Tesis por compendio / [EN] In the present Doctoral Thesis, different strategies to improve functional properties of starch films for food packaging applications were analysed: study of the effect of amylose:amylopectin ratio, blend with other polymers poly(vinyl alcohol) (PVA), and incorporation of different fillers (rice bran and cellulose nanocrystals-CNCs) and antimicrobial agents (neem oil-N, oregano essential oil-O and silver nanoparticles-AgNPs). Likewise, a biodegradation study of the films as affected by antimicrobials was carried out. Among different starches with distinct amylose:amylopectin ratio, pea starch was selected with higher values of this ratio. The high content of amylose gave rise to stiffer and more resistant to fracture films, with lower oxygen permeability, which decreased during storage. Pea starch-PVA (S-PVA) blend films represented a good strategy to improve film properties without a notable increase in cost. The PVA addition led to films which were less water soluble and not as sensitive to water sorption, more extensible and resistant than neat starch films, while they maintained the high oxygen barrier and provided stability to the matrix during ageing. In this sense, S-PVA ratios near to 1:1 are recommendable. When rice bran with the smallest particle size was used as filler, it improved the elastic modulus of the films, but reduced the film stretchability and barrier properties, due to the enhancement of the water binding capacity and the introduction of discontinuities in the matrix. Incorporation of CNCs into S-PVA films, as a reinforcing material, enhanced phase separation of polymers, did not imply changes in water vapour barrier of the films but improved the film mechanical performance: they became stiffer and more stretchable, while crystallization of PVA was partially inhibited. Silver loaded S-PVA films exhibited antimicrobial activity against the fungi (Aspergillus niger and Penicillium expansum) and bacteria (Listeria innocua and Escherichia coli) genera, depending on the silver concentration. Silver nanoparticles provoked notable changes in the film colour and transparency but no relevant changes in the other physical properties. Silver was completely delivered to aqueous simulants within the firsts 60 minutes of contact, but the film release capacity drastically decreased in the non-polar simulant, where the overall migration limit for food contact packaging materials (60 mg/Kg simulant) was accomplished. So, the use of the developed films as food packaging materials should be restricted to fat-rich foodstuffs. The incorporation of oregano essential oil (O), as antimicrobial agents, into the S-PVA matrix gave rise to active films against bacteria and fungi, whereas films containing neem oil (N) were not effective. Higher O concentration in the films was required to observe antifungal effect with respect to the antibacterial activity. Oils did not notably affect water sensitivity and water barrier properties of the films, but at high ratio, oils implied weaker film networks, affecting their mechanical performance. Blend of starch with PVA significantly improved PVA biodegradation and disintegration behaviour. Incorporation of silver species to S-PVA films slowed down their biodegradation kinetics while increased their degradation ratio. However, no significant effect of O was observed on the biodegradability indices despite the antimicrobial activity detected for this oil. N even promoted biodegradation of S-PVA films. Finally, a food application of biopolymer coatings was studied, using chitosan and essential oils (oregano or rosemary) to prevent weight loss and fungal development of semi-hard goat's milk cheeses. Coating were highly effective at reducing fungal growth and cheese weight loss while slightly reduced lipolytic and proteolytic activities in the cheese. Sensory evaluation revealed that the cheeses double coated with chitosan-oregano oil were the best evaluated in terms of aroma and flavour. / [ES] En la Tesis Doctoral, se han analizado diferentes estrategias para mejorar las propiedades funcionales de películas de almidón para aplicaciones de envasado de alimentos: el estudio del ratio amilosa:amilopectina, mezclas con otros polímeros (alcohol de polivinilo-PVA), y la incorporación de diferentes refuerzos (salvado de arroz y nanocristales de celulose-CNCs) y agentes antimicrobianos (aceite de neem-N, aceite esencial de orégano-O y nanopartículas de plata-AgNPs). También se realizó un estudio de biodegradación de las películas observando el efecto de los antimicrobianos. Entre los diferentes almidones con distinto ratio amilosa:amilopectina, se seleccionó el almidón de guisante con altos valores de amilosa. El alto contenido en amilosa dio lugar a películas más rígidas y resistentes a la fractura, con baja permeabilidad al oxígeno, la cual disminuyó durante el almacenamiento. Las películas de mezcla de almidón-PVA (S-PVA) representaron una buena estrategia para mejorar las propiedades de las películas sin incrementar notablemente el precio. La adición de PVA dio lugar a películas menos solubles en agua, menos sensibles a su absorción y más extensible y resistentes que las de almidón puro, mientras mantuvieron alta barrera al oxígeno y dieron estabilidad a la matriz durante el envejecimiento. Son recomendables los ratios de S-PVA cercanos a 1:1. El salvado de arroz con menor tamaño de partícula, mejoró el modulo elástico de las películas, pero su extensibilidad y propiedades barrera empeoraron debido a la mejor capacidad de retención de agua y a las discontinuidades introducidas. La incorporación de CNCs en las películas de S-PVA incrementó la separación de fases de los polímeros, sin cambios en la permeabilidad al vapor de agua, y mejoró las prestaciones mecánicas: películas más rígidas y extensibles, mientras que inhibió parcialmente la cristalización del PVA. Las películas de S-PVA con partículas de plata exhibieron actividad antimicrobiana contra dos hongos y dos bacterias, dependiendo de la concentración de plata. Las AgNPs provocaron cambios en el color de las películas así como en su transparencia. La plata fue completamente liberada en los primeros 60 minutos en contacto con simulantes acuosos, sin embargo la liberación disminuyó en simulantes no polares, donde se cumple el límite de migración global. Por lo tanto, el uso de las películas desarrolladas para envasado de alimentos debe ser restringido a productos alimenticios ricos en grasas. La incorporación de O en la matriz de S-PVA dio lugar a películas activas contra bacterias y hongos, mientras que las películas con N no fueron efectivas. Se necesitaron concentraciones más altas de O en las películas para observar un efecto antifúngico respecto a la actividad bactericida. Los aceites no afectaron notablemente la sensibilidad ni las propiedades barreras al agua de las películas, aunque la mayor proporción de aceite dio lugar a películas con una red más débil, afectando sus prestaciones mecánicas. La mezcla de S con PVA mejoró significativamente el comportamiento de biodegradación y desintegración de las películas. La incorporación de AgNPs a películas de S-PVA disminuyó su cinética de biodegradación mientras aumentó su ratio de degradación. La adición de O no presentó efecto significativo en el índice de biodegradación a pesar de la actividad antimicrobiana detectada. El N incluso mejoró la biodegradación de las películas. Finalmente, se realizó una aplicación de recubrimientos basados en biopolímeros, usando quitosano-CH y aceite esencial de orégano o romero para evitar la pérdida de peso y el desarrollo de hongos en quesos de cabra semicurados. Los recubrimientos fueron efectivos en la reducción del crecimiento fúngico y la pérdida de peso de los quesos, mientras que la actividad lipolítica y proteolítica ligeramente disminuyó. El análisis sensorial reveló q / [CA] S'han analitzat diferents estratègies per a millorar les propietats funcionals de pel·lícules de midó per a aplicacions d'envasat d'aliments: l'estudi de la ràtio amilosa:amilopectina, mescles amb altres polímers (alcohol polivinílic-PVA), i la incorporació de diferents reforços (segó d'arròs i nanocristalls de celulosa-CNCs) i agents antimicrobians (oli de neem-N, oli essencial d'orenga-O i nanopartícules de plata). També es va fer un estudi de biodegradació de les pel·lícules per observar l'efecte dels antimicrobians. Entre els diferents midons amb distint ràtio amilosa:amilopectina, es va seleccionar el midó de pèsol amb alts valors d'amilosa. L'alt contingut en amilosa va donar lloc a pel·lícules més rígides i resistents a la fractura, amb baixa permeabilitat a l'oxigen, la qual va disminuir durant l'emmagatzemament. Les pel·lícules de mescla de S-PVA van representar una bona estratègia per a millorar les propietats de les pel·lícules sense incrementar notablement el preu. L'addició de PVA va donar lloc a pel·lícules menys solubles en aigua, menys sensibles a la seua absorció i més extensible i resistents que les de midó pur. A més van mantenir l'alta barrera a l'oxigen i van donar estabilitat a la matriu durant l'envelliment. Son recomanables les ràtios de S- PVA pròxims a 1:1. El segó d'arròs amb menor tamany de partícula, va millorar el mòdul elàstic de les pel·lícules, però la seua extensibilitat i propietats barrera van empitjorar. La incorporació de CNCs en les pel·lícules de S-PVA, va incrementar la separació de fases dels polímers, sense implicar canvis en la permeabilitat al vapor d'aigua, però millorant les prestacions mecàniques: pel·lícules més rígides i extensibles, al mateix temps que es va inhibir parcialment la cristal·lització del PVA. Les pel·lícules de S-PVA amb partícules de plata van exhibir activitat antimicrobiana front a dos de fongs i dos bacteris, depenent de la concentració de plata. Les AgNPs van provocar canvis en el color de les pel·lícules així com en la seua transparència. La plata va ser completament alliberada en els primers 60 minuts en contacte amb simulants aquosos. La capacitat d'alliberament va disminuir en simulants no polars, on es complix el límit de migració global. Per tant, l'ús de les pel·lícules desenvolupades per a l'envasat d'aliments ha de ser restringit a productes alimentaris rics en greixos. La incorporació d'O en la matriu de S-PVA va donar lloc a pel·lícules actives front a bacteris i fongs. Pel contrari les pel·lícules amb N no van ser efectives. Van ser necessàries concentracions més elevades d'O en les pel·lícules per a observar un efecte antifúngic respecte a l'activitat bactericida. Els olis no van afectar la sensibilitat a l'aigua ni les propietats barrera a l'aigua de les pel·lícules, però la major proporció d'oli va donar lloc a pel·lícules amb una xarxa més dèbil, afectant les seues prestacions mecàniques. La mescla de S amb PVA va millorar significativament el comportament de biodegradació i desintegració. La incorporació de partícules de plata a pel·lícules de S-PVA va disminuir la seua cinètica de biodegradació mentre que va augmentar la seua ràtio de degradació. No obstant això, l'addició d'O no va presentar un efecte significatiu en els índexs de biodegradació a pesar de l'activitat antimicrobiana detectada. L'N fins i tot va millorar la biodegradació de les pel·lícules de S-PVA. Finalment, es va realitzar una aplicació de recobriments basats en biopolímers, fent ús de quistosà-CH i olis essencials de orenga i romer per evitar la pèrdua de pes i el desenvolupament de fongs en formatges de cabra semi-curats. Els recobriments van ser altament efectius en la reducció del creixement fúngic i la pèrdua de pes dels formatges. L'activitat lipolítica i proteolítica en els formatges va disminuir suaument. L'anàlisi sensorial va revelar que els form / Cano Embuena, AI. (2015). Different strategies to improve the functionality of biodegradable films based on starch and other polymers [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/55383 / TESIS / Premios Extraordinarios de tesis doctorales / Compendio

Thesis (MScEng (Civil Engineering))--University of Stellenbosch, 2005. / 192 leaves on CD format, preliminary i-xii pages and numbered pages 1-135. Includes bibliography, list of figures and tables. / ENGLISH ABSTRACT: As a fibre reinforced material, engineered cementitious composite (ECC) has tough, strain-hardening behaviour in tension despite containing low volumes of fibres. This property can be brought about by developments in fibre, matrix and interfacial properties. Poly Vinyl Alcohol (PVA) fibre has been developed in recent years for ECC, due to its high tensile strength and elasticity modulus. However, the strong interfacial bond between fibre surface and matrix is a challenge for its application. This study focuses on the tailoring of matrix and fibre/matrix interfacial properties by cement replacement with fly ash (FA) and Ground Granulated Corex Slagment (GGCS). In this study the direct tensile test, three point bending test, micro-scale analysis, such as X-Ray Fluorescence Spectrometry analysis (XRF), Scanning Electron Microscope (SEM), are employed to investigate the influence of cement replacement, aging, Water/Binder (W/B) ratio, workability on ECC behaviour. This study has successfully achieved the aim that cement replacement by FA and GGCS helps to improve the fibre/matrix interfacial properties and therefore enhances the ECC tensile behaviour. Specifically, a high volume FA-ECC has stable high tensile strain capacity at the age of 21 days. This enables a constant matrix design for the investigation of other matrix influences. The Slag-ECC has a higher tensile strength but lower tensile strain capacity. The combination of FA and GGCS, moderate tensile strength and strain capacity is achieved Both tensile tests and Micro-scale analyses infer that the high volume FA-ECC has an adhesive type fibre/matrix interfacial interaction, as opposed to the cohesive type of normal PVA fibre-ECC. The different tensile behaviour trend of steel fibre-ECC and PVA fibre-ECC with the FA content is presented and discussed in this research. The investigations of aging influence indicate that the high volume FA-ECC has a beneficial effect on the properties of the composite at an early stage. However, at a high age, it has some difficulty to undergo multiple cracking and then leads to the reduction of tensile strain capacity. The modified mix design is made with the combination of FA and GGCS, which successfully increases the interfacial bond and, thereby, improves the shear transfer to reach the matrix crack strength. Therefore, an improved high age tensile behaviour is achieved. The W/B and fresh state workability influence investigations show that the W/B can hardly affect the tensile strain at early age. However, the workability influences on composite tensile strain significantly, because of the influence on fibre dispersion. Other investigations with regard to the hybrid fibre influences, the comparison of bending behaviours between extruded plate and cast plate, the relation between bending MOR and tensile stress, and the relation between compression strength and tensile strength contribute to understand ECC behaviour. / AFRIKAANSE OPSOMMING: As ‘n veselversterkte materiaal, het ontwerpte sementbasis saamgestelde materiale, taai vervormingsverhardingseienskappe in trek, ten spyte van lae veselinhoud. Hierdie eienskap word bewerkstellig, deur ontwikkelings in vesel, matriks en tussenveselbindingseienskappe. Poli-Viniel Alkohol (PVA) vesels is ontwikkel vir ECC, as gevolg van die hoë trekkrag en hoë modulus van hierdie veseltipe. Die sterk binding tussen die PVA-veseloppervlak en die matriks is egter ‘n uitdaging vir sy toepassing. Hierdie studie fokus op die skep van gunstige matriks en vesel/matriks tussenvesel-bindingseienskappe deur sement te vervang met vlieg-as (FA) en slagment (GGCS).In hierdie navorsing is direkte trek-toetse, drie-punt-buigtoetse, mikro-skaal analise (soos die X-straal ‘Fluorescence Spectrometry’ analise (XRF) en Skanderende Elektron Mikroskoop (SEM))toegepas. Hierdie metodes is gebruik om die invloed van sementvervanging,veroudering, water/binder (W/B)-verhouding en werkbaarheid op die meganiese gedrag van ECC te ondersoek.Die resultate van hierdie navorsing toon dat sementvervanging deur FA en GGCS help om die vesel/matriks tussenveselbindingseienskappe te verbeter. Dus is die ECC-trekgedrag ook verbeter. Veral ‘n hoë volume FA-ECC het stabiele hoë trekvervormingskapasiteit op ‘n ouderdom van 21 dae. Dit bewerkstellig ‘n konstante matriksontwerp vir die navorsing van ander matriks invloede. Die Slag-ECC het ‘n hoër treksterkte, maar laer trekvervormingskapasiteit. Deur die kombinasie van FA en GGCS word hoë treksterkte, sowel as gematigde vervormbaarheid in trek verkry. Beide trektoetse en mikro-skaal analise dui aan dat die hoë volume FA-ECC ‘n adhesie-tipe vesel/matriks tussenvesel-bindingsinteraksie het, teenoor die ‘kohesie-tipe van normale PVA vesel-ECC. Die verskille in trekgedrag van staalvesel-ECC en PVA vesel-ECC ten opsigte van die FA-inhoud is ondersoek en word bespreek in die navorsing. Die navorsing toon verder dat die hoë volume FA-ECC goeie meganiese eienskappe het op ‘n vroeë ouderdom. Op hoër ouderdom word minder krake gevorm, wat ‘n verlaging in die trekvervormingskapasiteit tot gevolg het. Met die kombinasie van FA en GGCS, word die vesel-matriksverband verhoog, waardeur ‘n verbetering in die skuifoordrag tussen vesel en matriks plaasvind. Verbeterde hoë omeganiese gedrag word daardeur tot stand gebring. Navorsing ten opsigte van die invoed van die W/B en werkbaarheid dui daarop dat die W/B slegs geringe invloed het op die trekvormbaarheid, terwyl die werkbaarheid ‘n dominerende rol speel in hierdie verband.Verdere studies sluit in die invloed van verskillende vesels, die vergelyking van die buigingsgedrag van geëkstueerde plate en gegote plate, die verhouding tussen buigsterkte en treksterkte, en die verhouding tussen druksterkte en treksterkte dra by tot beter begrip van die gedrag van ECC.

Este trabalho contemplou o estudo do desenvolvimento de amidos termoplásticos (TPS) obtidos a partir da raiz de mandioca bruta e de seus derivados (amido e resíduo). A técnica de preparação deu-se por mistura física dos componentes, via estado fundido, empregando-se o plasticizante glicerol em proporções variadas. Contemplou ainda a busca de alternativas que viessem a melhorar o desempenho mecânico e a resistência à absorção de umidade dos TPS. Foi realizado um estudo inicial de caracterização dos materiais originais e constatou-se que a presença de açúcares na raiz e de fibras no resíduo é o principal diferencial com relação à composição do amido industrial. Os TPS preparados a partir de amido industrial e de raiz apresentaram fraco desempenho mecânico. Por outro lado, as fibras presentes no resíduo foram capazes de gerar TPS com melhores propriedades mecânicas. Os açúcares naturalmente presentes na raiz ocasionaram um efeito adicional de plasticização ao TPS influenciando principalmente nas propriedades de alongamento na ruptura. Os TPS preparados apresentaram comportamentos semelhantes frente à absorção de água. As estratégias empregadas na tentativa de melhorar o desempenho do TPS preparado a partir de amido de mandioca industrial foram: desenvolvimento de blendas de TPS com poli (álcool vinílico) (PVA); adição de látex de borracha natural às blendas TPS/PVA; uso de partículas minerais (alumina e carbeto de silício) aos TPS e uso de nanofibras de celulose (whiskers) como reforço aos TPS. Estas nanofibras foram extraídas a partir das fibras contidas no resíduo da industrialização do amido de mandioca. Em todos os casos foram realizados estudos da morfologia e do desempenho dos materiais resultantes. Os resultados revelaram que as blendas TPS/PVA e TPS/PVA/látex foram, em sua maioria, imiscíveis, porém compatíveis, pois o desempenho mecânico e de resistência à umidade foram aumentados. O látex, empregado em conjunto com o PVA, gerou materiais com módulo elástico cerca de 1330% maior que a combinação TPS/látex, além de reduzir a absorção de água das blendas TPS/PVA em 12%. A alumina (Al2O3) promoveu um efeito de plasticização no TPS ocorrendo um aumento de 68% no alongamento. Em contrapartida, houve uma redução de 70% no módulo elástico e de 40% na tensão de tração na ruptura. O carbeto de silício (SiC) mostrou-se efetivo no aumento do módulo elástico (aumento de 230%). O efeito de reforço acarretado pelos ´whiskers´ foi limitado devido à presença de açúcares decorrentes da hidrólise ácida do amido residual contido no resíduo. Os testes de resistência à tração não foram sensíveis para a completa determinação das propriedades mecânicas. Entretanto, os resultados de análise térmico-dinâmico-mecânica revelaram que houve um aumento de 26% no módulo de armazenamento. A principal contribuição do uso destas nanofibras deu-se na redução de absorção de água (34% em relação ao TPS sem ´whiskers´). Como um todo, os resultados obtidos nesta tese revelaram a possibilidade de obtenção de TPS a partir da mandioca e de seus derivados e que as estratégias adotadas para melhorar o desempenho final dos TPS foram satisfatórias. / In this work it was studied the development of thermoplastic starches (TPS) prepared from raw cassava root and its derivatives, starch and bagasse (residue). The TPS were prepared by melt-processing employing glycerol as plasticizer in distinct proportions. It was searched for alternatives that could improve both, the mechanical performance and resistance to water of the TPS. It was made a previous characterization of the original materials. It was verified that the presence of sugars in the cassava root and of fibres in the bagasse is the main distinction in relation to the composition of industrial starch. The TPS from industrial starch and cassava root presented the poorer mechanical performance. On the other hand, the fibres in the bagasse allowed the obtainment of a more mechanical resistant TPS in relation to the other TPS. The presence of natural sugars in the cassava root promoted an additional effect on the plasticization of TPS, influencing mainly the elongation properties. The prepared TPS presented similar behaviors in relation to water absorption. The strategies adopted to improve the performance of TPS prepared from industrial starch were: the development of TPS blends with polyvinyl alcohol (PVA); addition of latex of natural rubber to TPS/PVA blends TPS/PVA; the use of mineral particles (alumina and silicon carbide) to the TPS and also, utilization of cellulose nanofibres (whiskers), as reinforcement to the TPS. These whiskers were extracted from the fibres contained in the cassava bagasse. For all the cases the morphology and final performance of the resulting materials were investigated. The results revealed that TPS/PVA and TPS/PVA/latex blends were in a greater number immiscible, although, compatibles since, the mechanical performance and water resistance were increased. The latex, employed together PVA, promoted a 1330% increase in the elastic modulus compared to TPS/latex. Also, the water absorption of TPS/PVA blends was reduced in 12%. The alumina (Al2O3) promoted a plasticizing effect in the TPS with an increase of 68% in elongation. On the other hand, the elastic modulus and tensile strength were reduced in 70% and 40%, respectively. The silicon carbide (SiC) was effective to increase the elastic modulus (increase of 230%). The reinforcement effect of the whiskers was limited due to the presence of sugars resultants of the acid hydrolysis of residual starch present in the bagasse. The tensile tests were not sensitive to determine the mechanical properties. However, from dynamicmechanical tests it was verified an increase of 26% in the storage modulus. The main contribution of the use of nanofibers was on the reduction of water absorption in 34% compared to TPS without nanofibers. As a whole, the results obtained in this work revealed the possibility of preparation of TPS from cassava root and its derivatives and that the strategies adopted to improve the final performance of the TPS ware successful.

Devido à importância industrial e tecnológica dos látices estabilizados com poli(álcool vinílico)/PVA e a dificuldade encontrada na etapa de polimerização em emulsão, na presença de monômeros hidrofóbicos e de PVA\'s com alto grau de hidrólise (>92%), a síntese de novos estabilizantes poliméricos derivados de PVA para utilização em reações de polimerização em emulsão e em miniemulsão se torna muito atraente e desafiadora. O objetivo principal deste trabalho foi sintetizar novos estabilizantes poliméricos do tipo poli(álcool vinílico-co-neodecanoato de vinila)/PVA-VV com alto grau de hidrólise e conseqüentemente com propriedades diferenciadas, para serem utilizados como estabilizantes nas reações de polimerização em emulsão e em miniemulsão do acetato de vinila (VAc) com o neo-nonanoato de vinila (VEOVA-9), visando a obtenção de adesivos com propriedades diferenciadas para colagem de madeiras. Os novos estabilizantes poliméricos foram obtidos em duas etapas: i) copolimerização em solução do VAc com o neo-decanoato de vinila (VEOVA-10); ii) hidrólise alcalina (NaOH/Metanol) do poli(acetato de vinila-coneodecanoato de vinila). As miniemulsões de VAc com VEOVA-9 com diferentes tipos de estabilizantes poliméricos foram preparadas em um homogeneizador de alta pressão do tipo \"Manton Gaulin\". Foi estudado o efeito dos estabilizantes poliméricos (PVA e PVA-VV) na etapa de emulsificação (diâmetro médio das gotas, polidispersão, estabilidade das miniemulsões) e na copolimerização em emulsão e em miniemulsão do VAc com o VEOVA-9, em processo batelada. O efeito do tipo de iniciador (persulfato de amônio/APS e hidroperóxido de tércio butila/TBHP e peróxido benzoato de tércio butila/TBPB, juntamente com o formaldeído sulfoxilato de sódio/SFS) na cinética da polimerização em miniemulsão do VAc com o VEOVA-9 foi estudado em processo semi-contínuo. A distribuição dos estabilizantes poliméricos (PVA e PVA-VV) entre a fase aquosa e a superfície das partículas de polímero (adsorvido/enxertado) foi determinada e correlacionada com a viscosidade e a estabilidade coloidal dos látices. Látices na condição ideal de cópia (1:1) das gotas de monômero para as partículas de polímero foram obtidos via polimerização em miniemulsão, apresentando propriedades diferenciadas, tais como, menores valores de viscosidade, menor concentração de coágulos e maior estabilidade de estocagem, em comparação com os látices obtidos em emulsão. / Due to the technological and industrial importance of latexes stabilized with poly(vinyl alcohol)/PVA and the difficulties related to the emulsion polymerization of hydrophobic monomers and the use of PVA having a high degree of hydrolysis (> 92%), the synthesis of new PVA based polymeric stabilizers for use in emulsion and miniemulsion polymerizations becomes very attractive and challenging. The aim of this work was to synthesize a new class of polymeric stabilizer, poly(vinyl alcohol-co-vinyl neo-decanoate)/PVA-VV, with a high degree of hydrolysis and differentiated properties to be used as stabilizers in the emulsion and miniemulsion copolymerization of vinyl acetate (VAc) with vinyl neo-nonanoate (VEOVA-9), that can be used as adhesive for wood bonding. New PVA based polymeric stabilizers with high degree of hydrolysis (94 - 98%) were synthesized in two steps: i) solution copolymerization of vinyl acetate (VAc) with vinyl neo-decanoate (VEOVA-10) and ii) alkaline hydrolysis (NaOH/Methanol) of poly(vinyl acetate-co-vinyl neodecanoate). Miniemulsions of VAc/VEOVA-9 were prepared using the different polymeric stabilizers in a \"Manton Gaulin\" high pressure homogenizer. The effect of different initiators (ammonium persulfate/APS or tert-butyl hydro peroxide/TBHP and tert-butyl peroxide benzoate/TBPB in the presence of sodium formaldehyde sulfoxylate/SFS) in the polymerization kinetic was evaluated. The effect of the type and concentration of polymeric stabilizer, in the emulsification step (average diameter of drops, stability of miniemulsions) as well in the polymerizations (rate of consumption of monomers, particle size and particles number) was investigated in this work. The partition of the polymeric stabilizers between the aqueous phase and the polymer particle surface (grafted/adsorbed) was determined and correlated with the viscosity and colloidal stability of latexes. Latexes with differentiated properties such as low-viscosity, lower grits content and improved storage stability, were obtained by miniemulsion polymerization with an ideal condition copy (1:1) of the monomer droplets to the polymer particles.

Pervaporation (PV), a non-porous membrane separation process, is gaining considerable attention for solvent separation in a variety of industries ranging from chemical to food and pharmaceutical to petrochemicals. The most successful application has been the dehydration of organic liquids, for which hydrophilic membranes are used. However, during pervaporation, excessive affinity of water towards hydrophilic membranes leads to undesirable swelling (water absorption) of the membrane matrix. To control swelling, often hydrophilic membranes are crosslinked to modify physicochemical (surface and bulk) properties. Since the transport of species in pervaporation is governed by sorption (affected by surface and bulk properties) and diffusion (affected by bulk properties), it is essential to study the effect of crosslinking on the surface and bulk physicochemical properties and their effects on separation performance. This thesis focuses on the effect of crosslinking on the physicochemical properties (e.g., crystallinity, hydrophilicity, surface roughness) of hydrophilic polymeric membranes and their dehydration performance alcohol-water mixtures. Poly(vinyl alcohol), PVA was used as the base polymer to prepare membranes with various morphologies such as homogeneous, blended (with Chitosan, CS) and composite (with poly(sulfone), PSf) structures. Before applying the crosslinked membranes for the PV dehydration of alcohols, the physicochemical characterization were carried out using Attenuated Total Reflection-Fourier Transform Infrared Spectroscopy (ATR-FTIR), X-Ray Diffraction (XRD), Differential Scanning Calorimetry (DSC), Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), tensile testing, contact angle and swelling experiments. The crosslinked membranes showed an increase in surface hydrophobicity from the contact angle measurements as compared to the uncrosslinked membranes. AFM surface topography showed that the membrane surfaces have nodular structures and are rough at the nanometer scale and affected by the crosslinking conditions such as concentration and reaction time. Surface hydrophobicity and roughness was found to increase with increasing degree of crosslinking. DSC measurements showed an increase in melting temperature of the polymer membranes after crosslinking. For the PV dehydration of ethanol, a decrease in flux and an increase in selectivity were observed with increase in the degree of crosslinking. Effects of membrane thickness (of PVA layer) for crosslinked PVA-PSf composite membranes were studied on PV dehydration of ethanol. Total flux and selectivity were statistically analyzed as a function of the membrane thickness. In general, the outcome agrees with the solution-diffusion (S-D) theory: the total flux was found to be significantly affected by the PVA layer thickness, while the selectivity remains nearly unaffected. Using the S-D theory, the mass transfer resistance of the selective layers was calculated and found to increase with thickness. The relatively small change observed for selectivity has been related to the crosslinking of the PVA layer that increases the surface hydrophobicity of the membrane. Chitosan-Poly(vinyl alcohol), or CS-PVA, blended membranes were prepared by varying the blending ratio to control membrane crystallinity and its effect on the PV dehydration of ethylene glycol. The blended membranes were crosslinked interfacially with trimesoyl chloride (TMC)/hexane. The crystallinity of the membrane was found to decrease with increasing CS wt% in the blend. Although the crosslinked CS-PVA blend membranes showed improved mechanical strength, they became less flexible as detected in tensile testing. The resulting crosslinked CS-PVA blended membranes showed high flux and selectivity simultaneously, for 70-80wt% CS in the blend. The effect of feed flow-rate was studied to find the presence of concentration polarization for 90wt% EG in feed mixture as well. The crosslinked blend membrane with 75wt% CS showed a highest total flux of 0.46 kg/m2/h and highest selectivity of 663 when operating at 70oC with 90wt% EG in the feed mixture. Effects of crosslinking concentration and reaction time of trimesoyl chloride (TMC) were studied on poly(vinyl alcohol)-poly(sulfone) or PVA-PSf composite membranes. Results showed a consistent trend of changes in the physicochemical properties: the degree of crosslinking, crystallinity, surface roughness, hydrophilicity and swelling degree all decrease with increasing crosslinking agent (TMC) concentration and reaction time. The crosslinked membrane performance was assessed with PV dehydration of ethylene glycol-water mixtures at a range of concentrations (30 to 90wt% EG). The total flux of permeation was found to decrease, while the selectivity to increase, with increasing TMC concentration and reaction time. The decrease in flux was most prominent at low EG concentrations in the feed mixtures. A central composite rotatable design (CCRD) of response surface methodology was used to analyze PV dehydration performance of crosslinked poly(vinyl alcohol) (PVA) membranes. Regression models were developed for the flux and selectivity as a function of operating conditions such as, temperature, feed alcohol concentration, and flow-rate. Dehydration experiments were performed on two different alcohol-water systems: isopropanol-water (IPA-water) and ethanol-water (Et-water) mixtures around the azeotrope concentrations. Judged by the lack-of-fit criterion, the analysis of variance (ANOVA) showed the regression model to be adequate. The predicted flux and selectivity from the regression models were presented in 3-D surface plots over the whole ranges of operating variables. For both alcohol-water systems, quadratic effect of temperature and feed alcohol concentration showed significant (p < 0.0001) influence on the flux and selectivity. A strong interaction effect of temperature and concentration was observed on the selectivity for the Et-water system. For the dehydration of azeotropic IPA-water mixture (87.5wt% IPA), the optimized dehydration variables were found to be 50.5oC and 93.7 L/hr for temperature and flow-rate, respectively. On the other hand for azeotropic Et-water mixture (95.5wt% Et), the optimized temperature and flow-rate were found to be 57oC and 89.2 L/hr, respectively. Compared with experiments performed at optimized temperature and feed flow-rate, the predicted flux and selectivity of the azeotropic mixtures showed errors to be within 3-6 %.

Pervaporation (PV), a non-porous membrane separation process, is gaining considerable attention for solvent separation in a variety of industries ranging from chemical to food and pharmaceutical to petrochemicals. The most successful application has been the dehydration of organic liquids, for which hydrophilic membranes are used. However, during pervaporation, excessive affinity of water towards hydrophilic membranes leads to undesirable swelling (water absorption) of the membrane matrix. To control swelling, often hydrophilic membranes are crosslinked to modify physicochemical (surface and bulk) properties. Since the transport of species in pervaporation is governed by sorption (affected by surface and bulk properties) and diffusion (affected by bulk properties), it is essential to study the effect of crosslinking on the surface and bulk physicochemical properties and their effects on separation performance. This thesis focuses on the effect of crosslinking on the physicochemical properties (e.g., crystallinity, hydrophilicity, surface roughness) of hydrophilic polymeric membranes and their dehydration performance alcohol-water mixtures. Poly(vinyl alcohol), PVA was used as the base polymer to prepare membranes with various morphologies such as homogeneous, blended (with Chitosan, CS) and composite (with poly(sulfone), PSf) structures. Before applying the crosslinked membranes for the PV dehydration of alcohols, the physicochemical characterization were carried out using Attenuated Total Reflection-Fourier Transform Infrared Spectroscopy (ATR-FTIR), X-Ray Diffraction (XRD), Differential Scanning Calorimetry (DSC), Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), tensile testing, contact angle and swelling experiments. The crosslinked membranes showed an increase in surface hydrophobicity from the contact angle measurements as compared to the uncrosslinked membranes. AFM surface topography showed that the membrane surfaces have nodular structures and are rough at the nanometer scale and affected by the crosslinking conditions such as concentration and reaction time. Surface hydrophobicity and roughness was found to increase with increasing degree of crosslinking. DSC measurements showed an increase in melting temperature of the polymer membranes after crosslinking. For the PV dehydration of ethanol, a decrease in flux and an increase in selectivity were observed with increase in the degree of crosslinking. Effects of membrane thickness (of PVA layer) for crosslinked PVA-PSf composite membranes were studied on PV dehydration of ethanol. Total flux and selectivity were statistically analyzed as a function of the membrane thickness. In general, the outcome agrees with the solution-diffusion (S-D) theory: the total flux was found to be significantly affected by the PVA layer thickness, while the selectivity remains nearly unaffected. Using the S-D theory, the mass transfer resistance of the selective layers was calculated and found to increase with thickness. The relatively small change observed for selectivity has been related to the crosslinking of the PVA layer that increases the surface hydrophobicity of the membrane. Chitosan-Poly(vinyl alcohol), or CS-PVA, blended membranes were prepared by varying the blending ratio to control membrane crystallinity and its effect on the PV dehydration of ethylene glycol. The blended membranes were crosslinked interfacially with trimesoyl chloride (TMC)/hexane. The crystallinity of the membrane was found to decrease with increasing CS wt% in the blend. Although the crosslinked CS-PVA blend membranes showed improved mechanical strength, they became less flexible as detected in tensile testing. The resulting crosslinked CS-PVA blended membranes showed high flux and selectivity simultaneously, for 70-80wt% CS in the blend. The effect of feed flow-rate was studied to find the presence of concentration polarization for 90wt% EG in feed mixture as well. The crosslinked blend membrane with 75wt% CS showed a highest total flux of 0.46 kg/m2/h and highest selectivity of 663 when operating at 70oC with 90wt% EG in the feed mixture. Effects of crosslinking concentration and reaction time of trimesoyl chloride (TMC) were studied on poly(vinyl alcohol)-poly(sulfone) or PVA-PSf composite membranes. Results showed a consistent trend of changes in the physicochemical properties: the degree of crosslinking, crystallinity, surface roughness, hydrophilicity and swelling degree all decrease with increasing crosslinking agent (TMC) concentration and reaction time. The crosslinked membrane performance was assessed with PV dehydration of ethylene glycol-water mixtures at a range of concentrations (30 to 90wt% EG). The total flux of permeation was found to decrease, while the selectivity to increase, with increasing TMC concentration and reaction time. The decrease in flux was most prominent at low EG concentrations in the feed mixtures. A central composite rotatable design (CCRD) of response surface methodology was used to analyze PV dehydration performance of crosslinked poly(vinyl alcohol) (PVA) membranes. Regression models were developed for the flux and selectivity as a function of operating conditions such as, temperature, feed alcohol concentration, and flow-rate. Dehydration experiments were performed on two different alcohol-water systems: isopropanol-water (IPA-water) and ethanol-water (Et-water) mixtures around the azeotrope concentrations. Judged by the lack-of-fit criterion, the analysis of variance (ANOVA) showed the regression model to be adequate. The predicted flux and selectivity from the regression models were presented in 3-D surface plots over the whole ranges of operating variables. For both alcohol-water systems, quadratic effect of temperature and feed alcohol concentration showed significant (p < 0.0001) influence on the flux and selectivity. A strong interaction effect of temperature and concentration was observed on the selectivity for the Et-water system. For the dehydration of azeotropic IPA-water mixture (87.5wt% IPA), the optimized dehydration variables were found to be 50.5oC and 93.7 L/hr for temperature and flow-rate, respectively. On the other hand for azeotropic Et-water mixture (95.5wt% Et), the optimized temperature and flow-rate were found to be 57oC and 89.2 L/hr, respectively. Compared with experiments performed at optimized temperature and feed flow-rate, the predicted flux and selectivity of the azeotropic mixtures showed errors to be within 3-6 %.

This study illustrates the ability of SWNT to nucleate and template polymer crystallization and orientation, and produce materials with improved properties and unique polymer morphologies. This research work focuses primarily on the physical interaction between single-wall carbon nanotubes (SWNT) and the flexible polymer system polyvinyl alcohol (PVA). Polymer crystallization in the near vicinity of SWNT (interphase) has been studied to understand the capability of SWNT in influence polymer morphology in bulk films and fibers. Fibrillar crystallization was achieved by shearing PVA/SWNT dispersions and resulted in the formation of oriented PVA/SWNT fibers or ribbons, while PVA solutions produce unoriented fibers. PVA single crystals were grown in PVA solutions as well as PVA/SWNT dispersions over a period of several months at room temperature (25 C). PVA single crystal growth in PVA/SWNT dispersions is templated by SWNT, and these crystals show the presence of new morphologies for PVA. PVA single crystals of differing morphology were also grown at elevated temperatures, and show morphology dependant electron beam irradiation resistance. Gel-spinning was used to produce PVA, and PVA/SWNT fibers where, PVA crystallization in the bulk fiber was observed. With 1 wt% SWNT loading in PVA, the fiber tensile strength increased from 1.6 GPa for the control PVA to 2.6 GPa for PVA/SWNT. Analysis of this data suggests stress of up to ~120 GPa on the SWNT. This is the highest reported stress on the SWNT to date and confirm excellent reinforcement and load transfer of SWNT in the PVA matrix. Raman spectroscopy data show high SWNT alignment in the fiber where the ratio is measured to be 106. High-resolution transmission electron microscopy (HR-TEM) is used to characterize polymer morphology near the polymer-SWNT interface for PVA/SWNT fibers. HR-TEM studies of Polymer/CNT composites show distinct morphological differences at the polymer-SWNT interface/interphase for semi-crystalline and amorphous polymer systems which may be related to polymer-SWNT interaction in the composite. Studies on polymer crystallization, carbon nanotube (CNT)/polymer composite, and polymer composite interfacial literature in summarized in Chapter 1. Fibrillar crystallization of PVA and PVA/SWNT is presented in Chapter 2. PVA single crystal grown at varying temperatures is discussed in Chapter 3, followed by single crystal growth studies in PVA/SWNT dispersions in Chapter 4. Chapter 5 summarizes the gel-spinning studies of PVA and PVA/SWNT fibers. Conclusions and recommendations for future work pertaining to this study are given in Chapter 6. Results of HR-TEM studies on other polymer/SWNT composites are given in Appendix A, Appendix B summarizes work on PE crystallization in the SWNT/DMF dispersions, and studies of PVA and PVA/SWNT gel films are summarized in Appendix C.

Submitted by Daniele Amaral (daniee_ni@hotmail.com) on 2016-09-21T20:58:24Z No. of bitstreams: 1 DissVBS.pdf: 1740289 bytes, checksum: f0f9dfa6182cf0c0dfe8b39ff3cda89c (MD5) / Approved for entry into archive by Marina Freitas (marinapf@ufscar.br) on 2016-10-04T18:07:59Z (GMT) No. of bitstreams: 1 DissVBS.pdf: 1740289 bytes, checksum: f0f9dfa6182cf0c0dfe8b39ff3cda89c (MD5) / Approved for entry into archive by Marina Freitas (marinapf@ufscar.br) on 2016-10-04T18:08:06Z (GMT) No. of bitstreams: 1 DissVBS.pdf: 1740289 bytes, checksum: f0f9dfa6182cf0c0dfe8b39ff3cda89c (MD5) / Made available in DSpace on 2016-10-04T18:08:13Z (GMT). No. of bitstreams: 1 DissVBS.pdf: 1740289 bytes, checksum: f0f9dfa6182cf0c0dfe8b39ff3cda89c (MD5) Previous issue date: 2015-11-10 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Poly(vinyl alcohol) - PVA is a high hydrophilic semicrystalline polymer which has excellent properties such as good chemical resistance and high biodegradability and biocompatibility. Due to its semi-crystalline nature, crystalline domains, under controlled conditions, may act as physical crosslinking points, while maintaining the integrity of the structure under swelling. This feature makes PVA hydrogels promising for the development of drug, or other bioactive substances, delivery systems. Another interesting feature of this kind of hydrogels is the ability to form high stable network from crystalline domains formed through freezing and thawing cycles. This method shows the formation of crystallites which act as physical crosslinks while maintaining the insolubility of the material in water. Recently many studies show the use of nanostructures to improve mechanics properties and diffusional behavior of small molecules. Paromomycin is an aminoglycoside antibiotic widely used for cutaneous leishmaniasis therapeutics in Brazil. In the last years some studies have revealed that the patience adhesion to the treatments of cutaneous leishmaniasis with ointments form is low. Therefore hydrogels are an interesting alternative to the ointment forms. As the main objective of this work was the preparation and characterization of poly(vinyl alcohol) hydrogels containing sepiolite nanoparticles for the preliminary feasibility of using as controlled release system for paromomycin, hydrogels were prepared by cryogelation process. This ensures the formation of the hydrogel, as long as the crystalline domains formed during the PVA cycles act as crosslinking points, allowing the membranes water transport measurements of the drug in the presence of sepiolite. In this investigation membranes were characterized by differential calorimetry, thermogravimetry and X-ray diffraction. Furthermore polymer retention, swelling in simulated body fluid, hemocompatibility and drug delivery were studied to establish structure-properties correlations. The results show that cryogelation cycles significantly alter the swelling of the membranes; interactions polymer-nanoparticle increases the rigidity of the amorphous phase. Comparing to pure PVA hydrogels, in nanocomposites hydrogels the hemolysis decreased. Increasing the percentage of nanoparticles the membrane crystallinity decreases. The samples degradation profile, the thermal stability and drug delivery profile are not modified by the amount of nanoparticles incorporated. / Poli(álcool vinílico) - PVA é um polímero semicristalino altamente hidrofílico que possui excelentes propriedades, como boa resistência química e elevada biodegradabilidade e biocompatibilidade. Devido à sua natureza semicristalina, os domínios cristalinos, sob condições controladas de crescimento, podem atuar como pontos de reticulação físicos, mantendo a integridade da estrutura sob inchamento. Esta característica torna hidrogéis de PVA bastante promissores em relação ao desenvolvimento de sistemas de carreamento de fármacos e outras substâncias bioativas. Soluções aquosas de PVA podem formar hidrogéis com boas propriedades mecânicas através de ciclos de resfriamento e aquecimento. Este método resulta na formação de cristalitos que atuam como reticulações físicas, mantendo a insolubilidade do material em água. Recentemente muitos estudos mostram o uso de nanoestruturas para melhorar as propriedades mecânicas e o comportamento difusional de pequenas moléculas. Paromomicina é um antibiótico aminoglicosídeo muito utilizado para o tratamento de Leishmaniose cutânea (LC) no Brasil. Nos últimos anos, estudos mostraram que a adesão de pacientes ao tratamento de LC com pomadas é baixa. Portanto hidrogéis são uma interessante alternativa para este tratamento. Como o principal objetivo deste trabalho foi o preparo e a caracterização de hidrogéis poliméricos nanocompósitos de PVA contendo nanopartículas de SEP para a viabilidade preliminar do uso como sistema de liberação controlada para paromomicina, os hidrogéis foram preparados através de um processo de criogelificação. Este procedimento garante a formação do hidrogel, pois os domínios cristalinos do PVA formados durante os ciclos atuam como pontos de reticulação da membrana, permitindo a avaliação das medidas de transporte de água e do fármaco das membranas na presença de SEP. Neste estudo as membranas foram caracterizadas através de calorimetria diferencial, termogravimetria e difração de raios-X. Ainda foram feitos estudos de retenção polimérica, inchamento em plasma simulado, hemocompatibilidade, carreamento e liberação de fármaco. Os resultados mostram que os ciclos de criogelificação alteram significativamente o inchamento das membranas; as interações polímero-nanopartícula aumentam a rigidez da fase amorfa. O grau de hemólise diminui nos hidrogéis nanocompósitos quando comparados com os hidrogéis puros. O aumento da porcentagem de nanopartícula diminui a cristalinidade da membrana. O perfil de degradação, a estabilidade térmica das amostras e a liberação do fármaco não são modificados pela quantidade de nanopartícula incorporada.

Submitted by ANA KARLA PEREIRA RODRIGUES (anakarla_@hotmail.com) on 2017-08-02T15:41:08Z No. of bitstreams: 1 arquivototal.pdf: 5765942 bytes, checksum: 274481954c5d791369e586a0fa87060c (MD5) / Made available in DSpace on 2017-08-02T15:41:08Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 5765942 bytes, checksum: 274481954c5d791369e586a0fa87060c (MD5) Previous issue date: 2016-02-25 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Polymer blends are a prompt and economical way to obtain new materials and have attracted considerable interest. Xanthan gum (GX) and poly (vinyl alcohol) (PVA) are polymers of great interest because of their properties. The high hydrophilic nature of these materials limits their applications, so they need to be submitted to the crosslinking process. In this work were prepared and characterized polymeric films (1% w / v) consisting of xanthan gum and poly (vinyl alcohol) without crosslinking agent and crosslinked with citric acid (CA) by casting for use in controlled drug release. The infrared analysis demonstrated possible interactions between the polymers in the blend and the incorporation of crosslinker into the polymer matrix. The scanning electron microscope revealed that the surfaces of the films are smooth and homogeneous even with the addition of crosslinking agent. The solubility, swelling and permeability to water vapor tests showed synergism between properties of polymers in the blend and citric acid attributed to the film water resistance. The compositions are stable in an inert atmosphere (N2), and films crosslinked with citric acid exhibited better thermal stability when compared with no crosslinking. The thermal degradation kinetics study complemented the results of thermal analysis showing that the PVA films are more stable and the crosslinking agent has improved thermal properties of the films. Biodegradability tests in soil revealed greater degradation to the polymer blends over a period of 160 days. The films exhibited no antimicrobial activity against the microorganisms studied. The application of crosslinked films with citric acid on controlled drug release showed that acetaminophen, propranolol and fluconazole release mechanism was controlled primarily by diffusion, swelling and relaxation of the polymer chains, with constant release profiles for 24 h, demonstrating that the developed films are promising materials for controlled drug release. / Blendas poliméricas representam uma forma rápida e econômica para obtenção de novos materiais e vêm atraindo bastante atenção. A goma xantana (GX) e o poli (álcool vinílico) (PVA) são polímeros de interesse devido as suas propriedades. O alto caráter hidrofílico desses materiais limitam suas aplicações, por isso eles precisam passar pelo processo de reticulação. Neste trabalho foram preparados e caracterizados filmes poliméricos (1% m/v) constituídos por goma xantana e poli (álcool vinílico) sem agente reticulante e reticulados com ácido cítrico (AC) pelo método da evaporação do solvente para aplicação na área de liberação controlada de fármacos. Os dados de espectroscopia de infravermelho sugeriram possíveis interações entre os polímeros na blenda e a incorporação do reticulante na matriz polimérica. A microscopia eletrônica de varredura revelou que as superfícies dos filmes são lisas e homogêneas, mesmo com a adição do agente reticulante. Os ensaios de solubilidade, intumescimento e permeabilidade ao vapor de água mostraram o sinergismo das propriedades dos polímeros na blenda e que o ácido cítrico atribuiu aos filmes resistência à água. As composições mostraram-se estáveis em atmosfera inerte (N2), e os filmes reticulados com ácido cítrico exibiram melhor estabilidade térmica quando comparados com os sem reticulante. O estudo de cinética de degradação térmica complementou os resultados de análise térmica mostrando que os filmes de poli (álcool vinílico) são mais estáveis e que o agente reticulante aumentou as propriedades térmicas dos filmes. Os ensaios de biodegradabilidade em solo mostraram maior degradação para as blendas poliméricas em um período de 160 dias. Os filmes não demonstraram atividade antimicrobiana frente aos microrganismos estudados. A aplicação dos filmes reticulados com ácido cítrico na área de liberação controlada mostrou que o mecanismo de liberação de paracetamol, propranolol e fluconazol foi controlado principalmente por difusão, intumescimento e relaxamento das cadeias poliméricas, apresentando perfis de liberação constantes em 24 h, demonstrando que os filmes desenvolvidos são materiais promissores para liberação controlada de fármacos.

Submitted by Biblioteca da Faculdade de Farmácia (bff@ndc.uff.br) on 2018-01-16T14:11:34Z No. of bitstreams: 1 HINGRED BOSCH.pdf: 3018248 bytes, checksum: 606ae06709470089da6bd43d30cd5b37 (MD5) / Made available in DSpace on 2018-01-16T14:11:34Z (GMT). No. of bitstreams: 1 HINGRED BOSCH.pdf: 3018248 bytes, checksum: 606ae06709470089da6bd43d30cd5b37 (MD5) / Este trabalho teve como objetivo estudar a produção e as características de filmes poliméricos constituídos por poli(álcool vinílico) (PVA) e carboximetilcelulose (CMC) a serem utilizados posteriormente na produção de curativos primários para tratamento de feridas. Os polímeros escolhidos apresentam grau farmacêutico e suas misturas foram preparadas na proporção de PVA/CMC 9:1. Os polímeros inicialmente foram misturados em câmara fechada de mistura Haake Rheomix na intenção de promover misturas físicas. Nesta etapa foram estabelecidas 6 condições de mistura variando-se a temperatura da câmara e a velocidade de mistura. Esperava-se que ocorresse a fusão dos componentes durante o processo, o que não ocorreu. Para a formação dos filmes poliméricos foi testado o processo de prensagem em prensa hidráulica a quente e o processo de vazamento de soluções poliméricas em placas de vidro com posterior secagem. Não foram obtidos filmes adequados aos ensaios com a técnica de prensagem a quente, porém com técnica de vazamento se conseguiu a formação de bons filmes; com isso os filmes obtidos por esta técnica foram caracterizados quanto a propriedades físico-químicas, térmicas e mecânicas. Pode-se concluir que os filmes de PVA/CMC, obtidos pela técnica de vazamento, apresentaram características físicas, como a alta capacidade de inchamento em água e PBS, e mecânicas, como a resistência a ruptura e ao rasgamento, adequadas à utilização destes filmes como curativos para feridas / This work aimed to study the production and characteristics of poly(vinyl alcohol) (PVA) and carboxymethylcellulose (CMC) polymer films to be used later in the production of primary dressings for wound treatment. The polymers chosen were pharmaceutical grade and mixtures thereof were prepared in the ratio of 9:1 PVA / CMC. The polymers were initially mixed in a closed Haake Rheomix blend chamber in order to promote physical blends. In this step, 6 mixing conditions were established by varying the chamber temperature and the mixing speed. The melting of the components was expected to occur during the process, which did not occur. For the formation of the polymer films the pressing process was tested in a hot hydraulic press and the process of casting polymer solutions into glass plates with subsequent drying. It was not obtained films suitable for the tests with the technique of hot pressing, but with casting technique the formation of good films was achieved; and the films obtained by this technique are characterized by physical, chemical, thermal and mechanical properties. It can be concluded that the PVA/CMC films, obtained by the casting technique, presented physical characteristics, such as high swelling capacity in water and PBS, and mechanical, such as tear strength and tear resistance, suitable for the use of these films as wound dressings