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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Polyurethanes plastic sheets and foams synthesized from aromatic triols

Dumont, Marie-Jose 06 1900 (has links)
Novel plastic sheets and foams from vegetable oil-based monomers were produced. These new polyurethanes were synthesized from aromatic polyols, with erucic acid as the starting material. These monomers have the unique feature of containing an aromatic ring which was hypothesized to improve the rigidity of the polyurethane matrices and the overall physical properties of the plastics and foams. The benefits of the aromatic ring were proposed to be enhanced due to three terminal primary hydroxyl groups within the structure of the polyols. Reactions to produce hexasubstituted benzene derivatives containing alcohol groups in positions 1,2,4- and 1,3,5- around the benzene ring were suitably scaled up to provide amounts necessary for polyurethane production and characterization. These isomers (asymmetric and symmetric triols) were separated using chromatography. The pure triols were crosslinked with 4,4-methylenebis(phenyl isocyanate) into polyurethanes sheets (asymmetric and symmetric polyurethane respectively). The physico-chemical properties of these PUs were studied by Fourier transform infrared spectroscopy, x-ray diffraction,, differential scanning calorimetry dynamic mechanical analysis, thermogravimetric analysis coupled with Fourier transform infrared spectroscopy, and tensile analysis. The asymmetric polyurethane sheet and the symmetric polyurethane sheet differed in their glass transition temperatures and crosslinking densities. This variation could be explained by the differences in crosslinking densities, related to the increase in steric hindrance between adjacent hydroxyl groups of the asymmetric triol monomers. It was found that both polyurethanes had similar mechanical and thermal properties. Due to the similar properties of the asymmetric polyurethane and symmetric polyurethane sheets, the monomers were combined together in order to synthesize PU foams. The physical properties of these foams were studied by Fourier transform infrared spectroscopy, differential scanning calorimetry, dynamic mechanical analysis, scanning electron microscopy, thermogravimetric analysis and were analyzed for close cell content and compression strength. The effect of the benzene ring in the monomer structure on the physical properties of these new polyurethane foams was mainly compared with high density canola polyurethane foams previously investigated. It was demonstrated that the physical properties of polyurethane foams made with aromatic monomers are comparable to those made with aliphatic monomers when enhanced with glycerol. / Bioresource and Food Engineering
12

Experimental Characterization of Canola Oil Emulsion Combustion in a Modified Furnace

Bhimani, Shreyas Mahesh 2011 May 1900 (has links)
Vegetable oils have been researched as alternative source of energy for many years because they have proven themselves as efficient fuel sources for diesel engines when used in the form of biodiesel, vegetable oil–diesel blends, vegetable oil-water-diesel blends and mixtures thereof. However, very few studies involving the use of emulsified low grade alcohols in straight vegetable oils, as fuels for combustion have been published. Even, the published literature involves the use of emulsified fuels only for compression ignition diesel engines. Through this project, an attempt has been made to suggest the use of alcohol-in-vegetable oil emulsions (AVOE) as an alternate fuel in stationary burners like electric utility boiler producing steam for electricity generation and more dynamic systems like diesel engines. The main goal of this study is to understand the effect of the combustion of different methanol-in-canola oil emulsions, swirl angle and equivalence ratio on the emission levels of NOx, unburned hydrocarbons (UHC), CO and CO2. The 30 kW furnace facility available at Coal and Biomass Energy Laboratory at Texas A & M University was modified using a twin fluid atomizer, a swirler and a new liquid fuel injection system. The swirler blades were positioned at 60° and 51° angles (with respect to vertical axis) in order to achieve swirl numbers of 1.40 and 1.0, respectively. The three different fuels studied were, pure canola oil, 89-9 emulsion [9 percent methanol – in – 89 percent canola oil emulsion with 2 percent surfactant (w/w)] and 85-12.5 emulsion [12.5 percent methanol – in – 85 percent canola oil (w/w) emulsion with 2.5 percent surfactant]. All the combustion experiments were conducted for a constant heat output of 72,750 kJ/hr. One of the major findings of this research work was the influence of fuel type and swirl number on emission levels. Both the emulsions produced lower NOx, unburned (UHC) hydrocarbon and CO emissions than pure canola oil at both swirl numbers and all equivalence ratios. The emulsions also showed higher burned fraction values than pure oil and produced more CO2. Comparing the performance of only the two emulsions, it was seen that the percentage amount of methanol added to the blend had a definite positive impact on the combustion products of the fuel. The higher the percentage of methanol in the emulsions, the lesser the NOx, UHC and CO emissions. Of all the three fuels, 85-12.5 emulsion produced the least emissions. The vorticity imparted to the secondary air by the swirler also affected the emission levels. Increased vorticity at higher swirl number led to proper mixing of air and fuel which minimized emission levels at SN = 1.4. The effect of equivalence ratio on NO_x formation requires a more detailed analysis especially with regards to the mechanism which produces nitrogen oxides during the combustion of the studied fuels.
13

Life Cycle Assessment of a Pilot Scale Farm-Based Biodiesel Plant

Wasserman, Eli Shawn Jordan 07 May 2013 (has links)
This study used environmental life cycle assessment (LCA) to investigate waste vegetable oil (WVO) biodiesel production at the University of Guelph, Ridgetown Campus, Centre for Agricultural Renewable Energy and Sustainability (CARES). CARES production data and Natural Resources Canada’s GHGenius LCA data were utilized to conduct a well-to-gate LCA. A range of scenarios were studied including using soybean oil feedstock and implementing methanol recovery. Results suggest that methanol is the environmental bottleneck of the WVO biodiesel production system. Results also suggest soybean biodiesel production released more GHG emissions and consumed more energy than both WVO biodiesel or petroleum diesel production. LCA is an iterative process. Due to the study’s limited scope, and status as a screening study, it is recommended that the study of the impacts of the CARES facility be redone with more reliable facility data, that it include the anaerobic digester, as well as a well-to-wheels boundary. / University of Guelph
14

Polyurethanes plastic sheets and foams synthesized from aromatic triols

Dumont, Marie-Josée Unknown Date
No description available.
15

STRATEGIES TO INCREASE HIGHLY-UNSATURATED N-3 FATTY ACIDS IN RAINBOW TROUT FED VEGETABLE OILS

2013 February 1900 (has links)
A series of experiments were conducted to examine the effect of petroselinic acid, found in coriander oil, on fillet, hepatocyte and whole body FA composition and Δ6 desaturase gene expression in hepatocytes of rainbow trout (Oncorhynchus mykiss) fed vegetable oil (VO) based diets containing no fishmeal (FM) or fish oil (FO). In the first experiment, rainbow trout were fed one of eight diets containing fish, flax, canola or Camelina sativa oil with or without coriander oil. Coriander oil in the diet increased concentrations of eicosapentaenoic acid (EPA; 20:5n-3) and docosahexaenoic acid (DHA; 22:6n-3, P < 0.05) in the fillet. There was a trend to increased 20:5n-3 + 22:6n-3/20:4n-6 ratios when coriander oil was added to the diet (P = 0.067). The second trial set out to investigate the effects of varied levels of coriander oil in canola oil based diets, on i) the capacity of rainbow trout hepatocytes to desaturate, elongate and esterify [1-14C] α-linolenic acid (18:3n-3; ALA) and [1-14C] linoleic acid (18:2n-6, LA), ii) reducing the production of 20:4n-6 in hepatocytes and iii) gene expression. This experiment demonstrated a significant increase in 22:6n-3 (P = 0.011) and a decrease 20:4n-6 (P = 0.023) in rainbow trout hepatocytes. Furthermore, there was a three-fold decrease in acetate for the [1-14C] 18:2n-6 and nearly a two-fold increase for the [1-14C] 18:3n-3 substrate when coriander was added at increasing levels, illustrating an increase in peroxisomal β-oxidation. Relative gene expression of ∆6 desaturase decreased with addition of coriander oil at the 0.5 inclusion level of coriander oil. The final experiment was conducted to determine if bypassing the first ∆6 desaturase and rate-limiting step in the n-3 FA pathway causes increased conversion of stearidonic acid (SDA; 18:4n-3) to 20:5n-3 and 22:6n-3. Rainbow trout were fed one of six diets containing either fish, conventional linseed (flax), or SDA enriched linseed oil (LO) with and without coriander oil. Inclusion of coriander oil did not affect any growth or feed intake parameters of rainbow trout. However, the addition of coriander oil caused a significant increase in whole body 22:6n-3 and 20:4n-6 concentrations in fish fed SDA enriched LO with coriander oil (SDA+C) compared to fish fed conventional linseed oil (LO). These results suggest that petroselinic acid, found in coriander oil, has the ability to influence FA bioconversion of the n-3 and n-6 FA pathway thereby increasing 22:6n-3 and possibly 20:5n-3 in rainbow trout and reducing ARA when fed VO-based diets. Furthermore, it seems as though petroselinic acid causes improved bioconversion to 22:6n-3 when the first ∆6 desaturase is bypassed. Further studies are needed to determine the mechanism of action that petroselinic acid has on FA bioconversion.
16

Caracterização e modificação de poliuretano derivado de óleo vegetal para confecção de órteses / Characterization and modification of vegetable oil based polyurethane to orthosis fabrication

Mônica Cristina Assaiante de Souza 12 September 2014 (has links)
As patologias que acometem os membros superiores são bastante incapacitantes para os seres humanos, pois elas são sua principal ferramenta de interação com o mundo tanto pelo papel nas tarefas cotidianas quanto pelo simbolismo que carregam. Na Terapia Ocupacional o objetivo é promover uma melhor qualidade de vida, maior autonomia e participação no cotidiano e, dentre os recursos e abordagens possíveis no processo de reabilitação, as órteses têm grande destaque, pois seu uso correto pode \"aumentar a função, prevenir ou corrigir deformidade, proteger estruturas em processo de cicatrização, restringir o movimento e permitir o crescimento ou remodelação tecidual\" (FESS, 2002, p.98). As órteses mais utilizadas na prática clínica são confeccionadas em material termomoldável de baixa temperatura. Não há opções nacionais deste material, implicando na necessidade de importação que pode gerar dificuldades no acesso a este tipo de material. Leite (2007) desenvolveu um poliuretano derivado do óleo vegetal (mamona) que se mostrou apto para a confecção de órteses após ensaios mecânicos, térmicos e clínicos, mas que necessita de melhorias, principalmente em relação aos aspectos de maleabilidade (moldabilidade) e memória do material. O presente trabalho tem como objetivos caracterizar o material desenvolvido e alguns existentes no mercado e modificar o material desenvolvido por Leite (2007). Para tanto, foram introduzidas modificações - acréscimo de cargas e mudanças na proporção poliol e pré-polímero - e realizados ensaios mecânicos e térmicos de Memória, Dureza, Moldabilidade, Análise Dinâmico-Mecânica, Tração, Temperatura no Contato com a Pele Humana e a velocidade de Resfriamento do material. Os resultados indicam que o acréscimo de Sílica Pirogênica e o aumento da proporção de poliol em relação ao pré-polímero melhoraram a moldabilidade do material e tornaram a memória adequada aos propósitos. Conclui-se que o novo material, o compósito CPU POS, é mais rígido que os importados, suportando maior carga, é seguro para o paciente do ponto de vista de temperatura e possui uma grande validade. A moldabilidade é rápida e necessita que o terapeuta posicione o material, pois ele não se acomoda com a ação da gravidade. A dureza foi diminuída, embora ainda seja maior que a dos materiais de comparação. Assim, o presente estudo contribuiu para um maior conhecimento dos termomoldáveis existentes no mercado utilizados para confecção de órteses e aponta o poliuretano derivado de óleo vegetal, modificado com cargas, como um material adequado para este propósito. / Pathologies that affect the upper limbs are very incapacitating to humans, because they are your primary tool for interaction with the world, both thé role of everyday tasks as the symbolism they carry. In Occupational Therapy the objective is promote a better quality of life, more autonomy and participation in daily life and, among the resources and possible approaches in the rehabilitation process, the orthosis have great prominence, because their correct use can \"enhance function, prevent or correct deformities, protect structures in the healing process, restrict movement and support the growth or tissue remodeling\" (FESS, 2002, p.98). The most used orthosis in clinical practice are fabricated with low temperature thermoplastic. There are no national options of this material, resulting in import which can create difficulties in accessing this type of material. Leite (2007) developed a vegetable (castor) oil based polyurethane that proved suitable for orthosis, after mechanical, thermal and clinical testing, but needs improvements especially aspects of malleability (moldability) and memory of the material. The current work aims at characterizing the material developed and some of the existing materials and modify the material developed by Leite (2007). Therefore, changes have been introduced - increase of fillers and changes in the proportion polyol to prepolymer - and performed mechanical and thermal tests of Memory, Hardness, Moldability, Dynamic Mechanical Analysis, Traction, Temperature in contact with human skin and the speed Cooling the material. The results indicate that the addition of Pyrogenic Silica and increased proportion of polyol in relation to the prepolymer improved moldability ofthe material and made appropriate memory to the purpose. We conclude that the new material, composite CPU POS, is more rigid than the imported, supporting higher load, it is safe for the patient in terms of temperature and has a great validity. The moldability is fast and requires the therapist to position the material, because it does not settle by gravity. The hardness was decreased, although it is still higher than the comparison material. Thus, the present study contributed to a better understanding of existing market thermoformables used for orthosis and points the polyurethane derived from vegetable oil, modified with fillers, as a suitable material for this purpose.
17

Evaluation of biotic succession in the Con Joubert Bird Sanctuary wetland after a vegetable oil spill

Selala, Mapurunyane Callies January 2013 (has links)
Please read the abstract in the thesis. / Thesis (PhD)--University of Pretoria, 2013. / gm2014 / Paraclinical Sciences / Unrestricted
18

LOW TRANS FATTY ACID CONTAINING HYDROGENATED EDIBLE OILS

Xiao, Haiyi 27 November 2007 (has links)
No description available.
19

Alkyd-Based High-Solid and Hybrid Organic Coatings

Nalawade, Priyanka 26 May 2015 (has links)
No description available.
20

Biodegradation Patterns and Toxicity of the Constituents of Canola Oil

Zhao, Yuechen 16 July 2009 (has links)
No description available.

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