Made available in DSpace on 2014-12-17T14:06:55Z (GMT). No. of bitstreams: 1 PauloABFS.pdf: 4582501 bytes, checksum: 584f0137b6a82bb6929f46d4a543c41c (MD5) Previous issue date: 2007-12-21 / Population growth experienced in major cities, allied to society s need of infra-structure, especially ones related to habitational demands, increases the consumption of construction materials. As a consequence, consumption of natural resources itself. Thus, due to this process, concrete is one of the most produced materials in civil construction. This is also due to the great diversity of its application, easiness in its execution and adequate mechanical performance, as well as low production costs. Following the same tendencies in construction development, the ceramic industry has intensified the production of porcelain ceramic tiles and floors. These are achieved by a fine finishing and receive polishing at the end of the fabrication process. This work researched the use of porcelain residues in polishing for the production of concrete. All of which; due to economical and environmental issues. This process aims to prove adequate destiny for this type of residue, due to environmental issues, incorporating it to the concrete itself; all of which provides economy in consumption of the materials that constitute concrete. Thus, the main characteristics of concrete were investigated through the inclusion of different concentration of the porcelain residue as additional trait element. The residue rates incorporated to the trait varied from 10% to 50% in relation to the cement mass, in the traits with plastic additives and without plastic additives. It is observed that the inclusion of porcelain residue produced a meaningful alteration in the consistency of fresh concrete. This residue has a fine granulometry and it considerably absorbed the water used in the concrete spreading, influencing the way this material is dealt with. Thus, the value of cement striking decreases with the increase of residues present in trait. The maximal incorporation of the residue was of 50%, massively, for the same factor water/initial cement. The use of residues in concrete results in an 40% increase in the compression resistance. It is also proportional to residue concentration of porcelain in the trait. The microstructure was also favored once porosity and concrete absorption decreases with the use of this residue. The parameters demonstrate the quality and durability of the concrete produced with this residue. The use of porcelain residue in concrete composition has not produced meaningful thermal behavior changes. Thermal conductivity, heat capacity and thermal diffusivity have been maintained basically constant / O crescimento populacional nos grandes centros, aliado a necessidade de gera??o de infra-estrutura ? sociedade, est? obrigando a ind?stria da constru??o civil a intensificar suas atividade, principalmente no que se refere ? demanda habitacional, resultando no aumento do consumo de materiais de constru??o e, consequentemente, dos recursos naturais. Decorrente desse processo, o concreto destaca-se como um dos materiais mais produzidos na constru??o civil, pela grande diversidade de aplica??o, facilidade de execu??o e adequado desempenho mec?nico, al?m de apresentar baixo custo de produ??o. Seguindo a mesma tend?ncia de desenvolvimento da constru??o, a ind?stria cer?mica tem intensificado a produ??o de pisos cer?micos do tipo porcelanato, que consistem em elementos de acabamento fino e, por isso, recebem polimento ao final do processo de fabrica??o. Este trabalho pesquisou o emprego do res?duo do polimento de porcelanato para a produ??o de concreto por motivos econ?micos e ambientais. O objetivo consiste em gerar um destino adequado para o res?duo, por motivos ambientais, incorporando-o ao concreto, e, ainda, propiciar uma economia no consumo dos materiais constituintes do concreto. Para tanto, foram investigadas as principais caracter?sticas do concreto a partir da inclus?o de diferentes concentra??es do res?duo de porcelanato como elemento adicional no tra?o. Os teores de res?duo incorporados ao tra?o variaram de 10% a 50% em rela??o ? massa de cimento, em tra?os com aditivo plastificante e sem aditivo plastificante. O acr?scimo do res?duo de porcelanato alterou significativamente a consist?ncia do concreto fresco. O res?duo apresenta uma granulometria muito fina e, por isso, absorveu consideravelmente a ?gua de amassamento do concreto, influenciando, assim, na trabalhabilidade do mesmo. Portanto, o valor do abatimento diminui com o aumento da concentra??o do res?duo no tra?o. A incorpora??o m?xima de res?duo foi de 50% , em massa, para o mesmo fator ?gua/cimento inicial. A utiliza??o do res?duo no concreto resultou em um aumento de at? 40% na resist?ncia ? compress?o, sendo proporcional a concentra??o do res?duo de porcelanato no tra?o. A microestrutura tamb?m foi favorecida, ? medida que a porosidade e a absor??o do concreto diminu?ram com a utiliza??o do res?duo. Esses par?metros atestam a qualidade e a durabilidade do concreto produzido com res?duo. A utiliza??o do res?duo de porcelanato na composi??o do concreto n?o gerou mudan?as significativas no comportamento t?rmico. A condutividade t?rmica, a capacidade calor?fica e a difusividade t?rmica se mantiveram basicamente constantes

Made available in DSpace on 2014-12-17T14:07:07Z (GMT). No. of bitstreams: 1 LuizFMC_TESE.pdf: 3268756 bytes, checksum: e846724b8b5adbbee4ec9a2ecaf76796 (MD5) Previous issue date: 2011-06-20 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / The use of raw materials from renewable sources for production of materials has been the subject of several studies and researches, because of its potential to substitute petrochemical-based materials. The addition of natural fibers to polymers represents an alternative in the partial or total replacement of glass fibers in composites. In this work, carnauba leaf fibers were used in the production of biodegradable composites with polyhydroxybutyrate (PHB) matrix. To improve the interfacial properties fiber / matrix were studied four chemical treatments to the fibers..The effect of the different chemical treatments on the morphological, physical, chemical and mechanical properties of the fibers and composites were investigated by scanning electron microscopy (SEM), infrared spectroscopy, X-ray diffraction, tensile and flexural tests, dynamic mechanical analysis (DMA), thermogravimetry (TGA) and diferential scanning calorimetry (DSC). The results of tensile tests indicated an increase in tensile strength of the composites after the chemical treatment of the fibers, with best results for the hydrogen peroxide treated fibers, even though the tensile strength of fibers was slightly reduced. This suggests a better interaction fiber/matrix which was also observed by SEM fractographs. The glass transition temperature (Tg) was reduced for all composites compared to the pure polymer which can be attributed to the absorption of solvents, moisture and other low molecular weight molecules by the fibers / O uso de mat?rias-primas de fontes renov?veis para a produ??o de materiais vem sendo objeto de diversos estudos e pesquisas, devido ao seu potencial na substitui??o de derivados petroqu?micos. A adi??o de fibras vegetais a pol?meros representa uma alternativa na substitui??o parcial ou total de fibras de vidro em comp?sitos. Neste trabalho, fibras da folha de carna?ba (Copernicia prun?fera) foram utilizadas na produ??o de comp?sitos biodegrad?veis com matriz de polihidroxibutirato (PHB). Para melhorar as propriedades interfaciais fibra/matriz foram estudados quatro tratamentos qu?micos, para as fibras. O efeito dos diferentes tratamentos qu?micos nas propriedades morfol?gicas, f?sicas, qu?micas e mec?nicas das fibras e dos comp?sitos foram investigados por microscopia eletr?nica de varredura (MEV), espectroscopia no infravermelho, difra??o de raios-X, ensaios mec?nicos de tra??o e flex?o, an?lise din?mico-mec?nica (DMA) e an?lises t?rmicas por termogravimetria (TG) e calorimetria explorat?ria diferencial (DSC). Os resultados dos ensaios de tra??o dos comp?sitos indicaram um acr?scimo de resist?ncia ? tra??o ap?s modifica??o qu?mica das fibras, sendo o melhor resultado obtido com o tratamento de per?xido de hidrog?nio, mesmo havendo uma pequena redu??o na resist?ncia ? tra??o das fibras tratadas. Isto indica uma melhor intera??o entre as fibras e a matriz polim?rica que foi tamb?m observada nas imagens de microscopia eletr?nica de varredura. A temperatura de transi??o v?trea (Tg) foi reduzida para todos os comp?sitos em rela??o ao pol?mero puro o que foi atribu?do a absor??o de solventes, umidade e outras mol?culas de baixo peso molecular pelas fibras

Made available in DSpace on 2014-12-17T14:07:12Z (GMT). No. of bitstreams: 1 JucikleciaSR_DISSERT.pdf: 18878091 bytes, checksum: 13af0d90d6b4b0980975e46b7393cd8c (MD5) Previous issue date: 2013-08-23 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / This work studied the immiscible blend of elastomeric poly(methyl methacrylate) (PMMA) with poly(ethylene terephthalate) (PET) bottle grade with and without the use of compatibilizer agent, poly(methyl methacrylate-co-glycidyl methacrylate - co-ethyl acrylate) (MGE). The characterizations of torque rheometry, melt flow index measurement (MFI), measuring the density and the degree of cristallinity by pycnometry, tensile testing, method of work essential fracture (EWF), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were performed in pure polymer and blends PMMA/PET. The rheological results showed evidence of signs of chemical reaction between the epoxy group MGE with the end groups of the PET chains and also to the elastomeric phase of PMMA. The increase in the concentration of PET reduced torque and adding MGE increased the torque of the blend of PMMA/PET. The results of the MFI also show that elastomeric PMMA showed lower flow and thus higher viscosity than PET. In the results of picnometry observed that increasing the percentage of PET resulted in an increase in density and degree crystallinity of the blends PMMA/PET. The tensile test showed that increasing the percentage of PET resulted in an increase in ultimate strength and elastic modulus and decrease in elongation at break. However, in the phase inversion, where the blend showed evidence of a co-continuous morphology and also, with 30% PET dispersed phase and compatibilized with 5% MGE, there were significant results elongation at break compared to elastomeric PMMA. The applicability of the method of essential work of fracture was shown to be possible for most formulations. And it was observed that with increasing elastomeric PMMA in the formulations of the blends there was an improvement in specific amounts of essential work of fracture (We) and a decrease in the values of specific non-essential work of fracture (βWp) / Neste trabalho ? estudada a blenda imisc?vel poli(metacrilato de metila) (PMMA) elastom?rico com poli(tereftalato de etileno) (PET) grau garrafa com e sem o uso do agente compatibilizante, poli(metacrilato de metila-co-metacrilato de glicidilaco- acrilato de etila) (MGE). As caracteriza??es de reometria de torque, medida de ?ndice de fluidez (MFI), determina??o da densidade e do grau de cristalinidade por picnometria, ensaio de tra??o uniaxial, m?todo do trabalho essencial fratura (EWF), microscopia eletr?nica de varredura (MEV) e microscopia eletr?nica de transmiss?o (MET), foram realizadas nos pol?meros puros e nas blendas PMMA/PET. Os resultados reol?gicos apresentaram ind?cios de rea??o qu?mica entre o grupo ep?xi do MGE com os grupos finais de cadeias do PET e, tamb?m, com a fase elastom?rica do PMMA. O aumento na concentra??o de PET reduziu o torque e a adi??o do MGE aumentou o torque da blenda PMMA/PET. Os resultados de MFI mostraram tamb?m que, o PMMA elastom?rico apresentou menor fluidez e, consequentemente, maior viscosidade que o PET. Nos resultados de picnometria observou-se que, o aumento da porcentagem de PET proporcionou um aumento na densidade e no grau de cristalinidade das blendas PMMA/PET. Os ensaios de tra??o mostraram que, o aumento da porcentagem de PET proporcionou um aumento na resist?ncia m?xima e no m?dulo de elasticidade e uma diminui??o no alongamento na ruptura. Entretanto, na invers?o de fase, onde a blenda apresentou ind?cios de uma morfologia cocont?nua e tamb?m, com 30% de fase dispersa PET e compatibilizada com 5% de MGE, verificaram-se resultados expressivos de alongamento na ruptura em rela??o ao PMMA elastom?rico. A aplicabilidade do m?todo do trabalho essencial de fratura mostrou-se poss?vel para a maioria das formula??es. Observou-se ainda que, com o aumento do PMMA elastom?rico nas formula??es das blendas, ocorreu uma melhoria nos valores do trabalho essencial espec?fico de fratura (We) e uma redu??o nos valores do trabalho n?o essencial espec?fico de fratura (βWp)

Made available in DSpace on 2014-12-17T14:07:20Z (GMT). No. of bitstreams: 1 ElvioAG_TESE.pdf: 3444604 bytes, checksum: d60cf497e4c263de969e02bb2eefe56f (MD5) Previous issue date: 2013-12-20 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / This research was motivated by the requirement of asbestos s replacement in building systems and the need to generate jobs and income in the country side of the state of Bahia, Brazil. The project aimed at using fibers from licuri leaves (syagrus coronata), an abundant palm in the region, to produce composites appropriate for the sustainable production of cement fibre reinforced products in small plants. The composites were produced in laboratory using Portland cement CP-II-F32, sand, water, licuri palm fiber contents of 1.0, 1.5 and 2.0% by weight of binder (two different fiber length) and metakaolin. The latter was chosen as an additional binder for its efficiency to reduce the alkalinity of cementitious matrixes therefore preventing the degradation of vegetable fibers. The characterization of the composite components was carried out by sieving and laser particle size analyses, thermal analysis, fluorescence and X-ray diffraction. The composites performance was evaluated by 3- point-bending tests, compressive strength, ultrasound module of elasticity, free and restrained shrinkage, water capillarity absorption and apparent specific gravity. It has been found that the addition of fibers increased the time to onset of cracking over 200.00% and a 25% reduction in cracks opening in the restrained shrinkage test. The capillary absorption reduced about 25% when compared to fiber-free composites. It was also observed with regard to flexural strength, compressive strength and specific gravity, that the addiction of fibers did not affect the composite performance presenting similar results for compounds with and without fibers. In general it can be stated that the reinforced composite fibers of palm licuri presents physical and mechanical characteristics which enable them to be used in the intended proposals of this research / A exig?ncia da substitui??o do amianto em sistemas construtivos em conjunto com a necessidade de gera??o de renda no sert?o da Bahia fez nascer o projeto do aproveitamento da fibra da palma do licuri (syagrus coronata), palmeira abundante na regi?o, na produ??o de comp?sitos para a fabrica??o artefatos de cimento refor?ados com fibras para a constru??o civil de maneira sustent?vel, em pequenas unidades fabris. Os comp?sitos foram produzidos em laborat?rio utilizando cimento Portland CP II-F32, areia, ?gua, metacaulinita e fibra da palma do licuri. As fibras foram adicionadas em teores de 1,0, 1,5 e 2,0% da massa do aglomerante e com dois comprimentos de fibra diferentes. A metacaulinita foi selecionada como aglomerante suplementar de forma a agir na redu??o da alcalinidade da matriz ciment?cia na perspectiva de diminuir ou at? mesmo eliminar a degrada??o das fibras vegetais em meio alcalino. Foram realizados ensaios de caracteriza??o dos componentes do comp?sito, incluindo granulometria, an?lise t?rmica, fluoresc?ncia e difratometria de Raios-X. A verifica??o do desempenho dos comp?sitos foi feita com ensaios de flex?o em tr?s pontos, resist?ncia ? compress?o axial, m?dulo de elasticidade por ultrassom, retra??o livre e restringida, absor??o de ?gua por capilaridade e massa espec?fica aparente. Verificou-se que a presen?a das fibras de licuri aumentou o tempo para o surgimento da fissura??o acima de 200,00% e redu??o de 25% na abertura das fissuras no ensaio de retra??o restringida. Com rela??o ? absor??o capilar ocorreu uma redu??o de 25%, quando comparados com os materiais sem fibras. Observou-se que, com rela??o ? resist?ncia a flex?o, compress?o axial e massa espec?fica aparente, a adi??o de fibras n?o afeta o desempenho dos materiais, apresentando resultados similares para materiais com e sem fibras. De uma maneira geral pode-se afirmar que os comp?sitos refor?ados com fibras da palma do licuri apresentam caracter?sticas f?sicas e mec?nicas que viabilizam sua aplica??o dentro das condi??es estabelecidas neste trabalho

Made available in DSpace on 2014-12-17T14:57:43Z (GMT). No. of bitstreams: 1 AlyssonRFB.pdf: 2167882 bytes, checksum: 8299a168b4ffa71ad51d65356a2a5ae5 (MD5) Previous issue date: 2006-12-21 / The advantage in using vegetable fibres in place of synthetic fibres such as glass fibre, for reinforcements in composites are: biodegradability, low cost, low density, good tenacity, good thermal properties, low energy content and reduced use of instruments for its treatment or processing. Even though, problems related to low mechanical performance of some of the natural fibres, has caused difficulty in their direct application in structural elements. The use of alternative materials like hybrid composites has been encouraged, thus trying to better the structural performance of the composites with natural fibres. This work presents a comparative study of the strength and stiffness of hybrid composites with orthopthalic polyester matrix reinforced with E-fibre glass, jute and curau?. The experimental part includes uniaxial tension and three point bending tests to determine the mechanical properties of the final product. The hybrid composite was manufactured in a local industry and was in the form of laminates. All the samples were projected to withstand the possible structural applications as reservoirs and pipes. CH (laminated hybrid composite with glass and curau? fibres). The results obtained show clearly the influence of the hybridization in all the types tested and indicate a good mechanical performance of the composite with glass/curau? fibres in relation to the composite with glass fibres. Aspects in relation to the interfaces glass/curau? composites besides the fracture characteristics for all loading types were also analysed / As vantagens do uso de fibras vegetais sobre as fibras sint?ticas, como as fibras de vidro, no refor?o de comp?sitos s?o: biodegradabilidade, baixo custo, baixa densidade, boa tenacidade, boas propriedades t?rmicas e uso reduzido de instrumentos para o seu tratamento ou processamento. Por?m, problemas relacionados com o baixo desempenho mec?nico de algumas fibras naturais, t?m dificultado seu uso direto em elementos estruturais. Neste sentido, o aparecimento de materiais alternativos, como os comp?sitos h?bridos, vem sendo incentivado buscando-se melhorar o desempenho estrutural dos comp?sitos com fibras naturais. O presente trabalho de investiga??o apresenta um estudo comparativo da resist?ncia e rigidez de comp?sito de matriz poli?ster ortoft?lica refor?ada com fibras de vidro-E e h?brido com fibras naturais de curau?. A investiga??o experimental inclui testes de absor??o de umidade, tra??o uniaxial e de flex?o-em-tr?s-pontos para a determina??o das propriedades mec?nicas do produto final. Os comp?sitos de fibra de vidro e h?bridos s?o de fabrica??o industrial e foram desenvolvidos na forma de laminados. Todos foram projetados para atender poss?veis aplica??es estruturais como reservat?rios e tubula??es: Laminados de fibras de vidro (CV) e h?bridos (CH) (comp?sito laminado h?brido de fibras de vidro/curau?). Os refor?os utilizados nos comp?sitos foram na formas de tecidos aleat?rios (vidro-E) e mechas de fios cont?nuos (curau?). Os resultados obtidos mostram claramente a influ?ncia da hibridiza??o e meios de absor??o de umidade e indicam um bom desempenho mec?nico do comp?sito curau?/vidro. Tamb?m foram analisados aspectos referentes ? interface curau?/vidro e as caracter?sticas finais da fratura para todos os tipos de carregamentos estudados

Made available in DSpace on 2014-12-17T14:57:44Z (GMT). No. of bitstreams: 1 LeonardoPSR.pdf: 5835314 bytes, checksum: 12deb1964ac794f5dcc1b8fb3ba5e4c9 (MD5) Previous issue date: 2007-12-26 / The advantages of the use of vegetable fibers on the synthetic fibers, such as glass fibers, in the reinforcements in composites are: low cost, low density, good tenacity, good thermal properties and reduced use of instruments for their treatment or processing. However, problems related to poor performance of some mechanical natural fibers, have hindered its direct use in structural elements. In this sense, the emergence of alternative materials such as hybrids composites, involving natural and synthetic fibers, has been encouraged by seeking to improve the performance of structural composites based only on natural fibers. The differences between the physical, chemical and mechanical properties of these fibers, especially facing the adverse environmental conditions such as the presence of moisture and ultraviolet radiation, is also becoming a concern in the final response of these composites. This piece of research presents a comparative study of the strength and stiffness between two composite, both of ortoftalic polyester matrix, one reinforced with fibers of glass-E (CV) and other hybrid reinforced with natural fibers of curau? and fiberglass-E (CH). All the comparative study is based on the influence of exposure to UV rays and steam heated water in composites, simulating the aging environment. The conditions for the tests are accelerated through the use of the aging chamber. The composites will be evaluated through tests of uniaxial static mechanical traction and bending on three points. The composite of glass fiber and hybrid manufacturing industry are using the rolling manual (hand lay-up) and have been developed in the form of composites. All were designed to meet possible structural applications such as tanks and pipes. The reinforcements used in composites were in the forms of short fiber glass-E quilts (450g/m2 - 5cm) of continuous wires and fuses (whose title was of 0.9 dtex) for the curau? fibers. The results clearly show the influence of aging on the environmental mechanical performance of the composite CV and CH. The issues concerning the final characteristics of the fracture for all types of cargoes studied were also analyzed / As vantagens do uso de fibras vegetais sobre as fibras sint?ticas, como as fibras de vidro, no refor?o de comp?sitos s?o: baixo custo, baixa densidade, boa tenacidade, boas propriedades t?rmicas e uso reduzido de instrumentos para o seu tratamento ou processamento. Por?m, problemas relacionados com o baixo desempenho mec?nico de algumas fibras vegetais, t?m dificultado seu uso direto em elementos estruturais. Neste sentido, o aparecimento de materiais alternativos, como os comp?sitos h?bridos, envolvendo fibras sint?ticas e naturais, vem sendo incentivado buscando-se melhorar o desempenho estrutural dos comp?sitos a base s? de fibras vegetais. As diferen?as entre as propriedades f?sicas, qu?micas e mec?nicas dessas fibras, principalmente frente ?s condi??es ambientais adversas, como a presen?a de umidade e radia??o ultravioleta, vem se tornando uma preocupa??o a mais na resposta final desses comp?sitos. No presente trabalho de investiga??o apresenta-se um estudo comparativo da resist?ncia e rigidez entre dois comp?sitos, ambos de matriz poli?ster ortoft?lica, sendo um refor?ado com fibras de vidro-E (CV) e o outro h?brido refor?ado com fibras vegetais de curau? e fibra de vidro-E (CH). Todo o estudo comparativo teve como base a influ?ncia da exposi??o ? raios UV e vapor d ?gua aquecido nos comp?sitos, simulando o envelhecimento ambiental. As condi??es de ensaios s?o aceleradas atrav?s do uso da c?mara de envelhecimento. Os comp?sitos ser?o avaliados atrav?s de ensaios mec?nicos est?ticos de tra??o uniaxial e flex?o em tr?s pontos. Os comp?sitos de fibra de vidro e h?bridos s?o de fabrica??o industrial utilizando o processo de lamina??o manual (hand lay-up) e foram desenvolvidos na forma de comp?sitos. Todos foram projetados para atender poss?veis aplica??es estruturais, como reservat?rios e tubula??es. Os refor?os utilizados nos comp?sitos foram na formas de mantas de fibras vidro-E curtas (450g/m2 5cm) e mechas de fios cont?nuos (cujo t?tulo foi de 0,9 dtex) para as fibras de curau?. Os resultados obtidos mostram claramente a influ?ncia do envelhecimento ambiental no desempenho mec?nico dos comp?sitos CV e CH. Tamb?m foram analisados aspectos referentes ?s caracter?sticas finais da fratura para todos os tipos de carregamentos estudados

Made available in DSpace on 2014-12-17T14:57:46Z (GMT). No. of bitstreams: 1 MirtaniaAL.pdf: 1813042 bytes, checksum: 3d26a66f383220285205f479f11b4656 (MD5) Previous issue date: 2009-09-27 / This research is based, at first, on the seeking of alternatives naturals reinforced in place of polymeric composites, also named reinforced plastics. Therein, this work starts with a whole licuri fiber micro structural characterization, as alternative proposal to polymeric composites. Licuri fiber is abundant on the Bahia state flora, native from a palm tree called Syagrus Coronata (Martius) Beccari. After, it was done only licuri fiber laminar composite developing studies, in order to know its behavior when impregnated with thermofix resin. The composite was developed in laminar structure shape (plate with a single layer of reinforcement) and produced industrially. The layer of reinforcement is a fabric-fiber unidirectional of licuri up in a manual loom. Their structure was made of polyester resin ortofit?lica (unsaturated) only reinforced with licuri fibers. Fiber characterization studies were based on physical chemistry properties and their constitution. It was made by tension, scanning electron microscopy (SEM), x-ray diffraction (RDX) and thermal analyses (TG and DTA) tests, besides fiber chemistry analyses. Relating their mechanical properties of strength and hardness testing, they were determined through unit axial tension test and flexion in three points. A study in order to know fiber/matrix interface effects, in the final composites results, was required. To better understand the mechanical behavior of the composite, macroscopic and microscopic optical analysis of the fracture was performed / Esta investiga??o baseia-se, em principio, na busca de refor?os naturais alternativos aos comp?sitos polim?ricos, tamb?m denominados de pl?sticos refor?ados. Neste sentido, o presente trabalho de pesquisa se inicia com um completo estudo de caracteriza??o micro estrutural da fibra de licuri, essa como proposta alternativa de refor?o aos comp?sitos polim?ricos. A fibra de licuri ? abundante na flora do estado da Bahia e origin?ria da palmeira denominada Syagrus Coronata (Martius) Beccari. Em seguida, foi realizado um estudo do desenvolvimento de um comp?sito laminar somente a base de fibras de licuri, de forma a se conhecer o comportamento da fibra quando impregnada com resina termofixa. O comp?sito foi desenvolvido na forma de estrutura laminar (placa com uma ?nica l?mina de refor?o) e fabricado industrialmente. A l?mina de refor?o ? de um tecido unidirecional de fibras de licuri confeccionado em um tear manual. O comp?sito tem em sua estrutura resina poli?ster ortofit?lica (insaturada) refor?ada somente com fibras de licuri. O estudo da caracteriza??o da fibra teve como base a determina??o das propriedades f?sicas, qu?micas e de constitui??o. As mesmas foram realizadas atrav?s dos ensaios de: tra??o uniaxial, an?lise por microscopia eletr?nica de varredura (MEV), ensaio de difra??o de raios X (RDX), an?lises t?rmicas (TG e DTA), al?m da an?lise qu?mica das fibras. Com rela??o ?s propriedades mec?nicas de resist?ncia e rigidez do comp?sito, estas foram determinadas atrav?s dos ensaios de tra??o uniaxial e flex?o em tr?s pontos. Um estudo com o objetivo de conhecer a influ?ncia da ader?ncia da interface fibra/matriz, na resposta final do comp?sito, se fez necess?rio. Para melhor entendimento do comportamento mec?nico do comp?sito, an?lises macrosc?picas e microsc?picas ?pticas da fratura foram realizadas

Made available in DSpace on 2014-12-17T14:57:50Z (GMT). No. of bitstreams: 1 RannierMM.pdf: 3580955 bytes, checksum: f892200d861ab62414259c44c459e1b9 (MD5) Previous issue date: 2009-03-30 / The use of polymer based coatings is a promising approach to reduce the corrosion problem in carbon steel pipes used for the transport of oil and gas in the oil industry. However, conventional polymer coatings offer limited properties, which often cannot meet design requirements for this type of application, particularly in regard to use temperature and wear resistance. Polymer nanocomposites are known to exhibit superior properties and, therefore, offer great potential for this type of application. Nevertheless, the degree of enhancement of a particular property is greatly dependent upon the matrix/nanoparticle material system used, the matrix/nanoparticle interfacial bonding and also the state of dispersion of the nanoparticle in the polymer matrix. The objective of the present research is to develop and characterize polymer based nanocomposites to be used as coatings in metallic pipelines for the transportation of oil and natural gas. Epoxy/SiO2 nanocomposites with nanoparticle contents of 2, 4, and 8 wt % were processed using a high-energy mill. Modifications of the SiO2 nanoparticles‟ surfaces with two different silane agents were carried out and their effect on the material properties were investigated. The state of dispersion of the materials processed was studied using Scanning and Transmission Electron Microscopy (SEM and TEM) micrographs. Thermogravimetric analysis (TG) were also conducted to determine the thermal stability of the nanocomposites. In addition, the processed nanocomposites were characterized by dynamic mechanical analysis (DMA) to investigate the effect of nanoparticles content and silane treatment on the viscoelastic properties and on the glass transition temperature. Finally, wear tests of the pin-on-disc type were carried out to determine the effects of the nanoparticles and the silane treatments studied. According to the results, the addition of SiO2 nanoparticles treated with silane increased the thermal stability, the storage modulus and Tg of the epoxy resin and decreased wear rate. This confirms that the interaction between the nanoparticles and the polymer chains plays a critical role on the properties of the nanocomposites / A utiliza??o de pol?mero como revestimento ? algo promissor para redu??o de corros?o interna de dutos de a?o carbono utilizados no transporte de petr?leo e g?s natural na ind?stria petrol?fera. No entanto, os revestimentos polim?ricos convencionais apresentam propriedades limitadas, que muitas vezes n?o podem satisfazer os requisitos necess?rios, particularmente em rela??o ? temperatura empregada e ao desgaste. Nanocomp?sitos polim?ricos s?o conhecidos por apresentarem propriedades superiores e, portanto, apresentam potencial para este tipo de aplica??o. Por?m, o grau de refor?o de uma propriedade particular ? fortemente dependente dos materiais utilizados no sistema matriz/nanopart?culas, da liga??o interfacial e, tamb?m, do estado de dispers?o das nanopart?culas na matriz polim?rica. O objetivo do presente trabalho ? desenvolver e caracterizar nanocomp?sitos polim?ricos para utiliza??o como revestimento de dutos met?licos da ind?stria do petr?leo. Nanocomp?sitos Ep?xi/SiO2 com 2, 4 e 8% em massa de nanopart?culas foram processados usando um moinho de alta energia. Modifica??es nas superf?cies das nanopart?culas de SiO2 foram realizadas com dois tipos diferentes de silano e seus efeitos sobre as propriedades dos materiais foram investigados. O estado de dispers?o do material processado foi estudado usando micrografias de Microscopia Eletr?nica de Varredura e de Transmiss?o (MEV e MET). Foram realizadas an?lises termogravim?tricas (TG) para verificar a estabilidade t?rmica dos nanocomp?sitos. Al?m disso, foram realizadas an?lises din?mico-mec?nicas (DMA) para estudar os efeitos das nanopart?culas e dos tratamentos com silano nas propriedades viscoel?sticas e na temperatura de transi??o v?trea (Tg). Por fim, testes de desgaste do tipo esfera-disco foram realizados para determinar os efeitos da adi??o de nanopart?culas e dos diferentes tipos de tratamento de silaniza??o estudados. De acordo com os resultados, a adi??o nanopart?culas de SiO2 tratadas com silano aumentou a temperatura de in?cio de degrada??o do pol?mero, o m?dulo de armazenamento e a Tg da resina ep?xi, al?m de ter proporcionado uma menor taxa de desgaste. Isto confirma que a intera??o entre as nanopart?culas e as cadeias polim?ricas desempenha um papel cr?tico sobre as propriedades dos nanocomp?sitos

Made available in DSpace on 2014-12-17T14:58:07Z (GMT). No. of bitstreams: 1 SistanleyJLB_DISSERT.pdf: 3362424 bytes, checksum: 30d67bc0b13dba47c7002133ab1bb63d (MD5) Previous issue date: 2011-06-20 / This research presents an approach to the addition of curau? fibers and licuri fibers in a polypropylene resin matrix, such as an alternative proposal to reinforce the polymeric composites. Fiber content of 0 %, 5 %, 10 %, and 20% were analyzed for verification of their mechanical properties comparing them, inclusive with the properties of polypropylene. The grainulated biocomposites had been prepared in an extrusora. The test bodies had been molded by injection and submitted to the mechanical essays uniaxial traction, flexion on three points, impact, in addition to thermal tests (HDT). These biocomposites had been also subjected the essay physicist-chemistry index of fluidity (IF). It was observed that the biocomposites of PP with 20% curau?, obtained bigger increase in the modulus of elasticity and a bigger reduction in the resistance to the impact. In the mechanical behavior, for all the biocomposites, these were increases in values of the limit of drainage and tension of rupture, when tested by uniaxial traction, as they added the fibers. Another important point was the increase of the resistance the flexion. It was also noted that the addition of fibers reduced the thermal degradation of the mixture natural fibers / polypropylene. / Esta pesquisa apresenta uma abordagem da adi??o de fibras de licuri e curau? em uma matriz de resina de polipropileno, essa como uma proposta alternativa de refor?o aos comp?sitos polim?ricos. Teores de fibras de 0 %, 5 %, 10 %, e 20 % foram analisados para verifica??o de suas propriedades mec?nicas comparando-as, inclusive com as propriedades do polipropileno. Os biocomp?sitos granulados foram preparados em uma extrusora. Os corpos de prova foram moldados por inje??o e submetidos aos ensaios mec?nicos de tra??o uniaxial, flex?o em tr?s pontos, impacto, al?m de ensaios t?rmicos (HDT). Estes biocomp?sitos tamb?m foram submetidos a ensaio f?sico-qu?mico de ?ndice de fluidez (IF). Observou-se que os biocomp?sitos de PP com 20% curau? obteve maior aumento no m?dulo de elasticidade, e uma maior diminui??o na resist?ncia ao impacto. No comportamento mec?nico, para todos os biocomp?sitos, houve acr?scimos nos valores do limite de escoamento e tens?o de ruptura quando ensaiados por tra??o uniaxial, ? medida que se adicionavam as fibras. Outro ponto importante foi o aumento da resist?ncia ? flex?o. Verificou-se tamb?m que a adi??o de fibras reduziu a degrada??o t?rmica da mistura fibras naturais / polipropileno.

Made available in DSpace on 2014-12-17T14:58:09Z (GMT). No. of bitstreams: 1 HallyjusADB_DISSERT.pdf: 2542860 bytes, checksum: a76cbfa6200b38f0f8ff5811d0315d59 (MD5) Previous issue date: 2011-02-18 / Composite materials have a wide application in various sectors, such as the medical field in the manufacture of prostheses, in automotive and aerospace. Thus it is essential to the development of new composite and a better understanding in the face of various loading conditions and service. Several structural elements are manufactured in the presence of geometric discontinuity (notch, hole, etc ) in their longitudinal sections and/or cross-cutting, and these affect the mechanical response of these elements. The objective is to study the mechanical response of laminated polymer matrix hybrid composites reinforced with glass fiber/jute in a uniaxial tensile test. The mechanical response takes in account both the influence of the presence of a geometric discontinuity (semicircular notches) and the orientation of fibers in the layers (anisotropy). The semicircular notches are located in longitudinal section (with a reduction in cross section) of the same. In this analysis, the anisotropy is characterized by types of configurations (with different orientations of fibers in the outer layers). A comparative study of mechanical properties with and without the presence of notches is developed. Both configurations consist of four layers of woven jute fiber bidirectional and a central layer of bidirectional woven glass fibers. In addition to the mechanical properties was also studied the characteristics of the fracture developed in each composite laminate. The results showed that in the comparative study, the anisotropy and the presence of semicircular notches directly influences the mechanical behavior of laminates composites, mainly in reducing the tensile strength, and well as the final characteristics of the fracture / Os materiais comp?sitos t?m uma ampla aplica??o nos mais variados setores, como por exemplo, na ?rea m?dica na confec??o de pr?teses, na ind?stria automotiva e no setor aeroespacial. Assim ? essencial o desenvolvimento de novos comp?sitos e uma melhor compreens?o frente ?s mais diversas condi??es de carga e servi?o. V?rios elementos estruturais s?o fabricados na presen?a de descontinuidade geom?trica (entalhe, furo etc.) em suas se??es longitudinais e/ou transversais, e essas prejudicam a resposta mec?nica desses elementos. O objetivo do trabalho ? estudar a resposta mec?nica de laminados comp?sitos h?bridos de matriz polim?rica refor?ado com fibras de vidro/juta em um ensaio de tra??o uniaxial. A resposta mec?nica leva em conta tanto a influ?ncia da presen?a de uma descontinuidade geom?trica (entalhes semicirculares) quanto da orienta??o das fibras nas camadas (anisotropia). Os entalhes semicirculares est?o localizados na se??o longitudinal (com redu??o da se??o transversal) dos mesmos. Nessa an?lise, a anisotropia ? caracterizada por dois tipos de configura??es (com diferentes orienta??es das fibras nas camadas externas). Um estudo comparativo das propriedades mec?nicas com e sem a presen?a dos entalhes ? desenvolvido. As duas configura??es consistem de quatro camadas de tecidos bidirecionais de fibras de juta e uma camada central de tecido bidirecional de fibras de vidro. Al?m das propriedades mec?nicas, tamb?m foi estudada as caracter?sticas da fratura desenvolvidas em cada laminado comp?sito. Os resultados mostraram que, no estudo comparativo, a anisotropia e a presen?a dos entalhes semicirculares influi diretamente no comportamento mec?nico dos laminados comp?sitos, principalmente na redu??o da resist?ncia ? tra??o, e bem como na caracter?stica final da fratura