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The focus of this work was to understand the fundamental dispersion mechanism of cellulose based nanofibers in bionanocomposites. The cellulose nanofibers were extracted from soybean pod and hemp fibers by chemo-mechanical treatments. These are bundles of cellulose nanofibers with a diameter ranging between 50 to 100 nm and lengths of thousands of nanometers which results in very high aspect ratio. In combination with a suitable matrix polymer, cellulose nanofiber networks show considerable potential as an effective reinforcement for high quality specialty applications of bio-based nanocomposites. Cellulose fibrils have a high density of –OH groups on the surface, which have a tendency to form hydrogen bonds with adjacent fibrils, reducing interaction with the surrounding matrix. The use of nanofibers has been mostly restricted to water soluble polymers. This thesis is focused on synthesizing the nanocomposite using a solid phase matrix polypropylene (PP) or polyethylene (PE) by hot compression and poly (vinyl alcohol) (PVA) in an aqueous phase by film casting. The mechanical properties of nanofiber reinforced PVA film demonstrated a 4-5 fold increase in tensile strength, as compared to the untreated fiber-blend-PVA film. It is necessary to reduce the entanglement of the fibrils and improve their dispersion in the matrix by surface modification of fibers without deteriorating their reinforcing capability. Inverse gas chromatography (IGC) was used to explore how various surface treatments would change the dispersion component of surface energy and acid-base character of cellulose nanofibers and the effect of the incorporation of these modified nanofibers into a biopolymer matrix on the properties of their nano-composites. Poly (lactic acid) (PLA) and polyhydroxybutyrate (PHB) based nanocomposites using cellulose nanofibers were prepared by extrusion, injection molding and hot compression. The IGC results indicated that styrene maleic anhydride coated and ethylene-acrylic acid coated fibers improved their potential to interact with both acidic and basic resins. From transmission electron micrograph, it was shown that the nanofibers were partially dispersed in the polymer matrix. The mechanical properties of the nanocomposites were lower than those predicted by theoretical calculations for both nanofiber reinforced biopolymers.

The focus of this work was to understand the fundamental dispersion mechanism of cellulose based nanofibers in bionanocomposites. The cellulose nanofibers were extracted from soybean pod and hemp fibers by chemo-mechanical treatments. These are bundles of cellulose nanofibers with a diameter ranging between 50 to 100 nm and lengths of thousands of nanometers which results in very high aspect ratio. In combination with a suitable matrix polymer, cellulose nanofiber networks show considerable potential as an effective reinforcement for high quality specialty applications of bio-based nanocomposites. Cellulose fibrils have a high density of –OH groups on the surface, which have a tendency to form hydrogen bonds with adjacent fibrils, reducing interaction with the surrounding matrix. The use of nanofibers has been mostly restricted to water soluble polymers. This thesis is focused on synthesizing the nanocomposite using a solid phase matrix polypropylene (PP) or polyethylene (PE) by hot compression and poly (vinyl alcohol) (PVA) in an aqueous phase by film casting. The mechanical properties of nanofiber reinforced PVA film demonstrated a 4-5 fold increase in tensile strength, as compared to the untreated fiber-blend-PVA film. It is necessary to reduce the entanglement of the fibrils and improve their dispersion in the matrix by surface modification of fibers without deteriorating their reinforcing capability. Inverse gas chromatography (IGC) was used to explore how various surface treatments would change the dispersion component of surface energy and acid-base character of cellulose nanofibers and the effect of the incorporation of these modified nanofibers into a biopolymer matrix on the properties of their nano-composites. Poly (lactic acid) (PLA) and polyhydroxybutyrate (PHB) based nanocomposites using cellulose nanofibers were prepared by extrusion, injection molding and hot compression. The IGC results indicated that styrene maleic anhydride coated and ethylene-acrylic acid coated fibers improved their potential to interact with both acidic and basic resins. From transmission electron micrograph, it was shown that the nanofibers were partially dispersed in the polymer matrix. The mechanical properties of the nanocomposites were lower than those predicted by theoretical calculations for both nanofiber reinforced biopolymers.

Hydraulic fracturing is a well-established technology of generating highly conductive flow path inside the rock by injecting massive amount of fracturing fluid and proppant with sufficient pressure to break the formation apart. But as the concern for environment and health effects of hydraulic fracturing becomes intense, many efforts are made to replace the conventional fracturing fluid with more environment-friendly materials. The degradable biopolymer is one of the novel materials that is injected in the form of solid pellets containing proppant, degrades in the presence of water to form a viscous gel fluid, leaving no gel residue or harmful material. This work develops a methodology and computer program to determine the best candidate wells for the field test of degradable biopolymer as fracturing fluid. The unique properties of degradable biopolymer is captured in the selection of decision criteria such as bottomhole temperature and treatment volume as well as traditional hydraulic fracturing candidate well selection criteria such as formation permeability, productivity index.

Made available in DSpace on 2014-06-11T19:32:55Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-02-10Bitstream added on 2014-06-13T19:43:45Z : No. of bitstreams: 1 paula_fc_dr_rcla.pdf: 1312616 bytes, checksum: 37d3ba636c09c8b0df0d9d23402e492d (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Os polihidroxialcanoatos (PHAs) são poliésteres biodegradáveis, sintetizados como grânulos intracelulares em células bacterianas, na presença de excesso de fonte de carbono e limitação de nutrientes necessários ao crescimento. Estes biopolímeros são atraentes substitutos para os polímeros derivados do petróleo, devido às suas propriedades similares com vários termoplásticos e elastômeros. Atualmente, a produção de biocombustíveis é outra grande alternativa para a substituiçã do petróleo, especialmente o biodiesel produzido a partir da transesterificação de gorduras e óleos vegetais e animais. O glicerol bruto é o principal subproduto da produção deste biocombustível, o qual tem baixo custo devido à presença de impurezas. O desafio na produção de PHAs é a competitividade com os preços dos polímeros derivados do petróleo. Uma solução para este problema tem sido propor a implementação de biorefinarias que obtém outros produtos, agregando valores à cadeia de produção do biodiesel, tal como, a produção de biopolímeros bacterianos, utilizando glicerol bruto como fonte de carbono. Portanto, torna-se necessária a descoberta de novas linhagens bacterianas promissoras, na produção de PHAs a partir deste insumo. Neste trabalho, realizou-se a busca por micro-organismos capazes de produzir polihidroxialcanoatos (PHAs) utilizando glicerol em meios de cultivo. Para verificar o potencial de produção destes polímeros a partir desta fonte de carbono, foram avaliadas 107 linhagens de micro-organismos através da reação com o corante Sudan Black B. Entre os quais, estavam 76 isolados obtidos de solo de Floresta Ombrófila Densa (Mata Atlântica) e 31 de solo de Mangue. Além disso, foram também avaliadas 7 linhagens de P. aeruginosa provenientes de solos contaminados com hidrocarbonetos e manipueira... / The polyhydroxyalkanoates (PHAs) are biodegradable polyesters that are synthesized intracellularly and deposited as granules in bacterial cultures in the presence of excess carbon source and a growth limiting nutrient. These biopolymers are attractive substitute for petrochemical-based plastics due to their similar material properties to various thermoplastics and elastomers. Actually, the biofuels production is another great alternative to replace the petroleum, specially the biodiesel generated from the transesterification of vegetable or animal fats and oils. The crude glycerol is the main byproduct of biodiesel production, which has a relative low value due to the presence of impurities. The challenge in the PHAs production is the competitive prices of petroleum polymers. A solution for this problem has been proposed with the implementation of biorefineries that co-produce additional valueadded products along with biodiesel, such as bacterial biopolymers production utilizing crude glycerol as a carbon source. Therefore, it is necessary to discover a new promising PHAsproducing bacterial strains. In this work, was carried out the search for PHA-producer microorganisms utilizing glycerol as a sole carbon source. For this, 107 bacterial strains were evaluated by Sudan Black B staining reaction. Among which were 76 strains isolated from a tropical moist forest soil (Atlantic forest) and 31 from Mangrove ecosystem. Furthermore, 7 P. aeruginosa strains isolated from hydrocarbon-contaminated soil and cassava wastewater were also evaluated for PHAs production. In this experiments were determined the pH, carbon source consumption e cell dry weight. The freeze-dried cells were subjected to propanolysis for PHAs determination.The propyl esters were assayed by gas chromatography... (Complete abstract click electronic access below)

Orientador: Jonas Contiero / Banca: José Gregório Cabrera Gomez / Banca: Eloizio Júlio Ribeiro / Banca: Elisabeth Loshchagin Pizzolitto / Banca: Andre Henrique Rosa / Resumo: Os polihidroxialcanoatos (PHAs) são poliésteres biodegradáveis, sintetizados como grânulos intracelulares em células bacterianas, na presença de excesso de fonte de carbono e limitação de nutrientes necessários ao crescimento. Estes biopolímeros são atraentes substitutos para os polímeros derivados do petróleo, devido às suas propriedades similares com vários termoplásticos e elastômeros. Atualmente, a produção de biocombustíveis é outra grande alternativa para a substituiçã do petróleo, especialmente o biodiesel produzido a partir da transesterificação de gorduras e óleos vegetais e animais. O glicerol bruto é o principal subproduto da produção deste biocombustível, o qual tem baixo custo devido à presença de impurezas. O desafio na produção de PHAs é a competitividade com os preços dos polímeros derivados do petróleo. Uma solução para este problema tem sido propor a implementação de biorefinarias que obtém outros produtos, agregando valores à cadeia de produção do biodiesel, tal como, a produção de biopolímeros bacterianos, utilizando glicerol bruto como fonte de carbono. Portanto, torna-se necessária a descoberta de novas linhagens bacterianas promissoras, na produção de PHAs a partir deste insumo. Neste trabalho, realizou-se a busca por micro-organismos capazes de produzir polihidroxialcanoatos (PHAs) utilizando glicerol em meios de cultivo. Para verificar o potencial de produção destes polímeros a partir desta fonte de carbono, foram avaliadas 107 linhagens de micro-organismos através da reação com o corante Sudan Black B. Entre os quais, estavam 76 isolados obtidos de solo de Floresta Ombrófila Densa (Mata Atlântica) e 31 de solo de Mangue. Além disso, foram também avaliadas 7 linhagens de P. aeruginosa provenientes de solos contaminados com hidrocarbonetos e manipueira... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The polyhydroxyalkanoates (PHAs) are biodegradable polyesters that are synthesized intracellularly and deposited as granules in bacterial cultures in the presence of excess carbon source and a growth limiting nutrient. These biopolymers are attractive substitute for petrochemical-based plastics due to their similar material properties to various thermoplastics and elastomers. Actually, the biofuels production is another great alternative to replace the petroleum, specially the biodiesel generated from the transesterification of vegetable or animal fats and oils. The crude glycerol is the main byproduct of biodiesel production, which has a relative low value due to the presence of impurities. The challenge in the PHAs production is the competitive prices of petroleum polymers. A solution for this problem has been proposed with the implementation of biorefineries that co-produce additional valueadded products along with biodiesel, such as bacterial biopolymers production utilizing crude glycerol as a carbon source. Therefore, it is necessary to discover a new promising PHAsproducing bacterial strains. In this work, was carried out the search for PHA-producer microorganisms utilizing glycerol as a sole carbon source. For this, 107 bacterial strains were evaluated by Sudan Black B staining reaction. Among which were 76 strains isolated from a tropical moist forest soil (Atlantic forest) and 31 from Mangrove ecosystem. Furthermore, 7 P. aeruginosa strains isolated from hydrocarbon-contaminated soil and cassava wastewater were also evaluated for PHAs production. In this experiments were determined the pH, carbon source consumption e cell dry weight. The freeze-dried cells were subjected to propanolysis for PHAs determination.The propyl esters were assayed by gas chromatography... (Complete abstract click electronic access below) / Doutor

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