Made available in DSpace on 2014-12-17T15:42:26Z (GMT). No. of bitstreams: 1
ZilvamMS_TESE_reduzido.pdf: 9108618 bytes, checksum: 613dad3fd1a359dce84e2af73b067934 (MD5)
Previous issue date: 2013-02-22 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / Surfactant-polymer interactions are widely used when required rheological
properties for specific applications, such as the production of fluids for oil exploration.
Studies of the interactions of chitosan with cationic surfactants has attracted attention by
being able to cause changes in rheological parameters of the systems making room for
new applications. The commercial chitosan represents an interesting alternative to these
systems, since it is obtained from partial deacetylation of chitin: the residues sites
acetylated can then be used for the polymer-surfactant interactions. Alkyl ethoxylated
surfactants can be used in this system, since these non-ionic surfactants can interact
with hydrophobic sites of chitosan, modifying the rheology of solutions or emulsions
resultants, which depends on the relaxation phenomenon occurring in these systems. In
this work, first, inverse emulsions were prepared from chitosan solution as the dispersed
phase and cyclohexane as the continuous phase were, using CTAB as a surfactant. The
rheological analysis of these emulsions showed pronounced pseudoplastic behavior.
This behavior was attributed to interaction of "loops" of chitosan chains. Creep tests
were also performed and gave further support to these discussions. Subsequently, in
order to obtain more information about the interaction of chitosan with non-ionic
surfactants, solutions of chitosan were mixed with C12E8 and and carried out rheological
analysis and dynamic light scattering. The systems showed marked pseudoplastic
behavior, which became less evident when the concentration of surfactant was
increased. Arrhenius and KWW equations were used to obtain parameters of the
apparent activation energy and relaxation rate distribution, respectively, to which were
connected to the content of surfactant and temperature used in this work / As intera??es tensoativo-pol?mero s?o amplamente usadas quando s?o necess?rias
propriedades reol?gicas para aplica??es espec?ficas, como a produ??o de fluidos para
explora??o do petr?leo. Estudos das intera??es de quitosana com tensoativos cati?nicos
tem chamado aten??o por serem capazes de causar mudan?as nos par?metros reol?gicos
dos sistemas abrindo espa?o para novas aplica??es. A quitosana comercial representa
uma alternativa interessante para estes sistemas, uma vez que ela ? obtida a partir da
desacetila??o parcial da quitina: os s?tos acetilados residuais podem, ent?o, ser usados
para as intera??es pol?mero-tensoativo. Tensoativos alquil etoxilados podem ser
utilizados neste sistema, pois estes tensoativos n?o i?nicos podem interagir com s?tios
hidrof?bicos da quitosana, modificando a reologia de solu??es ou emuls?es resultantes,
os quais dependem do fen?meno de relaxa??o ocorrendo nestes sistemas. Neste
trabalho, primeiramente, foram preparadas emuls?es inversas de solu??o de quitosana
como fase dispersa e cicloexano como fase cont?nua usando CTAB como tensoativo. A
an?lise reol?gica destas emuls?es mostrou pronunciado comportamento pseudopl?stico.
Esta pseudoplasticidade foi atribu?da ? intera??o por la?os loops de cadeias de
quitosana. Ensaios de flu?ncia tamb?m foram executados e deram maior suporte a estas
discuss?es. Em seguida, a fim de se obter maiores informa??es sobre as intera??es da
quitosana com tensoativos n?o i?nicos, solu??es de quitosana foram misturadas com
C12E8 e levadas ?s an?lises reol?gica e de espalhamento din?mico de luz. Os sistemas
tiveram elevado comportamento pseudopl?stico, o qual se tornava menos evidente,
quando o teor de tensoativo foi aumentado. Equa??es de Arrhenius e de KWW foram
usadas para obter par?metros de energia de ativa??o aparente e de distribui??o da taxa
de relaxa??o, respectivamente, aos quais foram relacionados em fun??o do teor de
tensoativo e da temperatura, usados neste trabalho
| Identifer | oai:union.ndltd.org:IBICT/oai:repositorio.ufrn.br:123456789/17775 |
| Date | 22 February 2013 |
| Creators | Santos, Zilvam Melo dos |
| Contributors | CPF:90623207753, http://buscatextual.cnpq.br/buscatextual/visualizacv.do?id=K4788562T6, Wanderley Neto, Alcides de Oliveira, CPF:00738841463, http://lattes.cnpq.br/4789528535524269, Caroni, Ana Luiza Porpino Fernandes, CPF:00998342432, http://lattes.cnpq.br/9297712365536731, Anna, Carlos Mauricio Rabello de Sant', CPF:82723222772, http://lattes.cnpq.br/2087099684752643, Ambr?sio, Renato Canha, CPF:86613324949, http://lattes.cnpq.br/1372410614687954, Fonseca, Jos? Luis Cardozo |
| Publisher | Universidade Federal do Rio Grande do Norte, Programa de P?s-Gradua??o em Qu?mica, UFRN, BR, F?sico-Qu?mica; Qu?mica |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/doctoralThesis |
| Format | application/pdf |
| Source | reponame:Repositório Institucional da UFRN, instname:Universidade Federal do Rio Grande do Norte, instacron:UFRN |
| Rights | info:eu-repo/semantics/openAccess |
Page generated in 0.0019 seconds