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Copolymères greffés et matériaux nanostructurés à base de polyméthacrylate de méthyle et de polyamide-6Freluche, Mathilde 30 November 2005 (has links) (PDF)
Cette étude porte sur l'élaboration de matériaux polymères nanostructurés à base de poly(méthacrylate de méthyle) (PMMA) et de polyamide-6 (PA-6). Les mélanges sont réalisés par extrusion réactive, c'est à dire par mélangeage en fondu de chaînes de polymères portant des groupes mutuellement réactifs. La réaction de greffage a lieu entre la fonction amine en bout de chaîne du PA-6 et des groupes anhydride le long des chaînes de PMMA. Les compositions des mélanges extrudés et des copolymères formés peuvent être déterminées, dans la plupart des systèmes, à l'aide d'une méthode de caractérisation principalement basée sur la chromatographie d'exclusion stérique. Ces résultats combinés à la microscopie électronique en transmission ont permis de déterminer les caractéristiques optimales des polymères employés (composition du PMMA réactif et taille des chaînes de PA-6) afin de former des mélanges nanostructurés. Dans ce système, la formation de mélanges nanostructurés est limitée à des PA-6 de faible masse molaire. En revanche, lorsqu'un copolymère à bloc contenant deux blocs PMMA fonctionnalisés anhydride et un bloc central incompatible est utilisé dans les mélanges, la taille de la dispersion n'est que légèrement affectée par la taille des chaînes de PA-6. La cristallinité du PA dans les matériaux nanostructurés a été étudiée. Les propriétés des matériaux étudiées ici (résistance aux solvants et évolution du module de conservation avec la température) peuvent être corrélées à leur structuration et à la connectivité des domaines de PA-6 dans le matériau.
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Effect of different rice flours on extruded rice puffsSirisee, Ulai, January 1999 (has links)
Thesis (Ph. D.)--University of Missouri-Columbia, 1999. / Typescript. Vita. Includes bibliographical references (leaves 165-183). Also available on the Internet.
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Texture, microstructure et propriétés d'un alliage Fe-40AI à grains fins obtenus par métallurgie des poudres et extrusion : influence des paramètres du procédé et de traitements thermiquesLenhard, Sébastien. Wagner, Thierry. January 2001 (has links) (PDF)
Thèse de doctorat : Sciences de l'ingénieur. Option sciences des matériaux : Metz : 2001. / Thèse : 2001METZ028S. Bibliogr. p. 128-132.
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Conception et développement de systèmes retardateurs de flamme pour fibres synthétiquesDrevelle, Christophe Delobel, René. Le Bras, Michel January 2007 (has links)
Reproduction de : Thèse de doctorat : Structure et dynamique des systèmes réactifs : Lille 1 : 2005. / N° d'ordre (Lille 1) : 3721. Résumé en français et en anglais. Titre provenant de la page de titre du document numérisé. Bibliogr. à la suite de chaque chapitre.
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Etude de la résistance aux chocs de tubes PVC à parois structurées Influence du procédé de fabrication sur les propriétés finales /Truchassou, Anne-Sophie Caillaud, Emmanuel. January 2007 (has links) (PDF)
Thèse doctorat : Sciences de l'Ingénieur : Strasbourg 1 : 2007. / Titre provenant de l'écran-titre. Bibliogr. 6 p.
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Numerical analysis of corn flour melt flow in extruder die and extrusion of corn puffs with wheat starchesXie, Wei, January 1999 (has links)
Thesis (Ph. D.)--University of Missouri-Columbia, 1999. / Typescript. Vita. Includes bibliographical references (leaves 151-159). Also available on the Internet.
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Multilayered membranes for modified atmosphere packagingOfford, Grant Thomas 31 October 2013 (has links)
This dissertation discusses, in brief, the production and transport property characterization of films made from the extrusion and biaxial stretching of [beta] nucleated isotactic polypropylene and the extrusion of PEBAX block copolymers. Multilayered films for modified atmosphere packaging applications were also produced by coextrusion and biaxial stretching of these two materials and similarly characterized. Current membranes for packaging applications are generally produced by coating a porous support with a polymeric solution to deposit an active layer for separation. The goal of this project is to displace membranes produced by solvent-based processes, which are environmentally hazardous and thus costly, with equivalent or superior materials produced using melt extrusion. / text
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Twin screw extrusion pre-treatment of wheat straw for biofuel and lignin biorefinery applicationsNg, Thian Hong January 2013 (has links)
Pre-treatment of wheat straw(lignocellulosic) biomass is a crucial step as it has direct impact on the subsequent yield of enzymatic saccharification and alcohol fermentation processes in the production of biofuel. Twin screw extrusion is a highly feasible pretreatment method and has been received great interest in the recent year pre-treatment studies. Twin screw extrusion is a continuous process, where the biomass feedstock can be subjected to a combination of simultaneous physical, thermal and chemical treatments. Steam explosion is a batch process and is the most commonly used method for lignocellulosic pre-treatment. In the initial stage of this study, the yield of glucose obtained from enzymatic saccharification for both methods (extrusion and steam explosion) were compared to identify the most effective pre-treatment approach. Effectiveness of the conventional steam explosion pre-treatment was used as benchmark for the directions of development of effective extrusion fractionation for wheat straw. In subsequent study, the impact of physical operating parameters (moisture, barrel temperature, compaction, screw speed and size reduction before extrusion) over twin screw extrusion with and without NaOH were studied. Low temperature (50°C) and increased moisture extrusion were preferred extrusion conditions. Yield of glucose can be improved by addition of NaOH (0.04g / g straw) and barrel temperature profile optimisation. Post extrusion washing was recommended. Findings from FTIR and TGA help to understand the chemical and structural changes took place in the pre-treatment and can be correlated with the glucose yield at the end of enzymatic hydrolysis. Characterisation analysis was extended to FT-NIR, morphology, crystallinity and specific surface area analysis to analyse the structural changes of lignocellulose biomass in extrusion pre-treatment and correlation with glucose yield. Chemometric analysis was used to statistically process large amounts of spectral data. The PCA scores plots showed good cluster segregation of the samples and were thus able to distinguish the effects of different pre-treatment conditions. The PLS regression models for both FTIR and FT-NIR showed good statistical regression and predictive ability correlated to the glucose yield. For the lignin ultilisation study, crude lignin was recovered from black liquor and fractionated with solvents. Lignin and the fractions were characterised with solvent solubility, SEC, UV, FTIR, 1H and 13C NMR and evaluated for the antioxidant activity with AAI ranged from 0.3 to 2.4. Reason for the low performance was proposed and experiment was extended to the intended application performance screening. Lignin application study was further extended to assess the feasibility of using lignin as an antioxidant in carboxylated acrilonitrile-butadiene rubber, XNBR glove. Evaluation involved physical observation, mechanical properties and thermal analysis – DSC-OIT after incorporation of lignin into XNBR glove. Lignin antioxidant performance was compared with current chemical antioxidant in used in industry. A part from antioxidant behaviour, lignin was also found can enhance the softness of XNBR film after accelerated heat aging.
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Hot-melt Extrusion Through SyringesO'Connell, Sean Patrick January 2014 (has links)
The use of solid dispersions to formulate poorly water soluble drugs is a growing field in the pharmaceutical sciences. Hot-melt extrusion is a common method for producing dispersions. However, bench-top extruders require large amounts of powder to run and are inappropriate for early formulation screens. Plastic and glass syringes are readily available in most laboratories. 250 mg of drug-polymer blend is placed in a plastic syringe body that has the tip covered with a bent needle. The syringe is heated for 5 minutes and the extrudate is pushed through the syringe. Extrudates are characterized by differential scanning calorimetry and powder x-ray diffraction. Acetaminophen, griseofulvin, indomethacin, salicylamide, and sulfamethoxazole extruded with polyvinylpyrrolidone K12 match or exceed the performance of solvent evaporated controls. Glass syringes can be used when polymers have processing ranges above the melting point of the plastic syringes. Syringe extrusion is effectively demonstrated as a rapid process for early formulation screening.
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The glycaemic index of muffins baked with extruded dried bean flour compared to muffins baked with whole wheat flour / Jacqueline GouwsGouws, Jacqueline January 2004 (has links)
Emphasis on using the glycaemic index (GI) in addition to carbohydrate
exchange lists has led to a greater variety of foods from which to choose for the diabetic
population. Breakfast is regarded as the most important meal of the day and the
glycaemic response to lunch can be improved by decreasing the GI of breakfast.
However, most conventional breakfast cereals and bread exhibit a high GI. Dried beans
have a low GI and various processes such as cooking and canning increase GI values, but
still in the low GI range. In recent years, extrusion cooking has become one of the popular
new processes developed by the food industry. Extrusion provides a convenient
alternative for the ingestion of dry beans in the diet. Muffins are eaten by many South
Africans and may be an ideal alternative for breakfast cereals and bread, especially if the
GI of the muffins is low. The aim of this study was to determine the GI of a muffin baked
with extruded bean flour and compare it to the GI of a muffin baked with whole wheat flour.
Subjects and methodology: The study cohort consisted of ten healthy males and ten
healthy females. Subjects randomly consumed test meals of glucose (the reference),
bean muffins and whole wheat muffins on different days. Each test meal provided 509
available carbohydrate as analysed by the Englyst method.
Results: The GI of the muffin baked with extruded bean flour (mean 53.0%, Confidence
intervals (CI): 41.7; 64.2) was not significantly different from that of the whole wheat muffin
(mean 55.5%, CI: 41.8; 69.2) but still in the low to intermediate GI category.
Conclusion: Extrusion of dried beans results in a fine flour with relatively no intact starch
which may explain the very low resistant starch content (1.6I100g) of the muffins. The
small particle size of the fine flour could further have contributed to the higher than
expected GI of the bean muffin because the size of the particle is inversely related to
glycaemic response. Muffins baked with extruded dried bean meal are nevertheless
regarded as an excellent choice for breakfast and as part of the prudent diet. Beans have
additional health benefits and are included in the South African Food Based Dietary
Guidelines. / Thesis (M.Sc. (Dietetics))--North-West University, Potchefstroom Campus, 2004.
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