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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.
61

CHARACTERIZATION AND ANALYSIS OF HIGH VOLTAGE ATMOSPHERIC COLD PLASMA TREATMENT OF SOYBEAN OIL

Ximena V. Yepez (5930444) 16 January 2020 (has links)
<p>Findings presented in this dissertation show that polyunsaturated fatty acids of soybean oil effectively reacted with high voltage atmospheric cold plasma gas species of various gases including hydrogen, nitrogen, and oxygen at room temperature without a catalyst. Hydrogenation, nitration, and epoxidation reactions were observed along with polymerization. Unexpectedly, hydrogen gas was not the primary source of atomic hydrogen observed under these experimental conditions. Rather, it is suggested that water vapor, present as an impurity, supplied hydrogen ions to the hydrogenation reactions. Nitrogen gas modified atmosphere is an electron-rich medium that catalyze reactions. Further investigation is suggested for optimizing the process of oil hydrogenation, as well as for exploring the potential to produce bio-based gels, lubricants, and greases.</p>
62

Enhancing UV-protection of clear coated wood by utilizing reactive UV-absorber and epoxyfunctionalized soybean oil

Olsson, Sara January 2012 (has links)
This work presents the development of a new pretreatment for clear coated wood, that aims to increase the photoprotection of exterior wood products, and at the same time make the system more environmentally friendly. The pretreatment comprises the reactive UV absorber 2-hydroxy-4(2,3-epoxy­propoxy)-benzophenone (HEPBP), which has a primary epoxy group that can be covalently attached to the hydroxyl groups of the wood substrate. This reactant is accompanied by renewable epoxy functionalized soybean oil (ESBO), which contains a secondary epoxy group that also has the ability to react with the substrate and that promotes the compatibility between the two reactants. The ESBO further seems to have the advantage of increasing the flexibility of the pretreated veneers as well as decreasing the amount of water in the cell wall of the wood. The study was performed in two parts where the first part focused solely on the development and performance of the pretreatment, whereas the second part used the knowledge gained from part one to evaluate the pretreatment in combination with an acrylic clear coating. Grafting reactions were performed on thin wood veneers heated in solvent. In the first part the reaction parameters, temperature and reaction time, were varied to study their effects on the final properties of the pretreatments. The veneers where then analyzed using FTIR to determine if grafting was achieved. Results show that grafting was successful for reactions performed at temperatures above 90 °C. For part two, grafting was successful for both the boil- and dip process, indicating that a considerably shorter reaction time can be used. Samples from both part one and two where then exposed to accelerated ageing and the color change was measured to estimate the UV-resistance. The first part showed improved UV-resistance for some of the pretreatments, whereas the second part was more difficult to evaluate due to the top coat, but a slight improvement can be seen for samples using the pretreatment. A positive result for part two is also that the pretreatment do not appear to affect the adhesion between the substrate and the top coat. It is hence concluded that the proposed pretreatment is a possible way of increasing the photostability of exterior wood. / Detta arbete beskriver utvecklandet av en ny förbehandling för klarlackat trä som syftar till att öka UV-beständigheten av träprodukter för utomhusbruk. Arbetet syftar även till att utveckla systemet till att bli miljövänligare än nuvarande liknande produkter på marknaden. Förbehandlingen utnyttjar primära epoxidgrupper hos den reaktiva UV-absorbenten 2-hydroxy-4(2,3-epoxy­propoxy)-bensofenon (HEPBP) för att skapa kovalenta bindningar till hydroxylgrupper hos träet. Den andra komponenten i systemet är förnyelsebar epoxiderad sojaolja (ESBO) innehållande sekundära epoxidgrupper som även dessa kan binda kovalent till träytan, samt gynna kompatibiliteten mellan de två reaktanterna. Oljan verkar dessutom öka flexibiliteten av förbehandlingen, samtidigt som den minskar mängden vatten som tränger in i cellväggen. Studien utfördes i två delar där den första delen fokuserade enbart på att utveckla förbehandlingen, medan den andra delen utnyttjade information från den första delen för att utvärdera funktionen av förbehandlingen i kombination med en akrylatbaserad klarlack. Ympningsreaktionerna utfördes på tunna träfaner i uppvärmd lösning. I första delen studerades hur temperatur- och reaktionstidsförändringar påverkar den slutgiltiga prestationen av förbehandlingen, och FTIR användes då för att verifiera ympningen. Resultaten visar att ympningen var lyckad för reaktioner utförda vid reaktionstemperaturer över 90 °C. För del två ansågs ympningen lyckad för både dopp- och kokreaktionen, vilket tyder på att betydligt kortare reaktionstider skulle kunna användas. Prover från både del ett och två utsattes sedan för accelererad åldring där färgförändringen av proverna mättes för att uppskatta UV-resistensen av behandlingarna. Första delen visade på ökad UV-beständighet för vissa av behandlingarna. Del två var dock svårare att utvärdera till följd av klarlacken, men en liten förbättring kan noteras för prover som är förbehandlade. En positiv notering från del två är även att adhesionen mellan klarlacken och träytan inte verkar ha påverkats av förbehandlingen. Med detta som grund dras slutsatsen att den föreslagna förbehandlingen kan förbättra UV-resistensen av klarlackat trä för utomhusbruk. / QC 20120330
63

Evaluation of Lake Erie Algae as Bio-fuel Feedstock

Gottumukala, Vasudev 14 June 2010 (has links)
No description available.
64

Investigation of Natural Adhesives

Bradley C Mcgill (13949928) 13 October 2022 (has links)
<p>Adhesives  are  found  in  almost  every  aspect  of  the  modern  world.  They  are  found  in plywood used in buildings, electronics, shoes, plumbing and in almost every facet of your daily life. Nature also has an abundance of these adhesives that are used fora multitude of applications. Some  animals, like  the  blue  mussel, use  their  adhesive  for  protection  against  ocean  waves  and predators  while other animals, such  as  the  spider, use  it  to  trap  prey. Investigation  of  theses adhesives has led to the identification of several different proteins that allow for these animals to make  their  adhesive.  Some  of  them  are  composed of rare  amino  acids that  while  other  animals use  a combination  of  inorganic  and  organic  components.  Understanding  of  these  unique adhesives  can be  a  boon  for designof future  adhesives  that  do  not  have  the disadvantagesof current day commercialized glues.</p> <p>Increasing interest  in  the  restoration  of  natural  oyster  reefs  and  the  cement  that  holds them  together  has  resulted  in  the  identification  of  the  Shelk2  protein  that  is  found  both  in  the mantle  of  the  oyster’s  shell  as  well  as  the  cement  that  holds  the  reefs  together. Gaining  an understanding  of  how  this  protein  functions  and  its  part  in  the  oyster  reef  could  be  quite beneficial  for  projects  investing  in  reef  restorations  as  well  as  underwater  adhesion.  Gathering protein  from  the  animal  for  experimentation  and  characterization  can  be  labor  intensive  and extremely challenging. Luckily, cloning technology has become a useful tool for the expression of large quantities of proteins that can be difficult or impossible to gather from the native animal. Using <em>E. coli</em>, it  is  possible  to design  and express  this protein  in  hopes  of  gaining  a  better understanding of its impact on oyster settlement and adhesion.</p> <p>Sustainability is a major downside to current day adhesives that current technologies have not  been  able  to  solve. Most adhesives  that  are  on  the  market  today  are  primarily  derived  from petroleum. Current  research  has  begun  investigating  alternatives  to  the  large   epoxy   and formaldehyde  adhesive  market,  but  the  barrier  of  entry  is  hard  to  overcome.  To  replace  these glues  the  new  material  must  be  affordable,  non-petroleum  derived,  and  available  on  a  massive scale.  These  requirements  are  hard  to  meet  for  many  materials  and  due  to  that  the  current  bio-adhesive are generally very low strength.</p> <p>The work presented here will detail the characterization, and expression of some of these natural  adhesives that  have  been  found  in  the  Eastern  oyster. Another  aspect of  this  work includes the synthesis of a new bio-based adhesive system. Utilizing biomimetic chemistry along with  sustainably  sourced  materials  a  new  adhesive  has  been  formulated that  has  comparable adhesive strength to current day commercial adhesives.</p>
65

Process for Synthesis of Biodiesel from Used Cooking Oil: Feasibility and Experimental Studies

Patel, Rajnikant, Dawson, K., Butterfield, R., Khan, Amir, Ahada, B., Arellano-Garcia, Harvey January 2014 (has links)
No / Biodiesel has turned out to be an integral part of the discussion of renewable energy sources and has diverse advantages in terms of its flexibility and applicability. Considering the characteristics of the transesterification reaction, a laboratory-scale system has been developed in this work. Waste Vegetable Oil (WVO), mainly sunflower oil, from local sources has been used and the transesterification carried out using methanol in the presence of sodium hydroxide catalyst. Characterisation of the biodiesel produced has been carried out using a number of different techniques including rheology, calorimetry, and gas liquid chromatography. The main factors affecting the % yield of biodiesel are temperature, catalyst, and alcohol to triglyceride ratio. Thus, experimental work has been carried out so as to study the rate and yield of the reaction as a function of those factors. A model has also been developed to validate the experimental data and this should help in increasing the efficiency of these processes and reducing the energy input. Moreover, the novel use of ultrasound as a method of measuring progression of the reaction is correlated with in-situ pH monitoring of the reaction process.
66

Body Composition Changes in Response to Skeletal Muscle Phenotype and Fat Supplementation in Lactating Dairy Cattle

Samantha L Hanno (19014098) 10 July 2024 (has links)
<p dir="ltr">The production cycle of lactating dairy cattle consists of physiological adaptations and changes in body tissue reserves as energy and protein requirements shift and may not be able to be met by feed intake. Tissue reserves are mobilized in early lactation and accreted thereafter, which can be used as a pool of labile amino acids and energetic substrates used at the beginning of the subsequent lactation. Nutritional strategies can be employed to mitigate extensive tissue loss and gain as a management tool to enhance dairy performance. The first study's objective was to evaluate the effects of high oleic soybean oil (HOSO) supplementation on milk production, body composition, and apparent total tract digestibility variables. A cross-over design with 21-d periods was employed with thirty Holstein cows (n = 16 primiparous, n = 14 multiparous at 87 ± 26 DIM at start of trial). Treatments consisted of a control (CON) with no added soybean oil and a HOSO diet with 1.5% diet dry matter (DM) of high oleic soybean oil added. Milk production and DM were collected on the last 7 d of each period. Body weights (BW), milk, and fecal samples were collected on the last 3 d of each period. Ultrasound scans of the <i>longissimus dorsi </i>muscle and body condition scores (BCS) were collected on the last d of each period. Dry matter intake, milk production, and milk component yields were not impacted by HOSO supplementation, although milk fat concentration tended to be greater for HOSO cows. A treatment by parity interaction and treatment by parity tendency were observed for BCS and BW, respectively, with multiparous HOSO cows having increased BCS and BW compared to CON with no effect on primiparous cows. Compared with CON, HOSO increased backfat depth (BFD) by 0.44 mm as well as apparent total tract fat digestibility by 12 percentage units with no differences observed in muscle<i> </i>depth. The second study’s objective was to evaluate changes in <i>longissimus dorsi </i>depth and its impact on production parameters in cows with two muscle phenotypes. Forty multiparous dairy cows were categorized into two muscle phenotype groups of high muscle (HM; n = 18) and low muscle (LM; n = 22) as determined by <i>longissimus dorsi </i>depth immediately after parturition. Ultrasound images of the <i>longissimus dorsi </i>and body weights were collected monthly from 0 to 300 DIM. Blood samples were collected from the coccygeal vessels on d 7, 150, and 300 and analyzed for 3-methylhistidine (3-MH), creatinine, non-esterified fatty acids (NEFA), and insulin. Milk weight data was collected daily using AfiFarm and milk components were collected from monthly DHIA test day data. Neither BW nor BFD were different between HM and LM cows at any timepoint, although, a DIM effect was observed. Cows lost BW from 0 to 60 DIM and BFD from 0 to 90 DIM and began increasing thereafter until 300 DIM. A muscle group by DIM interaction was observed where HM cows had more <i>longissimus dorsi </i>depth (LDD) at 0 and 300 DIM and tended to have more at 60 DIM compared to LM cows, with no differences at any other timepoint. In both muscle groups, LDD was decreased from 0 to 60 DIM but substantial LDD accretion did not occur until 240 DIM. No differences were observed between muscle groups for blood analytes; however, significant DIM effects were observed and corresponded to the observed changes in body tissue reserves. Daily milk production was grouped by stage of lactation with DIM groups consisting of early lactation from 0 to 60 DIM, mid-lactation from 60-240 DIM, and late lactation from 240 to 300 DIM. There was a muscle group by DIM group interaction for daily milk yield as HM cows produced more milk/d in early and mid-lactation but produced less milk in late lactation compared to LM cows. The results of these studies indicate that oleic acid can be supplemented to lactating dairy cattle to increase adipose tissue reserves with no effect on muscle reserves. This could potentially be caused by the lack of muscle accretion throughout mid-lactation whereas adipose tissue is gained. These results also describe that nutrition and muscle phenotype play a role in body composition throughout lactation.</p>
67

The economics of an alternative bio-energy feedstock – the case of Jatropha curcas

Tee, Meng Y. January 1900 (has links)
Master of Agribusiness / Department of Agricultural Economics / Vincent R. Amanor-Boadu / Biofuels such as ethanol and biodiesel are looked upon as the future source of alternative energy. These biofuels will supplement the needs of the ever increasing demand for fuel. Bio-energy feedstock is in high demand and current bio-crude oil prices such as soybeans and palm oil are higher than fossil fuel crude oil prices. Unless the price of fossil fuel crude oil increases beyond that, it would not be economically viable to produce biofuels from these feedstock. Jatropha curcas has been touted as the future of biodiesel. The seeds from the Jatropha curcas are crushed and processed using transesterification. The product of the chemical reaction results in bio-oil and glycerin. The objective of this paper is to study the economics of Jatropha curcas as an alternative bio-energy feedstock. Comparisons are done on Jatropha curcas oil, soybean oil, and palm oil. The Jatropha curcas industry is at its infancy, and crude Jatropha curcas oil is either not available in the open market or extremely difficult to find in any significant amount. However, soybean oil and crude palm oil are traded commodities and their prices are dependent on their demand and supply pressures. Given these conditions, the approach adopted here involved the establishment of a vertically integrated company that grows and harvests the Jatropha curcas feedstock and crushes the seeds to obtain the crude oil, and finally processes it to obtain biodiesel and glycerin. The financial analysis provided results that indicate that the Jatropha curcas has the potential to be a successful feedstock. The conclusion after conducting net present value comparisons shows that the price per kilogram of the Jatropha curcas seed would be the determining factor in the success of this bio-fuel feedstock. As more work goes into the genetic selection of Jatropha curcas for high yield varieties, the feedstock’s potential increases and its potential as a solution to the search for the competitive sources of biodiesel becomes more real.
68

Estabilidade oxidativa de óleo de soja adicionado de extratos de especiarias: correlação entre parâmetros físico-químicos e avaliação sensorial / Oxidative stability of soybean oil added of spices extracts: correlation between physicochemical parameters and sensory evaluation

Ravelli, Débora 11 October 2011 (has links)
Os antioxidantes são substâncias capazes de inibir a oxidação lipídica, responsável pela produção de compostos de cor, aroma e sabor indesejáveis. Na busca por produtos naturais associada à crescente preocupação com a saúde do consumidor, à vista dos possíveis riscos que o uso irregular dos antioxidantes sintéticos pode acarretar ao homem, torna-se essencial verificar a viabilidade do emprego de compostos naturais, com poder antioxidante, em um óleo cuja suscetibilidade à oxidação é reconhecidamente elevada. Com esse objetivo, o presente trabalho avaliou a proteção antioxidante oferecida por extratos hidroalcoólicos de especiarias ao óleo de soja. Os resultados físico-químicos do teor de compostos fenólicos totais, do sequestro do radical livre DPPH (1,1-difenil-2-picrilidrazil), Trolox, da estabilidade oxidativa, através de teste acelerado em estufa e em Rancimat, e da qualidade oxidativa, como o índice de peróxido e a absortividade na faixa do UV, foram base para a seleção dos extratos de alecrim, sálvia, tomilho e orégano, os quais apresentaram maior potencial antioxidante. Os extratos de alecrim, sálvia e tomilho, adicionados ao óleo de soja, foram igualmente eficientes em sua ação antioxidante no teste acelerado em estufa. O óleo, adicionado destes extratos, foi avaliado sensorialmente para verificar o mais preferido pelos consumidores quanto às características de cor, aroma e sabor. Houve uma preferência pelo óleo de soja adicionado de extrato de alecrim. / Antioxidants are compounds able of inhibiting lipid oxidation, responsible for the production of compounds of undesirable color, aroma and flavor. The search for natural products associated with the growing concern over the health of the consumer, in view of the possible risks that the irregular use of synthetic antioxidants can lead to man becomes essential to checking the feasibility of employing natural compounds with antioxidant power, in oil whose susceptibility to oxidation is high. With this purpose, the present study aimed to evaluate the antioxidant protection offered by hydroalcoholic extracts of spices to soybean oil. Analytical results of total phenol compounds, content of kidnapping free radical DPPH (1,1-diphenyl-2-picrilidrazil) substances, Trolox, oxidative stability, through accelerated test in Schaal oven and Rancimat tests, oxidative status, as the acid value and peroxide and absorptivity in the UV range, had been the basis for the selection of extracts of rosemary, sage, thyme and oregano, which presented the highest antioxidant potential. Rosemary, sage and thyme extracts added to soybean oil were similarly efficient as antioxidant in the Schaal Oven Test. Oil added of these extracts were sensorially evaluated according to their colour and flavor. Based on these sensorial characteristics, consumers preferred soybean oil added of rosemary extract.
69

Fontes de gordura alteram o desempenho e o metabolismo de vacas mantidas em pastagens tropicais / Sources of fat alters performance and metabolism of dairy cows grazing a tropical pasture

Souza, Jonas de 07 February 2014 (has links)
Objetivou-se avaliar a inclusão de fontes de gordura na forma de sais de cálcio na dieta sobre o desempenho e metabolismo de vacas em início e meio da lactação mantidas em pastagens tropicais. No Capítulo 3, foi realizada uma meta-análise para avaliar os efeitos da suplementação de gordura para vacas mantidas em pastagens sobre a produção e a composição do leite. A produção de leite aumentou com a suplementação de gordura, e a suplementação com fontes insaturadas deprimiu o teor de gordura do leite. No capítulo 4, objetivou-se comparar o uso do dióxido de titânio (TiO2) como marcador externo em substituição ao óxido crômico (Cr2O3) para estimar a excreção fecal e calcular o consumo de forragem e a digestibilidade. A excreção fecal tendeu ser maior para os valores estimados pelo Cr2O3. O Cr2O3 superestimou a excreção fecal comparado com a coleta total de fezes. O consumo de forragem e o consumo de MS total foram superestimados pelo Cr2O3, enquanto não foram observadas diferenças entre os valores observados de consumo e estimados pelo TiO2. A digestibilidade aparente da MS foi subestimada tanto pelo Cr2O3 quanto pelo TiO2. No capítulo 5 objetivou-se avaliar os efeitos da suplementação de vacas em início da lactação mantidas em pastagem tropical com diferentes fontes de gordura sobre o desempenho, composição do leite e variáveis produtivas ao longo da lactação. A suplementação de sais de cálcio de óleo de soja (SCOS) aumentou a produção de leite quando comparado com o grupo controle, porém foi inferior a produção dos animais suplementados com sais de cálcio de óleo de palma (SCOP). Apesar do aumento em produção de leite com SCOS, nesse tratamento o teor de gordura do leite reduziu significativamente quando comparado com o grupo controle e ao SCOP. Durante o período residual a produção do grupo que recebeu SCOP continuou maior e refletiu na produção ao longo de toda a lactação (7328 kg lactação-1) comparado ao SCOS (6575 kg lactação-1) e ao controle (6094 kg lactação-1). No capítulo 6, objetivou-se avaliar a suplementação de duas fontes e duas doses de sais de cálcio de ácidos graxos sobre o desempenho, composição do leite, parâmetros ruminais e metabólicos e balanço energético de vacas no meio da lactação mantidas em pastagem tropical. A produção de leite foi afetada pela adição de gordura, sendo influenciada pela fonte e pela dose de gordura. O teor de gordura do leite foi influenciado pela fonte de gordura suplementada. O pH ruminal não foi afetado pelos tratamentos experimentais. A suplementação com SCOS prejudicou a degradação da fibra, reduziu a produção de AGV\'s, reduziu a síntese microbiana e a produção de gordura do leite quando comparado com a fonte de SCOP. Portanto, as estimativas de consumo e digestibilidade foram melhores preditas com o uso do dióxido de titânio como marcador. Além disso, a suplementação com sais de cálcio de óleo de palma aumentou a produção de leite na lactação, não reduziu o consumo e nem a degradação da fibra. / The objective of this study was to evaluate inclusion of different sources of fat as calcium salts in the diet on performance and metabolism of early lactation cows grazing tropical pastures. In Chapter 3, a meta-analysis was performed to evaluate the effects of fat supplementation to grazing dairy cows on milk yield and milk composition. Milk yield increased with fat supplementation, and supplementation with unsaturated sources depressed milk fat content. In Chapter 4, the objective was to compare the use of titanium dioxide (TiO2) as an external marker to replace chromium oxide (Cr2O3) to estimate fecal excretion and calculate forage intake and digestibility. Fecal excretion tended to be greater for values estimated by Cr2O3. The Cr2O3 overestimated and TiO2 tended to overestimate fecal excretion compared to total fecal collection. Forage intake and total DM intake were overestimated by Cr2O3, while no differences were observed between the observed values of consumption and estimated by TiO2. The apparent DM digestibility was underestimated by both Cr2O3 and TiO2. In the chapter 5, it was evaluated the effects of fed different sources of fat to early lactation cows (from 15 to 105 DIM) grazing a tropical pasture on production variables throughout lactation (until 280 DIM). Calcium salts of soybean oil (CSSO) increased milk yield compared to control, but was lower than the production of animals supplemented with calcium salts of palm oil (CSPO). Despite the increase in milk yield with CSSO, this treatment decreased milk fat content and yield when compared with control and CSPO. During the residual period (from 106 to 280 DIM) the group that received CSPO had greater milk yield and reflected in the greater milk yield throughout lactation (7328 kg lactation-1) compared to CSSO (6575 kg lactation-1) and the control (6094 kg lactation-1). In chapter 6, the objective was to evaluate the supplementation with two sources (CSSO vs. CSPO) and two doses (400g vs 700g/day) of calcium salts of fatty to mid lactating dairy cows grazing a tropical pasture on performance, milk composition, ruminal and metabolic parameters and energy balance. Milk yield was increased by the addition of fat, being influenced by source and by dose. The milk fat was influenced by source of fat supplementation. The ruminal pH was not affected by experimental treatments. Supplementation with CSSO damaged the fiber degradation, reduced production of VFA \'s, reduced microbial synthesis and the production of milk fat compared with the source of CSPO. In conclusion, DM intake and digestibility were better predicted with the use of titanium dioxide as a marker. Furthermore, supplementation with calcium salts of palm oil increased milk production in lactating without decreasing DM intake and degradation of the fiber.
70

Potencialidade do uso de formulações de óleo de soja epoxidado e éster metílico de ácido graxo como fluidos de resfriamento no tratamento térmico de têmpera de aços / Potential use of epoxidized soybean oil and fatty acid methyl ester formulations as quenchants to steel heat treatment

Otero, Rosa Lucia Simencio 30 May 2014 (has links)
A demanda pelo uso de formulações biodegradáveis e provenientes de fontes renováveis tem motivado o desenvolvimento de biofluidos de resfriamento para aplicação em têmpera de aços. Os óleos vegetais são potenciais candidatos a serem empregados como base destas formulações, porém, a baixa estabilidade termo-oxidativa inibe sua maior utilização pela indústria. As modificações químicas na cadeia carbônica dos óleos vegetais podem promover melhoria nesta característica, sendo epoxidação uma das mais comuns. O presente trabalho estudou, primeiramente, a estabilidade termo-oxidativa de formulações contendo óleo de soja epoxidado (ESBO) e éster metílico de ácido graxo (FAME), em diferentes concentrações, por Calorimetria Exploratória Diferencial com Pressão (PDSC). Posteriormente, o desempenho destes biofluidos, no tratamento térmico de têmpera, foi avaliado pela análise microestrutural e medições de dureza (curvas em U) nos aços SAE 1045 e SAE 4140, comparando-o com o desempenho promovido pelos fluidos derivados de petróleo. As tensões térmicas residuais foram simuladas com o ABAQUS, usando os coeficientes de transferência de calor obtidos pela solução do problema inverso. As distorções causadas pelos biofluidos foram estudadas em corpos Navy-C-rings modificados de aço SAE 4140. Além disto, a viscosidade dos biofluidos também foi estudada em função da temperatura por estar diretamente relacionada à propriedade de molhamento, que influencia a transferência de calor durante o processo de resfriamento. A adição de FAME no ESBO foi eficiente na redução da viscosidade das formulações propostas, em função da temperatura, adequando-as para utilização como fluidos de resfriamento. As formulações EF30 e EF38 apresentaram temperatura inicial de oxidação (OOT) superior ao óleo de soja, indicando assim, maior estabilidade termo-oxidativa. Todas bioformulações foram eficientes na têmpera de ambos os aços, nos diâmetros ensaiados, promovendo dureza mínima de aproximadamente 52 HRC no centro dos corpos SAE 4140, dureza esta, comparável àquela promovida pelos fluidos minerais. Comportamento similar foi observado para o aço de menor temperabilidade. As tensões térmicas residuais simuladas não variam em magnitude em função da composição das formulações, enquanto que as distorções tenderam a aumentar em função do aumento do FAME nas formulações. / The search for biodegradable and renewable basestocks has motivated the development of bioquenchants for steel heat treatment. Vegetable oils are potential candidates, however, their poor thermo-oxidative stability inhibits a wide industrial application. Modifications of the chemical structure of vegetable oils may be used to improve this characteristic and epoxidation is one of the most common approaches reported to date. The first step of the study reported here was to analyze and compare the thermo-oxidative stability of soybean oil, epoxidized soybean oil (ESBO) and different blend ratios of ESBO with a soybean oil-derived fatty acid methyl ester (FAME) by Pressure Differential Scanning Calorimetry (PDSC). Subsequently, the quenching performance of the formulations was evaluated by cooling curve analysis and microstructural analysis and hardness measurements by U-curves analysis of SAE 1045 and SAE 4140 steels and then, compared with results obtained using commercially available petroleum oil quenchants. Thermal residual stress profiles were simulated with ABAQUS, using the heat transfer coefficients obtained by an inverse method. Bioquenchant distortions were determined using SAE 4140 steel and a so-called modified Navy C-ring test. Moreover, the viscosity-temperature property of bioquenchants was also studied, since it is directly related to the heat transfer and wetting behavior occurring during the cooling process. Although the viscosity of ESBO was too high for use as a quenchant, increasing FAME addition to ESBO provided sufficient reduction of resulting kinematic viscosities to permit their potential use as quenchants. EF30 and EF38 (30% and 38% FAME, respectively) exhibited onset oxidation temperatures (OOT) higher than soybean oil, thus indicating better thermo-oxidative stability. All bioquenchants were effective for both steels, at the specimen diameters tested, producing a minimum hardness of approximately 52 HRC at the center of the SAE 4140 test specimen. This hardness is comparable to that obtained with the petroleum-based fluids. Comparable results were obtained for the lower hardenability SAE 1045 steel. The simulated residual stress profiles did not vary in terms of magnitude as a function of formulation composition while the distortions tended to increase as FAME is added in the formulations.

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