Desenvolvimento e caracterização de compósitos poli(tereftalato de etileno) reciclado (PET reciclado) com flocos de vidro.

The growing concern with the solid residues management, observed in the last decade, due to its huge amount and impact, has motivated the search for recycling processes, where these residues can be reprocessed to generate new products, enlarging the cycle of materials and energy which are present. Among the polymeric residues, there is poly (ethylene terephthalate) (PET). PET is used in food packaging, preferably in the bottling of carbonated beverages. The reintegration of post-consumer PET in half can be considered a productive action mitigation of environmental impacts caused by these wastes and it is done through the preparation of several different products at the origin, i.e. food packaging, with recycling rates increasing to each year. This work focused on the development and characterization mechanical, thermal, thermo-mechanical, dynamic mechanical thermal and morphology of the pure recycled PET and recycled PET composites with glass flakes in the weight fraction of 5%, 10% and 20% processed in a single screw extruder, using the following analytical techniques: thermogravimetry (TG), differential scanning calorimetry (DSC), tensile, Izod impact, Rockwell hardness, Vicat softening temperature, melt flow rate, burn rate, dynamic mechanical thermal analysis (DMTA) and scanning electron microscopy (SEM). The results of thermal analysis and mechanical properties leading to a positive evaluation, because in the thermograms the addition of glass flakes showed increasing behavior in the initial temperatures of thermal decomposition and melting crystalline, Furthermore was observed growing behavior in the mechanical performance of polymer composites, whose morphological structure was observed by SEM, verifying a good distribution of glass flakes, showing difference orientation in the center and in the surface layer of test body of composites with 10 and 20% of glass flakes. The results of DMTA Tg values of the composites obtained from the peak of tan ä showed little reductions due to poor interfacial adhesion between PET and recycled glass flakes.

Produtos têxteis inteligentes incorporando filamentos compósitos com nanotubos de carbono

Programa Doutoral em Engenharia Têxtil.

Estimativa das propriedades de flexão estática de seis espécies de madeiras amazônicas por meio da técnica não-destrutiva de ondas de tensão

A utilização de técnicas não-destrutivas (NDT) pode incrementar o nível de informação tecnológica sobre espécies de madeira conhecidas, bem como daquelas ainda não estudadas. A principal vantagem das técnicas NDT é que são rápidas e várias medidas podem ser feitas, melhorando assim o nível de confiança dos resultados. Nesse contexto, o trabalho objetivou avaliar a viabilidade de utilização da técnica de ondas de tensão na estimativa de propriedades de flexão de seis espécies de madeiras amazônicas. As espécies foram escolhidas com base na sua densidade: Balfourodendron riedelianum, Cedrela fissilis, Cordia goeldiana, Bowdichia virgilioides, Dipteryx odorata and Tabebuia sp. Foram obtidas vinte amostras por espécie nas dimensões segundo ASTM D143-94 para a determinação das propriedades de flexão, totalizando assim 120 amostras. Antes do ensaio destrutivo em flexão estática, as amostras foram avaliadas não-destrutivamente por meio da técnica de ondas de tensão para a determinação do módulo de elasticidade dinâmico e a velocidade de propagação das ondas tensão. De acordo com os resultados, os modelos de regressão foram altamente significativos para a predição das propriedades de flexão do conjunto de espécies. Dessa forma, pode-se concluir que o método é adequado para predizer as propriedades de flexão onde há variação, por exemplo, entre espécies. No entanto, quando a variabilidade é baixa, como dentro da espécie, os modelos apresentaram baixa previsibilidade.

Optimization of magnetoelectric composites based on electroactive polymers for energy harvesting and sensor application

Tese de Doutoramento em Engenharia de Materiais.

Angiogênese na Neoplasia Escamosa do Colo Uterino: Comparação entre dois Marcadores de Células Endoteliais

Objetivo: comparação entre a acurácia dos marcadores de células endoteliais anti-CD34 e anti-fator VIII em neoplasia cervical uterina, em lesões intra-epiteliais e no colo normal. Métodos: os antígenos CD34 e o fator VIII foram identificados, por meio de técnicas de imuno-histoquímica, em 18 fragmentos de neoplasia invasiva, 15 de lesão intra-epitelial de alto grau e 15 de baixo grau e 10 de colos normais, tidos como grupo controle. Fez-se a contagem dos vasos em 10 campos com aumento de 400X, na área de maior densidade vascular. O total de vasos de cada caso resultou da soma dos 10 campos. Resultados: as médias dos vasos corados com anti-CD34 no carcinoma invasivo, em lesão de alto grau, de baixo grau e no colo uterino normal foram 154, 135, 112 e 93 vasos, respectivamente. Com o uso do anti-fator VIII as médias das densidades vasculares foram 56, 44, 33 e 30 vasos, seguindo a mesma ordem das amostras. Lesões de alto grau e carcinomas invasivos do colo apresentaram médias de vasos maiores do que as de colos normais. Conclusões: o emprego do anti-CD34 permite detecção de maior número de vasos do que o uso de anti-fator VIII. Confirmou-se a utilidade de ambos os marcadores na avaliação da angiogênese. A angiogênese diferencia lesões de baixo e alto grau, utilizando-se anti-fator VIII, o que não ocorre com anti-CD34.

Processamento e caracterização de compósitos Poli(METACRILATO DE METILA)/Sílica (PMMA/SiO2)

Currently the search for new materials with properties suitable for specific applications has increased the number of researches that aim to address market needs. The poly (methyl methacrylate) (PMMA) is one of the most important polymers of the family of polyacrylates and polymethacrylates, especially for its unique optical properties and weathering resistance, and exceptional hardness and gloss. The development of polymer composites by the addition of inorganic fillers to the PMMA matrix increases the potential use of this polymer in various fields of application. The most commonly used inorganic fillers are particles of silica (SiO2), modified clays, graphite and carbon nanotubes. The main objective of this work is the development of PMMA/SiO2 composites at different concentrations of SiO2, for new applications as engineering plastics. The composites were produced by extrusion of tubular film, and obtained via solution for application to commercial PMMA plates, and also by injection molding, for improved the abrasion and scratch resistance of PMMA without compromising transparency. The effects of the addition of silica particles in the polymer matrix properties were evaluated by the maximum tensile strength, hardness, abrasion and scratch resistance, in addition to preliminary characterization by torque rheometry and melt flow rate. The results indicated that it is possible to use silica particles in a PMMA matrix, and a higher silica concentration produced an increase of the abrasion and scratch resistance, hardness, and reduced tensile strength

Biocompósitos poliméricos obtidos a partir da fração lignocelulósica e amilácea do caroço de manga (mangifera indica), Tommy atkins

This employment has the function the utilization of mango seeds Tommy Atkins, like starch source to obtain biopolymers and fibers source and nanowhiskers cellulose also, that will be use like reinforcing fillers in micro and nanobiocomposites polymeric. The fibers in natura removed from tegument mango seed were characterized, as weel as the treated fibers and nanowhiskers of cellulose extracted from them. The starch extracted from seed s almond showed a good performance (32%) and a high purity. The chemicals analyzes, of crystallinity and morphological of the fibers in natura, treated fibers and nanowhiskers of cellulose confirmed the efficacy of the chemical treatement performed to remove amorphous constituents (hemicellulose and lignina). The thermoplastic starch (TPS) obtained from two sources, corn starch and starchy material mango, was produced in a twin screw extruder with compositon mass of 62,5% of starch, 9,4% of water and 28,1% of glycerol. The starch material mango was the main objective of this work for the production of biodegradable materials, and the starch corn was utilized during the production stage to evaluate the processability of the starch and use as parameter for comparison, according of being a conventional source for obtaining conventional comercial starch. The incorporation of fibers (6% in mass) and nanowhiskers cellulose (1% in mass) in matrix of TPS to obtain composite and nanocomposite, respectively, it was performed in single screw extruder. The biocomposites and bionanocomposites polymeric were obtained and the TPS from starchy material mango presented better results of thermal and mechanicals properties when compared to TPS corn starch. Concludes that the sediment generated of the agroindustrial processing mango used presents potencial to producing of biodegradables materials

Envelhecimento ambiental acelerado em PRF a base de tecidos híbridos kevlar/vidro: propriedades e instabilidade estrutural

There are a number of damaging mechanisms that various materials can suffer in service. However, when working with polymer composite materials, this is something that requires analysis, especially when exposed to adverse environmental conditions. Thus, the objective of the present thesis is the study of the direct influence of environmental aging and the form of hybridization of the reinforcement woven on the structural stability, surfacedegradation and fracture process of polymer composites laminates. For this, the development of two polymer composite laminates was necessary, where one of them was reinforced with a bi-directional woven with hybrid strandsofkevlar-49/glass-Efibers, and the other also with a bi-directionalwoven, however with weft and warpformed of alternating strandsof Kevlar-49 fibers and glass-E fiber The reinforcementwoven are industrially manufactured. Both laminates use a polyester resin as a matrixand are made up of four layers each. All laminates were industrially prepared by the hand lay-up method of manufacturing. To do this, test specimens were manufactured of the respective laminates and submitted to environmental aging accelerated through the aging chamber. They were exposed to alternating cycles of UV radiation and moisture (heated steam) for a standard defined period. At the end of the exposure period the specimens were subjected to mechanical tests of uniaxial tensile and bending in three points and to the characterizationsof the fracture and surface deterioration. In addition, they were submitted to a structural degradation assessment by the measurement of mass variation technique (MMVT) and the measurement of thickness variation technique (MTVT), this last technique being developed in this thesis. At the end of the analysis it was observed that the form of hybridization of the reinforcement woven and the aging process directly influence with losses or gain in mechanical properties, with losses in the structural degradation and in the formation and propagation of damage mechanism of the developedcomposite laminates

Compósito Polimérico Híbrido: Comportamento Mecãnico, Descotinuidade Geométrica e Resistência Residual

The growing demand in the use of hybrid composite materials makes it essential a better understanding of their behavior face of various design conditions, such as the presence of geometric discontinuities in the cross section of structural elements. This way, the purpose of this dissertation is a study of the mechanical response (strength and stiffness), modes (characteristics) of fracture and Residual Strength of an hybrid polymeric composite with and without a geometric discontinuity in its longitudinal section (with a reduction in the cross section) loaded by uniaxial tension. This geometric discontinuity is characterized by central holes of different diameters. The hybrid composite was fabricated as laminate (plate) and consisting of ortho-tereftalic polyester matrix reinforced by 04 outer layers of Jute fibers bidirectional fabrics and 01 central layer of E-glass bidirectional fabric. The laminate was industrially manufactured (Tecniplas Nordeste Indústria e Comércio Ltda.), obtained by the hand lay-up technique. Initially, a study of the volumetric density of the laminate was made in order to verify its use in lightweight structures. Also were performed comparative studies on the mechanical properties and fracture modes under the conditions of the specimens without the central hole and with the different holes. For evaluating the possible influence of the holes in the structural stability of the laminate, the Residual Strength of the composite was determined for each case of variation in hole diameter. As a complementary study, analyses of the macroscopic final fracture characteristic of the laminates were developed. The presence of the central hole of any sizes, negatively changed the ultimate tensile strength. Regarding the elastic modulus, moreover, the difference found between the specimens was within the range of tests displacement, showing the laminate stability related to the stiffness

Avaliações térmica e reológica da matriz termoplástica PEKK utilizada em compósitos aeronáuticos

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Análise fractográfica do modo de falha de compósitos carbono/epóxi

A utilização de compósitos poliméricos na fabricação de aeronaves vem sendo cada vez mais intensa. em função disso, a possibilidade de ocorrer falhas em serviço de um componente fabricado em compósito polimérico torna-se cada vez maior. A análise de falhas de materiais compósitos ainda é um tema pouco explorado, principalmente no Brasil, porém vem tornando-se cada vez mais importante em apoio à área de prevenção e investigação de acidentes aeronáuticos. Este trabalho teve como objetivo a caracterização de fraturas em laminados unidirecionais de fibra de carbono de módulo intermediário com sistema de resina epóxi modificada, tipo 8552, em resistência ao cisalhamento interlaminar nas condições ambiente e saturado de umidade em câmara higrotérmica. A análise fractográfica no plano de falha dos laminados foi realizada por microscopias óptica e eletrônica de varredura. A comparação dos resultados mostrou que o condicionamento higrotérmico afetou significativamente a região de interface da resina sem alterar a adesão interfacial fibra/resina. Os aspectos de fratura presentes na região de resina, como cristas de galo e escarpas, e do reforço foram detalhados, podendo-se assim estabelecer a direção de propagação da trinca e caracterizar o modo de falha, por ser do tipo misto (arrancamento e cisalhamento simultaneamente).

Influência da temperatura no desempenho mecânico de compósitos PEI/fibras de vidro

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Uso do pó da palha de carnaúba em compósitos de quitosana

In this work a biodegradable composite using the carnauba straw s powder as reinforcement on chitosan matrix polymeric were manufactured. Firstly, were carried out the chemistry characterization of the carnauba straw s powder before and after treatments with NaOH and hexane. Goering and Van Soest method (1970), flotation test, moisture absorption, FTIR, TG/DTG, DSC and SEM have also being carried out. Composites were developed with variations in granulometry and in powder concentrations. They were characterized by TG/DTG, SEM and mechanicals properties. The results of chemical composition showed that the carnauba straw s powder is composed of 41% of cellulose; 28,9% of hemicellulose and 14% of lignin.The flotation test have indicated that the chemical treatment with NaOH decreased the powder s hidrophilicity.The thermal analysis showed increased of thermal stability of material after treatments. The results of FTIR and SEM revealed the removal of soluble materials from the powder (hemicelluloses and lignin), the material became rougher and clean. The composites obtained showed that the mechanicals properties of the composites were decreased in respect at chitosan films, and the composites with the powder at 150 Mesh showed less variation in the modulus values. The speed test of 10 mm/min showed the better reproducibility of the results and is in agreement to the standard ASTM D638. The SEM analysis of fracture showed the low adhesion between the fiber/matrix. The increase of volume of powder in the composite caused a decrease in values of stress and strain for the samples with untreated powder and treated with hexane. The composite with 50% of the powder s treated in NaOH didn t have significant variation in the values of stress and strain as compared with the composites with 10% of the powder, showing that the increase in the volume of fiber didn t affect the stress and strain of the composite. Thereby, it is concluded that the manufacture of polymeric composites of chitosan using carnauba straw s powder can be done, without need for pre-treatment of reinforcement, become the couple of carnauba straw s powder-chitosan a good alternative for biodegradable composites

Avaliação do risco cardiovascular em indivíduos com periodontite

Pós-graduação em Biociências e Biotecnologia Aplicadas à Farmácia - FCFAR