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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Desenvolvimento e caracterização de compósitos de Poli (E-Caprolactona) PCL e ß-Fosfato Tricálcico (ß-TCP) para uso em biomateriais / Development and characterization of composites Poly(episolon-caprolactone) (PCL) and Beta-Tricalcium Phosphate (TCP) for use in biomaterials

Solomão, Zenaide 17 August 2018 (has links)
Orientador: Cecília Amélia de Carvalho Zavaglia / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-17T22:38:20Z (GMT). No. of bitstreams: 1 Solomao_Zenaide_M.pdf: 4852275 bytes, checksum: e8aeb44e410022a37476432c0111160d (MD5) Previous issue date: 2011 / Resumo: A utilização de biomateriais para substituir, reparar tecidos e órgãos lesados dos seres humanos tem aumentado muito ultimamente devido a diversos fatores como o crescimento da população e a sua maior expectativa de vida. A engenharia tecidual é um campo interdisciplinar que integra princípios da biologia celular e molecular, química, genética, ciências dos materiais e engenharia biomédica, para produzir compósitos tridimensionais inovativos, capazes de substituir tecidos biológicos. O desenvolvimento de novo biomaterial pode ajudar a solucionar este problema, utilizando o método de evaporação de solvente. Este trabalho teve como objetivos: sintetizar e caracterizar o ß-TCP através do método via seca; desenvolver e caracterizar as membranas de poli ('epsilon'-caprolactona) densas e porosas (scaffolds) utilizando dois solventes; preparar e caracterizar os compósitos densos e porosos PCL/ß-TCP; fazer uma avaliação da biocompatibilidade in vitro desses materiais. As seguintes técnicas de caracterização foram utilizadas: MO, MEV, EDS, DRX, TGA,DSC, ensaios mecânicos de tração, teste de viabilidade celular e atividade de fosfatase alcalina. Foi também analisada a sua degradação hidrolitica em solução tampão fosfato (PBS). Essas técnicas foram adequadas para diferenciar as amostras preparadas com os dois solventes utilizados: clorofórmio e diclorometano. Os ensaios mostraram que o último forneceu amostras mais resistentes mecanicamente, mantendo as propriedades térmicas do PCL puro sem alterações, com a adição das partículas do ß-TCP. A biocompatibilidade foi analisada através das normas conhecidas (ASTM e ABNT) e foi possível concluir que os materiais confeccionados são biocompativeis e a atividade de fosfatase alcalina (ALP) favoreceu o crescimento celular na membrana porosa. As avaliações in vitro não mostraram mudanças significativas nas composições preparadas com o solvente clorofórmio. Os materiais estudados possuem um grande potencial para aplicação em substitutos do tecido ósseo / Abstract: The use of biomaterials to replace, repair damaged tissues and organs of humans has greatly increased lately due to various factors such as population growth and greater life expectancy. Tissue engineering is an interdisciplinary field that incorporates principles of molecular and cellular biology, chemistry, genetics, materials science and biomedical engineering to produce innovative three-dimensional composites, capable of replacing tissue. The development of new biomaterial can help solutions this problem by using on whole of evaporation of solvent. This work aimed to synthesize and characterize the ß-TCP by the dry method; develop and characterize the membranes of poly ('épsilon'-caprolactone) porous and dense (scaffolds) using two solvents, to prepare and characterize the dense and porous PCL composites / ß-TCP, perform an evaluation of in vitro biocompatibility of these materials. The following characterization techniques were used: OM, SEM, EDS, XRD, TGA, DSC, mechanical testing, testing cell viability, alkaline phosphatase activity. We also analyzed its hydrolytic degradation in phosphate buffer solution (PBS). These techniques were adequate to differentiate the samples prepared with two solvents used, chloroform and dichloromethane. The tests showed that the samples provided last more mechanically resistant, keeping the thermal properties of pure PCL unchanged with the addition of particles of ß-TCP. The biocompatibility was determined by known standards (ASTM and ABNT) and we can conclude that the materials are biocompatible and made (ALP), promoted cell growth in the porous membrane. The in vitro evaluations showed no significant changes in the compositions prepared with the solvent chloroform. The materials studied have a great potential for application in bone tissue substitutes / Mestrado / Materiais e Processos de Fabricação / Mestre em Engenharia Mecânica
2

Biodegradable polymer composites : synthesis, properties and application in water purification

Vilakati, Gcina Doctor 02 May 2012 (has links)
M.Sc. / The addition of lignocellulosic fibres to thermoplastic polymers is known to increase the toughness of the polymers but it compromises the tensile strength. On the other hand, inorganic fillers like TiO2 are known to improve the tensile strength of polymers. These plant fibres have been used as adsorbents of metal pollutants in water. Best results were obtained when such materials were ground to fine powder but due to low density, the fibres float and form aggregates in water. Being highly biodegradable in nature makes plant fibres unsuitable for water treatment over lengthy periods of time. They cannot be used as standalone materials. Mixing these adsorbents with polymers, which cannot only act as support for the adsorbents but also disperse the fibres within it thus preventing leaching, is a cause for concern. This study was aimed at fabricating plant fibre-polymer composites that will have improved mechanical and thermal properties. These composites were to be tested for their ability to be used as metal ion adsorbents. The composites were fabricated using a melt-mix compounding method. Two thermoplastic polymers, EVA and PCL were each mixed with either lignin or SCB and TiO2 in different ratios. A rheomex mixer coupled with a single screw extruder which was attached to a sheet die was used to synthesise the composites. TGA and DSC were used for thermal propagation while the mechanical properties were investigated using an instron. Metal ion adsorption measurements were analysed using an atomic absorption spectrometer (AAS). These adsorbents were used to remove Cr(VI), Cr(III) and Pb(II), varying different environmental parameters like pH, concentration, time and adsorbent at constant temperature. The reinforcing effect of both lignin and SCB resulted to poor thermal and mechanical properties. This was shown by a decrease in onset degradation temperature and the tensile and toughness of the composites compared to the neat polymers. The incorporation of TiO2 on SCB-EVA composites, however, improved the mechanical strength and resulted in a thermally stable composite compared to counterpart composites without TiO2. This observation was surpassed at high filler loading as the addition of TiO2 resulted in a decrease of the properties. For the tensile strength, neat EVA recorded 11.35 MPa while 2% TiO2-EVA registered 12.49 MPa for example. For the same composite, the onset degradation temperature for EVA was 353 oC but shifted to 368 oC after the addition of TiO2. At higher filler loading, no effect was observed when adding TiO2.

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