Dissertations / Theses on the topic 'Thermal properties'

In the perspective of manipulating and controlling heat fluxes, graphene represents a promising material revealing an unusually high thermal conductivity �. However, both experimental and theoretical previous works lack of a strict thermal conductivity value, estimating results in the range 89-5000 W m-1 K-1. In this scenario, I address graphene thermal transport properties by means of molecular dynamics simulations using the novel "approach to equilibrium molecular dynamics" (AEMD) technique. The first issue is to offer some insight on the active debate about graphene thermal conductivity extrapolation for infinite sample. To this aim, I perform unbiased (i.e. with no a priori guess) direct atomistic simulations aimed at estimating thermal conductivity in samples with increasing size up to the unprecedented value of 0.1 mm. The results provide evidence that thermal conductivity in graphene is definitely upper limited, in samples long enough to allow a diffusive transport regime for both single and collective phonon excitations. Another important issue is to characterize at atomistic level the experimental techniques used to estimate graphene thermal conductivity. Some of these use laser source to provide heat. For these reasons, I deal with the characterization of the transient response to a pulsed laser focused on a circular graphene sample. In order to reproduce the laser effect on the sample, the K - A01 and

This thesis investigated the physical properties of the macrolide antibiotics: Erythromycin dihydrate (EM-DH), Roxithromycin monohydrate (RM-MH) and Azithromycin dihydrate (AZM-DH). The abovementioned hydrate compounds were investigated in terms of the hydrate-anhydrate crystal structure stability, dehydration and observed polymorphism under controlled temperature heating programs. Identified hydrate and anhydrate polymorphs were subjected to physical stability testing during controlled storage. EM-DH was characterized by thermal analysis (DSC, TGA), X-ray diffraction, FTIR and microscopy. Dehydration of EM-DH at temperatures of 100, 157 and 200°C (followed by supercooling to 25°C) produced the form (I) anhydrate (Tm =142.9°C), form (II) anhydrate (Tm = 184.7°C ) and amorph (II) (Tg = 118°C) respectively. The attempts to produce amorph (I) from melting (in vicinity of form (I) melt over temperature range 133°C to 144°C) and supercooling was unsuccessful due to the high crystallization tendency of the form (I) melt. Brief humidity exposure and controlled temperature (40°C)/ humidity storage for 4 days (0-96% RH) revealed hygroscopic behaviour for the anhydrate crystal (forms (I) and (II)) and amorph (II) forms. Form (II) converted to a nonstoichiometric hydrate where extent of water vapour absorption increased with increased storage humidity (2.1% absorbed moisture from recorded TGA at 96% RH). Amorph (II) exhibited similar trends but with greater water absorption of 4.7% (recorded with TGA) at 96% RH. The pulverization and sieving process of amorph (II) (at normal environmental conditions) was accompanied by some water vapour absorption (1.1%). A slightly lower absorbed moisture content of 3.3% (from TGA) after controlled 4 days storage at 40°C/ 96% RH was recorded. This suggested some physical instability (crystallization tendency) of amorph (II) after pulverization. The thermally induced dehydration of RM-MH by DSC-TG was evaluated structurally (SCXRD), morphologically (microscopy) and by kinetic analysis. Various kinetic analysis approaches were employed (advanced, approximation based integral and differential kinetic analysis methods) in order to obtain reliable dehydration kinetic parameters. The crystal structure was little affected by dehydration as most H-bonds were intramolecular and not integral to the crystal structure stability. Kinetic parameters from thermally stimulated dehydration indicated a multidimensional diffusion based mechanism, due to the escape of water from interlinked voids in crystal. The hygroscopicity of the forms RM-MH, Roxithromycin-anhydrate and amorph glass (Tg = 81.4°C) were investigated. Roxithromycinanhydrate (crystalline) converted readily to RM-MH which were found to be compositionally stable over the humidity range 43-96%RH. Amorphous glass exhibited increased water vapour absorption with increasing storage humidity (40°C/ 0-96% RH). TG analysis suggested a moisture content of 3.5% at 96% RH after 4 storage days. DSC and powder XRD analysis of stored pulverised amorphous glass indicated some physical instability due to water induced crystallization. Commercial AZM-DH and its modifications were characterized by thermal analysis (DSC, TGA), SC-XRD and microscopy. Thermally stimulated dehydration of AZM-DH occurred in a two-step process over different temperature ranges. This was attributed to different bonding environments for coordinated waters which were also verified from the crystal structure. Dehydration activation energies for thermally stimulated dehydration were however similar for both loss steps. This was attributed to similarities in the mode of H- bonding. Different forms of AZM were prepared by programmed temperature heating and cooling of AZM-DH. The prepared forms included amorphous glass (melt supercooling), amorphous powder (prepared below crystalline melting temperature), crystalline anhydrate and crystalline partial dehydrate. Humidity exposure indicated hygroscopic behaviour for the amorphous, crystalline anhydrate and crystalline partial dehydrate modifications. Both the crystalline anhydrate and partial dehydrate modifications converted to the stoichiometric dihydrate form (AZM-DH) at normal environmental conditions at ambient temperature. Both the amorph glass and amorph powder exhibited increased moisture absorption with increased humidity exposure. TG analysis of the pulverised amorph glass indicated a moisture content of 5.1% at 96% RH after 4 storage days. The absence of crystalline melt in DSC and presence of Tg (106.9°C) indicated the sample remained amorphous after pulverisation and storage for 4 days at 40°C/ 96% RH.

The activation parameters for the temperature dependent irreversible loss of surface-enhanced Raman scattered (SERS) intensity from pyridine and chloride adsorbed at silver surfaces in an electrochemical environment have been determined. Laser-induced heating is introduced as a probe of the chemical nature of SERS-active sites. Surface temperatures are calculated from spectroscopic data. The activation energies associated with the destruction of SERS-active sites at a surface roughened by an illuminated oxidation-reduction cycle (ORC) are 12.8 ± 3.2 kcal/mole and 27.7 ± 3.1 kcal/mole for pyridine at two different types of sites on the Ag surface. Similarly, values for coadsorbed chloride are found to be 11.1 ± 2.4 kcal/mole and 24.5 ± 3.8 kcal/mole. An activation energy of 27.4 ± 1.9 kcal/mole is obtained for pyridine on a silver surface roughened by a nonilluminated ORC. Evidence for the desorption of pyridine and chloride is presented.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2011.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 74-76).
Buildings consume too much energy. For example, 16.6% of all the energy used in the United States goes towards just the heating and cooling of buildings. Many governments, organizations, and companies are setting very ambitious goals to reduce their energy use over the next few years. Because the time periods for these goals are much less than the average lifetime of a building, existing buildings will need to be retrofitted. There are two different types of retrofitting: shallow and deep. Shallow retrofits involve the quickest and least expensive improvements often including reducing infiltration around windows, under doors, etc and blowing more insulation into the attic. Deep retrofits are those that involve costly renovation and typically include adding insulation to the walls and replacing windows. A new, easily installable, inexpensive, and thin insulation would move insulating the walls from the deep retrofit category to the shallow retrofit category and thus would revolutionize the process of retrofitting homes to make them more energy efficient. This thesis provides an overview of a concept for a new, easily installable, inexpensive, thin aerogel-based insulation and goes into detail on how the thermal properties of the aerogel were measured and validated. The transient hot-wire method for measuring the thermal conductivity of very low thermal conductivity silica aerogel (1 0mW/m K at 1 atm) along with a correction for end effects was validated with the NIST (National Institute of Standards and Technology) Standard Reference Material 1459, fumed silica board to within 1 mW/mK. Despite the translucence of the aerogel at certain wavelengths, radiation is not an issue through the aerogel during the hot-wire test but may be an issue in actual use as an insulation. The monolithic aerogel thermal conductivity drops significantly with slightly reduced pressure (3.2 mW/m K at 0.1atm). For the final composite insulation, the new silica aerogel formula is a great choice and it is recommended to reduce the pressure around the aerogel to 1 / 1 0 th. In the future, a prototype of an insulation panel combining a 3-D truss structure, monolithic or granular silica aerogel, and reduced pressure will be constructed and tested.
by Ellann Cohen.
S.M.

Thermal properties of ten different seafood were measured in this research. They included bluefish (Pomatomus saltatrix), croaker (Micropogonias undulatus), spanish mackerel (Scomberomorus maculatus), pink salmon (Oncorhynhus gorbuscha), black seabass (Atractoscion nobilis), spot (Leiostomus xanthurus), shrimp(Pandalus borealis), tilapia (Tilapia aurea), grey sea trout(Cynoscion regalis), and yellow fin tuna (Thunnus albacares) (Wheaton, et al. 1985). Thermal properties measured were thermal conductivity, thermal diffusivity, and specific heat from 5 to 30^oC. Enthalpy was measured from -40 to 30^oC. Moisture and fat content were measured. Thermal conductivity and thermal diffusivity were measured by a rapid transient technique using a bead thermistor probe. Specific heat and enthalpy were measured using a differential scanning calorimeter. Moisture content and fat content were measured by the AOAC specified oven dry method and ether extraction method, respectively. The measured thermal properties agreed well with the scarcely available literature values. They were then statistically correlated with moisture and fat content. Based on statistical analysis, mathematical models relating thermal properties and composition were proposed and compared with the models available in the literature. Models for thermal conductivity and specific heat were recommended to predict these properties of meats and fish with similar composition.
Master of Science

Thesis (Ph. D.) -- University of Maryland, College Park, 2008.
Thesis research directed by: Dept. of Mechanical Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.

With electronic packaging becoming more complex, simple hand methods to model the thermal performance of the package are insufficient. As computer aided modeling methods came into use, a test system was developed to verify the predictions produced by such modeling methods. The test system is evaluated for operation and performance. Further, the premise of this type of test (the accurate calibration of packaged temperature-sensitive-parameter devices can be done) is investigated using a series of comparative tests. From this information, causes of possible/probable errors in calibration are identified and related to the different methodologies and devices used. Finally, conclusions are presented regarding the further improvement of the test system and methodologies used in this type of testing.

Composites, though used in a variety of applications from chairs and office supplies to structures of U.S. Navy ships and aircrafts, are not all designed to hold up to extreme heat flux and high temperature. Fiber-reinforced polymeric composites (FRPC) have been proven to provide the much needed physical and mechanical properties under fire exposure. FRPC notable features are its combination of high specific tensile strength, low weight, along with good corrosion and fatigue resistance. However FRPC are susceptible to thermal degradation and decomposition, which yields flammable gas, and are thus highly combustible. This property restricts polymeric material usage. This study developed a numerical model that simulated the degradation rate and temperature profiles of a fiber-reinforced polyester resin composite exposed to a constant heat flux and hydrocarbon fire in a cone calorimeter. A numerical model is an essential tool because it gives the composite designer the ability to predict results in a time and cost efficient manner. The goal of this thesis is to develop a numerical model to simulate a zonal-layer polyester resin and fiber-glass mat composite and then validate the model with experimental results from a cone calorimeter. By inputting the thermal properties of the layered composite of alternating polymer and polymer-infused glass fiber mat layers, the numerical model is one step closer to representing the experimental data from the cone calorimeter test. The final results are achieved through adding a simulated heat flux from the pilot ignition of the degraded gas of the polyester resin. The results can be coupled into a mechanical model, which may be separately constructed for future study on the mechanical strength of composites under fire conditions.
ID: 030646184; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Thesis (M.S.M.E.)--University of Central Florida, 2011.; Includes bibliographical references (p. 53-54).
M.S.M.E.
Masters
Mechanical and Aerospace Engineering
Engineering and Computer Science
Mechanical Engineering; Thermo-Fluids Track

In-situ determination of thermal properties in bedrock is important for the sizing of larger BTES systems. In-situ values of thermal conductivity may reduce required borehole length up to 30%. This thesis treats a new mobile thermal response test equipment (TED), developed in Luleå, Sweden, 1995-98. TED is set up on a small trailer, and is tried out on groundwater filled boreholes, fitted with single and double U-loop piping. It has been used at several commercial borehole direct cooling systems for telephone switching stations in Sweden, and on test-holes in a well documented closed down heat store in Luleå. The response tests show good accuracy and reliability of the measured thermal conductivity and thermal resistance provided good insulation of the equipment. The tests take into account the interaction of the bedrock with the duct piping and filling, the borehole geometry and groundwater and is a valuable tool for pre-investigations for BTES.
Godkänd; 1998; 20070404 (ysko)

In the search of clean and efficient energy sources intermediate temperature solid oxide fuel cells are among the prime candidates. What sets the limit of their efficiency is the solid electrolyte. A promising material for the electrolyte is ceria. This thesis aims to improve the characteristics of these electrolytes and help provide thorough physical understanding of the processes involved. This is realised using first principles calculations. The class of methods based on density functional theory generally ignores temperature effects. To accurately describe the intermediate temperature characteristics I have made adjustments to existing frameworks and developed a qualitatively new method. The new technique, the high temperature effective potential method, is a general theory. The validity is proven on a number of model systems. Other subprojects include low-dimensional segregation effects, adjustments to defect concentration formalism and optimisations of ionic conductivity.

Sorghum is a gluten free cereal and forms the staple diet of a majority of the populations living in the semi-arid tropics dough. It is usually consumed in the form of bread made from the grain flour. Dough made with sorghum flour has poor viscoelastic properties compared to wheat dough and mechanical methods for production of sorghum roti are scarce. This study was conducted to elucidate the rheological and thermal properties of sorghum dough to establish its behavior. The temperature and amount of water used for preparation of the dough and the composition of the flour were varied. Wheat, soya and black gram flours were used to prepare the composite doughs. Sensory characteristics of roti made with these dough samples by the traditional method and mechanical compression were studied. The results are presented and their implications are discussed.

Batters are highly complex systems with wide ranging ingredients including flours, water, flavorings, and spices. Interactions between the ingredients determine the performance of batters and the final quality of coated products. Addition of hydrocolloids into batters of different types of flour provides special effects on batter performance. The functionalities of hydrocolloids-flour mixtures in terms of the thermal and rheological properties of the resulting batter systems were investigated in this study.
The rheological properties of the batter were determined using a strain/stress control rheometer. A steady state method was used to measure the viscosity as a function of the shear rate varying from 0.5 to 150 s-1 at 15°C. The resulting data was then fitted to the Herschel-Bulkley Model. The viscoelastic properties were monitored as a function of temperature and were determined using a dynamic oscillatory test. Two different temperature profiles were used to simulate cooking and storage processes. Differential scanning calorimetry (DSC) was used to determine thermal properties (namely glass transition temperature, gelatinization temperature, ice melting temperature, and enthalpy) and to describe the phase transitions that occur during heating and cooling processes.
The rheological and thermal properties varied for different types of flours and their combination ratios, as well as different types of hydrocolloids at different concentrations. The replacement of corn flour greatly altered the viscosity and viscoelastic properties of wheat based and rice based batter systems. Using 100% corn flour based batter showed highest yield stress, whereas 100% rice flour based batter did not show any yield stress. Higher temperatures and longer times were required to gelatinize starch at the higher levels of rice flour for each batter system flour mix combination. The various combination ratios of the flours apparently did not significant influence the gelatinization temperatures of the batter systems. However they significantly influence the total enthalpies (DeltaHG) of the various samples. Wheat flour based batters showed the lowest glass transition temperatures. Thermal properties of wheat-based batters were influenced by the replacement of wheat with rice or corn flours. Corn flour based batters required considerably more energy for gelatinization during the cooking process.
Hydrocolloids lowered flow behavior index (n) and increased the consistency index (k) of all batters. The gums also changed the onset temperature of structure development and the storage and loss moduli of the batter systems. Hydrocolloids greatly influenced the thermal properties of batter systems. The gums shifted gelatinization temperature and depressed glass transition temperature of resulting batter systems. Further, MC increased the melting temperature (Tm) for the test batter systems as compared with the values for the control system without methylcellulose (MC). Carboxymethylcellulose (CMC) did not show statistically significant effects on the total enthalpies of ice melting for all samples. However, MC and CMC showed more pronounced effects on rice, corn, and their combined flour based batters than it did on wheat flour based batters. However, this characteristic does not show in batter systems containing xanthan gum.

FundaÃÃo Cearense de Apoio ao Desenvolvimento Cientifico e TecnolÃgico
The scientific interest on molecular crystals stems from their great versatility and ease of processing. For pharmaceutically active ingredients, the structure-activity relationship is of major importance. Topiramate, a white and crystalline solid, is a powerful drug efficiently employed to control epilepsy symptoms. The mechanism of action involves a negative modulatory effect on the AMPA/kainate subtypes of glutamate receptors and some types of voltage-gated Na+ and Ca2+ channels, and a positive modulatory effect on some types of GABAA receptors and at least one type of K+ channels in neurons. Despite its pharmacological attributes, the lack of publications regarding its physical-chemical properties in the literature is apparent. In order to fill this gap, a research comprising vibrational spectroscopy techniques (Raman and infrared), thermal analysis (TGA/DTA/DSC), and theoretical calculations, was carried out. With the aid of calculations employing density functional theory (DFT), most of the observed vibrational bands is assigned. Consideration of Raman spectra recorded at temperatures above and below room temperature, as well as under high hydrostatic pressures, indicated maintenance of the orthorhombic crystalline structure under the diverse thermodynamic conditions employed. Thermal analysis, however, showed that, after the melting point, the sample undergoes decomposition in a process comprising three stages, possibly initiated with loss of the sulfamate group by the molecule. This event inspired a theoretical study aimed at promoting the sulfamate group bond breakage in a controlled way by employing a laser instead of heat. This was accomplished by quantum dynamics simulations which showed that, by using a set of ultrashort pulses in the infrared region, it is possible to reach levels close to 70 % dissociation in less than 3 ps.
O interesse cientÃfico pelos cristais moleculares resulta da facilidade de processamento destes materiais, e de sua grande versatilidade. No caso de drogas, a relaÃÃo entre estrutura e atividade à de suma importÃncia. Topiramato, um sÃlido branco e cristalino, à um fÃrmaco utilizado com bastante eficiÃncia para controlar os sintomas da epilepsia. O mecanismo de aÃÃo envolve um efeito modulatÃrio negativo nos receptores de glutamato do subtipo AMPA/kainato e alguns tipos de canais de Na+ e Ca2+ voltagem-dependentes, bem como um efeito modulatÃrio positivo em alguns tipos de receptores GABAA e pelo menos um tipo de canal de K+ nos neurÃnios. A despeito de suas qualidades farmacolÃgicas, a escassez de trabalhos relacionados Ãs suas propriedades fÃsico-quÃmicas na literatura à evidente. Para ajudar a preencher esta lacuna, uma investigaÃÃo envolvendo tÃcnicas de espectroscopia vibracional (Raman e infravermelho), anÃlises tÃrmicas (TGA/DTA/DSC), e cÃlculos teÃricos, foi realizada. Com a ajuda de cÃlculos empregando a teoria do funcional de densidade (DFT), a atribuiÃÃo da maioria das bandas vibracionais observadas foi realizada. A observaÃÃo dos espectros Raman obtidos em temperaturas acima e abaixo da ambiente, bem como sob altas pressÃes hidrostÃticas, indicou que a estrutura cristalina ortorrÃmbica à mantida nas diferentes condiÃÃes termodinÃmicas empregadas. A anÃlise tÃrmica, entretanto, mostrou que, apÃs a fusÃo, o material sofre decomposiÃÃo em um processo que envolve trÃs etapas, possivelmente iniciado com a perda do grupo sulfamato pela molÃcula. Este fato motivou um estudo teÃrico a fim de modelar a quebra da ligaÃÃo do sulfamato de maneira controlada, utilizando um laser em lugar de calor. Isto foi realizado com simulaÃÃes de dinÃmica quÃntica, que mostraram que, atravÃs da utilizaÃÃo de uma combinaÃÃo de pulsos ultracurtos na regiÃo do infravermelho, à possÃvel atingir nÃveis prÃximos a 70% de dissociaÃÃo em menos de 3 ps.

Söderberg electrodes take part in the production of ferroalloys, copper, nickel, platinum, and calcium carbide. They are involved in a continuous and with low costs operation. The study of such electrodes is essential, since research and new findings will provide us with vital information regarding the operation of such furnaces leading to a more efficient production. Therefore, the study of Söderberg electrodes materials characteristics is of great importance. The current work refers to the thermal properties of Söderberg electrode paste by focusing on the thermal conductivity coefficient from room temperature up to 800 °C with the Transient Plane Source (TPS) method applied to an electrode paste material with softening point at 65°C. Another electrode paste with higher softening point at 90 °C and an already baked material are studied to some extent. The study gives significant results for the thermal conductivity coefficient for all the investigated cases. Results indicate variation of coefficients regarding the phase evolved during heating at different temperatures. In principle, thermal conductivity of the green paste with low softening point decreases until 400°C and increases after the baking point which is found in between 400-500°C. A few measurements for the green paste with higher softening point indicate the same trend. For the case of the fully baked electrode, thermal conductivity seems to keep an increasing trend according to temperature increase. On the two last mentioned materials, more experimental work will be conducted in future.
Söderberg-elektroder används till produktionen av ferrolegeringar, koppar, nickel, platina och kalciumkarbider. De är involverade i kontinuerliga och lågkostnadsoperationer. Studien av sådana elektroder är väsentlig eftersom forskning och nya fynd kommer att ge oss viktig information om driften av sådana ugnar vilket leder till en effektivare produktion. Därför är studien av Söderberg-elektrodens materialegenskaper av stor betydelse. Det nuvarande arbetet refererar till de termiska egenskaperna hos Söderberg-elektrodpastan genom att fokusera på den termiska konduktivitetskoefficienten från rumstemperatur upp till 800°C med den TPS-metoden (Transient Plane Source) tillämpad på ett elektrodpasta-material med en mjukningspunkt vid 65°C. En annan elektrodpasta med en högre mjukningspunkt vid 90°C samt ett redan bakat material studeras även till viss del. Studien ger signifikanta resultat för värmeledningsförmågan för alla undersökta fall. Resultaten indikerar på variationer av koefficienterna gällande fasen som utvecklas under uppvärmning vid olika temperaturer. I stort sett minskar värmeledningsförmågan hos den gröna pastan med låg mjukningspunkt upp till 400°C och ökar efter bakningspunkten som finns mellan 400-500°C. Några mätningar för den gröna pastan med en högre mjukningspunkt visar samma trend. När det gäller den helt bakade elektroden verkar värmdeledningsförmågan hålla en ökande trend beroende på temeperaturökningen. På de två sistnämnda materialen kommer mer experimentellt arbete att genomföras i framtiden.

The objectives of this work are to measure phase equilibria in the carbon dioxide + pyrrole system and to correlate and predict the phase behavior of this system with a thermodynamic model. This binary system is of interest due to the growing applications of supercritical carbon dioxide as a solvent or reaction medium for pyrrole. Polypyrrole is an electrically conducting polymer of interest in a number of applications such as anti-static coatings. Pyrrole has also been used as a reactant in enzymatic reaction. Knowledge of the phase behavior of carbon dioxide + pyrrole system is therefore necessary for evaluating optimal conditions and feasibility of such applications. Phase equilibria in the carbon dioxide + pyrrole system were measured at 313 K, 323 K, and 333 K using a synthetic method. Liquid-vapor (LV) phase behavior and liquid-liquid (LL) phase behavior were observed. The pressure in the experiments ranged from 84 to 151.1 bar. The Patel-Teja equation of state and the Mathias-Klotz-Prausnitz mixing rule with two temperature independent parameters was able to correlate the phase equilibrium data satisfactorily and was used to predict the phase behavior at other temperatures. A pressure-temperature diagram was then constructed from these calculations and suggests that the carbon dioxide + pyrrole system exhibit type IV phase behavior in the classification of Scott and van Konynenburg.

There is a raising need to design a safe and efficient cryogenic fuel tank for the new generation of reusable launch vehicles. The new tank design focuses on composite materials that can achieve the drastic reduction of empty/non-payload and structural weight. In addition to the materials to be compatible with cryogenic temperatures, interior components of the vehicle may be subjected to significantly elevated temperatures due to heat conduction from the vehicle surfaces during and after atmospheric re-entry. Therefore, there is the need to understand the performance of the composites after experiencing extreme thermal environments. Polymer-layered nanocomposites were studied to determine if they can reduce the permeation to the liquid nitrogen used as fuel in the next generation of space vehicles. Due to the non-permeable nature of the silicates and the exfoliated structure they adopt into the polymer matrix the addition of nanoclays into a polymer is expected to reduce the permeation to several gases without sacrificing the mechanical strength of the nanocomposite as well as providing additional improvements such as increase of thermal stability of the nanocomposite. Several types of matrixes modified with different types and content of nanoclays were tested and their permeability coefficient was calculated. The permeability values obtained for the different formulations assisted to understand the transport properties of nanoclay modified composites. In addition to this, thermal characterization was performed with the help of dynamic mechanical analysis, thermogravimetric analyses and differential scanning calorimetry studies. To determine if the nanoclay modified nanocomposites were affected by extreme temperatures the samples were subjected to thermal cycling. Comparison of the transport and thermal properties before and after cycling helped to analyze the effect of the addition of the nanoclays in the nanocomposites. Positron annihilation spectroscopy (PAS) was utilized to comprehend how the distribution of the free volume was affected by the presence of the nanoclays and by the thermal cycling applied. Different permeability models were utilized in an attempt to validate the experimental results of the different nanocomposite structures. This analysis was used to provide additional insight into many aspects of the experimental results obtained in this study.

We present a periodic technique for measuring the thermal conductivity and diffusivity of thin samples simultaneously. In samples of this type, temperature measurements must be made across the sample faces and are therefore subject to large error due to the interface resistance between the temperature sensor and the sample. The technique uses measurements of the amplitude and phase of the periodic temperature across both a reference sample and the unknown material at several different frequencies. Modeling of the heat flow in the sample allows the simultaneous determination of the thermal parameters of the sample as well as the interface resistance. Data will be presented for standard materials to show the viability of the technique.

La gestió tèrmica és un problema crític en el disseny de dispositius nanoelectrònics. Les solucions de refredament avançades i la recol·lecció eficient d'energia són clau per mantenir la tendència de productes electrònics cada vegada més petits i ràpids. Aquesta tesi se centra en la gestió tèrmica i l'ús de calor dissipada en materials emergents per a l'electrònica. En particular, els materials bidimensionals (2DM) i heteroestructures d'aquests són dels candidats més interessants per al futur de l'electrònica i s'estan investigant intensament. En aquesta tesi, s'exploren dos temes principals: (i) el transport tèrmic de 2DMs suspesos, inclòs el grafè CVD, dicalcògens de metalls de transició (TMDC) i heteroestructures de TMDC amb nitrur de bor hexagonal (hBN); i (ii) les propietats tèrmiques i de termoelectricitat de les pel·lícules primes (Bi1-xSbx)2Te3 (BST). Aquests materials s'estan considerant per interconnexions i transistors fins als THz (grafè), per a electrònica digital (TMDCs) i per a aïllament elèctric (hBN) i són ben coneguts com a generadors termoelèctrics, com ho són també materials recentment identificats com a aïllants topològics (BST). En primer lloc, l'objectiu era mesurar la conductivitat tèrmica de 2DMs utilitzant el mètode d'espectroscòpia Raman de dos làsers, recentment desenvolupat. La implementació fou dificultada per l'ús de membranes relativament petites obtingudes dels materials investigats i la seva alta conductivitat tèrmica. Demostràrem que la conductivitat tèrmica del grafè CVD és d'aproximadament 300 W/(m·K). Encara que menor que en el grafè exfoliat, això podria ser degut a les fronteres de gra i al desordre en el grafè CVD. Demostràrem també que les conductivitats tèrmiques de MoS2 i MoSe2 exfoliats (dos TMDC) són de 12 a 24 W/(m·K) i 60 W/(m·K), respectivament. I que per a membranes primes (de poques monocapes) de MoS2, la conductivitat incrementa amb el gruix. Afegint una membrana de hBN exfoliada sobre una mostra de MoS2 prèviament caracteritzada demostràrem un augment notable de la conductivitat tèrmica en l'heteroestructura de hBN/MoS2, quan s'introdueix calor al MoS2. Aquesta presenta una conductivitat tèrmica de 185 W/(m·K), gairebé un ordre de magnitud més gran que el MoS2 sol. En segon lloc, capes primes de BST crescudes mitjançant epitàxia de feix molecular s'estudiaren amb l'objectiu de correlacionar-ne les propietats termoelèctriques amb el seu nivell de Fermi, que sintonitzaria el pes relatiu del transport de volum i dels estats topològics de superfície (TSS). Primer demostràrem que és possible dissenyar l'estructura de la banda i ajustar el nivell de Fermi des de la valència fins a la banda de conducció simplement controlant la concentració de Sb. La demostració s'aconseguí utilitzant espectroscòpia de fotoemissió amb resolució angular en combinació amb conductivitat elèctrica i mesures d'efecte Hall en pel·lícules relativament primes (10 nm). S'identificà la concentració de Sb a la qual els TSSs dominen el transport i es dugueren a terme experiments termoelèctrics en les mateixes capes. No es trobà una correlació clara entre l'energia termoelèctrica i la naturalesa dels portadors de càrrega quan els TSSs eren dominants. Això indica que el transport dels TSSs té una influència limitada en les propietats termoelèctriques d'aquest material, i que per tal d'observar els efectes de superfície es necessitarien capes encara més primes. Finalment, una caracterització de les capes primes de BST usant espectroscòpia Raman demostrà variacions específiques en el comportament associat a la concentració de Sb. En particular, l'augment de la potència del làser va donar lloc a l'aparició de pics Raman no actius d'origen indeterminat. Aquests pics poden indicar la ruptura de simetries estructurals, modes de fonó de superfície o altres efectes com ara ressonàncies plasmòniques que són d'alt interès. La inesperada resposta observada en l'espectre Raman hauria de motivar investigacions addicionals.
La gestión térmica es un problema crítico en el diseño de dispositivos nanoelectrónicos. Las soluciones de enfriamiento avanzadas y la recolección eficiente de energía son clave para mantener la tendencia de productos electrónicos cada vez más pequeños y rápidos. Esta tesis se centra en la gestión térmica y el uso de calor disipado en materiales emergentes para la electrónica. En particular, los materiales bidimensionales (2DM) y las heteroestructuras basadas en ellos son candidatos muy interesantes para el futuro de la electrónica y se están investigando intensamente. La tesis trata dos temas principales: (i) el transporte térmico de 2DMs suspendidos, incluido el grafeno CVD, dicalcogenuros de metales de transición (TMDC) y heteroestructuras de TMDC con nitruro de boro hexagonal (hBN); y (ii) las propiedades térmicas y de termoelectricidad de películas delgadas de (Bi1-xSbx)2Te3(BST). Estos materiales están siendo considerados para interconexiones y transistores hasta THz (grafeno), electrónica digital (TMDCs) y aislamiento eléctrico (hBN) y son bien conocidos como generadores termoeléctricos, como también lo son materiales recientemente identificados como aislantes topológicos (BST). En primer lugar, el objetivo fue medir la conductividad térmica de 2DMs utilizando el método de espectroscopia Raman de dos láser, recientemente desarrollado. El desafío fue el uso de membranas relativamente pequeñas obtenidas y su alta conductividad térmica. Demostramos que la conductividad térmica del grafeno CVD es de aproximadamente 300 W/(m·K). Aunque menor que en el grafeno exfoliado, esto podría deberse a los bordes de grano y al desorden en grafeno CVD. Demostramos también que las conductividades térmicas de MoS2 y MoSe2 exfoliados (dos TMDC) son 12 a 24 W/(m·K) y 60 W/(m·K), respectivamente. Y que para membranas delgadas (pocas monocapas) la conductividad incrementa con su grosor. Agregando una membrana de hBN exfoliada sobre una muestra de MoS2 previamente caracterizada nos permitió demostrar un notable aumento de la conductividad térmica en la heteroestructura de hBN/MoS2, cuando se introduce calor en MoS2. Esta presenta una conductividad térmica de 185 W/(m·K), casi un orden de magnitud mayor que para MoS2. En segundo lugar, se estudiaron películas delgadas de BST crecidas mediante epitaxia de haz molecular con el objetivo de correlacionar sus propiedades termoeléctricas con su nivel de Fermi, que sintonizaría el peso relativo del transporte de volumen y de los estados topológicos de superficie (TSS). Primero demostramos que es posible diseñar la estructura de la banda y ajustar el nivel de Fermi desde la valencia hasta la banda de conducción simplemente controlando la concentración de Sb. Para ello se utilizó espectroscopia de fotoemisión con resolución angular en combinación con conductividad eléctrica y mediciones de Hall en películas relativamente delgadas (10 nm). También se identificó la concentración de Sb a la que los TSSs dominan el transporte y se llevaron a cabo experimentos termoeléctricos en las mismas películas. No se encontró una correlación clara entre la energía termoeléctrica y la naturaleza de los portadores de carga cuando los TSSs eran dominantes, indicando que el transporte de los TSSs tiene una influencia limitada en las propiedades termoeléctricas de este material y que para observar los efectos de superficie se necesitarían películas más delgadas. Finalmente, una caracterización de las películas delgadas de BST usando espectroscopia Raman demostró variaciones específicas en el comportamiento asociado a la concentración de Sb. En particular, el aumento de la potencia del láser dio lugar a la aparición de picos Raman no activos de origen indeterminado. Estos picos pueden indicar la ruptura de simetrías estructurales, modos de fonón de superficie u otros efectos tales como resonancias plasmónicas que son de alto interés, una respuesta que debería motivar investigaciones adicionales.
Thermal management is becoming a critical issue in the packaging and design of nanoelectronics. Advanced cooling solutions and efficient energy harvesting are key aspects to help keep the trend for ever smaller and faster electronics. This thesis is focused on thermal management and the use of heat waste in emerging materials for electronics. In particular, two-dimensional materials (2DM), and related heterostructures, are amongst the most intriguing prospects for future electronics and are being intensively investigated. Here, two main subjects were explored. First, the thermal transport of suspended 2DMs, including CVD graphene, transition metal dichalcogenides (TMDCs) and heterostructures of TMDCs with hexagonal boron nitride (hBN) and, second, the thermal properties and thermoelectricity of (Bi1-xSbx)2Te3 (BST) thin films. These materials are being considered for interconnects and THz transistors (graphene), digital electronics (TMDCs) and electrical insulation (hBN) and are well known as thermoelectric generators, as are also materials that have recently been identified as topological insulators (BST). In the first part, the objective was to demonstrate the measurement of the thermal conductivity of 2DMs using the recently developed two-laser Raman spectroscopy method. Its implementation was rendered difficult by the relatively small exfoliated flakes of the materials investigated and their high thermal conductivity. The thermal conductivity of CVD graphene was found to be about 300 W/(m·K). Although smaller than exfoliated graphene, it is argued that this could be due to grain boundaries and disorder. Exfoliated MoS2 and MoSe2 (two well-known TMDCs) presented thermal conductivities of 12 to 24 W/(m·K) and 60 W/(m·K). Measurements on different membranes of MoS2 further showed that the conductivity increases with the thickness in thin membranes (few monolayers). Furthermore, stacking an exfoliated hBN membrane on top of a previously characterized MoS2 sample allowed us to demonstrate a notorious increase of the thermal conductivity in the hBN/MoS2 heterostructure, when heat is introduced on MoS2. Indeed, when compared with MoS2 alone the thermal conductivity is found to be almost one order of magnitude larger, 185 W/(m·K). For the second part, BST thin films were grown by molecular beam epitaxy. The main objective was to investigate the correlation of the thermoelectric properties of these materials with the Fermi level, which would tune the relative weight of bulk and topological surface state (TSS) transport. It was first demonstrated that controlling the concentration of Sb we could engineer the band structure and tune the Fermi level from the valence to the conduction band. Such demonstration was achieved by using angle-resolved photoemission spectroscopy in combination with conductivity and Hall measurements in relatively thin (10 nm) films. The Sb concentration at which TSS dominated the transport was also identified. Thermoelectric experiments on the same films were then carried out but no clear correlation between the thermopower and the carrier nature was found when the TSSs were dominant. These results indicate that TSS transport has limited influence on the thermoelectric properties. Further studies should be carried our using even thinner films. Finally, a side characterization of the BST thin films using Raman spectroscopy demonstrated specific variations in the behaviour associated to Sb concentration. An increase of the laser power showed the emergence of non-active Raman peaks of undetermined origin. However, they can indicate the presence of broken structural symmetries, surface phonon modes or other effects such as plasmonic resonances. This interesting response is worthy of for further investigation.
Universitat Autònoma de Barelona. Programa de Doctorat en Física

Research concerning lignin has increased during the last years due to its renewability and ready availability in black liquor at pulp mills. Today, the kraft lignin found in black liquor is used as a fuel to gain energy in the recovery boiler at the mill. However, a new isolation concept, LignoBoost®, has enabled isolation of part of the lignin while allowing the use of black liquor as a fuel. This isolated lignin can be utilised as a fuel in, for example, thermal power stations or further upgraded to more value-added products. In this context, the most interesting value-added product is carbon fibre. The demand for carbon fibre has increased, but the biggest obstacle for a more extended use is the high production cost. About half of the production cost is related to the raw material.

In this work, the possibility of using kraft lignin as a precursor for carbon fibre production has been investigated through fundamental studies. Kraft lignins originating from birch, Eucalyptus globulus, softwoods and softwoods from liner production have been studied. By separating the lignin while still in solution in the black liquor, unwanted large particles such as carbohydrates can easily be removed. After isolation according to the LignoBoost process and purification with the use of an ion-exchanger, the lignins have been both chemically and thermally characterised. Identification of the released compounds at different temperatures has been performed because only 40% of carbon relative to original lignin remains, down from theoretical 60% after thermal treatment up to 1000°C. The main released compounds were phenols, as revealed by pyrolysis-GC/MS. Additionally, a pre-oxidation was done in order to try to stabilise the lignins. It was shown that an oxidation prior to the thermal treatment increases the yield by more than 10% and that the main release of compounds takes place between 400°C and 600°C. Fractionated lignin is better qualified as raw material for carbon fibre production because it is purer and its softening temperature can be detected. Fractionated kraft lignins from all investigated wood sources have high possibilities to act as precursors for the manufacture of carbon fibre.

Little has been published concerning the thermal properties of existing unbaked earth walls. In order to model the thermal behaviour of a building constructed using traditional cob walls, the thermal conductivity and thermal diffusivity need to be established. The Centre for Earthen Architecture (CEA), based at the University of Plymouth's School of Architecture has carried out research into various aspects of cob architecture typical to the Devon area. This study supplements other work concerning the moisture content, structure and pathology of cob as a building material. This research concentrates upon the development of a time dependent probe technique for the measurement of the thermal conductivity and thermal diffusivity of cob. The literature concerning the technique is reviewed. Methods of obtaining thermal data from the results are discussed. Particular emphasis is placed upon the measurement of the probe's thermal contact conductance with the test material. A series of laboratory tests and results from specific test materials are described. From this work, a link between the improvement of the thermal contact between the probe and the specimen and the accuracy of the thermal diffusivity values is established. The development of field test apparatus is described and the results from three field tests are examined. Values for thermal conductivity, diffusivity and the probe thermal contact conductance are established. These results are used in a thermal simulation of a cob dwelling. The output from the simulation is compared with results from a modern timberframe house of identical dimensions and use. The thermal response of the modern timber-frame house was found to be similar to that of the cob dwelling. However, generally, the range of internal air temperature was found to be higher in the interior spaces of the timber framed dwelling than the cob dwelling.

"Composites of nanoparticles with complex fluids represent a unique physical system where thermal physical properties of the components partially or fully mix and new behavior can emerge. Traditional composites are relatively well understood as the superposition, weighted by volume or mass, of the components properties and the interfacial interactions play the role of holding the composite together. As the filler component, nanoparticle, decreases in size, the surface area begins to dominate, leading to unique behavior of the nanocomposites. The richness of the nanocomposites that can be designed by coupling various nanoparticles and complex fluid materials opens a wide field of active research. This dissertation presents a series of experimental studies on various nanocomposites using modulated differential scanning calorimetry, spectroscopic ellipsometry, dielectric spectroscopy, polarizing microscopy, and conductivity measurements of nanoparticles such as multi-wall carbon nanotubes and quantum dots on the phase transitions of several liquid crystals and polymers. The liquid crystals (LCs) and liquid crystalline polymer (LCP) of interest are: negative dielectric anisotropy alkoxyphenylbenzoate (9OO4), octylcyanobiphenyl (8CB), decylcyanobiphenyl (10CB), and isotactic polypropylene (iPP) which can form smectic liquid crystal (LC) phase. Studies have been carried out as a function of concentration and temperature spanning through various ordered phases. The results indicate a mixture of ordering and disordering effects of the nanoparticles on the phases of the complex fluids. In 9OO4/CNT system, dipole moment of liquid crystal and graphene like surface can allow a random dispersion of CNT to promote both orientational and positional order. For nCB/CNT, nCB/Quantum dot (QD) systems, nanoparticles induce net disordering effect in LC media. The effect of QDs on LC depends on the anchoring conditions and the QDs size. The results clearly demonstrate that the nematic phase imposes self-assembly on QDs to form one dimensional arrays. This leads to net disordering effect. The thermal/electrical conductivity changes in thin films of iPP/CNT sheared/un-sheared samples and it also varies with temperature for the purpose of inducing anisotropy of those properties in parallel and perpendicular to average orientation. The percolation threshold is clearly pronounced in both conductivities due to pressing and shearing treatment of the films. This will further our abilities to nano-engineer material for many important applications."

Thesis (S.M. in Mechanical Engineering and Naval Architecture and Marine Engineering)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2007.
Includes bibliographical references (p. 61-63).
High molecular weight polymers that are linear in molecular construction can be oriented such that some of their physical properties in the oriented direction are enhanced. For over 50 years polymer orientation and processing has been extensively studied to improve the mechanical properties of polymers. In more recent history the anisotropic thermal properties of oriented polymers have been studied. This thesis investigates the thermal properties of Ultra High Molecular Weight Polyethylene (UHMW-PE) and explores applications for the same. This thesis details an effective means of aligning the molecules in bulk polyethylene sheets through stretching in the gel state. Tests have shown that bulk UHMW-PE can be stretched 50-80 times in xylene. The thermal conductivity of bulk UHMW-PE is 0.3 W/mK, while that of a sample stretched 20-25 times is over 4.5 W/mK.
by Erik Skow.
S.M.in Mechanical Engineering and Naval Architecture and Marine Engineering

Wang, Ranshi = 透明电解质/氧化锌异质结热稳定性的研究 / 王然石.
Thesis (M.Phil.)--Chinese University of Hong Kong, 2007.
Includes bibliographical references (leaves 130-134).
Abstracts in English and Chinese.
Wang, Ranshi = Tou ming dian jie zhi/yang hua xin yi zhi jie re wen ding xing de yan jiu / Wang Ranshi.
Chapter I. --- Abstract
Chapter II. --- Acknowledgement
Chapter III. --- Table of contents
Chapter IV. --- List of figures
Chapter V. --- List of tables
Chapter 1 --- Introduction
Chapter 1.1 --- Motivations
Chapter 1.2 --- Outline of thesis
Chapter 2 --- Experimental Conditions and Techniques Used
Chapter 2.1 --- Sample preparation
Chapter 2.1.1 --- Radio frequency magnetic sputtering
Chapter 2.1.2 --- ITO glass
Chapter 2.1.3 --- Thermal evaporation
Chapter 2.1.4 --- Thermal annealing
Chapter 2.2 --- Optical characterization of ZnO
Chapter 2.2.1 --- Photoluminescence (PL) measurement
Chapter 2.2.2 --- SEM and cathodoluminescence spectroscopy
Chapter 2.3 --- Time-of-FIight Secondary Ion Mass Spectroscopy (TOF-SIMS )
Chapter 2.4 --- Electrical measurements
Chapter 3 --- Calibrations
Chapter 3.1 --- Sample Thickness
Chapter 3.2 --- Calibrations of cathodeluminescence measurements
Chapter 3.2.1 --- Probe current and specimen current
Chapter 3.2.2 --- Sample uniformity in CL measurement
Chapter 3.2.3 --- Mirror position
Chapter 3.2.4 --- Non-linear relation between CL emission and current
Chapter 3.2.5 --- CL band-edge emission stability
Chapter 3.2.6 --- Effect of magnification
Chapter 3.2.7 --- Effect of electron beam shift
Chapter 3.2.8 --- Conclusions
Chapter 3.3 --- C-V measurement
Chapter 4 --- Experimental Results and Data Analysis
Chapter 4.1 --- Optical properties
Chapter 4.1.1 --- Luminescence of ZnO
Chapter 4.1.2 --- Light emitting thermal stability of A10x (MgO) capped ZnO film
Chapter 4.1.2.1 --- Emission degradations in annealing treatment by PL
Chapter 4.1.2.2 --- Evidence about the interface degradation
Chapter 4.1.2.3 --- CL studies of the emission from sample surface
Chapter 4.2 --- Secondary Ion Mass Spectroscopy (SIMS) studies of AIOx-capped ZnO
Chapter 4.2.1 --- Data processing
Chapter 4.2.2 --- Diffusion width
Chapter 4.3 --- Simulation of Zn out diffusion to the dielectric layer
Chapter 4.3.1 --- Structure and assumptions
Chapter 4.3.2 --- Calculations of diffusion by Fick's Law
Chapter 4.3.3 --- Simulation of PL reduction from diffusion
Chapter 4.3.4 --- Short-time PL
Chapter 4.4 --- Simulation of defects generation in emission reduction process
Chapter 4.4.1 --- Some calculations of continuity equation
Chapter 4.4.2 --- First order equation for defect generation
Chapter 4.5 --- Electrical measurements
Chapter 4.5.1 --- Theory of C-V measurement for MOS structure
Chapter 4.5.1.1 --- MOS Structure
Chapter 4.5.1.2 --- Discussions about surface charge and energy level in C-V experiments of MOS
Chapter 4.5.1.3 --- Useful formulations
Chapter 4.5.2 --- Experimental results of C-V and parameter extraction
Chapter 4.5.2.1 --- Effect of series resistance correction
Chapter 4.5.2.2 --- Effect of thermal annealing to C-V curves on dielectric/ZnO/ITO
Chapter 4.5.2.3 --- Doping concentration (ND)
Chapter 4.5.2.4 --- Discussion about the fixed and mobile charge
Chapter 4.5.3 --- Simulation of C-V relation in dielectric/ZnO
Chapter 4.5.4 --- Current-voltage (I-V) measurements
Chapter 4.5.5 --- Conductance-voltage measurements (G-V) and interface trap density
Chapter 4.5.6 --- DLTS measurements for extracting interface trap density
Chapter 5 --- Discussions and Conclusion
Chapter 5.1 --- Mechanism
Chapter 5.2 --- Conclusions
Chapter 5.3 --- Future plan
Chapter 6 --- References

博士
國立清華大學
工程與系統科學系
101
The low-dimensional materials exhibit a lot of innovative behaviors different from the bulk materials. The interactions of phonon-electron, phonon-interface, and phonon-grain boundary in low dimension materials attracted a lot of attentions in the research society. This initiated my motivation to investigate the electrical and thermodynamic properties in low dimensional systems for understanding their fundamental physics. One important measuring technique is the 3ω method, which can be applied to evaluate the thermal conductivity for low dimensional systems. In this work, the techniques have been developed to measure the cross-plane and in-plane thermal conductivity of a thin film and the longitudinal direction thermal conductivity of an individual nanowire. By comparison with other methods, the techniques yield more information, which is very helpful for understanding the behavior of phonon and electron in low dimension materials. For two-dimensional system, we have measured the cross-plane thermal conductivity of CuFeSe2 thin film which is considered to be the photoelectric material. The results indicate thermal conductivity of the films is strongly dependent on film crystallization, the better crystallization the higher thermal conductivity. In the meantime, the interfacial thermal resistance between film and substrate should also be taken into account for obtaining accurate total thermal conductivity. For one-dimensional system, a series of single crystalline Bi2-xSbxTe3-y nanowires (150 - 890 nm) were fabricated for the thermoelectric properties measurement. The phonon thermal conductivity decreases as the wire diameter reduces at low temperatures, indicating the enhancement of boundary scattering in one-dimensional system. The Seebeck coefficient and electrical resistivity were also measured for the same nanowire subsequently. The results show the Seebeck coefficient and electrical resistivity are greatly dependent on the composition of the nanowires.

Chan Chun Wai = 納米鈀硅合金的熱性質 / 陳進偉.
Thesis (M.Phil.)--Chinese University of Hong Kong, 2000.
Includes bibliographical references (leaves 18-20).
Text in English; abstracts in English and Chinese.
Chan Chun Wai = Na mi ba gui he jin de re xing zhi / Chen Jinwei.
Acknowledgements --- p.III
Abstract --- p.IV
摘要 --- p.V
Chapter Chapter One ´ؤ --- Introduction
Chapter 1.1 --- Novel materials in the 21st century --- p.1
Chapter 1.2 --- What are Nanocrystalline Materials? --- p.1
Chapter 1.3 --- The superior properties of Nanocrystalline Materials --- p.2
Chapter 1.4 --- Fabrication of Nanocrystalline Materials --- p.3
Chapter 1.5 --- Flaws of the as-produced Nanophase Materials --- p.4
Chapter 1.6 --- Theory of Phase Separation --- p.4
Chapter 1.7 --- Nucleation and Growth --- p.6
Chapter 1.7.1 --- Homogeneous nucleation
Chapter 1.7.2 --- Heterogeneous nucleation
Chapter 1.8 --- Spinodal Decomposition
Chapter 1.8.1 --- How SD differs from the classical diffusion process?
Chapter 1.8.2 --- Dynamics of SD
Chapter 1.8.3 --- How can we distinguish SD from Nucleation and Growth?
Chapter 1.8.4 --- Pore-free nanophase materials produced by Liquid Phase SD
Chapter 1.9 --- Thermal properties of the pore-free nanostructured Pd82Si18 Alloy --- p.12
Chapter 1.9.1 --- A review of grain growth in nanophase materials
Chapter 1.9.2 --- Grain growth study on LSD Pd82Si18 alloy 一 aim and prospect
References --- p.18
Figures --- p.21
Chapter Chapter Two 一 --- Experimental
Chapter 2.1 --- Introduction --- p.28
Chapter 2.2 --- From preparation of samples to microstructure analysis --- p.28
Chapter 2.2.1 --- Alloying
Chapter 2.2.2 --- Fluxing
Chapter 2.2.3 --- Rapid Solification
Chapter 2.2.4 --- Annealing
Chapter 2.2.5 --- Microstructure analysis
Figures --- p.31
Chapter Chapter Three ´ؤ --- Results and discussions
Thermal stability of bulk nanostructured alloys prepared by liquid phase spinodal decomposition --- p.34
References --- p.40
Table --- p.43
Figures --- p.44
Chapter Chapter Four ´ؤ --- Conclusions --- p.61

碩士
明新科技大學
化學工程與材料科技系碩士班
106
A thermally conductive composite polymers was obtained from a particles mixture of Silicon carbide(SiC) , Aluminum nitride (AlN) ,Magnesium oxide(MgO) , Aluminum oxide(Al2O3), and High Density Polyethylene(HDPE) by a powder mixing, laboratory extrude and hot press molding. The properties of polymer composite films were measured by abrasion, thermal conductivity, thermogravimetric analysis (TGA) and differential scanning calorimetry(DSC). The thermal conductivity of the composites containing 50%(volume fraction) SiC , AlN and MgO filler was 2.17 W/m•K almost nearly five times that of pure HDPE. The abrasion resistance of most of the test pieces increased as the filler increased. From the results of thermogravimetric analysis (TGA), it was found that the decomposition temperature(Td) of almost HDPE composite films can be improved significantly. The experimental residue weight of almost HDPE composite films are in good agreement with theoretical residue weight. Moreover, polyethylene were added with different shapes and sizes of Silicon carbide, aluminum nitride, magnesium oxide and aluminum oxide. The polymer composite films in the proper proportions of fillers with high thermal conductivity would be achieved due to the high packing density. The smaller particles were filled into the gap of bigger fillers, would be decreased thermal resistance and thermal conductivity improved significantly.