This thesis describes the development of a novel method for the rapid identification of complex organic materials, including macromolecules, that involves a high temperature simultaneous hydrolysis and derivatisation reaction. In this procedure, aqueous quaternary alkylammonium hydroxides are made to react with a wide range of complex molecular species, including synthetic and natural polymers, under high temperature flash heating conditions. The hydrolysis products are converted to derivatives, such as alkyl esters or alkyl ethers. The reaction forms the basis for a modified pyrolysis gas chromatography (Py-GC) identification technique. Although the process is primarily intended for the rapid identification of polymers which are susceptible to hydrolysis, it is also valuable for characterisation of a variety of hydrolysable lower molecular weight species, such as polymer additives, triglycerides and natural waxes.The reaction takes place when an intimate mixture of an aqueous quaternary alkylammonium hydroxide solution is flash heated with the analyte in a conventional pyrolysis unit, and "on-line" GC-MS is used to separate and identify the reaction products. Analytes included synthetic polyester resins and phenolic polymers, natural products such as lipids and wood extractives, and natural polymers including lignocellulose, proteins and kerogen.Reaction variables, such as temperature, pH analyte particle size, substrate, and the derivatising reagent were studied, in order to find the optimum conditions for the reaction. While the reaction occurs at temperatures as low as 358 degrees celsius, a 770 degrees celsius reaction temperature was adopted to allow direct comparison with Py-GC data. A high pH of the derivatising reagent was found to be necessary to achieve an efficient hydrolysis of the macromolecule. Small particle size gives better conversion to derivatised ++ / products. The nature of the heating substrate did not appear to influence the reaction. Tetraalkylammonium hydroxides (TAAH) were found to be the most effective derivatising reagents for the reaction. Tetramethylammonium hydroxide (TMAH) was the most useful derivatising reagent, since the methyl derivatives of the hydrolysed products were conveniently chromatographed and usually had well known mass spectra. Other TA-AHs were useful for (i) producing higher molecular weight alkyl derivatives of low molecular weight side chains in some polymers, e.g., acetate groups in polyvinyl acetate, (ii) the purpose of determining sites of pre-existing methylation in natural products such as lignocellulose, or (iii) cases where methylation products could be confused with existing pyrolysis products.The reaction mechanism is believed to involve hydrolysis of the organic material, formation of the tetra-alkylammonium salt, and thermal degradation of the quaternary ammonium salt to alkylated derivatives. Some evidence is presented to support this mechanism, which is considered to be ionic in character, rather than a free radical reaction.A detailed study of the reaction of alkyd resins indicated that polyhydric alcohols, polybasic acids, degree of cure, oil length, and rosin acid and epoxy modification could be determined. The reaction of rosin modified phenolic resins (tert-butyl phenol formaldehyde and para-nonyl phenol formaldehyde), gave rosin acid methyl esters and easily identifiable products from the synthetic components.Fatty acid methyl esters could be obtained directly from lipids, such as vegetable oils, without time consuming preparative steps. The problems of base catalysed isomerisation of the double bonds in polyunsaturated fatty acids were overcome by reducing the amount of base used for the reaction. The reaction facilitated the identification of fatty acids in ++ / woolwax, the triglycerides in cosmetic products, and lipids in trace quantities of human fingerprint deposits.A more reliable representation of the chemical structure of lignocellulose in softwood and hardwood species was obtained by the reaction, as compared to conventional PyGC which underestimates the aromatic carboxylic acid moieties. Gymnosperm or angiosperm origin was indicated by the presence of solely guaiacyl, or both guaiacyl and syringyl derived groups, respectively. Other extraneous extractable material was identified simultaneously, including aliphatic and aromatic acids, which would not normally be detected by conventional Py-GC.An alternative method involved extracting the wood with TMAH, followed by pyrolysis of the extract, to give less complex but more specific GC profiles. The TMAH extraction procedure also indicated some characteristic biomarker species as well as guaiacyl and syringyl derived compounds. The pyrolysis of tetraethylammonium hydroxide (TEAH) extracts revealed the sites of pre-existing methylation in the Eucalyptus marginata species.The thermally assisted hydrolysis and alkylation method which has been developed is usually superior to the conventional Py-GC procedure for those polymers which are prone to hydrolysis, since it results in products which are more readily related to the polymer structure. For example, concerted hydrolysis and alkylation of polyester resins results in alkyl carboxylate esters and the alkyl ethers, whereas in conventional Py-GC the products are alkenes and carboxylic acids. Carboxylic acids are more difficult to chromatograph by GC, and aromatic carboxylic acids in particular are susceptible to decarboxylation under the pyrolysis conditions.The reaction procedure has provided an alternative approach to the characterisation of submicrogram quantities of a range of synthetic polymers, natural products and ++ / natural polymers, which has not previously been possible without lengthy chemical degradation procedures. Although it has not displaced the conventional Py-GC technique, it has given a new dimension to the characterisation of organic materials, providing a powerful tool for forensic science investigations and the analysis of complex materials.

abstract: A numerical study of incremental spin-up and spin-up from rest of a thermally- stratified fluid enclosed within a right circular cylinder with rigid bottom and side walls and stress-free upper surface is presented. Thermally stratified spin-up is a typical example of baroclinity, which is initiated by a sudden increase in rotation rate and the tilting of isotherms gives rise to baroclinic source of vorticity. Research by (Smirnov et al. [2010a]) showed the differences in evolution of instabilities when Dirichlet and Neumann thermal boundary conditions were applied at top and bottom walls. Study of parametric variations carried out in this dissertation confirmed the instability patterns observed by them for given aspect ratio and Rossby number values greater than 0.5. Also results reveal that flow maintained axisymmetry and stability for short aspect ratio containers independent of amount of rotational increment imparted. Investigation on vorticity components provides framework for baroclinic vorticity feedback mechanism which plays important role in delayed rise of instabilities when Dirichlet thermal Boundary Conditions are applied. / Dissertation/Thesis / M.S. Mechanical Engineering 2011

No description available.

Thermal barrier coatings have been widely used to provide thermal protection to components in the hot section of gas turbines. This research focuses on two influencing factors on coating behavior: thermal gradient and cyclic oxidation. The delamination mechanics under thermal gradient is analyzed, taking thermally grown oxide into consideration. Coatings experience thermal gradients at different stages during actual service flight. One is due to engine power shut down when landing and the other due to internal cooling of the substrate. Thermally grown oxide (TGO) also acts as a critical factor in delamination mechanics. The induced stress gradient and corresponding energy release rate for interface delamination and shallower delamination are presented. Mechanism maps that explain the criteria for preventing delamination from developing and propagating are established. Three cooling trajectories are envisaged to analyze the variation in the possibility of delamination. Multilayer coatings used in components of the hot section of aero turbine engines also experience cyclic temperature variation during flight cycles. As experiment conditions vary and coating performance is improved, the time required to run through the test of coating failure can be both time-consuming and prohibitive. Therefore, protocols providing prediction of quantified coating behavior are in demand to shorten life-time tests. Curves of mass change are obtained from quantifying scale growth and loss by different models such as Cyclic Oxidation Spall Program (COSP). A modification is made by combining COSP and a mechanic based model to obtain critical parameters for lifetime prediction from short time experiment. The time for coatings to reach peak temperature during cycling is discovered to influence prominently on modeling results. Predictions for several coating compositions and cycling conditions are consistent with the data from the existing experiments of the coating system.

Medidas de corrente termoestimuladas e de carga a temperatura constante, sob campo elétrico constante externo, foram realizadas no intuito de identificar além de cargas espaciais existentes em amostras comerciais de PVDF, também estudar o pico anômolo de corrente que se apresentou nas medidas isotérmicas. Este pico desaparecia em medidas subseqüentes, mas sua recuperação, apesar de lenta, foi registrada, principalmente se a amostra era conservada em ambiente úmido. Uma série de medidas feitas em diferentes umidades relativas do ar, cuidadosamente controladas, evidenciou que este fenômeno estava diretamente ligado à água absorvida pela amostra do ambiente externo. O efeito mostrou também ser fortemente dependente do campo aplicado. Um modelo baseado em dissociação iônica da água, provavelmente fracamente ligada a estrutura do polímero, foi desenvolvido, levando em consideração que o coeficiente de dissociação depende do campo elétrico, bem como do tempo de extração dos portadores dissociados da amostra. Nesta cinética controladora da corrente, é considerada também recombinação bi-iônica. / Thermally stimulated current and depolarization measurements were carried on commercially available samples of PVDF. The measurements were conducted under constant temperature and constant applied field in order to investigate an anomolous peak which appears in isothermal measurements, and also identify the presence of space charge. This peak is observed only in the first measurements, but it can recover if the sample is stored in a humid environment. Series of measurements was carried out with carefully controlled relative humidity from which one can conclude that the peak is directly linked to water absorved by the sample. This effect is shown to depend strongly on the applied electric field. A theoretical model based on ionic dissociation of water molecules - probably weakly attached to the polymer structure is developed to explain the experimental results. In the model, the dissociation coefficient and the time of escape of dissociated carriers are assumed to depend on the electric field. Bi-ionic recombination is also assumed to play an important role in the control of the kinetics of the process.

This thesis describes firstly, a study involving the thermal rearrangement of substituted 6-e̲x̲o̲-(1-alkenyl) bicyclo-[3.1.0]hexenes, and secondly, the application of this type of transformation to a total synthesis of (±)-sinularene (1̲2̲5̲). The 6-e̲x̲o̲-(1-alkenyl)bicyclo[3.1.0]hexenes (1̲8̲7̲, 1̲8̲9̲, 1̲9̲2̲, 1̲9̲4̲, 2̲4̲0̲, 2̲7̲4̲ and 340) were prepared and thermolyzed in sealed tubes to afford the corresponding bicyclo[3.2.1]octa-2,6-dienes (1̲8̲8̲, 1̲9̲0̲, 1̲9̲3̲, 1̲9̲5̲, 2̲4̲1̲, 2̲7̲6̲ and 3̲4̲1̲) in generally excellent yields. With the exception of 1̲9̲0̲, the thermolysis products were subjected to acid-catalyzed hydrolysis to give the respective bicyclo[3.2.1]octenones. From this study, it is clear that a) the Cope rearrangement of substrates, such as 2̲7̲4̲ and 3̲4̲0̲, containing even sterically bulky substituents on the 6-alkenyl side chain presents a viable means of generating functionalized bicyclo [ 3.2.1] octa-2 , 6-dienes, b) this methodology provides for the placement of synthetically useful functionalities on any of the carbon bridges of the bicyclo-[3.2.1]octane skeleton, and c) the transformations 2̲4̲0̲→2̲4̲1̲ and 2̲7̲4̲→2̲7̲6̲ provide strong evidence for the stereospecificity of the rearrangement process. In the total synthesis of (±)-sinularene (1̲2̲5̲), the key step involved the thermal rearrangement of 3̲2̲2̲ to afford the bicyclo[3.2.1]octadiene 3̲2̲1̲. The compound 3̲2̲2̲̲ was readily prepared as follows. 1-Lithio-3-methyl-1-butyne was treated with methacrolein to furnish the allylic alcohol 3̲3̲1̲, which was transformed into the ester 3̲3̲2̲ v̲i̲a̲ an orthoester Claisen rearrangement (hot triethyl .orthoacetate, propionic acid). Hydrolysis of the ester 3̲3̲2̲, followed by reaction of the resultant acid with oxalyl chloride in refluxing hexane gave the corresponding acid chloride 3̲3̲4̲. Treatment of 3̲3̲4̲ with a cold, ethereal solution of diazomethane afforded the diazo ketone 3̲3̲5̲, which in the presence of copper (II) acetoacetonate in refluxing benzene, underwent an intramolecular carbenoid cyclization to furnish the bicyclic ketone 3̲3̲6̲. Semihydrogenation of 3̲3̲6̲ using Lindlar’s catalyst gave stereoselectively the c̲i̲s̲-alkenyl ketone 3̲3̲7̲. The enone 3̲3̲8̲ was obtained by oxidizing the trimethylsilyl enol ether of 3̲3̲7̲ using palladium (II) acetate in acetonitrile. When the enone 3̲3̲8̲ was treated with lithium divinylcuprate, the two epimeric products 3̲3̲9̲ and 3̲4̲6̲ were obtained in a ratio of 9:1, respectively, and were sus-sequently separated by column chromatography. Trapping the lithium enolate of 3̲3̲9̲ with t̲-butyldimethylsilyl chloride led to the required enol ether 3̲3̲2̲. Thermolysis (220°C, sealed tube) of 3̲3̲2̲ in benzene produced exclusively in 86% yield the desired bicyclic triene 3̲2̲1̲. Subjection of 3̲2̲1̲ to hydroboration using disiamylborane gave, after oxidative workup, the alcohol 3̲4̲7̲, which on treatment with p̲-toluenesulfonyl chloride in the presence of 4-dimethylaminopyridine, afforded the ketone 3̲4̲9̲. Successive hydrogenation of 3̲4̲9̲ and Wittig olefination of the resultant ketone 2̲8̲0̲ completed the total synthesis of (±)-sinularene (1̲2̲5̲). [formula omitted] / Science, Faculty of / Chemistry, Department of / Graduate

TSDC (thermally stimulated depolarization current) is one of the most important and popular technique for investigating electret materials. TSDC technique can indicate the magnitude of polarization and depolarization, relaxation time, charge-storage, glass transition, and activation energy. To fully investigate polarization and relaxation for pure epoxy and filled epoxy materials, a TSDC system was built and verified by the research. The article describes the building processes and verification of the TSDC system. TSDC, TSPC, and TWC tests data for epoxy and filled epoxy samples are presented in the article. To compare TSDC technique with other related techniques, DEA (dielectric analysis), DMA (dynamic mechanical analysis), and DSC (differential scanning calorimetry) tests are introduced.

No description available.

Increasingly intensive efforts are being made to enhance energy systems via augmented introduction of renewable energy along with improved energy efficiency. Resource constraints and sustained high fossil fuel prices have created a new phenomenon in the world market. Enhanced energy security and renewable energy development are currently high on public agenda worldwide for achieving a high standard of welfare for future generations. Biomass and municipal solid waste (MSW) have widely been accepted as important locally-available renewable energy sources offering low carbon dioxide (CO2) emissions. Concerning solid waste management, it has become a critical issue in Southeast Asia since the most popular form for waste disposal still employs open dumping and landfilling. While the need for a complete sustainable energy solution is apparent, solid waste management is also an essential objective, so it makes sense to explore ways in which the two can be joined. Electricity production in combination with energy recovery from flue gases in thermal treatment plants is an integral part of MSW management for many industrialized nations. In Sweden, MSW is considered as an important fuel resource for partially meeting EU environmental targets within cogeneration. However it is normally difficult to justify traditional cogeneration in tropical locations since there is little need for the heat produced. Similarly, MSW-fired cogeneration usually operates with low capacity during non-heating season in Sweden. Therefore, it is very important to find new alternatives for energy applications from waste, such as the implementation of thermally driven cooling processes via absorption cooling in addition to electricity production. The work presented herein concentrates first on an investigation of electricity generation from MSW power plants and various energy applications from waste in tropical urban areas. The potential for various types of absorption chillers driven by MSW power plants for providing both electricity and cooling is of particular interest. Additionally a demonstration and analysis of decentralized thermally driven cooling in district heating network supplied by low temperature heat from a cogeneration of MSW have been conducted. This study aims at developing the best system configuration as well as finding improved system design and control for a combination of district heating and distributed thermally driven cooling. Results show that MSW incineration has the ability to lessen environmental impacts associated with waste disposal, and it can contribute positively towards expanding biomass-based energy production in Southeast Asia. For electricity production, the proposed hybrid dual-fuel (MSW/natural gas) cycles feature attractive electrical efficiency improvements, leading to greenhouse gas emissions reduction. Cogeneration coupled with thermally driven cooling is a solution that holds promise for uniting enhanced sustainability with economic advantages. The system offers great opportunity for primary energy saving, increasing electrical yield and can significantly reduce CO2 emissions per unit of cooling as compared to compression chiller. The demonstration and simulation have also revealed that there is a potential with some modifications and improvements to employ decentralized thermally driven cooling in district heating networks even in temperate regions like Sweden. Thus, expanding cogeneration towards trigeneration can augment the energy supply for summer months in Europe and for year-round cooling in tropical locations. / QC 20110408

The implementation of an energy recovery system for retreiving otherways wasted energy is an effective method for reducing the overall energy consumption of a mobile machine. In a fork lift, there are two subsystems that can be effectively modified for recovering energy. These are the driveline and the lift/lower function of the mast. This study focuses on the latter by studying a recovery system whose main component is a hydraulic transformer consisting of a hydraulic motor, a variable displacement pump and an induction motor. Since the flow rate/pressure - ratio can be modified, the utilization of the hydraulic transformer enables downsizing of the accumulator volume. However, the decrease of the gas volume leads to an increase in the compression ratio of the accumulator, which in terms leads to higher gas temperatures after charging and consequently to higher thermal losses during holding phase. In order to reduce these losses, a thermally regenerative unit was implemented to the gas volume of an accumulator to reduce the temperature build up during charging. In this study, the effect of improving the thermal characteristics of the accumulator to the efficiency of the whole energy recovery system is investigated by means of measurements.