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Previous issue date: 2013-04-26 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES / A nuclea??o de microtrincas durante aplica??o de cargas ? um problema
cr?tico em estruturas de pol?meros e comp?sitos polim?ricos. Materiais com
mecanismo de auto-reparo permitem que as microtrincas formadas sejam reparadas,
evitando assim que ocorra propaga??o com falha catastr?fica em componentes
estruturais. Uma das t?cnicas que tem sido sugerida na literatura para a promo??o
de reparo de microtrincas ? a aplica??o de solventes que reagem com o pol?mero.
Este trabalho tem como objetivo a obten??o de nanotubos de haloisita com agentes
encapsulados que possam ser adicionados a pol?meros ep?xi para promoverem
auto-reparo. A propaga??o de microtrincas no material provoca a ruptura dos
nanotubos, liberando o solvente encapsulado. Dois solventes foram considerados
neste estudo: dimetilsulf?xido (DMSO) e nitrobenzeno. Um procedimento de
encapsulamento camada-por-camada foi apresentado utilizando os polieletr?litos, de
cargas opostas, CTAB (Brometo de Cetil Trimetil Am?nio) e poliacrilato de s?dio. A
verifica??o do encapsulamento se deu pelas an?lises de difra??o de raios-X (DRX),
infravermelho por transformada de Fourier (FTIR), an?lise t?rmica via
termogravimetria (TG), adsor??o e dessor??o de nitrog?nio e microscopia eletr?nica
de varredura (MEV). Foi poss?vel comprovar a introdu??o do solvente DMSO na
cavidade interior dos nanotubos, o que n?o ocorreu com o nitrobenzeno, onde se
verificou apenas a agrega??o da argila. Os resultados sugerem que o polieletr?lito
CTAB interagiu com a haloisita formando a camada sobre os nanotubos e, portanto,
promoveu o encapsulamento, o que n?o foi verificado com o poliacrilato de s?dio. / Micro cracking during service is a critical problem in polymer structures and
polymer composite materials. Self-healing materials are able to repair micro cracks,
thus their preventing propagation and catastrophic failure of structural components.
One of the self-healing approaches presented in the literature involves the use of
solvents which react with the polymer. The objective of this research is to investigate
a procedure to encapsulate solvents in halloysite nanotubes to promote self-healing
ability in epoxy. Healing is triggered by crack propagation through embedded
nanotubes in the polymer, which then release the liquid sovent into the crack plane.
Two solvents were considered in this work: dimethylsulfoxide (DMSO) and
nitrobenzene. The nanotubes were coated using the layer-by-layer technique of
oppositely charged polyelectrolytes: cetyltrimethylammonium bromide (CTAB) and
sodium polyacrylate. Solvent encapsulation was verified by X-ray diffraction (XRD),
Fourier transform infrared (FTIR), analysis thermogravimetry (TGA), adsorption and
desorption of nitrogen and scanning electron microscopy (SEM). The introduction of
the solvent DMSO into the cavity of the nanotubes was confirmed by the techniques
employed. However, was not verified with nitrobenzene only promoted clay
aggregation. The results suggest that the CTAB reacted with the halloystite to form a
sealing layer on the surface of the nanotubes, thus encapsulating the solvent, while
this was not verified using sodium polyacrylate.
| Identifer | oai:union.ndltd.org:IBICT/oai:repositorio.ufrn.br:123456789/19821 |
| Date | 26 April 2013 |
| Creators | Melo, Gudson Nicolau de |
| Contributors | 46660640444, http://lattes.cnpq.br/6572298923055649, Paskocimas, Carlos Alberto, 06296687877, http://lattes.cnpq.br/2365059843175411, Carvalho, Laura Hecker de, 56905858404, http://lattes.cnpq.br/6358009621640820, Nascimento, Maria Carolina Burgos Costa do, 03449466496, Melo, Jos? Daniel Diniz |
| Publisher | Universidade Federal do Rio Grande do Norte, PROGRAMA DE P?S-GRADUA??O EM CI?NCIA E ENGENHARIA DE MATERIAIS, UFRN, Brasil |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/masterThesis |
| Source | reponame:Repositório Institucional da UFRN, instname:Universidade Federal do Rio Grande do Norte, instacron:UFRN |
| Rights | info:eu-repo/semantics/openAccess |
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