Made available in DSpace on 2014-12-17T14:06:51Z (GMT). No. of bitstreams: 1 TharsiaCCC.pdf: 1127571 bytes, checksum: caf0ffeeb86abc73d08cddd51d5f1c0b (MD5) Previous issue date: 2009-03-16 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / Natural nanoclays are of great interest particularly for the production of polymer-based nanocomposites. In this work, kaolinite clays from two natural deposits in the State of the Rio Grande do Norte and Paraiba were purified with thermal treatment and chemical treatments, and characterized. Front to the gotten data, had been proposals methodologies for elimination or reduction of coarse particle texts, oxide of iron and organic substance. These methodologies had consisted of the combination of operations with thermal treatments, carried through in electric oven, and acid chemical attacks with and hydrogen peroxide. The Analyzers Thermogravimetric was used to examine the thermal stability of the nanoclays. The analysis indicated weight losses at temperatures under 110 ?C and over the temperature range of 350 to 550 ?C. Based on the thermal analysis data, the samples were submitted to a thermal treatment at 500 ?C, for 8 h, to remove organic components. The X-ray diffraction patterns indicated that thermal treatment under 500 ?C affect the basic structure of kaolinite. The BET surface area measurements ranged from 32 to 38 m2/g for clay samples with thermal treatment and from 36 to 53 m2/g for chemically treated samples. Thus, although the thermal treatment increased the surface area, through the removal of organic components, the effect was not significant and chemical treatment is more efficient, not affect the basic structure of kaolinite, to improve particle dispersion. SEM analysis confirms that the clay is agglomerated forming micron-size particles / As nanoargilas naturais s?o de grande interesse tecnol?gico, particularmente para a obten??o de nanocomp?sitos com matriz polim?rica. Neste trabalho, foram estudadas duas argilas caulin?ticas provenientes de dep?sitos naturais localizados nos estados do Rio Grande do Norte e da Para?ba. Estas argilas foram caracterizadas f?sica e quimicamente. Frente aos dados obtidos, foram propostos metodologias para elimina??o ou redu??o dos teores de part?culas grosseiras, de ?xido de ferro e de mat?ria org?nica. Estas metodologias consistiram na combina??o de tratamentos t?rmicos, realizadas em forno el?trico, e ataques qu?micos com ?cidos e per?xido de hidrog?nio. Com a an?lise termogravim?trica verificou-se a estabilidade t?rmica das amostras, que indicou perdas de massa na temperatura de 110 ?C e numa faixa de temperatura de 350?C a 550?C. Baseado nesses dados, as amostras foram submetidas a um tratamento t?rmico de 500?C por 8 horas para a remo??o dos componentes org?nicos. Os difratogramas de raios-X indicaram que o tratamento t?rmico alterou a sua estrutura b?sica. As medidas da ?rea da superficial (BET) variaram de 32 a 38 m2/g para amostras da argila com tratamento t?rmico e 36 a 53 m2/g para amostras tratadas quimicamente. Verificouse que o tratamento t?rmico promove um aumento significativo na ?rea de superf?cie. No entanto, seu efeito ? superado pelos tratamentos qu?micos que, adicionalmente, preservam a estrutura b?sica da caulinita e melhoram a dispers?o de part?culas, conforme evidenciado por microscopia eletr?nica de varredura