Made available in DSpace on 2014-12-17T15:41:41Z (GMT). No. of bitstreams: 1 GuymmannCS.pdf: 1754712 bytes, checksum: 731ccc6c9bb4f783f3a118094959297b (MD5) Previous issue date: 2008-02-29 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / Latices based on acrylic acid and ethyl methacrylate, crosslinked with 1,6‐propoxylate‐hexanodiol diacrylate were synthesized via emulsion polymerization with different monomeric compositions. The resultant latices were thickened with different NaOH/(acrylic acid) molar ratios and were characterized by titrimetry, zeta potential measurements, turbidimetry, and capillary viscometry. Intrinsic viscosity was determined for an uncrosslinked copolymer, using toluene as solvent. All the latices were coagulated with NaCl and washed with water at 60?C analyzed by FTIR spectrophotometry, in order to characterize functional groups from the copolymer and crosslinking agent. / L?tices ? base de ?cido acr?lico e metacrilato de etila, reticulados com 1,6‐diacrilato de propoxilato hexanodiol, foram sintetizados via polimeriza??o em emuls?o, com diferentes composi??es monom?ricas. Os l?tices sintetizados foram espessados com diferentes raz?es molares NaOH/(?cido acr?lico) e caracterizados por titrimetria, medidas de potencial zeta, turbidimetria e viscometria capilar. Todos os l?tices foram coagulados com NaCl, lavados com ?gua destilada e em seguida secos a 60 0C, para a an?lise de FTIR. A viscosidade intr?nseca do l?tex n?o reticulado foi determinada utilizando tolueno como solvente. O potencial zeta foi usado para determinar a carga superficial das part?culas e o FTIR para caracterizar os grupos funcionais dos comon?meros.

Made available in DSpace on 2014-12-17T15:41:43Z (GMT). No. of bitstreams: 1 ZilvanMS.pdf: 850138 bytes, checksum: 377846a49fcf47805db83b68c5e1b5f7 (MD5) Previous issue date: 2007-07-31 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / Latexes based on acrylic acid, acrylamide, ethyl methacrylate, and ethyl acrylate were synthesized via emulsion polymerization with different monomer compositions. The resultant latices were thickened with different molar ratios of NaOH to acrylic acid and were analyzed in terms of acid‐basis titrimetry, turbidimetry, rheology, and tensiometry. Titrimetry, turbidimetry, and rheometry were used to analyze factors such as carboxyl group availability and particle solubilization, tensiometry monitoring the influence of carboxyl neutralization on polymer‐surfactant interactions. For the acrylic acid content used in this work (20 wt%), the results indicated that as carboxyl groups distribution became more homogeneous, the process of latex thickening became more effective / L?tices baseados em ?cido acr?lico, acrilamida, acrilato de etila e metacrilato de etila foram sintetizados via polimeriza??o em emuls?o com diferentes composi??es monom?ricas. Os l?tices resultantes foram espessados a diferentes raz?es molares de NaOH/?cido acr?lico. Titrimetria ?cido‐base, turbidimetria, reometria e tensiometria foram usados para analisar fatores tais como a disponibilidade de grupos carboxila e a solubiliza??o de part?culas, a tensiometria sendo usada para monitorar a influ?ncia da neutraliza??o de grupos carboxilas nas intera??es pol?mero‐surfactante. Para o teor de ?cido acr?lico usado neste trabalho (20 m/m%), os resultados indicaram que, a medida em que a distribui??o de grupos carboxilas torna‐se mais homog?nea, o processo de espessamento tornou‐se mais efetivo

Made available in DSpace on 2014-12-17T15:42:27Z (GMT). No. of bitstreams: 1 JulianaSN.pdf: 1926581 bytes, checksum: 39f0578ac55e6915852da779ae1734b5 (MD5) Previous issue date: 2007-10-18 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / Magnetic particles are systems with potential use in drug delivery systems, ferrofluids, and effluent treatment. In many situations, such as in biomedical applications, it is necessary to cover magnetic particles with an organic material, as polymers. In this work, magnetic particles were obtained through covering magnetite particles with poly(methyl methacrylate‐comethacrylic acid) via miniemulsion polymerization process. The resultant materials were characterized X‐ray diffraction (XRD), Fourier Transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), zeta potential (��) measurements and vibrating sample magnetometry (VSM). XRD results showed magnetite as the predominant cristalline phase in all samples and that cristallites had nanometric dimensions. Thermogravimetric analysis revealed an increase in polymer thermal stability as a result of magnetite encapsulation. TGA results showed also that the encapsulation efficiency was directly related to nanoparticles s hidrofobicity degree. VSM measurements showed that magnetic polymeric particles were superparamagnetic, so that they may be potentially used for magnetic (bio)separation / Part?culas magn?ticas s?o sistemas com potencial de uso em libera??o controlada f?rmacos, ferrofluidos e tratamentos de efluentes. Em muitas situa??es, como em aplica??es biol?gicas, ? necess?rio revestir as part?culas magn?ticas com um material org?nico, como pol?meros. Neste trabalho, part?culas magn?ticas foram obtidas pelo revestimento de part?culas de magnetita por poli(metacrilato de metila‐co?cido metacr?lico) via processo de polimeriza??o em miniemuls?o. Os produtos obtidos foram caracterizados por difra??o de raios X (DRX), espectroscopia de absor??o no infravermelho por transformada de Fourier (FTIR), an?lise termogravim?trica (TG), medidas de potencial zeta (��) e magnetometria de amostra vibrante (MAV). Os resultados de DRX mostraram que a magnetita ? a fase cristalina dominante em todas as amostras, tendo seus cristalitos dimens?es nanom?tricas. A an?lise termogravim?trica revelou um aumento na estabilidade t?rmica das amostras com magnetita encapsulada e que a efici?ncia de encapsula??o foi diretamente relacionada ao grau de hidrofobiza??o das nanopart?culas. Medidas de magnetiza??o mostraram que as part?culas polim?ricas magn?ticas foram superparamagn?ticas, podendo ser satisfatoriamente utilizadas em processos de (bio)separa??o magn?tica

Made available in DSpace on 2014-12-17T14:07:05Z (GMT). No. of bitstreams: 1 YaraFG_DISSERT.pdf: 4146827 bytes, checksum: 3586f66a1b391a184d1b6034e91b85c0 (MD5) Previous issue date: 2012-12-20 / In the ceramics industry are becoming more predominantly inorganic nature pigments. Studies in this area allow you to develop pigments with more advanced properties and qualities to be used in the industrial context. Studies on synthesis and characterization of cobalt aluminate has been widely researched, cobalt aluminate behavior at different temperatures of calcinations, highlighting especially the temperatures of 700, 800 and 900? C that served as a basis in the development of this study, using the method of polymerization of complex (CPM), economic, and this method applied in ceramic pigment synthesis. The procedure was developed from a fractional factorial design 2 (5-2) in order to optimize the process of realization of the cobalt aluminate (CoAl2O4), having as response surfaces the batch analysis data of Uv-vis spectroscopy conducted from the statistic software 7.0, for this were chosen five factors as input variables: citric acid (stoichiometric manner), puff or pyrolysis time (h), temperature (? C), and calcinations (? C/min), at levels determined for this study. By applying statistics in the process of obtaining the CoAl2O4 is possible the study of these factors and which may have greater influence in getting the synthesis. The pigments characterized TG/DSC analyses, and x-ray diffraction (XRD) and scanning electron microscope (SEM/EDS) in order to establish the structural and morphological aspects of pigment CoAl2O4, among the factors studied it were found to statically with increasing calcinations temperature 700?< 800 <900 ?C, the bands of Uv-vis decrease with increasing intensity of absorbance and that with increasing time of puff or pyrolysis (h) there is an increase in bands of Uv-vis proportionally, the generated model set for the conditions proposed in this study because the coefficient of determination can explain about 99.9% of the variance (R?), response surfaces generated were satisfactory, so it s possible applicability in the ceramics industry of pigments / Na ind?stria cer?mica utilizam-se cada vez mais pigmentos de natureza predominantemente inorg?nica. Os estudos nessa ?rea permitem desenvolver pigmentos com qualidades e propriedades mais avan?adas para serem empregados em ?mbito industrial. Estudos de s?ntese e caracteriza??o do aluminato de cobalto t?m sido amplamente pesquisados, o comportamento do aluminato de cobalto em diferentes temperaturas de calcina??es, destacando principalmente as temperaturas de 700, 800 e 900?C utilizando o m?todo de polimeriza??o de complexos (MPC), m?todo este, econ?mico e aplicado em s?ntese de pigmentos cer?micos. O procedimento foi desenvolvido a partir de um planejamento fatorial fracionado 2(5-2) com o objetivo de otimizar o processo de realiza??o do aluminato de cobalto (CoAl2O4), tendo como superf?cies de respostas os dados da an?lise de espectroscopia do Uv-vis realizados a partir do software statistic 7.0, para isso, foram escolhidos cinco fatores como vari?veis de entrada: concentra??es de ?cido c?trico (de maneira estequiom?trica), tempo de puff ou pir?lise (h), temperatura (?C), tempo e taxas de calcina??es(?C/min), em patamares determinados para este estudo. Atrav?s da aplica??o estat?stica no processo de obten??o do CoAl2O4 foi poss?vel estudar entre estes fatores quais possam ter maior influ?ncia na obten??o da s?ntese. Os p?s-precursores foram caracterizados pelas an?lises termogravim?tricas TG/DSC, e os p?s-calcinados (pigmentantes) foram analisados pela difra??o de raios- x (DRX) e microscopia eletr?nica de varredura com energia dispersiva (MEV/EDS) a fim de comprovar os aspectos estruturais e morfol?gicos do CoAl2O4, entre os fatores estudados estaticamente verificou-se que com o aumento da temperatura de calcina??o 700<800<900?C, as bandas do Uv-vis diminuem com o aumento da intensidade da absorb?ncia e que com o aumento do tempo de puff ou pir?lise (h) h? um aumento das bandas do Uv-vis proporcionalmente, o modelo gerado ajustou-se para as condi??es propostas neste estudo, pois o coeficiente de determina??o consegue explicar cerca de 99,9%, da vari?ncia (R?), as superf?cies de respostas geradas foram satisfat?rias, sendo assim sua poss?vel aplicabilidade na ind?stria cer?mica de pigmentos

Made available in DSpace on 2014-12-17T15:42:31Z (GMT). No. of bitstreams: 1 ClaudioLV.pdf: 1496908 bytes, checksum: 9da02c26d9351b21019488117fc27924 (MD5) Previous issue date: 2007-05-28 / Dispersions composed of polyelectrolyte complexes based on chitosan and poly(methacrylic acid), PMAA, were obtained by the dropping method and template polymerization. The effect of molecular weight of PMAA and ionic strength on the formation of chitosan/poly(methacrylic acid), CS/PMAA, complexes was evaluated using the dropping method. The increase in molecular weight of PMAA inhibited the formation of insoluble complexes, while the increase in ionic strength &#64257;rst favored the formation of the complex followed by inhibiting it at higher concentrations. The polyelectrolyte complexation was strongly dependent on macromolecular dimensions, both in terms of molecular weight and of coil expansion/contraction driven by polyelectrolyte effect. The resultant particles from dropping method and template polymerization were characterized as having regions with different charge densities: chitosan predominating in the core and poly(methacrylic acid) at the surface, the particles being negatively charged, as a consequence. Albumin was adsorbed on templatepolymerized CS/PMAA complexes (after crosslinking with glutardialdehyde) and pH was controlled in order to obtain two conditions: (i) adsorption of positively charged albumin, and (ii) adsorption of albumin at its isoelectric point. Adsorption isotherms and zeta potential measurements showed that albumin adsorption was controlled by hydrogen bonding/van der Waals interactions and that brushlike structures may enhance adsorption of albumin on these particles / Dispers?es formadas a partir de complexos polieletrol?ticos de quitosana e de poli(?cido metacr?lico), PMAA, foram obtidas tanto pelo m?todo de gotejamento, como pelo m?todo de polimeriza??o em molde. O efeito da massa molar do PMAA e da for?a i?nica na forma??o dos complexos de quitosana/poli(?cido metacr?lico), CS/PMAA, foi avaliado usando o m?todo de gotejamento. O aumento da massa molar do PMAA inibiu a forma??o dos complexos insol?veis, enquanto o aumento da for?a i?nica primeiramente favoreceu a forma??o dos complexos, depois a inibiu, em altas concentra??es de eletr?litos de baixa massa molar. A complexa??o dos polieletr?litos foi fortemente dependente das dimens?es macromoleculares, tanto em termos da massa molar quanto do efeito de expans?o/contra??o dos novelos, devido ao efeito polieletrol?tico. As part?culas resultantes tanto do m?todo de gotejamento, como da polimeriza??o em molde foram caracterizadas por apresentarem regi?es com diferentes densidades de carga: a quitosana predominantemente presente na regi?o central e o poli(?cido metacr?lico), na superf?cie, sendo, portanto, as part?culas carregadas negativamente. A albumina foi adsorvida nos complexos de CS/PMAA obtidos por polimeriza??o em molde (depois de sofrerem reticula??o covalente usando glutaralde?do) e o pH foi controlado a &#64257;m de se obter duas condi??es: (i) adsor??o de albumina carregada positivamente e (ii) adsor??o de albumina em seu ponto isoel?trico. As isotermas de adsor??o e as medidas de potencial zeta mostraram que a adsor??o da albumina foi controlada por liga??es de hidrog?nio/intera??es de van der Waals e que as estruturas em forma de escova puderam aumentar a adsor??o da albumina nessas part?culas