Дисертації з теми "Thermal and Thermokinetic Characterization"
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Flity, Hassan. "Modélisation de la dégradation et combustion du bois de construction." Electronic Thesis or Diss., Université de Lorraine, 2023. http://www.theses.fr/2023LORR0250.
The use of wood in construction offers numerous advantages, but also poses fire safety risks. Several studies available in the literature, whether experimental or numerical, have investigated the fire behavior of wood. However, the diverse and varied results do not allow the identification of the intrinsic behavior of wood, and regulatory frameworks have to rely on numerous simplifying assumptions. The objective of this thesis is to study the thermal degradation of wood at the cone calorimeter scale. The uniqueness of the study lies in the adoption of an increasingly complex approach, the use of meticulous metrology, and the most comprehensive characterization of the properties of the wood samples under investigation. Degradation involves numerous interacting processes such as drying, pyrolysis, and combustion with or without flames, resulting in heat and mass transfer. Given the complexity of studying all these phenomena simultaneously, the strategy adopted was to separate the different phenomena as much as possible through models and specific experiments. In order to overcome the problem of drying and hydric transfer, all the work was carried out on dry wood. First, specific characterization methods were used to determine the thermal properties of wood and charcoal. These experiments helped to establish behavioral laws for some of these properties, facilitating their integration into a model. Subsequently, an experimental campaign was conducted at the material scale of wood using techniques such as thermogravimetric analysis and differential scanning calorimetry under an inert atmosphere. At this scale, wood is thermally thin, which allowed the development of a kinetic model capable of predicting mass loss, mass loss rate, and heat absorbed or generated by wood during pyrolysis as a function of temperature. Next, an experimental campaign was carried out on wood samples at the scale of the cone calorimeter in an inert atmosphere to validate the 3D pyrolysis model developed to predict wood pyrolysis in the absence of combustion, driven primarily by heat transfer within the material. Finally, tests in an air environment were conducted for a comprehensive modeling of dry wood combustion, which requires a precise characterization of char combustion, the associated heat generated, and the heat flux supplied by the flame
De, Indrayush. "Thermal characterization of nanostructures using scanning thermal microscopy." Thesis, Bordeaux, 2017. http://www.theses.fr/2017BORD0563/document.
The objective of this thesis is to master quantitative aspects when using nearfield thermal microscopy by using the scanning thermal microscopy technique (SThM). We start by taking an in-depth look into the work performed previously by other scientist and research organizations. From there, we understand the progress the SThM probes have made through the decades, understand the probe sensitivity to the range of conductivity of the materials under investigation, verify the resistances encountered when the probe comes in contact with the sampl and the applications of SThM.Then we look into the equipment necessary for performing tests to characterize material thermal properties. The SThM we use is based on atomic force microscope (AFM) with a thermal probe attached at the end. The AFM is described in this work along with the probes we have utilized.For the purpose of our work, we are only using thermoresistive probes that play the role of the heater and the thermometer. These probes allow us to obtain sample temperature and thermalconductivity. We use two different types of thermal probes – 2-point probe and 4-point probe with SiO2 or with Si3N4 cantilever. Both the probes are very similar when it comes to functioning with the major difference being that the 4-point probe doesn’t have current limiters. Then, we present the use of recent heat-resistive probes allowing to reach a spatial resolution of the orde rof 100 nm under atmosphere and of 30 nm under vacuum. These probes can be used in passive mode for measuring the temperature at the surface of a material or component and in activemode for the determination of the thermal properties of these systems. Using thermoresistive probes means that no specialized devices are necessary for operation. Using simple commercialsolutions like simple AC or DC current and Wheatstone bridge are sufficient to provide basic thermal images. In our case we have also utilized other industrial devices and a home madeSThM setup to further improve the quality of measurement and accuracy. All the elements of the experimental setup have been connected using GPIB and that have been remotely controlled from a computer using a code developed under Python language. This code allows to make the frequency dependent measurement as well as the probe calibration. [...]
Li, Yifan Li. "NANOSCALE THERMAL CHARACTERIZATION BY SCANNING THERMAL MICROSCOPY (STHM)." University of Akron / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=akron159057422807603.
Shope, David Allen 1958. "Thermal characterization of VLSI packaging." Thesis, The University of Arizona, 1988. http://hdl.handle.net/10150/276686.
Crain, Kevin Richard. "Mechanical characterization and thermal modeling of a MEMS thermal switch." Online access for everyone, 2005. http://www.dissertations.wsu.edu/Thesis/Fall2005/k%5Fcrain%5F120905.pdf.
Ferrando, Villalba Pablo. "Thermal characterization of Si-based nanostructures." Doctoral thesis, Universitat Autònoma de Barcelona, 2016. http://hdl.handle.net/10803/399339.
Thermoelectricity is a promising technology for scavenging energy from environmental temperature differences. The development of materials that transform heat into electricity in a more efficient way making use of this principle is necessary for opening new application niches. Nanostructuring a material has been demonstrated to increase the thermoelectric figure of merit of crystalline materials via a thermal conductivity reduction driven by enhanced phonon scattering. This thesis is committed to give a better insight into the processes that affect thermal transport in potential Si-based nanomaterials for thermoelectric generation. In Chapter 1, a general introduction exposes the need for reducing fossil fuel consumption and generally using renewable energies. Also, the benefit of tuning the thermal conductivity of materials for thermal management applications is discussed. Chapter 2 provides an overview of the theory behind thermal transport. First, the heat equation is derived from the classical irreversible thermodynamics framework. Then, phonons are introduced as heat carrying quasiparticles. The application of the Boltzmann Transport Equation to both phonons and electrons allows understanding the effect of different scattering mechanisms on the thermoelectric properties of materials. Finally, several strategies for enhancing the figure of merit of materials are reviewed. In Chapter 3, the necessary tools for measuring the thermal conductivity of nanomaterials are developed. Two cryostats are set up along with the temperature control systems that allow measuring at stable temperatures. Later, three sensors are developed for measuring the thermal conductivity of different materials. First, suspended structures intended for measuring the in-plane thermal conductivity of suspended membranes and nanowires are fabricated, and the errors and uncertainties produced in such measurements are characterized. Second, the 3ω method is introduced, allowing the measurement of the out-of-plane thermal conductivity in thin films. The emergence of the 3ω voltage is demonstrated, and the relation between this voltage and the thermal conductivity of the substrate and the thin-film is found. Finally, a sensor for the 3ω-Völklein method is developed, which allows characterizing the in-plane thermal conductivity of thin-films during the layer growth. In Chapter 4, the thermal conductivity of suspended Si membranes is measured, finding the expected reduction in thermal conductivity due to phonon surface scattering, as well as confinement effects in the 17.5 nm thick membrane. Moreover, the nanopatterning of these Si membranes with focused ion beam (FIB) is optimized through a systematic study of its amorphization finding an optimal spatial resolution of 200 nm when using 50 μC/cm2. In Chapter 5, the thermal conductivity of porous Si nanowires is studied for wires with different porosity, length and diameters, showing an unexpected dependence on its diameter that suggests that the wire core is generally less porous than the shell. The structural Si thermal conductivity is found to be one fiftieth of that of the bulk, promising a good thermoelectric figure of merit. In Chapter 6, the thermal conductivity of a novel SiGe graded superlattice is measured, showing a considerable reduction in its thermal conductivity, even below the thin-film alloy limit. The measurement of the thickest superlattice confirms the absence of coherent phonon effects. In Chapter 7, the thermal conductance of a suspended SiNx membrane is measured with a high precision while depositing on it organic (TPD) and metallic (Indium) materials. The results show an initial conductance reduction that cannot be explained with the Fourier law. This reduction is found to be related to an increased diffusive boundary scattering, which could be easily extrapolated to other thermoelectric nanomaterials, reducing their thermal conductivity. Also, the growth dynamics of both materials are characterized through their signal in the conductance.
Mutnuri, Bhyrav. "Thermal conductivity characterization of composite materials." Morgantown, W. Va. : [West Virginia University Libraries], 2006. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=4468.
Title from document title page. Document formatted into pages; contains vii, 62 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 61-62).
Wei, Xiaohao, and 魏晓浩. "Nanofluids: synthesis, characterization and thermal conductivity." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2010. http://hub.hku.hk/bib/B44765861.
Hanuska, Alexander Robert Jr. "Thermal Characterization of Complex Aerospace Structures." Thesis, Virginia Tech, 1998. http://hdl.handle.net/10919/36617.
Master of Science
VanDerheyden, Andrew Louis. "Characterization of thermal coupling in chip multiprocessors." Thesis, Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/51892.
Drummond, Kevin P. "Thermal Characterization of Graphitic Carbon Foams for Use in Thermal Storage Applications." Ohio University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1345476294.
Oener, Erhan. "Thermal characterization of polyester/cellulosic blended materials." Thesis, University of Leeds, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.329259.
Whang, Jihye 1976. "Thermal characterization and modeling of LDMOS FETs." Thesis, Massachusetts Institute of Technology, 2000. http://hdl.handle.net/1721.1/86560.
Mayhew, Eric Kenji. "THERMAL CHARACTERIZATION OF ONE-DIMENSIONAL CARBON NANOSTRUCTURES." Case Western Reserve University School of Graduate Studies / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=case1370033766.
Demko, Michael Thomas. "Novel Thermal Characterization Methods for Micro/Nanomaterials." Case Western Reserve University School of Graduate Studies / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=case1215008098.
Bai, Mingwen. "Fabrication and characterization of thermal barrier coatings." Thesis, University of Manchester, 2015. https://www.research.manchester.ac.uk/portal/en/theses/fabrication-and-characterization-of-thermal-barrier-coatings(172aebcf-e7a5-45e3-977a-5d79140ff2bc).html.
Copenhaver, David C. "Thermal characterization of honeycomb core sandwich structures." Thesis, This resource online, 1996. http://scholar.lib.vt.edu/theses/available/etd-11182008-063547/.
Bohnert, Alex M. "Thermal characterization of a Hall Effect thruster /." Wright-Patterson Air Force Base, Ohio : Ft. Belvior, VA : Alexandria, Va. : Air Force Institute of Technology ; Available to the public through the Defense Technical Information Center ; Available to the public through the National Technical Information Service, 2008. http://www.dtic.mil/dtic/.
"Presented to the Faculty, Department of Aeronautics and Astronautics Graduate School of Engineering and Management, Air Force Institute of Technology Air University, Air Education and Training Command in partial fulfillment of the requirements for the Degree of Master of Science in Aeronautical Engineering, March 2008."--P. [ii]. Thesis advisor: Dr. William Hargus. "March 2008." "AFIT/GA/ENY/08-M01." Includes bibliographical references. Also available online in PDF from the DTIC Online Web site.
Botha, Subelia Senara. "Synthesis and characterization of nanofluids for cooling applications." Thesis, University of the Western Cape, 2006. http://etd.uwc.ac.za/index.php?module=etd&action=viewtitle&id=gen8Srv25Nme4_1995_1210758997.
Low thermal conductivity is a primary limitation in the development of energy-efficient heat transfer fluids that are required in numerous industrial sectors. Recently submicron and high aspect ratio particles (nanoparticles and nanotubes) were introduced into the heat transfer fluids to enhance the thermal conductivity of the resulting nanofluids. The aim of this project was to investigate the physico-chemical properties of nanofluids synthesized using submicron and high aspect ratio particles suspended in heat transfer fluids .
Gurrum, Siva P. "Thermal Modeling and Characterization of Nanoscale Metallic Interconnects." Diss., Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/10435.
Ramadurai, Krishna. "Carbon nanostructures for thermal applications: Synthesis and characterization." Connect to online resource, 2007. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3284482.
SANO, MONICA ARI. "SYNTHESIS AND CHARACTERIZATION OF LOW THERMAL EXPANSION OXIDES." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2007. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=11333@1.
Materiais que apresentam expansão térmica baixa ou negativa possuem grande potencial de emprego em diversas aplicações que requerem resistência ao choque térmico, assim como para aplicações odontológicas, em placas de circuitos eletrônicos, em componentes ópticos e para produzir compósitos em que compensam a expansão térmica positiva de outros materiais. Por este motivo, o estudo e a produção de materiais com expansão térmica controlada têm crescido nos últimos anos. No presente trabalho, foram estudadas algumas famílias de óxidos com estruturas que apresentam este tipo de comportamento. Foi avaliada a expansão térmica em três sistemas da família A2M3O12 com o intuito de produzir materiais com expansão térmica controlada pela substituição química do cátion A pelos cátions Al, Cr e Fe. Os sistemas produzidos foram: Cr2xFe2-2xMo3O12 (molibdato de cromo - ferro), Al2xCr2- 2xMo3O12 (molibdato de alumínio - cromo) e Al2xFe2-2xMo3O12 (molibdato de alumínio - ferro). Além destes, o composto HfMgMo3O12 foi também sintetizado para testar a viabilidade de substituição dos cátions A trivalentes por um cátion divalente e um tetravalente. Foi possível obter soluções sólidas monofásicas e seus parâmetros de rede variam linearmente com o aumento no conteúdo do cátion de maior tamanho, conforme a lei de Vegard. Análise térmica realizada por DSC permitiu determinar a temperatura de transição de fase da estrutura monoclínica (P21a) à ortorrômbica (Pbcn). Os valores encontrados foram: para o Al2Mo3O12, 200oC, para o Cr2Mo3O12 , 403oC e para o Fe2Mo3O12, 512oC. Coeficientes de expansão térmica intrínsecos foram determinados por difração de raios-X utilizando luz síncrotron, encontrando-se valores bem reduzidos para todos os sistemas estudados, a saber: para o Al2Mo3O12, (alfa)l = 2,32 x 10- 6/oC, para o Cr2Mo3O12 , (alfa)l = 0,65 x 10-6/oC e para o Fe2Mo3O12, (alfa)l = 1,72 x 10-6/oC.
Negative and low thermal expansion materials have important potential applications as resistance to thermal shock, as well as, for odontological applications, printed circuit boards, optical components and to produce composites to compensate the positive thermal expansion of materials. For this reason, the study and production of materials with controlled thermal expansion have increased in the recent years. In the present work, some oxide families with structures that present this type of behavior were investigated. The thermal expansion in three systems of A2M3O12 family was evaluated in order to produce materials with controlled thermal expansion through the chemical substitution of cation A with Al, Cr and Fe. The produced systems were: Cr2xFe2-2xMo3O12 (chromium - iron molybdate), Al2xCr2-2xMo3O12 (chromium - aluminum molybdate) and Al2xFe2-2xMo3O12 (aluminum - iron molybdate). Besides that, HfMgMo3O12 was synthesized to test the viability of substitution of trivalent cations for one divalent plus one tetravalent. It was possible to obtain single- phase solid solutions and their lattice parameters increased linearly with the increase of the largest cation content, following the Vegard`s law. Thermal analysis carried out by DSC allowed the determination of the phase transition temperature from monoclinic (P21a) to orthorhombic (Pbcn) structure. The values were 200oC for Al2Mo3O12, , 403oC for Cr2Mo3O12 , and 512oC for Fe2Mo3O12. Intrinsic thermal expansion coefficients were determined by X-rays diffraction using syncrotron radiation, and low values were found for all studied systems: (alfa)1 = 2,32 x 10- 6/oC for Al2Mo3O12, (alfa)1 = 0,65 x 10-6/oC for Cr2Mo3O12 , and (alfa)1 = 1,72 x 10-6/oC for Fe2Mo3O12.
Foster, Daniel. "Mechanical and Thermal Characterization of Ultrasonic Additive Manufacturing." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1398997070.
Emeric, Pierre Richard. "Characterization of composite materials from temporal thermal response." W&M ScholarWorks, 1995. https://scholarworks.wm.edu/etd/1539623868.
Li, Buxuan. "Synthesis and characterization of high thermal conductive polymers and fabrication of polymer based thermal strap." Thesis, Massachusetts Institute of Technology, 2021. https://hdl.handle.net/1721.1/130863.
Cataloged from the official PDF version of thesis.
Includes bibliographical references (pages 66-70).
Polymers have infiltrated almost every aspect of modern technology. Without polymer products, the society would look very different. As one of the most important and common engineering materials, traditional polymers are both electrically and thermally insulating, due to its organic nature and amorphous structures. In the late 20th century, electrically conductive polymers has been discovered. Thermally conductive polymers, however, were not demonstrated until the recent decades. Polymers are shown to have great potential in thermal conduction, even divergent thermal conductivity in theory. This counterintuitive finding is attributed to its one-dimensional periodic structure, where repeating monomers are connected by strong covalent bonds.
Researchers have learned that special dynamics exist in non-linear one-dimensional chains since the Fermi-Pasta-Ulam-Tsingou report, where the evolution of state space was found to be non-ergodic, enabling an infinite long lifetime of excitations. As a result, such 1D nonlinear system favors scatter-free phonon transport. Molecular dynamics simulation shows a single polyethylene (PE) chain could have divergent thermal conductivity. Calculations from first principle also confirm the thermal conductivity is approximately 160 W/mK for bulk PE and 1400 W/mK for a single PE chain, with a three phonon process taken into consideration. In experiments, researchers measured enhanced thermal conductivity in stretched PE in the 1970s. In the last decades, researchers have made progress by demonstrating PE nanofibers with a thermal conductivity of over 100 W/mK. Recently, 2D PE films were fabricated and measured to have metal-like thermal conductivity of over 60 W/mK.
With all these progresses, in this thesis, we aimed to develop scalable polyethylene films with high thermal conductivity and investigating temperature-dependent thermal transport properties. A differential steady state method was used to measure the thermal conductivity of the synthesized PE films. A thermal annealing of PE films was performed along with the temperature dependence test where a transition temperature was identified. Below the transition temperature, thermal annealing increased the thermal conductivity at room temperature. Above the transition temperature, thermal annealing irreversibly decreased the thermal conductivity. Our PE films featured reasonable thermal conductivity of 20~60 W/mK depending on draw ratio and much lower density comparing to metals such as copper and aluminum. A potential application of such films is a light-weight thermal strap, which is important for space technologies.
We designed a strategy to overcome the issue that such films have a poor cross-plane thermal conductivity. We proved the idea based on both simulation and experiments. In simulations, we derived a steady state solution of a full-size physical device with conduction and radiation included. In experiments, we conducted a unit test on laboratory scale samples and argued its ability of scaling up by showing that multilayer PE films performed as expected.
by Buxuan Li.
S.M.
S.M. Massachusetts Institute of Technology, Department of Mechanical Engineering
Kaleli, Kadir. "Nano Structural Metal Composites: Synthesis, Structural And Thermal Characterization." Master's thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/12609674/index.pdf.
Cr <
Au3+ indicating stronger coordination in the same order.
Bagherifam, Shahla. "Thermal Characterization Of Phenol And Bisphenol-a Based Polybenzoxazines." Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/12610409/index.pdf.
cleavage of O-CH2 bond of the oxazine ring and attack of n-CH2 group to phenol or bisphenol-A ring. However, the direct pyrolysis mass spectrometry analyses of polymerization and thermal degradation of benzoxazines pointed out that after the cleavage of O-CH2 bond of the oxazine ring, polymerization proceeded through opposing pathways. Strong evidences confirming coupling of (CH3)NCH2 or (C6H5)NCH2 groups yielding dimers involving diamine linkages were detected. Polymerization of the dimer by the reactions with the corresponding monomers was proposed. In case of benzoxazines based on bisphenol-A, the results indicated polymerization of the dimer ii by coupling of both of the oxazine rings. On the other hand, polymerization of the dimer through the ethylene units (vinyl polymerization) in case of benzoxazine monomer based on phenol and methyl amine was also noted. For polybenzoxazines based on aniline another polymerization pathway involved attack of radicals generated by cleavage of the oxazine ring to aniline ring. Multi-step thermal decomposition was observed for all the polybenzoxazines under investigation confirming the presence of units with different structures and stabilities.
Tonolla, Diego [Verfasser]. "Acoustic and thermal characterization of river landscapes / Diego Tonolla." Berlin : Freie Universität Berlin, 2011. http://d-nb.info/102551114X/34.
Johnson, Jeremy A. (Jeremy Andrew). "Optical characterization of complex mechanical and thermal transport properties." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/68543.
Page 176 blank. Cataloged from PDF version of thesis.
Includes bibliographical references (p. 163-175).
Time-resolved impulsive stimulated light scattering (ISS), also known as transient grating spectroscopy, was used to investigate phonon mediated thermal transport in semiconductors and mechanical degrees of freedom linked to structural relaxation in supercooled liquids. In ISS measurements, short optical pulses are crossed to produce a periodic excitation profile in or at the surface of the sample. Light from a probe beam that diffracts off the periodic material response is monitored to observe the dynamics of interest. A number of improvements were put into practice including the ability to separate so-called amplitude and phase grating signal contributions using heterodyne detection. This allowed the measurement of thermal transport in lead telluride and gallium arsenide-aluminum arsenide superlattices, and also provided the first direct observation of the initial crossover from diffusive to ballistic thermal transport in single crystal silicon and gallium arsenide at room temperature. Recent first-principles calculations of the thermal conductivity accumulation as a function of phonon mean free path allowed direct comparison to our measured results. In an effort to test theoretical predictions of the prevailing first principles theory of the glass transition, the mode coupling theory (MCT), photoacoustic measurements throughout much of the MHz acoustic frequency range were conducted in supercooled liquids. Longitudinal and shear acoustic waves were generated and monitored in supercooled liquid triphenyl phosphite in order to compare the dynamics. An additional interferometric technique analogous to ISS was developed to probe longitudinal acoustic waves at lower frequencies than was typically accessible with ISS. Lower frequency acoustic data were collected in supercooled tetramethyl tetraphenyl trisiloxane in conjunction with piezotransducer, ISS, and picosecond ultrasonics measurements to produce the first truly broadband mechanical spectra of a viscoelastic material covering frequencies continuously from mHz to hundreds of GHz. This allowed direct testing of the MCT predicted connection between fast and slow relaxation in supercooled liquids. Measurements of the quasi-longitudinal speed of sound in the energetic material cyclotrimethylene trinitramine (RDX) were also performed with ISS and picosecond ultrasonics from 0.5 to 15 GHz in order to resolve discrepancies in published low and high frequency elastic constants.
by Jeremy A. Johnson.
Ph.D.
Maheswaram, Manik Pavan Kumar. "Characterization of Pharmaceutical Materials by Thermal and Analytical Methods." Cleveland State University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=csu1358131244.
Shrestha, Binod. "Characterization of lignin thermal processing in a biorefinery perspective." Electronic Thesis or Diss., Université de Lorraine, 2016. http://www.theses.fr/2016LORR0007.
The thermo-chemical conversion of lignin is an important aspect of lignocellulosic biorefinery in order to produce carbon fibers, polymer additives, green aromatics or biofuels. Protobind 1000 lignin was characterized by thermogravimetry, calorimetry, in-situ rheology, in-situ 1H NMR, solution state 13C and 31P NMR. A multiple techniques including elemental analysis, GPC-UV, FTIR, solid-state NMR and LDI-FTICRMS, were performed to understand the softening and pyrolysis of lignin. An overall physical and chemical mechanism of thermo-chemical conversion of lignin has been proposed. A twin screw extrusion of lignin was carried out using Process 11, following the in-situ high temperature rheology and rheomix internal mixing. The operating window was derived from torque evolution at varying throughputs of 0.1-0.3kg.h-1 and rotation speed of 300-600 rpm at barrel temperature of 150°C for two screw configurations. The lignin extrudates obtained at key extrusion conditions were characterized by FTIR, GPC-UV/ELSD, solution state 1H-13C HSQC NMR. The analysis of lignin melts shows no major structural changes concluding twin screw extruder as a hot melt feeder. The lignin characterization in a liquid media i.e. H2O, ethanol and aq. NaOH, were studied by wet rheology, DLS, zeta potential measurement, SAXS and real-time visual analysis. The lignin liquefaction was carried out in ethanol and the liquefaction products were analysed by UV resonance Raman spectroscopy, GPC-UV and UV-Visible absorption and fluorescence spectroscopy. The structural changes undergone by lignin during liquefaction was accounted
Assy, Ali. "Development of two techniques for thermal characterization of materials : Scanning Thermal Microscopy (SThM) and 2ω method". Thesis, Lyon, INSA, 2015. http://www.theses.fr/2015ISAL0001/document.
Two techniques to characterize the thermal properties of materials and to analyze the heat transfer at the micro/nanoscales have been studied and are presented in this manuscript. The first technique is an Atomic Force Microscopy (AFM)-based Scanning Thermal Microscopy (SThM) technique. Operating in its active mode, the AFM probe integrates a resistive element that is electrically heated. Used in AFM contact mode, it allows the localized thermal excitation of the material to be studied. The determination of the sample thermal properties requires the analysis of the probe thermal response through the modeling of the probe-sample system including its surrounding. Through a state of the art of the SThM studies, the current scientific questions and the analytical models used to analyze the probe-sample system are exposed. Special attention is given to the probe-sample thermal interaction that conditions the tip-sample interface temperature. In this work, a new methodology based on the analysis of the dependence of force-distance curves on probe temperature obtained in ambient air has been established. It permits the study and the specification of the heat rate exchanged between probe and sample through thermal conduction through water meniscus. The methodology has been applied with samples with different thermal properties, surface roughness and wettability to three resistive probes different in size and heater configurations: Wollaston, KNT and doped silicon (DS) probes. Whatever the probe and the sample are, the contribution of water meniscus in the probe-sample interaction has been shown to be lower than the one through air. The thermal conductances at the solid-solid contact were determined for various samples. This allowed identifying the phonon transmission coefficient in the case of KNT probe and a nonmetallic sample. The heat conduction through air strongly depends on the sample thermal conductivity. Moreover, the sensitivity to sample thermal conductivity for the Wollaston and KNT probes is shown to be strongly reduced for thermal conductivities larger than 10 and few W.m-1.K-1 respectively. The second technique developed in this thesis is a less local thermal analysis method. It operates by contact, requiring the implementation of the sample with a network of resistive wire probes. One wire of the network is heated by an alternating current at frequency f and has the role of heating source, continuous and at 2f frequency, for the sample. A 2D analytical model, based on the principle of thermal-waves, was developed to identify though the measurements the effective thermal properties of anisotropic samples. Finite element simulations and this model were used to design the experimental set-up and validate the method on a sample of pure silicon. The results obtained at sample temperatures ranging from ambient to 500 K are consistent with literature
Shrestha, Ramesh. "Micro-Pipette Thermal Sensor: A Unique Technique for Thermal Characterization of Microfluids, Microspheres, and Biological Cells." Thesis, University of North Texas, 2020. https://digital.library.unt.edu/ark:/67531/metadc1703406/.
Katsis, Dimosthenis C. "Thermal Characterization of Die-Attach Degradation in the Power MOSFET." Diss., Virginia Tech, 2003. http://hdl.handle.net/10919/26206.
Ph. D.
Wu, Zhaohui. "Modeling and characterization of high-temperature silicon-based thermal sensors." Click to view the E-thesis via HKUTO, 2005. http://sunzi.lib.hku.hk/hkuto/record/B31057652.
Kutukcu, Mehmet Nuri. "Synthesis and Characterization of Low and Negative Thermal Expansion Materials." Thesis, Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/7636.
Argin, Emir. "Structural And Thermal Characterization Of Polymers Via Pyrolysis Mass Spectrometry." Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/12606680/index.pdf.
evolution of low molecular weight species, evolution of dopant based products and evolution of degradation products of polymer.
Orhan, Tugba. "Nano Structural Metal Nano Composites: Synthesis, Structural And Thermal Characterization." Master's thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/12610799/index.pdf.
1718 cm-1 decreased in intensity while a new absorption peak appeared at around 1600 cm-1. This results reveals that electron deficient gold (III) ion prefers the coordination from both donor atoms namely carbonyl oxygen PMMA and pyridine nitrogen of P2VP in order to compensate its electron deficiency. In the UV-Vis spectrum of copolymers, Cr-functional copolymers showed a sharp absorption peak appeared at around 290 nm is attributed to a MLCT transition from chromium atom to * orbital of pyridine group. Furthermore, Au-functional copolymers showed a completely new absorption band at around 320 nm which can be associated again with a LMCT transition since gold is electron deficient and more willing to accept electrons from the ligand. Pyrolysis mass spectrometry analysis showed that poly2vinylpyridine blocks for each copolymers were affected similarly but polyisoprene block was not affected much from the coordination of metal compared to poly(methyl methacrylate) block in copolymers. For (PI-b-P2VP), Au3+ coordination to copolymer resulted in the higher thermal stability compared to Cr coordination. For (PMMA-b-P2VP), different from Cr, Au3+ coordination to P2VP nitrogen atom was extensive and PMMA based products changed drastically due to the coordination of electron deficient Au3+ to PMMA carbonyl group.
Kulkarni, Raghav Shrikant. "Characterization of carbon fibers: coefficient of thermal expansion and microstructure." Texas A&M University, 2004. http://hdl.handle.net/1969.1/3073.
Jadhav, Amol D. "Processing, characterization, and properties of some novel thermal barrier coatings." Columbus, Ohio : Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1183851697.
Patel, Niranjan M. "Multicomponent network and linear polymer systems : thermal and morphological characterization /." Diss., This resource online, 1990. http://scholar.lib.vt.edu/theses/available/etd-07122007-103930/.
Galyean, Christina Pilkey. "Investigation and characterization of a thermal infrared all-sky imager." Thesis, Georgia Institute of Technology, 1991. http://hdl.handle.net/1853/28004.
Wu, Zhaohui, and 吳朝暉. "Modeling and characterization of high-temperature silicon-based thermal sensors." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2005. http://hub.hku.hk/bib/B31057652.
Granestrand, Jonas. "Material characterization for studying thermal deactivation of automotive SCR catalysts." Thesis, KTH, Skolan för kemivetenskap (CHE), 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-147524.
Baliga, Radhika. "Thermal and electrical characterization of a micro-hotplate for calorimetry." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/33101.
Includes bibliographical references (p. 104-105).
This thesis characterizes a micro-hotplate designed at Draper Laboratory. This hotplate will be integrated into a calorimetry system that measures the heat released or absorbed by a reaction. An analytical thermal model is developed to quantify the heat transfer mechanisms between the hotplate and the environment. The analytical model is verified through experimental measurements conducted with the device operating in both ambient conditions and vacuum. In ambient conditions, the heat transfer is dominated by air conduction as predicted by the model. Air conduction can be reduced by operating the device in a medium with a lower thermal conductivity. The relatively short timescale over which the hotplate comes to thermal equilibrium with the environment limits the types of reactions that can be measured with the device. The performance of the hotplate can be improved by operating it in vacuum, by constructing it from a material with a lower emissivity, or by decreasing its surface area. The noise spectral density of the hotplate's resistive temperature sensor is characterized. The hotplate's ability to resolve temperature is limited by the flicker noise in the sensor.
by Radhika Baliga.
M.Eng.
Hauf, Dagmar E. (Dagmar Elisabeth). "Two-parameter characterization of crack-tip fields during thermal transients." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/36473.
Carnicero, Dominguez Bernardo Antonio. "Characterization of Pyranometer Thermal Offset and Correction of Historiacal Data." Thesis, Virginia Tech, 2001. http://hdl.handle.net/10919/33785.
Master of Science
Kelly, Shawn Michael. "Characterization and Thermal Modeling of Laser Formed Ti-6Al-4V." Thesis, Virginia Tech, 2002. http://hdl.handle.net/10919/33104.
A thermal model has been developed to assist in the prediction and interpretation of the as-processed microstructure. The model is used to explain that the microstructural evolution of the layer bands and gradient microstructure in layer n is due to the deposition of layer n+2. The difference in the two analyses of microstructural evolution based on microstructural observations and thermal model results are due to differences in the parameter sets used to build and model the deposit.
Master of Science
Zhao, Qi. "Characterization and Thermal Decomposition Behavior of Carbon Nanotubes and Nanocomposites." University of Cincinnati / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1378113311.
Gupta, Tripti Thapa. "Characterization and Optimization of Non-thermal Plasma for Biofilm Sterilization." University of Toledo / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=toledo152547566313079.