Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2017-01-12T13:44:03Z No. of bitstreams: 1 ThiagoVasquesDeSouza_DISSERT.pdf: 2115756 bytes, checksum: 3e6dfd05005f83b2fb41d4caa8e343d8 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2017-01-17T11:45:14Z (GMT) No. of bitstreams: 1 ThiagoVasquesDeSouza_DISSERT.pdf: 2115756 bytes, checksum: 3e6dfd05005f83b2fb41d4caa8e343d8 (MD5) / Made available in DSpace on 2017-01-17T11:45:14Z (GMT). No. of bitstreams: 1 ThiagoVasquesDeSouza_DISSERT.pdf: 2115756 bytes, checksum: 3e6dfd05005f83b2fb41d4caa8e343d8 (MD5) Previous issue date: 2016-07-27 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / Os espessantes de l?tex acr?lico ?lcali-sol?veis s?o amplamente utilizados em atividades como fabrica??o de revestimento, cosm?ticos, ind?stria do petr?leo e t?xtil. Eles t?m a fun??o de aumentar a viscosidade aparente do meio, como resultado da neutraliza??o dos grupos carboxila presentes nas part?culas do l?tex. Os espessantes acr?licos hidrofobicamente modificados (HASE) atualmente s?o os mais utilizados como modificadores de reologia e as t?cnicas de reometria s?o o principal m?todo utilizado para monitorar a atividade reol?gica e efici?ncia destas subst?ncias. Nesta disserta??o, propomos o uso de espalhamento din?mico de luz (DLS) como m?todo complementar para obter par?metros quantitativos como taxa de relaxa??o caracter?stica m?dia e largura de distribui??o assim como correlacion?-los com o aumento da viscosidade e a neutraliza??o dos grupamentos carboxila. A partir de an?lise de dados obtidos com a utiliza??o de t?cnicas tradicionais de caracteriza??o como reometria, condutividade e turbidez em compara??o com a t?cnica de espalhamento din?mico de luz (DLS). Identificou-se uma concentra??o cr?tica de ?ons OH- para a neutraliza??o dos grupos carboxila. Foi poss?vel ainda, a partir dos dados de taxa de relaxa??o m?dia ter um melhor entendimento do mecanismo de espessamento deste tipo de pol?mero. / The alkali soluble latex thickeners are extensively used in activities such as coating manufacturing, cosmetics, oil and textile industry. They increase apparent viscosity as a result of neutralization of carboxyl groups in latex particles. The Hydrophobic alkali soluble emulsion (HASE), currently are the thickener most used to increase the material?s rheology and the rheometry techniques is the main method used to monitor the rheological activity of these substances and its efficiency. In this work, we propose the use of dynamic light scattering (DLS) as an additional method to get quantitative parameters like characteristic relaxation rate and distribution width to correlate them to viscosity increase and carboxylic groups neutralization. We got the information obtained from traditional characterization methods as rheometry, conductivity and turbidity to compare with dynamic light scattering parameters. The critical OH- ions concentration was identified using the information about the carboxylic groups neutralization and we could to get more information about this polymer thickening process using de Dynamic Light Scattering for a better understanding about this mechanism.

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2016-05-30T22:35:17Z No. of bitstreams: 1 WildsonArcanjoDeMorais_TESE.pdf: 7950168 bytes, checksum: 6a3da8d5da57db90a9fa474b79780a53 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2016-06-01T21:32:38Z (GMT) No. of bitstreams: 1 WildsonArcanjoDeMorais_TESE.pdf: 7950168 bytes, checksum: 6a3da8d5da57db90a9fa474b79780a53 (MD5) / Made available in DSpace on 2016-06-01T21:32:38Z (GMT). No. of bitstreams: 1 WildsonArcanjoDeMorais_TESE.pdf: 7950168 bytes, checksum: 6a3da8d5da57db90a9fa474b79780a53 (MD5) Previous issue date: 2015-08-18 / A ind?stria de petr?leo necessita de v?rias subst?ncias qu?micas em seus processos de extra??o e investe em novas tecnologias a todo o momento. Os sistemas micelares do tipo-minhoca-WLM e os complexos polieletrol?ticos-PECs est?o sendo estudados para ingressar como novas tecnologias na extra??o de ?leo. Esta tese objetiva obter, caracterizar e identificar esses sistemas coloidais utilizando t?cnicas de espalhamento de luz como principais ferramentas; possibilitando o conhecimento de base para poss?veis aplica??es na ind?stria petrol?fera. Os par?metros obtidos no DLS, b, GC e n sofreram transi??es na concentra??o tensoativo/co-tensoativo 200g/L. A adi??o da fase ?leo, xileno, dificulta a transi??o de micelas esf?ricas para micelas minhoca. No SAXS, a rela??o RG,O/ RG,S atinge um m?ximo que corrobora com a transi??o no DLS. b aumenta bruscamente, n se torna mais homog?neo, GC,2 e a contribui??o para o segundo processo, f2, foram visualizados para raz?es poli?nion/polic?tion WAC pr?ximas de 2. Essa regi?o, no SAXS, aglomerados de PECs se adsorvem nas part?culas prim?rias, que contribuiu para o comportamento dos gr?ficos de Kratky. As fun??es P(r) perdem seu formato ?sino? e se alargam. As contribui??es de ?rea S17 e S29 foram maiores para menores valores de WAC e S37 foi influente em valores maiores. / The oil industry needs various chemicals compounds in their extraction processes and invests in new technologies all the time. Worm-like micelles-WLM and polyelectrolyte complexes-PECs have been studied to join as new technologias in oil extraction processes. This thesis aims to obtain, characterize and identify these colloidal systems using as a tool light scattering experiments; enabling the required knowledge to applied them in oil industry. To the surfactants systems, the parameters from DLS, b, GC and n in a function of surfactant/co-surfactant concentrations suffered transitions around 200 g/L. The addition of oil phase, xylene, hinders the transition from spherical micelles to worm-like micelles. In SAXS, the ratio RG,O/ RG,S reaches a maximum value which corroborates with the transition in DLS. To PECs, b increases sharply, n becomes more homogeneous, GC,2 and second contribution to the process, f2, were visualized for polyanion/polycation ratio with WAC next 2. This region in SAXS, PECs clusters adsorb in primary particles, which contributed to the behavior of Kratky graphics. The pair distribution functin, P(r), lose its bell shape and widen. The S17 and S29 were higher for lower values of WAC ratio. S37 was influential in higher values.