, sendo que, das 144 peças cerâmicas do estudo, metade receberam aplicação de hidrofugante. Sobre as peças cerâmicas foram aplicadas argamassas confeccionadas com areia natural de rio e cimento Portland CP II-Z-32, no traço 1:3, em massa, com e sem adição de 5% de pó de quartzo. A partir dos resultados encontrados observou-se que a maior resistência de aderência à tração foi obtida nos blocos cerâmicos com temperatura de queima de 800°C, que apresentam simultaneamente maior rugosidade e maior absorção capilar de água. Verificou-se também que a adição de fíler à argamassa aumentou a resistência de aderência quando aplicada sobre os blocos de maior rugosidade, não sendo observado o mesmo comportamento nos blocos de baixa rugosidade. De um modo geral, o uso de hidrofugante sobre as peças cerâmicas diminuiu os resultados de resistência de aderência além de alterar a forma de ruptura dos revestimentos. / The durability of coating mortars applied on substrates are influenced by the water absorption, porosity and roughness of the substrate surface; the preparation of the coating´s substrate, the method used to apply and the cure conditions of the mortar; beyond the climatic conditions, through the wind, humidity and temperature; and the mortar itself with its components. Based on this context, this research aims to evaluate factors related to the coating´s substrate and the rendering mortar that influence the adhesion strength of mortar coating systems. The experimental program aimed to evaluate the influence of total water absorption, capillary absorption and roughness of three ceramic substrates, as well as the use of filler in the mortar, in the adhesion strength of mortar coating systems. The ceramic substrates were burned at 800°C, 900°C and 1000°C, and of the 144 ceramic pieces of the study, 72 were painted with water repellent. The coating mortars were made with natural river sand and Portland cement CP II-Z-32, in the proportion 1: 3 (by mass), with and without adding 5% of quartz filler. It was observed that the highest tensile strength was obtained with the substrates of ceramic blocks burned at 800°C, which simultaneously present the higher roughness and higher water absorption. The use of filler in the mortar composition increased the adhesion strength when applied on the blocks of greater roughness. In general, the use of water repellent on the ceramic substracts decrease the adhesion strength of mortar coating systems and modify the kind of rupture of the coatings.

Submitted by Maicon Juliano Schmidt (maicons) on 2015-06-15T17:46:32Z No. of bitstreams: 1 Iara Janaína Fernandes.pdf: 17712029 bytes, checksum: b6e13ee1cb18381155281d91bedc3233 (MD5) / Made available in DSpace on 2015-06-15T17:46:32Z (GMT). No. of bitstreams: 1 Iara Janaína Fernandes.pdf: 17712029 bytes, checksum: b6e13ee1cb18381155281d91bedc3233 (MD5) Previous issue date: 2015-02-25 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / CNPQ – Conselho Nacional de Desenvolvimento Científico e Tecnológico / FAPERGS - Fundação de Amparo à Pesquisa do Estado do Rio Grande do Sul / Artecola Química S/A / A escassez de recursos naturais não renováveis e o aumento da poluição ambiental tem aumentado a necessidade de materiais com características específicas, e que ao mesmo tempo sejam atóxicos e sustentáveis. Neste sentido, a inserção de coprodutos, outrora resíduos industriais, em novos ciclos produtivos, contribui para minimização destas problemáticas. A casca de arroz é um resíduo amplamente gerado no Brasil e no mundo, é o principal subproduto do beneficiamento do arroz e tem sido utilizada como biomassa para geração de energia, o que reduz o impacto ambiental negativo causado pela sua destinação, porém gera grande quantidade de outro resíduo, a cinza de casca de arroz (CCA). A CCA é composta basicamente por sílica e carbono, além de outros componentes em menores quantidades. Pelo elevado teor de sílica, é um resíduo com potencial para ser transformado em coproduto para diversas indústrias. Uma aplicação importante é o uso como agente de reforço na produção de compósitos poliméricos. O polímero epóxi é um excelente material de matriz para compósitos e largamente utilizado em diferentes aplicações. Considerando que a sílica é uma das cargas mais comumente usadas em compósitos de matriz epóxi, o objetivo deste trabalho foi desenvolver e avaliar compósitos de CCA como carga em matriz epóxi em comparação com sílicas comerciais. Para isso, foi realizado primeiramente o beneficiamento e preparação de CCAs oriundas de distintos processos de combustão, por métodos de segregação granulométrica, moagem e lixiviação ácida. Após, as CCAs e sílicas foram caracterizadas utilizando análises de distribuição granulométrica, massa específica, área superficial, perda ao fogo, carbono total, análise química, pH, espectroscopia de infravermelho, análise termogravimétrica, microscopia eletrônica de varredura e difração de raios-X. Depois da determinação dos parâmetros mais adequados ao desenvolvimento dos compósitos, foi realizada a preparação e moldagem dos mesmos utilizando as CCAs e sílicas nos percentuais de 20, 40 e 60%. A avaliação das propriedades dos compósitos foi realizada por meio de ensaios de viscosidade, espectroscopia de infravermelho, análise termogravimétrica, calorimetria exploratória diferencial, microscopia eletrônica de varredura, ensaios mecânicos e absorção de água. O processo de lixiviação ácida utilizado nas CCAs mostrou-se efetivo na redução ou eliminação de Fe2O3, K2O, CaO, Cl e P2O5. Com relação à caracterização das cargas, várias das propriedades foram semelhantes para CCAs e sílicas, indicando a viabilidade de substituição da sílica por CCA para diversos tipos de materiais poliméricos. No entanto, as sílicas mostraram maior pureza e menor área superficial comparadas às CCAs. Quanto à produção dos compósitos, estes foram produzidos com sucesso, porém em escala laboratorial e o processo de moldagem utilizado mostrou dificuldade de remoção de bolhas para as misturas mais viscosas. Os valores obtidos para as temperaturas de transição vítrea dos compósitos após a cura foram satisfatoriamente elevados, em torno de 140°C, assim como as temperaturas de degradação térmica, que ficaram acima de 370°C para todas as amostras analisadas. Através das análises mecânicas e absorção de água, pode-se constatar que a CCA tem comportamento semelhante ao da sílica, podendo ser substituída sem maiores adversidades. Os ensaios de MEV revelaram que houve uma boa dispersão e distribuição das cargas na matriz polimérica, e que a interface de adesão entre as partículas e a matriz foi melhor para os compósitos de cinza. No entanto, a análise de viscosidade evidenciou que a viscosidade das misturas contendo CCA aumenta exponencialmente, podendo causar problemas de processamento, dependendo da aplicação. / The scarcity of non-renewable natural resources and the increasing of environmental pollution have enlarged the need for materials with special properties, which have been at the same time non-toxic and sustainable. Regarding the inclusion of byproducts, which were industrial wastes before, into new productive processes, could minimize such problems. Rice husk is a solid waste widely generated not only in Brazil but also worldwide. It is considered the main industrial byproduct of rice manufacture and has been used as biomass for power generation, reducing the negative environmental impact caused by its disposal. Nevertheless, this application also generates large amount of another waste, named rice husk ash (RHA). RHA is basically composed by silica, carbon and other components in smaller amounts. Due to the high silica content, it is supposed to claim that this is a waste with potential to be transformed into byproduct for several industries. The use of this byproduct as a reinforcing agent for producing polymer composites could be an important application alternative. The epoxy polymer is widely used in different applications even as matrix material for composites. Considering that silica is one of the most commonly used fillers reinforced epoxy composites, this study aims to develop and evaluate RHA as filler in epoxy composites., comparing it to commercial silica. For this, it was performed the processing and the preparation of RHAs (from different combustion processes) by particle size segregation, grinding and acid leaching methods. After this stage, the RHAs and silica were characterized using particle size distribution analysis, density, surface area, loss on ignition, total carbon, chemical analysis, pH, infrared spectroscopy, thermal analysis, scanning electron microscopy (SEM) and X-ray diffraction. The most appropriate parameters for the composite development were determined. The preparation and molding of composites using RHAs and silica as filler in percentages of 20, 40 and 60%wt were performed. The composites properties evaluation was performed by testing viscosity, infrared spectroscopy, thermogravimetric analysis, differential scanning calorimetry, scanning electron microscopy, mechanical testing and water absorption. The acid leaching process used in the RHAs was effective in reducing or eliminating Fe2O3, K2O, CaO, P2O5 and Cl. According to the characterization results, RHAs and silica presented similar properties, indicating the feasibility of replacing the silica by RHA for different types of polymeric materials. However, the silica showed higher purity and low surface area compared to the RHAs. The composites production was successfully performed on a laboratory scale, but the molding process used showed bubbles hard removing from more viscous mixtures. The values obtained for the glass transition temperature after composites curing (around 140°C) and the thermal degradation temperature (above 370°C) were satisfactorily high for all samples. Through mechanical analysis and water absorption results, it was verified that the RHA composites presented similar behavior when compared with the silica composites. Therefore, they could be replaced with no negative aspects in terms of final product. SEM tests showed that there was a good distribution and dispersion of the fillers in the polymeric matrix. The adhesion interface between the particles and the RHA composites matrix was improved when compared with silica composites. However, the viscosity of mixtures containing RHA increased exponentially, could lead processing problems, depending on the application.

Submitted by Silvana Teresinha Dornelles Studzinski (sstudzinski) on 2015-10-28T11:36:30Z No. of bitstreams: 1 Daniel Gustavo Brusius Wilbert_.pdf: 4731645 bytes, checksum: 08c801a9545a481516dfe01632256d9c (MD5) / Made available in DSpace on 2015-10-28T11:36:30Z (GMT). No. of bitstreams: 1 Daniel Gustavo Brusius Wilbert_.pdf: 4731645 bytes, checksum: 08c801a9545a481516dfe01632256d9c (MD5) Previous issue date: 2015-07-22 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / FAPERGS - Fundação de Amparo à Pesquisa do Estado do Rio Grande do Sul / O setor da construção civil é responsável por um grande impacto ambiental, destacando-se dois principais fatores, a quantidade de matéria-prima consumida e de resíduos gerados. Estes resíduos, em grande parte apresentam um grande potencial de reciclagem. Dentre estes resíduos, os de concreto apresentam um excelente potencial de utilização. Inúmeras pesquisas já comprovaram a viabilidade de utilização do Agregado Reciclado de Concreto (ARC). Porém, a menor qualidade do ARC em comparação aos agregados naturais, resultada em queda no desempenho destes concretos, principalmente nas propriedades de durabilidade. Como consequência ocorre um enfraquecimento da zona de transição entre a argamassa velha e a nova. Em função desta queda de desempenho ao se utilizar ARC, a presente pesquisa teve por objetivo a análise desta zona de transição, através do estudo da interface entre duas argamassas de concreto por meio da técnica de nanoindentação. Para esta análise foram moldados agregados reciclados de concretos modificados, todos no traço referência (sem adição), e posteriormente aplicada uma nova camada de argamassas com diferentes traços. Os traços variaram entre dois tipos de adição (Finos Basálticos – FB e Cinza da Casca de Arroz – CCA), em diferentes teores de adição ao cimento, 0, 5, 10 e 15% para os finos e 0, 5 7,5 e 10% para a CCA. Após cura de 63 dias, as amostras foram preparadas para a realização dos ensaios. Para a análise das medidas de nanoindentação na interface, foram propostos três métodos de análise. As propriedades macroestruturais foram avaliadas aos 28 dias, como módulo de elasticidade dinâmico, resistência à compressão, resistência à tração por compressão diametral e absorção de água por capilaridade. Os resultados demonstraram a melhora das propriedades macroestruturais das argamassas com 15% de FB e CCA em relação à referência. Foram identificadas alterações na região de interface entre as argamassas no traço com 15% de finos de basalto e em todos os traços com CCA, que apresentaram os melhores resultados. A comparação entre a região mais próxima à zona de transição resultou, para todos os traços, em valores semelhantes aos obtidos em regiões de pastas mais distantes à zona de transição, demonstrando que o uso de uma argamassa antiga na condição seca (simulando um agregado reciclado seco) melhorou as condições da zona de transição com a argamassa nova. / Construction is responsible for a large environmental impact, highlighting two main factors: consume of raw materials and generation of waste materials. By other hand, construction and demolition waste has a good potential of recycling. Many studies have demonstrated the viability of using recycled concrete coarse aggregate (RCA) in new concrete. However, due to the RCA’s properties, most results point to a lower durability of the concrete. It is also consensus that the main reasons for the lower quality of the new concrete are the mortar layer adhered to the natural aggregate and the weakening in the new Interfacial Transition Zone (ITZ) between the old and the new mortar. This study analyze the new interfacial transition zone in these concretes through nanoindentation. There were produced recycled concrete aggregates without addition of filler, and over these aggregates there were produced a new mortar layer with different mix compositions. There were used basaltic filler and rice husk ash-RHA in different levels of addition: 0, 5, 10 and 15% for the filler, and 0, 5, 7,5 and 10% for the ash. Their interfaces were evaluated using different methodologies. Modulus of elasticity, compressive strength, tensile strength and capillarity were determined. The use of fines improved the mortar properties in relation to the reference, especially those with 15% filler and the samples with RHA. The region near to the ITZ shows similar elastic moduli values to those obtained in the paste, in all mortars, proving that using dry recycled aggregates the new mortar loose water to the aggregates and increase their mechanical properties.

Polymeric membranes exhibit a trade-off between permeability and selectivity in gas separations which limits their viability as an economically feasible post-combustion carbon capture technology. One approach to improve the separation properties of polymeric membranes is the inclusion of particulate materials into the polymer matrix to create what are known as mixed matrix membranes (MMMs). By combining the polymer and particulate phases, beneficial properties of both can be seen in the resulting composite material. One of the most notable challenges in producing mixed matrix membranes is in the formation of performance-hindering defects at the polymer-filler interface. Non-selective voids or polymer chain rigidification are but two non-desirable effects which can be observed. The material selection and synthesis route are key to minimising these defects. Thin membranes are also highly desirable to achieve greater gas fluxes and improved economical separation processes. Hence smaller nano-sized particles are of particular interest to minimise the disruption to the polymer matrix. This is a challenge due to the tendency of some small particles to form agglomerations. This work involved introducing novel nanoscale filler particles into PEBAX MH1657, a commercially available block-copolymer consisting of poly(ethylene oxide) and nylon 6 chains. Poly(ether-b-amide) materials possess an inherently high selectivity for the CO2/N2 separation due to polar groups in the PEO chain but suffer from low permeabilities. Mixed matrix membranes were fabricated with PEBAX MH1657 primarily using two filler particles, nanoscale ZIF-8 and novel nanoscale MCM-41 hollow spheres. This work primarily investigated the effects of the filler loading on both the morphology and gas transport properties of the composite materials. The internal structure of the membranes was examined using scanning electron microscopy (SEM), and the gas transport properties determined using a bespoke time-lag gas permeation apparatus. ZIF-8 is a zeolitic imidazolate framework which possesses small pore windows that may favour CO2 transport over that of N2. ZIF-8-PEBAX membranes were successfully synthesised up to 7wt.%. It was found that for filler loadings below 5wt.%, the ZIF-8 was well dispersed within the polymer phase. At these loadings modest increases in the CO2 permeability coeffcient of 0-20% compared to neat PEBAX were observed. Above this 5wt.% loading large increases in both CO2, N2 and He permeability coeffcients coincided with the presence of large micron size clusters formed of hundreds of filler ZIF-8 particles. The increases in permeability were attributed to voids observed within the clusters. MCM-41 is a metal organic framework that has seen notable interest in the field of carbon capture, due to its tunable pore size and ease of functionalisation. Two types of novel MCM-41 hollow sphere (MCM-41-HS) of varying pore size were incorporated into PEBAX and successfully used to fabricate MMMs up to 10wt.%. SEM showed the MCM-41 generally interacted well with the polymer with no signs of voids and was generally well dispersed. However, some samples of intermediate loading in both cases showed highly asymmetric distribution of nanoparticles and high particle density regions near one external face of the membrane which also showed the highest CO2 permeability coeffcients. It is suspected that these high permeabilities are due to the close proximity of nanoparticles permitting these regions to act in a similar way to percolating networks. It was determined that there was no observable effect of the varying pore size which was expected given the transport in the pores should be governed by Knudsen diffusion.

A atividade de mineração de caulim, no Pará, produz cerca de 1,5 milhões de toneladas/ano de caulim beneficiado para uso na indústria de papel e, em consequência, é gerado um grande volume de rejeito de caulim, cujo aproveitamento como material de pavimentação pode reduzir o passivo ambiental. O objetivo desta pesquisa foi avaliar a viabilidade técnica do uso de rejeito de caulim como fíler em concretos asfálticos, considerando aspectos relacionados à dosagem Marshall e propriedades de engenharia. Para isso, foram produzidas doze misturas asfálticas, que resultaram da combinação dos fatores: tipo de ligante asfáltico (CAP 50/70 e CAP 30/45) e tipo/teor de fíler (granito, 1,5%, 3,0% e 6,0% de caulim, 1,5% de cal e 3,0% de caulim + 1,5% de cal), as quais foram avaliadas à luz dos resultados de dosagens Marshall, de ensaios mecânicos (RT, MR, fadiga e creep estático) e relacionados à durabilidade (de susceptibilidade térmica e ao dano por umidade). Adicionalmente, foram testadas correlações entre os parâmetros de caracterização do fíler \"teor de caulim\", \"D10\", \"D30\", \"D60\" e \"módulo de finura\" (MF) versus parâmetros de dosagens e propriedades mecânicas e de durabilidade. Os resultados das dosagens indicaram que as mudanças do tipo de CAP e/ou do tipo e teor de fíler não influenciaram significativamente os teores de projeto (TP variaram entre 5,3 e 5,6%); no entanto, os valores de estabilidade das misturas com CAP 30/45 foram superiores aos das misturas com CAP 50/70, e as misturas com 6,0% de caulim apresentaram baixa estabilidade e elevada fluência, para ambos os ligantes asfálticos. As misturas sem cal não atenderam a RRT mínima de 70%, o que foi atribuído à má adesividade do granito com os ligantes asfálticos. Por isso, em termos de dosagem, apenas as misturas contendo cal atenderam a todas as exigências do DER/SP. Quanto aos ensaios mecânicos, constatou-se que nas misturas com CAP 30/45, a rigidez e as resistências à tração e à fadiga foram maiores e a susceptibilidade térmica foi menor em relação às misturas com CAP 50/70. Para ambos ligantes asfálticos, a adição de rejeito de caulim aumentou a rigidez e a vida de fadiga e melhorou a susceptibilidade térmica, porém reduziu as resistências à tração e à deformação permanente. Identificou-se que o efeito do tipo de ligante asfáltico está mais relacionado às propriedades mecânicas e à susceptibilidade térmica, e o efeito do tipo de fíler, às propriedades volumétricas, aos parâmetros de deformação permanente e de susceptibilidade ao dano por umidade. Complementarmente, mostrou-se que os parâmetros de caracterização \"teor de caulim\" e \"MF\" se correlacionaram melhor com os parâmetros das dosagens Marshall e do ensaio de creep estático, respectivamente. Por fim, conclui-se que o uso de rejeito de caulim como fíler em concreto asfáltico é tecnicamente viável, para ambos os tipos de ligante asfáltico, em teores de adição de até 3,0% e associado à cal. / Mining activity of kaolin, in Pará, produces around 1.5 million ton/year of processed Kaolin for paper industry, as a consequence, a substantial volume of waste is generated. The use of kaolin waste might reduce the environmental legacy. The main purpose of this research was to evaluate the technical feasibility of kaolin waste as filler in hot mix asphalt, considering aspects related to mix design and engineering properties. For this, twelve asphalt mixtures were produced from the combination of factors: type of asphalt binder (CAP 50/70 e CAP 30/45) and type/content of filler (granite, 1.5, 3.0 and 6.0% of kaolin waste, 1.5% of lime and 3.0% of kaolin waste+1.5% of lime). Asphalt mixtures were evaluated based on results from Marshall design, mechanical (ITS, RM, fatigue and static creep) and durability (thermal and moisture susceptibilities) tests. Additionally, filler-characterization parameters (kaolin content, D10, D30, D60 and fineness modulus, FM) were correlated to the Marshall\'s parameters and to the mechanical and durability properties. Marshall design results indicated that the changes of asphalt binder and types/content of filler did not significantly influence asphalt content (variation from 5.3 to 5.6%), however, stability values of mixtures with CAP 30/45 were higher than the mixtures with CAP 50/70. Mixtures containing 6% of Kaolin presented low stability and high flow, for both asphalt binders. Mixtures without lime did not reach minimum TSR value (70%), which was attributed to the poor adhesion between granite aggregates and asphalt binders. Therefore, regarding Marshall parameters, only asphalt mixtures with lime met all of DOT/Sao Paulo\'s standard requirements. Concerning mechanical tests, it was showed that, in mixtures with CAP 30/45, stiffness, tensile strength and fatigue resistance were higher and the thermal susceptibility was lower when compared to mixtures with CAP 50/70. Kaolin addition increased stiffness and fatigue life, but, decreased tensile strength and rutting resistance. Mechanical properties and thermal susceptibility were quite affected by asphalt binder whereas volumetric and rutting properties and moisture damage were most influenced by filler type and content. Furthermore, kaolin content and FM well correlated with Marshall and rutting parameters, respectively. Finally, it was concluded that the use of kaolin waste as filler in hot mix asphalt is technically feasible, for both tested asphalt binders, at contents up to 3.0% and combined with 1.5% of lime.

Direct compression has gained significant interest since its advent in the late 1950's due to its potential ease compared to wet granulation. The primary prerequisites for powders used in direct compression are (i) good flow properties (ii) good compressibility and (iii) an acceptable dilution potential to accommodate a relative high percentage of active ingredient. Several filler/binders have been manufactured especially for direct compression and co–processing is one of the recent methods used to produce good compressible excipients with acceptable flow properties. In this study, lactose–based filler/binders were used which included simple and modified lactose materials (Granulac, Lactopress, Flowlac and Tablettose) as well as co–processed excipients (Starlac, Cellactose and Microcelac). A comprehensive literature study on direct compression revealed the importance of the physical properties of filler/binders such as interparticle forces, particle shape, particle size and distribution, powder density, particle surface structure and particle packing geometry which influence the flow of powders. All the materials were subjected to the various tests available to evaluate powder flow, namely (i) angle of repose (AoR), (ii) critical orifice diameter (COD), (iii) flow rate and percentage compressibility (%C) in terms of the powders' bulk and tap densities. The results of these tests confirmed the expected flow properties of the various filler/binders, with only one material exhibiting extremely poor flow properties. The following rank order in terms of all flow tests conducted was established; Starlac >> Microcelac ~ Flowlac >> Cellactose > Tablettose > Lactopress >>> Granulac. The co–processed filler/binders presented with superior flow compared to the other lactose–based materials. During the next phase of the study, the compaction properties of the various fillers were evaluated, employing direct compression. Compacts of pure filler were tabletted on an eccentric tablet press at different compression pressures (manipulated by the upper punch setting of the tablet press). The modified lactose filler/binders (Lactopress, Flowlac and Tablettose) exhibited unexpectedly poor compression profiles, where the co–processed filler/binders (Starlac, Cellactose and Microcelac) produced compacts with acceptable appearance and compact properties. Two lubricants (Mg–St or Pruv), which were tested separately in formulations were added since no compacts could be produced from the pure filler/binders. None of the modified lactose filler/binders, in combination with a lubricant, were able to produce an acceptable compact, since lamination occurred during compression. The co–processed filler/binders produced satisfactory compacts with the addition of a lubricant, but lactose–cellulose fillers (Cellactose and Microcelac) also required the inclusion of a disintegrant (Ac–Di–Sol) to induce satisfactory compact disintegration. Poor compressible active ingredients (paracetamol), which exhibit very poor flow properties, are usually difficult to use during direct compression. Many excipients (tested in this study) are formulated to accommodate these drugs and produce acceptable functional tablets. After identifying the best filler/binders (co–processed fillers), according to their flow and compressible properties, paracetamol was added to the formulations. During a pilot study, the percentage paracetamol these fillers could accommodate in a 400 mg tablet was determined. Both Microcelac and Cellactose could accommodate 24.5% w/w paracetamol, whilst Starlac could only accommodated 19.5% w/w. Paracetamol is well known for its tendency to cause tablet capping and lamination. An acceptable upper punch setting range (20–22) was chosen for tabletting, followed by quality control tests done. All three formulations produced suitable tablets for testing and exhibited good tablet properties. All tablets disintegrated within two minutes, with hardness profiles between 120 N and 148 N and friability percentages less than 1%. Dissolution studies, however, are probably the ultimate test to distinguish between the capability of filler/binders to release the optimum percentage drug after disintegration. Dissolution studies were done on all three formulations using the AUC (area under the curve) and IDR (initial drug release) as parameters to evaluate drug release. All tablets exhibited high initial dissolution rates (between 0.018 - 0.023 mg/min/ml) and 100% drug release was observed. Starlac presented with a lower amount of drug released compared to the other two, but can be explained by the lower percentage (19.5%) paracetamol present in the formulation. It was once again confirmed that the physical and compressible properties of potential directly compressible filler/binders play a major role in direct compression. It was concluded that co–processed filler/binders (Starlac, Microcelac and Cellactose) definitely exhibited better tabletting properties during direct compression. They were able to accommodate a certain percentage of paracetamol, although it was expected that they would accommodate a higher amount (at least 50% of total tablet weight). / Thesis (M.Sc. (Pharmaceutics))--North-West University, Potchefstroom Campus, 2011.

Direct compression has gained significant interest since its advent in the late 1950's due to its potential ease compared to wet granulation. The primary prerequisites for powders used in direct compression are (i) good flow properties (ii) good compressibility and (iii) an acceptable dilution potential to accommodate a relative high percentage of active ingredient. Several filler/binders have been manufactured especially for direct compression and co–processing is one of the recent methods used to produce good compressible excipients with acceptable flow properties. In this study, lactose–based filler/binders were used which included simple and modified lactose materials (Granulac, Lactopress, Flowlac and Tablettose) as well as co–processed excipients (Starlac, Cellactose and Microcelac). A comprehensive literature study on direct compression revealed the importance of the physical properties of filler/binders such as interparticle forces, particle shape, particle size and distribution, powder density, particle surface structure and particle packing geometry which influence the flow of powders. All the materials were subjected to the various tests available to evaluate powder flow, namely (i) angle of repose (AoR), (ii) critical orifice diameter (COD), (iii) flow rate and percentage compressibility (%C) in terms of the powders' bulk and tap densities. The results of these tests confirmed the expected flow properties of the various filler/binders, with only one material exhibiting extremely poor flow properties. The following rank order in terms of all flow tests conducted was established; Starlac >> Microcelac ~ Flowlac >> Cellactose > Tablettose > Lactopress >>> Granulac. The co–processed filler/binders presented with superior flow compared to the other lactose–based materials. During the next phase of the study, the compaction properties of the various fillers were evaluated, employing direct compression. Compacts of pure filler were tabletted on an eccentric tablet press at different compression pressures (manipulated by the upper punch setting of the tablet press). The modified lactose filler/binders (Lactopress, Flowlac and Tablettose) exhibited unexpectedly poor compression profiles, where the co–processed filler/binders (Starlac, Cellactose and Microcelac) produced compacts with acceptable appearance and compact properties. Two lubricants (Mg–St or Pruv), which were tested separately in formulations were added since no compacts could be produced from the pure filler/binders. None of the modified lactose filler/binders, in combination with a lubricant, were able to produce an acceptable compact, since lamination occurred during compression. The co–processed filler/binders produced satisfactory compacts with the addition of a lubricant, but lactose–cellulose fillers (Cellactose and Microcelac) also required the inclusion of a disintegrant (Ac–Di–Sol) to induce satisfactory compact disintegration. Poor compressible active ingredients (paracetamol), which exhibit very poor flow properties, are usually difficult to use during direct compression. Many excipients (tested in this study) are formulated to accommodate these drugs and produce acceptable functional tablets. After identifying the best filler/binders (co–processed fillers), according to their flow and compressible properties, paracetamol was added to the formulations. During a pilot study, the percentage paracetamol these fillers could accommodate in a 400 mg tablet was determined. Both Microcelac and Cellactose could accommodate 24.5% w/w paracetamol, whilst Starlac could only accommodated 19.5% w/w. Paracetamol is well known for its tendency to cause tablet capping and lamination. An acceptable upper punch setting range (20–22) was chosen for tabletting, followed by quality control tests done. All three formulations produced suitable tablets for testing and exhibited good tablet properties. All tablets disintegrated within two minutes, with hardness profiles between 120 N and 148 N and friability percentages less than 1%. Dissolution studies, however, are probably the ultimate test to distinguish between the capability of filler/binders to release the optimum percentage drug after disintegration. Dissolution studies were done on all three formulations using the AUC (area under the curve) and IDR (initial drug release) as parameters to evaluate drug release. All tablets exhibited high initial dissolution rates (between 0.018 - 0.023 mg/min/ml) and 100% drug release was observed. Starlac presented with a lower amount of drug released compared to the other two, but can be explained by the lower percentage (19.5%) paracetamol present in the formulation. It was once again confirmed that the physical and compressible properties of potential directly compressible filler/binders play a major role in direct compression. It was concluded that co–processed filler/binders (Starlac, Microcelac and Cellactose) definitely exhibited better tabletting properties during direct compression. They were able to accommodate a certain percentage of paracetamol, although it was expected that they would accommodate a higher amount (at least 50% of total tablet weight). / Thesis (M.Sc. (Pharmaceutics))--North-West University, Potchefstroom Campus, 2011.

Fabrication of SWCNT-PMMA and Activated Charcoal- PMMA composites was carried out by the compression moulding technique. Then Mechanical and Electrical properties of the composites were investigated. The morphological studies of composites showed a) good dispersion of fillers and b) good interaction between fillers and matrix. Electrical conductivity of SWCNT-PMMA composites was increased by 9 orders of magnitude (at 0.8 % volume fraction of SWCNT) and that of AC-PMMA composites increased by 16 orders of magnitude (at 17 % volume fraction of AC). The percolation threshold of both composites turned out to be lower compared to the theoretical values. A significant improvement in mechanical properties was obtained ??? particularly in AC-PMMA composites which showed a 400 % improvement in Vickers microhardness ??? raising the polymer matrix abrasion property literally to that of Aluminium alloys (Dobrazanski et al 2006). In conclusion, it is to be noted that Activated Charcoal - PMMA composites have a great potential for cost effective conducting polymer composite production by the use of cheap filler: In addition, the compression moulding technique shows good potential for cost effective fabricating technique for amorphous polymers with high electrical and mechanical properties.

The cement being used in the construction industry is the result of a chemical process<p>linked to the decarbonation of limestone conducted at high temperature and results in a<p>significant release of CO2. This thesis is part of the project EcoBéton (Green concrete) funded<p>by the French National Research Agency (ANR), with a purpose to show the feasibility of<p>high substitution of cement by mineral additions such as blast furnaces slag, fly ash and<p>limestone fillers. Generally for high percentages of replacements, the early age strength is<p>lower than Portland cement concrete. To cope with this problem, an optimisation method for<p>mix design of concrete using Bolomey’s law has been proposed. Following the encouraging<p>results obtained from mortar, a series of tests on concretes with different substitution<p>percentages were carried out to validate the optimisation method. To meet the requirements of<p>the construction industry related to performance of concrete at early age, which determine<p>their durability, a complete experimental study was carried out. Standard tests for the<p>characterization of the mechanical properties (compressive strength, tensile strength, and<p>setting) allowed to validate the choice of mix design on the basis of equivalent performance.<p>We focused on the hydration process to understand the evolution of the mechanical<p>properties. Setting time measurement by ultrasound device at different temperatures (10°C,<p>20°C and 30°C) showed that ground granulated blast furnace slag (GGBFS) and fly ash<p>delayed the setting process, while use of limestone filler may accelerate this process.<p>Calorimetric studies over mortars and concretes made possible to calculate the activation<p>energy of the different mixtures and a decrease in heat of hydration of concretes with mineral<p>additions was observed which is beneficial for use in mega projects of concrete. Scanning<p>Electron Microscopy observations and thermal analysis have given enough information about<p>the hydration process. It was observed that the hydration products are similar for different<p>concrete mixtures, but the time of their appearance and quantity in the cement matrix varies<p>for each concrete mix.<p>Last part of the thesis was dedicated to the study of main types of shrinkage. First of all,<p>deformations measured were correlated to hydration, capillary depression and porosity<p>evolution. Results allowed concluding that the use of mineral additions has an actual effect on<p>the plastic shrinkage behaviour, but its impact is not proportional to the percentage of<p>additions. Substitution of cement by the additions seems to have a marked influence on the<p>kinetics of the shrinkage without any effect on its long term amplitude. The study of<p>restrained shrinkage under drying conditions by means of ring tests showed that concretes<p>with high percentage of slag addition seem more prone to cracking than the Portland cement<p>concretes. / Doctorat en Sciences de l'ingénieur / info:eu-repo/semantics/nonPublished