Les mélanges de polymères ouvrent une importante voie à l’obtention de nouveaux matériaux dont les propriétés peuvent être très différentes de celles de chacun des constituants des mélanges. La plupart des polymères sont immiscibles. Ainsi leurs mélanges constituent des phases distinctes et les propriétés de ces mélanges sont souvent médiocres. Afin de relever ce défi, copolymères à bloc ou greffés synthétisés séparément ou générés in-situ lors du procédé de mélanges sont souvent utilisés en tant que agents compatibilisants. Beaucoup d’études ont porté sur l’efficacité de compatibilisation de copolymères à bloc et peu d’études sur celle de copolymères greffés, en partie en raison des difficultés dans le contrôle de leurs structures moléculaires. Cette thèse porte sur l’étude de l’efficacité d’émulsification de copolymères greffés. Elle est composée de trois parties : (1) développement d’un nouveau procédé d’extrusion réactive pour la synthèse de copolymères greffés avec polystyrène (PS) comme squelette et polyamide 6 (PA6) comme greffons ; (2) efficacité d’émulsification du copolymère greffé, PS-g-PA6 pour les mélanges à base de PS et PA6 ; et (3) développement d’un nouveau concept dit d’agent émulsifiant – traceur / Polymer blending offers an important route to new materials with combinations of properties not available in constituent polymers. Most polymer pairs are immiscible, leading to phase separation at equilibrium and yield a material with poor properties. To address this challenge, block or graft copolymers pre-made or generated in-situ by reactive blending are often used as compatibilizers. Most studies are focused on the compatibilizing efficiency of block copolymers and few studies address that of graft copolymers, partly because of difficulties of controlling their molecular structures.This thesis is devoted to the study of the emulsification efficiency of graft copolymers. It is composed of three parts: (1) development of a novel reactive extrusion process for synthesizing graft copolymers with polystyrene (PS) as backbone and polyamide 6 (PA6) as grafts; (2) emulsification efficiency of PS-g-PA6 graft copolymers for PS/PA6 blends; and (3) concept of emulsifier- tracer

Thesis (Ph. D.)--University of Missouri-Columbia, 1999. / Typescript. Vita. Includes bibliographical references (leaves 154-159). Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 1999. / Typescript. Vita. Includes bibliographical references (leaves 154-159). Also available on the Internet.

No description available.

The extrusion blow molding process is an important polymer processing operation which involves a complex thermo-mechanical history. / Specimens were obtained from two commercial, blow molding grade, high density polyethylene resins, employing an instrumented Impco reciprocating screw blow molding machine. High speed cinematography was employed in conjunction with a parison pinch-off mold and a transparent blow mold to characterize the dimensional changes of the parison during the parison formation and the clamping and inflation stages. The contact temperature and the heat removal rate were measured during the cooling stage. Numerical methods were employed to investigate the thermal history during various stages. After molding at various operating conditions, the molded specimens were extensively characterized in relation to the distribution of thickness, crystallinity, orientation and impact behavior. / The distributions were analyzed in relation to the data obtained regarding the thermo-mechanical history during the molding process and some theoretical considerations of the relevant flow and heat transfer phenomena.

Thesis (Ph. D.)--University of Missouri-Columbia, 1996. / Typescript. Vita. Includes bibliographical references (leaves 118-130). Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 1996. / Typescript. Vita. Includes bibliographical references (leaves 118-130). Also available on the Internet.

Thesis (M.S.)--Wildlife and Fisheries Sciences Dept., South Dakota State University, 2009. / Includes bibliographical references (leaves 80-102). Also available via the World Wide Web.

Orientador: Carlos Raimundo Ferreira Grosso / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-07-28T13:04:51Z (GMT). No. of bitstreams: 1 Rocha_WaniaSilveirada_M.pdf: 3219314 bytes, checksum: a77e30ab714e5583c0203c6f280b4bb0 (MD5) Previous issue date: 2001 / Resumo: Polimeros naturais e sinteticos são utilizados como suporte ns imobilização de inúmeros tipos de recheio incluindo proteinas, enzimas, microorganismos, aditivos alimenticios, pesticidas e compostos com atividade farmacológica / Abstract: Natural and Synthetic Polymers are used as backing s detention of many types of fillings including proteins, enzymes, microorganisms, food additives, pesticides and compounds for pharmacological activity / Mestrado / Mestre em Alimentos e Nutrição

Orientador: Ahmed Attia El-Dash / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-09T10:21:41Z (GMT). No. of bitstreams: 1 Nabeshima_ElizabethHarumi_D.pdf: 3097984 bytes, checksum: 77e08e594e028d38f49a3e8469958214 (MD5) Previous issue date: 2007 / Resumo: Esta pesquisa consistiu em apresentar uma alternativa de utilização da farinha de arroz através da modificação química (fosfatação ou acetilação), agregando-lhe valor e possibilitando ampliar sua utilização como ingrediente alimentício, especialmente na produção de massas alimentícias instantâneas sem glúten. Inicialmente a farinha de arroz foi modificada quimicamente, sendo acetilada ou fosfatada, utilizando-se anidrido acético (0,465; 1,500; 4,000; 6,500 e 7,535g/100g farinha) ou oxicloreto de fósforo (0,018; 0,030; 0,059; 0,088 e 0,100g/100g farinha), respectivamente. Observou-se que a adição de grupos químicos modificou as propriedades de viscosidade, propriedades térmicas e características dos géis. As farinhas modificadas obtidas em diferentes graus de substituição foram utilizadas na formulação das massas alimentícias, misturada com farinha de arroz nativa, 0,5% de emulsificante (estearoil lactil lactato de sódio), água para obter 23% de umidade final e a seguir submetida ao processo de extrusão termoplástica (Brabender de rosca única). Foi utilizada a Metodologia de Superfície de Resposta do tipo composto central rotacional de 2a ordem, para estudar os efeitos físicos, de cozimento da massa alimentícia, de textura e de propriedades de pasta das variáveis independentes. Numa primeira etapa foram estudados teores de anidrido acético utilizados no preparo das farinhas de arroz acetiladas e temperaturas da penúltima zona do extrusor (84; 90; 105; 120 e 126°C) e numa segunda etapa, teores de oxicloreto de fósforo utilizado na formulação de farinhas de arroz fosfatadas e as mesmas condições de temperatura da 2a zona do extrusor citada acima. Observou-se que a combinação de farinha de arroz acetilada e utilização de temperaturas de extrusão menores que 120°C no preparo de massas alimentícias resultaram na diminuição do índice de solubilidade em água (ISA) e das propriedades de cor (valor a e b). A perda de sólidos aumentou com o aumento das duas variáveis, sendo que o maior valor obtido (8,89%) foi ainda considerado aceitável. A elasticidade sofreu influência somente da temperatura, onde o seu aumento provocou valores baixos desta propriedade. Na segunda etapa, usando farinha de arroz fosfatada para produção de massas alimentícias, a temperatura de extrusão afetou principalmente o índice de absorção de água (IAA), o índice de solubilidade em água (ISA) e as propriedades de viscosidade. As concentrações de oxicloreto de fósforo na farinha modificada tiveram maior influência sobre as propriedades de cozimento e de textura. A combinação dessas variáveis, nas condições utilizadas, resultou na diminuição do IAA e do peso das massas cozidas e aumento da adesividade e do tempo de cozimento. As massas alimentícias apresentaram tempos de cozimento entre 3,40 a 5,30 minutos / Abstract: This research consisted to present an alternative use to rice flour modified chemically (phosphatation or acetylation), adding value and increasing its use as food ingredient, specially in gluten free instant pasta production. The rice flour was modified chemically, being acetylated or phosphated, using acetic anhydride (0.465; 1.500; 4.000; 6.500 and 7.535g/100g flour) or phosphorus oxychloride (0.018; 0.030; 0.059; 0.088 and 0.100g/100g flour), respectively. It was observed that the addition of chemical groups modified the viscosity, thermal and gel properties. To the pasta formulation, each modified flour with different degree of substitution was mixed with native rice flour, 0.5% emulsifier (sodium stearoyl lactylate), water to obtain 23% final humidity and submitted to thermoplastic extrusion (Brabender single-screw). Response Surface Methodology of the type central rotational composed of 2a order was used to study the physical, pasta cooking properties, texture and pasta properties of the independent variables. In the first stage, it were studied the percentage of acetic anhydride used in the rice flour acetylation and temperature of the 2ª zone of extruder (84; 90; 105; 120 and 126°C) and in the second stage, the percentage of phosphorus oxychloride used in the rice flours phosphation and the same temperature of the 2a zone of extruder cited above. It was observed the combination of acetylated rice flour and estrusion temperature smaller than 120°C, showed a reduction of the water solubility index (WSI) and of the properties of color (value a and b). The solids loss increased with increase of both variables, but the higher value (8.89%) was still adequate. The elasticity suffered influence only the temperature, it increased with the decreasing of this value. In the second stage, using for phosphated flour, the extrusion temperature affected mainly the cooking and color properties of the pastas. The modified flour with phosphorus oxychloride influenced the texture and cooking properties. The combination of these variables, in the used conditions, resulted in decreasing of gain of weight and increasing of stickness and the cooking time. The pasta showed cooking time between 3.40 to 5.30 minutes / Doutorado / Doutor em Tecnologia de Alimentos