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Previous issue date: 2016-08-26 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES / The development of methodologies able to prepare new materials, using graphene in its structure, is technological innovation that converts low-cost products in advanced materials with aggregate amount. The present work is related with the preparation of graphene oxide (GO) and reduced graphene oxide (RGO) in reasonable quantities directed to prepare nanocomposites based on biodegradable polymeric matrix. Initiating from natural graphite, Grafine, experimental conditions were investigated to obtain the GO and its reduced form, RGO, by the method of chemical exfoliation followed by thermal reduction. In order to optimize the process were evaluated oxidation time (12, 24 and 48 hours) and temperature reduction (600?C and 1000?C). The films of the nanocomposites containing different amounts of graphene (0.5; 3 and 5% w/w) dispersed in the chitosan matrix were prepared using solvent evaporation method. The characterization analyses of materials obtained were made by: Scanning Electron Microscopy, Transmission and Atomic Force, X-ray Diffraction, Thermogravimetric analysis, Elemental Analysis, Raman spectroscopy and Electric Conductivity Analysis. The 24 hours of oxidation time was sufficient for the intercalation of functional groups between the sheets of graphene and obtain GO with 29% oxygen. The reduction in temperature of 1000?C was effective in restoring graphitic network and resulted in RGO with a stack of 7-8 sheets, thermally stable and electrical conductivity of 55 S/cm. Addition of graphene in the biodegradable matrix did not modify the thermal stability and it did not change substantially the process of degradation of the prepared nanocomposites. / O desenvolvimento de metodologias capazes de preparar novos materiais, que utilizem grafeno na sua estrutura, representa inova??o tecnol?gica que transforma produtos de baixo custo em materiais avan?ados com alto valor agregado. O presente trabalho est? relacionado com a prepara??o de ?xido de grafeno (OG) e ?xido de grafeno reduzido (OGR) em quantidades razo?veis visando ? prepara??o de nanocomp?sitos baseados em matriz polim?rica biodegrad?vel. Partindo do grafite natural, Grafine, foram investigadas condi??es experimentais para obten??o do OG e sua forma reduzida, OGR, pelo m?todo da esfolia??o qu?mica, seguida de redu??o t?rmica. A fim de otimizar o processo foram avaliados tempo de oxida??o (12, 24 e 48 horas) e temperatura de redu??o (600?C e 1000?C). Os filmes dos nanocomp?sitos com diferentes quantidades de grafenos (0,5; 3 e 5% m/m) dispersos na matriz de quitosana foram preparados usando a metodologia da evapora??o do solvente. A caracteriza??o dos materiais preparados deu-se por: Microscopia Eletr?nica de Varredura, de Transmiss?o e de For?a At?mica, Difra??o de Raios X, An?lise Termogravim?trica, An?lise Elementar, Espectrometria RAMAN e An?lise de condutividade el?trica. O tempo de oxida??o de 24 horas foi suficiente para a intercala??o de grupos funcionais entre as l?minas de grafeno e obten??o de OG com 29% de oxig?nio. A redu??o na temperatura de 1000?C foi eficiente na restaura??o da rede graf?tica e resultou em OGR com um empilhamento de 7-8 l?minas, est?vel termicamente e com condutividade el?trica de 55 S/cm. A adi??o dos grafenos na matriz biodegrad?vel n?o modificou a sua estabilidade t?rmica e n?o alterou significativamente o processo de perda de massa dos nanocomp?sitos preparados.
| Identifer | oai:union.ndltd.org:IBICT/oai:tede2.pucrs.br:tede/7065 |
| Date | 26 August 2016 |
| Creators | Maraschin, Thuany Garcia |
| Contributors | Basso, Nara Regina de Souza |
| Publisher | Pontif?cia Universidade Cat?lica do Rio Grande do Sul, Programa de P?s-Gradua??o em Engenharia e Tecnologia de Materiais, PUCRS, Brasil, Faculdade de Engenharia |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/masterThesis |
| Format | application/pdf |
| Source | reponame:Biblioteca Digital de Teses e Dissertações da PUC_RS, instname:Pontifícia Universidade Católica do Rio Grande do Sul, instacron:PUC_RS |
| Rights | info:eu-repo/semantics/openAccess |
| Relation | -7432719344215120122, 600, 600, 600, 600, -655770572761439785, 4518971056484826825, 2075167498588264571 |
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