Dissertations / Theses on the topic 'Mesophase'
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1
Takekawa, T. "Chemistry of mesophase formation." Thesis, University of Newcastle Upon Tyne, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.379323.
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Kasuh, Takahiro. "Oxidation of mesophase pitch." Thesis, University of Newcastle Upon Tyne, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.346433.
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Burgoyne, John. "The mesophase structure of surfactants." Thesis, University of Central Lancashire, 1994. http://clok.uclan.ac.uk/20171/.
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The binary surfactant system nona (ethylene glycol) mono-( 11 -oxa- 14,18.22,26-tetramethylheptacosylether) in heavy water has been investigated using deuterium nuclear magnetic resonance, optical polarising microscopy and small angle scattering techniques. The phase diagram has been established and the phases encountered exist for the most part from 24 to 60% surfactant by weight. Above and below these concentrations exist isotropic and lamellar phases respectively. The phase diagram features three main phases, a hexagonal phase of circular rods, a lamellar phase and an intermediate phase. The length of the alkyl chain is shown to be the most important factor in stabilising intermediate phases in preference to the bicontinuous cubic phases usually encountered between hexagonal and lamellar phases in shorter chain homologues. A nematic phase has also been observed in the water penetration scan. The intermediate phase is extensive, ranging from 32 to 60% surfactant by weight and is about 5°C wide. It has a body centred tetragonal mesh structure, comprised of layers of surfactant with regularly spaced holes which are also correlated between the layers, the hole of one layer overlapping the intersection of the layer below. As the concentration is decreased, from 60% to 30% (surfactant by weight) this correlation relaxes. The actual form of the aggregate appears to be elliptical rods (ellipticity - 1.7) joined four by four to form the basis of the mesh structure. A simplified version of the model based on circular rods joined by cube junction regions has been used to quantitatively investigate this phase. The results from this crude model produce results very close to those anticipated and produces results to within 2% of those generated using a more sophisticated model. This system is unusual in that the nature of the interaction between aggregates appears to be dominated by a single interaction - 'headgroup overlap force. This arises from the repulsive pressure experienced by the headgroups penetrating from the aggregate interface and also between headgroups on the same aggregate.
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Wang, Lei. "Pattern formation in mesophase carbon fibers." Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=24045.
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The principles governing pattern formation in discotic nematic liquid crystalline fibers subjected to uniaxial extensional flows are established. Computational and analytical methods are used in conjunction with bifurcational techniques to simulate the structural characteristics of the orientational patterns that arise by stretching discotic nematic liquid crystalline materials. The analytical and numerical results are in excellent agreement with actual cross-sectional fiber textures obtained by melt spinning carbonaceous mesophases. This work reproduces the main structural features of the oscillatory zig-zag pattern commonly observed in mesophase carbon fibers, and identifies the process conditions that lead to this peculiar fiber texture. In addition, the temperature driven texture transitions and the emergence of random pattern also observed during the industrial manufacturing of mesophase carbon fibers are captured by the simulations and thoroughly explained using classical viscoelastic theories of liquid crystalline materials.
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Gregory, Lee Garry. "Structural investigations of lyotropic mesophase systems." Thesis, University of Huddersfield, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.327166.
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Shen, Dong. "Syntheses and mesophase characterizations of novel bent core molecules." [S.l. : s.n.], 2000. http://deposit.ddb.de/cgi-bin/dokserv?idn=961481889.
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Sansom, James Anthony. "The stabilisation process in mesophase pitch based carbon materials." Thesis, University of Leeds, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.515788.
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Horne, Timothy James. "NMR studies of flexible molecules in the nematic mesophase." Thesis, University of Southampton, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.303057.
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Cockett, Sean. "Synthesis and characterisation of silicone based mesophase forming materials." Thesis, Sheffield Hallam University, 1992. http://shura.shu.ac.uk/19486/.
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The aim of this project was to synthesise and characterise a range of novel cyclic and linear mesogenic siloxanes. A synthetic strategy based upon the synthesis of linear side-chain siloxanes was adopted. End-functionalised linear siloxane precursors were synthesised via ring opening polymerisation reactions. The coupling of mesogen and siloxane was carried out via a hydrosilylation reaction in solution. Products were isolated by phase-separation and gel permeation chromatography (GPC).Thermotropic behaviour was studied using optical microscopy, differential scanning calorimetry (DSC) and, in some cases, X-ray diffraction. An overview of the lyotropic behaviour of the amphiphiles was obtained using the penetration technique. The principles explaining the thermotropic behaviour of conventional amphiphiles appear to be generally applicable to these amphiphilic siloxanes. Thus, the amphiphiles aggregate in the neat state. The shape of these aggregates is determined primarily by packing constraints. The amphiphiles undergo a step-wise melting process, with the non-polar and the oolar moieties dominating the low and the high temperature transitions, respectively. The behaviour of different molecules can be explained by reference to the nature of the respective polar and non-polar moieties. The aqueous lyotropic phase behaviour of NaD4 appears to be similar to that of sodium myristate. Thus, the effect of attaching amphiphiles to a siloxane chain is to extend the non-polar chain of the amphiphile by approximately three methylene units. The linear amphiphiles did not form any aqueous lyotropic mesophases. This was explained in terms of the reversed micelle structure, which was dictated by packing constraints. There was no mesophase behaviour in non-polar solvents due to the strong forces of attraction between polar groups. The model considerations applied to non-amphiphilic side-chain polymers appear to applicable to the non-amphiphilic cyclics studied here. Thus, suitable flexible spacer groups will decouple the motions of mesogenic side-chains from those of an oligomeric cyclic backbone such that the mesogens may align. However, more efficient spacers are required to decouple the motions and steric effects of the cyclic backbone than is the case with the equivalent linear backbones.
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Delport, Matthys Reinhard. "Production and sintering of mesophase pitch from anthralene oil." Diss., University of Pretoria, 2015. http://hdl.handle.net/2263/56132.
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When certain oils and polymers are heated under an inert atmosphere, a high viscosity liquid forms. Examples include crude oil, coal tar, and PVC. Upon further heating, this liquid becomes a progressively harder solid called pitch. Pitch that contains crystalline areas is called mesophase pitch. Mesophase pitch is required for the production of graphite. The purpose of the research was to investigate whether anthracene oil can be used for the production of mesophase pitch for sintering purposes. Sintering involves heating a powder under pressure to produce a solid. Anthracene oil is a low-value by-product of coke production from coal. Despite its low market value, it has unique properties. It consists primarily of polycyclic aromatic hydrocarbons and it is free of primary quinoline insoluble material. Polycyclic aromatic hydrocarbons are the precursors for mesophase pitch formation, while quinoline insoluble material hinders mesophase growth. These attributes make it a good potential starting material for the production of mesophase pitch, which may be used for sintering and carbon fibre production.
In the search for a mesophase pitch that can be sintered, a variety of pitches were produced from anthracene oil. This was done by varying the heat treatment time and temperature. The pitches produced were characterised to determine their glass transition temperature, melting temperature, carbon yield and optical microstructure. This was done to determine their sintering potential. A high mesophase content, high softening temperature and high carbonisation yield were considered essential for effective sintering.
Pitches with a high mesophase content were produced. Longer heat treatment led to higher carbon yields, higher glass transition temperatures, higher softening temperatures and higher mesophase content.Dissertation (MEng)--University of Pretoria, 2015.
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Chemical Engineering
MEng
Unrestricted
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Asakawa, Harutoshi. "Formation of Giant Single Crystals of Isotactic Polypropylene via Mesophase." 京都大学 (Kyoto University), 2012. http://hdl.handle.net/2433/157611.
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Yan, Jun 1974. "Theory and simulation of texture formation in mesophase carbon fibers." Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=34001.
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Carbonaceous mesophases are discotic nematic liquid crystals that are spun into high performance carbon fibers using the melt spinning process. The spinning process produces a wide range of fiber textures and cross-sectional shapes. The circular planar polar (PP), circular planar radial (PR), ribbon planar radial (RPR), and ribbon planar line (RPL) textures are the most frequently observed in industrial fiber making. This thesis presents, solves, and validates models of mesophase fiber texture formation based on the classical Landau-de Gennes theory of liquid crystals, adapted here to carbonaceous mesophases. The model captures the microstructure and the formation of the four (PP, PR, RPR, RPL) textures. In cylindrical fibers, the computed PP and PR textures phase diagram, given in terms of temperature and fiber radius, establishes the processing conditions and geometric factors that lead to the selection of these textures. The influence of elastic anisotropy to the textures' formation and structure is thoroughly characterized. The multi-stage formation process of the PP texture is reproduced, including defect nucleation, defect migration, and overall texture geometry. The mechanisms that control the PP texture geometry are characterized using analytical methods. The role of elasticity and flow-induced orientation on texture selection mechanism in ribbon-shaped mesophase fibers are characterized using an anisotropic viscoelastic model. The model is able to predict the formation of the commonly observed line defect in the RPL texture, and the fine structure of the line is reproduced and explained in terms of classical liquid crystal defect physics. The results of this thesis provide new knowledge on how to optimize and control mesophase fiber textures.
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Towlson, David Stephen. "Mesophase behaviour in a system of self-assembling discotic amphiphiles." Thesis, University of Leeds, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.238552.
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Galanopoulos, Emmanouil. "Synthesis and characterisation of highly oriented mesophase pitch-based composites." Thesis, University of Leeds, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.418767.
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Gupta, Gaurav. "Computational material science of carboncarbon : composites based on carbonaceous mesophase matrices." Thesis, McGill University, 2005. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=83865.
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Carbon/Carbon composites belong to the generic class of fiber reinforced composites and are widely used because of their high strength as well as chemical and thermal stability. Like other fiber reinforced composites they consist of the fibers which act as reinforcements and matrix which acts as a glue that binds the fibers. c/c composites from pitch based precursor are unique since the matrix in this case is a liquid crystal or mesophase. This makes them remarkable in the sense that unlike c/c composites from other precursors such as PAN, rayon etc. they have extremely high degree of molecular orientation and exhibit texture. An important characteristic of their textures is the presence of topological defects. It is hence of great interest to understand and elucidate the principles that govern the formation of textures so as to optimize their properties. In this work we present a computational study of structure formation in carbon-carbon composites that describes the emergence of topological defects due to the distortions in the oriented matrix created by the presence of fiber matrix interaction. Dynamical and structural features of texture formation were characterized using gradient elasticity and defect physics.
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Sharma, Dinesh 1972. "Theory and simulation of texture selection mechanisms in mesophase carbon fibers." Thesis, McGill University, 2003. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=79239.
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Carbon fiber precursors are spun from carbonaceous mesophases using standard melt spinning techniques. These melt spun carbon fibers exhibit a multitude of cross sectional fiber textures. The two widely reported textures in literature are planar radial (PR) and planar polar (PP). This thesis uses a mesoscopic model, based on the classical Landau de-Gennes theory of liquid crystals and adapted here to carbonaceous mesophases, to study the steady state and transient phenomena involved in the mesophase carbon fiber texture formation. The model is successfully able to capture the microstructure and the formation of the PR and PP textures. A phase diagram for classical PR and PP textures has been constructed cylindrical carbon fibers in terms of temperature and fiber radius, thus estabilishing the processing conditions and geometric factors that lead to the selection of these textures. The multi-path formation process of the planar polar texture through defect splitting, direct planar polar formation, and defect annihilation has been thoroughly characterized. A detailed analysis of defect core structure for defects of strengths s = +1 and s = +1/2 has be undertaken. The effect of various parameters namely temperature, elastic anisotropy, and fiber radii on the defect core structures of commonly observed fiber textures has been studied. The model is well suited for studying the defect core textures which are in the nano range and could be applied to the new emerging field of nano fibers. The results of this thesis provide us with knowledge for optimization and control of mesophase carbon fiber texture, and lay the ground work for the study of nano scale phenomena in nano fibers.
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Jonathan, Tietz I. "Thienothiophene-Based Liquid Crystals: Synthesis and Comparative Evaluation of Mesophase Properties." Kent State University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=kent1343074444.
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Jafari-Fini, Ali. "Design, synthesis and assessment of highly functionalised phthalocyanines." Thesis, University of East Anglia, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.267316.
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Guo, Hong. "Structure property relations in a range of mesophase pitch-based carbon fibres." Thesis, University of Leeds, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.578963.
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Qiu, Hong. "The mesophase behavior of the monoacylglycerol/water systems : application in drug delivery /." The Ohio State University, 1998. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487953567770767.
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Jahr, Michael. "Neue sternförmige Mesogene: Strukturbildung und Chromophore." Doctoral thesis, Universitätsbibliothek Chemnitz, 2011. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-68605.
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Gegenstand der vorliegenden Arbeit ist die Herstellung und Charakterisierung neuer sternförmiger Mesogene. Bei den aufgeführten Sternverbindungen, handelt es sich um Oligobenzoate, bestehend aus aromatischen Hydroxy- oder Aminocarbonsäuren, die durch Kupplungsreaktionen mit Dicylohexycarbodiimid, in einer konvergenten Synthesestrategie verknüpft wurden. Das besondere Augenmerk der Arbeit richtete sich auf die Charakterisierung der von den neuen Substanzen gebildeten Mesophasen, die mit Hilfe von Polarisationsmikrokopie, dynamischer Differenzialkalorimetrie und Röntgenstreuung erfolgte.
Zur Aufklärung spezieller dreidimensionaler Strukturen wurden als zusätzliche Methoden die Rasterkraftmikroskopie angewandt und der Zirkulardichroismus untersucht.
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Hope-Ross, Kyle Andrew. "Synthesis and characterization of C₂ symmetric liquid crystalline materials." Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/4088.
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A number of compounds were synthesized with the ultimate goal being the synthesis of
C₂ symmetric molecules which displayed thermotropic liquid crystalline behaviour. The
compounds prepared were 4-alkoxy benzophenones, 3,4-bis-alkoxy benzophenones, 4-
alkoxy dibenzylidene acetones, 3,4-bis-alkoxy dibenzylidene acetones and 4-alkoxy-
1, 9-diphenyl-nona-l,3,6,8-tetraen-5-ones. The length of the linear alkoxy side chain was
varied from C₆H₁₃ to C₁₂H₂₅.
All compounds were characterized by FTIR, ¹H, and ¹³C NMR spectroscopy. Mesophase
behaviour of the synthesized compounds was investigated using differential scanning
calorimetry and polarizing optical microscopy.
It was determined that both the alkoxy side chain length, as well as the number of alkoxy
side chains have an effect on the ability of this class of C₂ symmetric compounds to selfassemble
into liquid crystalline phases. In addition, the overall core size and extent of
conjugation also affected mesophase formation. The mono-alkoxy benzophenones and
dibenzylidene acetones were non-mesogenic, while all four of the mono-alkoxy 1,9-
diphenyl-nona-l,3,6,8-tetraen-5-ones (alkoxy side chain of lengths C₆H₁₃, C₈H₁₇, C₁₀H₂₁
and C₁₂H₂₅)self-assembled into nematic liquid crystalline phases. Increasing the number
of alkoxy side chains from one to two per aromatic moiety helped induce liquid
crystalline formation: the corresponding bis-C₆H₁₃ benzophenone and bis-C ₆H₁₃, bis
C₈H₁₇, and bis-C₁₀H₂₁ dibenzylidene acetones were mesogenic, displaying smectic A
(benzophenone) and nematic (dibenzylidene acetone) mesophases respectively.
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Cheng, Xiaohong. "Synthesis and mesophase characterization of non-conventional polyphilic block molecules with perfluorinated chains." [S.l. : s.n.], 2001. http://deposit.ddb.de/cgi-bin/dokserv?idn=963613111.
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Owen, Aaron. "ASSISTED DEVELOPMENT OF MESOPHASE PITCH WITH DISPERSED GRAPHENE AND ITS RESULTING CARBON FIBERS." UKnowledge, 2018. https://uknowledge.uky.edu/me_etds/126.
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The efficacy of dispersed reduced graphene oxide (rGO) as a nucleation site for the growth of mesophase in an isotropic pitch was investigated and quantified in this study. Concentrations of rGO were systematically tested in an isotropic petroleum and coal-tar pitch during thermal treatments and compared to pitch without rGO. The mesophase content of each thermally treated pitch was quantified by polarized light point counting. Further characterization of softening temperature and insolubles were quantified. Additionally, the pitches with and without rGO were melt spun, graphitized, and tensile tested to determine the effects of rGO on graphitized fiber mechanical properties and fiber morphology.
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Tatsumi, Mio. "Studies on Novel Anisotropic Polymer Composites Synthesized from Mesomorphic Colloidal Suspensions of Cellulose Nanocrystals." Kyoto University, 2015. http://hdl.handle.net/2433/202725.
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Kyoto University (京都大学)0048
新制・課程博士
博士(農学)
甲第19320号
農博第2141号
新制||農||1036(附属図書館)
学位論文||H28||N4948(農学部図書室)
32322
京都大学大学院農学研究科森林科学専攻
(主査)教授 西尾 嘉之, 教授 木村 恒久, 教授 髙野 俊幸
学位規則第4条第1項該当
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Golmohammadi, Mojdeh. "Theory and simulation of thermodynamics and flow induced order in carbonaceous mesophase binary mixtures." Thesis, McGill University, 2011. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=97066.
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Carbonaceous mesophases (CMs) obtained from petroleum pitches and naphthalene precursors are mixtures of discotic nematic liquid crystals (DNLCs) employed to produce high performance carbon fibers (CFs). Natural pitches are usually polydisperse while synthetic ones are currently produced with very narrow molecular weight distributions.To design and control the final structure and mechanical properties of CFs three key parameters have to be considered: (i) characteristics of the raw material including the molecular weight, molecular interactions and the concentration of each species, (ii) the processing temperature and (iii) the extensional flow applied in the fiber spinning process. Experimental synthesis, processing, and characterization of CM materials are expensive due to the required equipment and operating conditions. Hence the computational modeling methodology adopted in this thesis is a cost effective tool for these novel materials. This thesis uses theory, mathematical modeling and computational simulations to characterize the effect of three above mentioned major factors on the orientational and molecular ordering behavior of a mixture of two monodisperse DNLCs, of relevance to the manufacturing of high performance CFs.The statistical mechanics Maier-Saupe model which effectively predicts the molecular ordering behavior of pure discotic systems is first extended to binary mixtures and then further extended to incorporate uniaxial extensional flow effects. Thermodynamic and thermo-rheological phase diagrams of binary lyotropic/thermotropic CM mixtures are predicted by this theory and partially validated by previous theoretical results and experimental observations. The generic thermo-rheological phase diagram which specifies the orientational structure of each component and their degree of molecular orientation under extensional spinning flow is obtained. X-ray diffraction intensity and orientational specific heat are also simulated in the present thesis, verified by available data and used as characterization tools for the orientation behavior of CM mixtures. In summary the thesis provides a new practical route for targeted structure-property relations for high performance CFs, through the chemistry and composition of the precursors, thus extending the traditional routes based on modifications of operating conditions and process geometry. At the fundamental level, the thesis presents the first dynamical model for DNLC mixtures. The models and results of the thesis are also applicable to rod-like systems under biaxial extensional flow, and DNLC under magnetic and electric fields.Les mésophases de carbone (CMs) obtenu à partir de précurseurs de bitume et de naphtalène sont des mélanges de cristaux liquides nématiques discotiques (DNLCs) utilisés pour produire les fibres de carbone (CF) à hautes performances. Le bitume naturel est généralement polydispersé tandis que celui qui est synthétique est présentement produit avec des distributions étroites du poids moléculaires.Afin de concevoir et de contrôler la structure finale et les propriétés mécaniques des CFs, trois paramètres importants doivent être pris en compte: (i) les caractéristiques de la matière première dont le poids moléculaire et les interactions moléculaires (ii) la température du processus et (iii) l'écoulement extensionnel appliqué dans le processus de filage de la fibre. La synthèse expérimentale, le traitement et la caractérisation des matériaux CM sont chers en raison de l'équipement et des conditions d'opérations requises. C'est pourquoi la méthode de modélisation numérique adoptée dans cette thèse est un outil rentable pour l'étude ces nouveaux matériaux.Cette thèse s'appuie sur la théorie, la modélisation mathématique et des simulations numériques pour caractériser l'effet de chacun des trois facteurs principaux, mentionnés ci-dessus, sur le comportement et l'orientation moléculaires d'un mélange de deux DNLCs monodispersés, relevant pour la fabrication de CFs à hautes performances.Le modèle de mécanique statistique de Maier-Saupe qui prédit efficacement l'arrangement moléculaire des systèmes discotiques purs est d'abord étendu aux mélanges binaires puis étendu afin d'incorporer les effets d'écoulement extensionnel uniaxiaux. Les diagrammes de phases de thermodynamique et de thermo-rhéologie des mélanges binaires de CM lyotrope / thermotrope prédis par cette théorie et partialement validée par les résultats théoriques et les observations expérimentales précédentes. Le diagramme de phase de thermo-rhéologie générique qui spécifie la structure d'orientation de chaque composant et leur degré d'orientation moléculaire sous extension est obtenu. L'intensité de la diffraction à rayon X ainsi que la chaleur spécifique orientée sont également simulées dans la présente thèse, vérifié par les données disponibles et utilisés comme outils de caractérisation du comportement d'orientation des mélanges de CM. En résumé, la thèse propose une nouvelle démarche pratique pour les relations ciblées propriété-structure pour les CFs à haute performance, grâce à la chimie et la composition des précurseurs, ainsi étendant les démarches traditionnelles basées sur des modifications de conditions d'exploitation et de la géométrie des processus. Au niveau fondamental, la thèse présente le premier modèle dynamique pour les mélanges DNLC. Les modèles et les résultats de cette thèse sont aussi applicables aux systèmes allongés sous écoulements extensionnel biaxial et sous l'effet de champs électriques et magnétiques.
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Crane, Andrew J. "Coarse-grained simulations of the self-assembly and mesophase behaviour of polyphilic liquid crystals." Thesis, Imperial College London, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.526371.
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Mc, Sherry Ian. "The synthesis and mesophase behaviour of some chiral heterocyclic mesogens containing the thiophene nucleus." Thesis, University of Nottingham, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.308311.
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Cheng, Anchi. "Kinetics and mechanism of lipid mesophase structural changes induced by pressure and X-radiation damage /." The Ohio State University, 1995. http://rave.ohiolink.edu/etdc/view?acc_num=osu148786179681917.
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Yang, Bin. "Surfactant and polyelectrolytes templated mesostructured inorganic materials." Thesis, University of Bath, 2010. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.528113.
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In this work we have explored the possibility of using surfactant/polyelectrolyte complexes as templates to synthesize inorganic mesostructured materials mainly with a film morphology. Inorganic species deposit in those regions of the films which are filled with a polymer hydrogel, surrounding the arrays of ordered surfactant micelles. This method produced thick robust films where the inorganic regions are reinforced and functionalized by the polymer, thus these materials are expected to have potential applications in separation, absorption, catalysis and chemical sensing. Initial work involved mixing silicate precursors directly into CTAB/PEI solutions to form highly ordered 2D hexagonal silica films at the air/water interface. Time resolved synchrotron SAXS allowed investigation of processes occurring in solution during the reaction, from which a film growth mechanism was proposed. Films had good thermal properties and after post-synthesis TMOS vapour treatment, retained structure upon template removal. Silica gel monoliths with various mesostructures were also rapidly fabricated in one minute with surfactant/LPEI complexes. Cat-ionic surfactant mixtures with polymers were also employed to template silica films with different cubic mesostructures at the air/water interface. The mesophases of the interfacial films were enriched due to more complicated interactions between the polymers and two surfactants. Polymer molecular weight, total composite concentration, chemical nature of the polymer as well as the cationic-anionic surfactant molar ratio was used to systematically control the silica film mesophase. Robust titania films were also prepared with cat-anionic surfactant mixtures and polymers at the air/water interface. Although the film mesostructure was lost after calcination, the in-situ and dry free-standing films display ordered cubic mesostructures and the films are stable to calcination after post-synthesis treatment. Ordered lamellar iron oxide films templated by SDS/LPEI complexes were also prepared at the air/water interface.
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Clark, John Graham. "The modification of Waxy Oil for preparing a potential feedstock for needle coke production." Thesis, University of Pretoria, 2011. http://hdl.handle.net/2263/26510.
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This research study determines the potential to increase substantially the anisotropy of a coke from an aliphatic Waxy Oil produced by Sasol Synfuels at Secunda, South Africa. Experimental modifications included filtration, distillation and thermal treatment, followed by distillation with the aim of producing a carbonised product similar to needle coke. The substantial concentration of an iron oxide catalyst (up to 2%) in Waxy Oil is increased by an order of magnitude upon carbonisation and calcination due to low coke yield and reactivity factors. The catalyst also promotes oxidative polymerisation of the residue, acts as a barrier to mesophase formation and promotes multi-phase graphitisation. Filtration of Waxy Oil using a 0.5 ìm sintered metal filter reduces the ash content to 0.006% and increases the anisotropy of the carbonised product to 54% flow domains compared with 22% for the carbonised product of virgin Waxy Oil. Thermal treatment followed by distillation of Waxy Oil reduces the effect of organic reactivity promoters (mainly multi-alkylated aliphatics/aromatics and oxygenates), while increasing the concentration of thermally stable (C18 to C30) normal alkanes to 85% compared with 38% in the filtered Waxy Oil. Compared with the filtered Waxy Oil, thermally stabilised Waxy Oil reduces the amount of the pre-carbonisation residue (from 98.7 to 43.0%), while “static” carbonisation thereof increases the green coke yield (from 19.8 to 36.3%) and increases the anisotropicity (from 54 to 100% flow domains). The carbonisation mechanism of filtered and thermally treated Waxy Oil involves initial cracking of high molecular weight normal alkanes (C18 to C30), thus concentrating the molecular weight of normal alkanes (C18 to C22). This is followed by a slow cyclisation step involving both self condensation and cyclo addition reactions to form two- to six-ring cyclo-alkanes or hydro-aromatics. The hydro-aromatics are dehydrogenated rapidly to form methyl and di-methyl three- to six-ring substituted aromatics. Further thermal degradation dealkylates these molecules to form stable four- to six-ring “pre-mesogens”. The mesospheres are nucleated from the isotropic matrix and grow to more than 0.050 mm in diameter, with a volume of 2.61 x 10-3 mm3. Subsequent coalescence of the mesospheres produces mesospheres with diameters of over 0.200 mm and volumes of 41.82 x 10-3 mm3. The resultant microstructure of the solid carbon is composed of flow domains more than 400 ìm in length. Although needle cokes have historically been produced from aromatic residues, this research is the first to show that a coke with a similar microstructure can be produced from a totally aliphatic residue. The research thus provides potential for the development of a needle coke from a totally unique Waxy Oil residue with negligible sulphur (< 0.008%) and nitrogen (< 0.09%) contents. This is the first academic study of the chemistry of Waxy Oil.Thesis (PhD)--University of Pretoria, 2011.
Chemical Engineering
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Pjontek, Dominic. "Fluid Dynamic Studies in Support of an Industrial Ebullated Bed Hydroprocessor." Thesis, Université d'Ottawa / University of Ottawa, 2014. http://hdl.handle.net/10393/31345.
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Commercial ebullated bed hydroprocessors, such as the LC-Finer, are used for the production of synthetic crude oil by upgrading bitumen extracted from the Alberta oil sands. The objective of this thesis was to investigate the impact of an increased vacuum distillation tower bottoms feed fraction on the reactor fluid dynamics (e.g., bed and freeboard phase holdups, bubble characteristics and local fluidization behaviour). Industrial conditions were simulated in a high pressure gas-liquid-solid fluidization system based on dimensional and geometric similitude. Considering important geometric characteristics and matching dimensionless groups, base-case conditions resulted in an ebullated bed of nitrogen, 0.5 wt.% aqueous ethanol, and aluminum cylinders (average lengths and diameters of 7.5 and 3.2 mm, respectively) operating at 6.5 MPa and a gas-to-liquid superficial velocity ratio of 0.78. The proposed scale-down method resulted in high gas holdup conditions similar to industrial measurements. The use of the Sauter mean diameter to account for particle size and shape at the simulation conditions was investigated by comparing glass spheres with diameters of 4 and 1.5 mm to aluminum cylinders with equivalent volume-to-surface area ratios. Local bubble characteristics, including gas holdups, bubble rise velocities, and chord lengths, were then investigated under various operating conditions using a monofibre optical probe. Overall fluid dynamics were studied when increasing the liquid viscosity and varying the gas and liquid superficial velocities due to their relevance for industrial ebullated bed hydroprocessors. Freeboard and bed region gas holdup relations were studied and correlations were developed for gas and solid holdups at the simulation conditions based on the dimensionless groups. Mesophase generation in hydroprocessors due to undesired secondary reactions was also considered for an increased vacuum residue feed fraction. Adding a dispersed immiscible liquid phase which preferentially wetted the particles was therefore experimentally studied at non-simulating conditions using nitrogen, biodiesel, glycerol and various particles, where fluidization behaviour and phase holdups were considerably affected due to particle clustering. A study on the impacts of particle size, shape and material demonstrated the influences of fluid and particle properties, specifically the relative surface energies and viscous forces, on agglomeration due to interparticle liquid bridging.
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Garland, Andrew Douglas. "A study of the factors determining mesophase type range and occurrence in some novel phthalocyanines and naphthalocyanines." Thesis, University of East Anglia, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.267503.
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Yan, Han. "Electrospinning-Derived Carbon/Graphite Nanofiber Mats from a Polyimide-Mesophase Pitch Blend Precursor for Flexible Thermal Management Thin Films." University of Akron / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=akron1309678439.
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Fiester, Steven E. "Characterization of Optically Active Biopolymers." Kent State University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=kent1302187683.
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Biswas, Soma. "EFFECT OF LINKER CHEMISTRY AND TERMINAL SUBSTITUENTS ON THE LIQUID CRYSTALLINE PROPERTIES OF BIS(AZOBENZENE) MESOGENS." Thesis, The University of Arizona, 2008. http://hdl.handle.net/10150/193436.
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Azobenzene upon photochemical E/Z isomerization changes both its shape and size. The E-azobenzene moiety falls in the class of calamitic liquid crystalline mesogens, producing a wide variety of mesophases. Two series of linear bis(azobenzene) compounds, one with phenyl benzoate linkage and the other with benzyl benzoate linkage were synthesized. The termini of these molecules ranged from a dodecyloxy chain to hydrophobic amphiphilic dendrons up to first generation. We determined the effects of both the linkages and generation number on the mesogenic properties of these compounds. Our results show that the mesogenic behavior of these bis(azobenzene) compounds are highly dependent on the linkages between individual azobenzenes and that for the bis(azobenzene) compounds of the phenyl benzoate series, generation number had an effect on the liquid crystalline mesophase of the compounds
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Langry, Arthur. "Evaluation of IN SITU synthesis route of layered hydroxides in the presence of amphiphilic polymers in comparison with their corresponding physical mixtures." Thesis, Clermont-Ferrand 2, 2015. http://www.theses.fr/2015CLF22603/document.
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L’originalité du manuscrit de thèse est basée sur une preuve de concept selon laquelle il peut être possible de générer IN SITU des matériaux plaquettaires au sein même d’une matrice polymère à renforcer. Cette approche est basée sur une nouvelle voie de préparation de matériaux hybrides à base d’hydroxydes lamellaires. Cette méthode combine une voie de synthèse par polyol et la génération IN SITU de plaquettes inorganiques, en présence d’oligomères BOLA à caractère amphiphile. La voie polyol consiste en l’hydrolyse en milieu alcoolique d’un ou de plusieurs sels acétate métalliques comme précurseur, en vue de former les phases LSH et HDL suivantes, LSH-Zn, LDH-Zn2Al ;-LiAl2. Les BOLA possèdent des segments téléchéliques composés de chaînes hydrophobes terminées par deux groupes anioniques hydrophiles, l’ensemble est neutralisé par un cation ammonium. L'impact de la voie de synthèse IN SITU, les systèmes plaquettaires choisis ainsi que les contre-ions organiques à partir de la morphologie des phases hybrides obtenues, est étudié en comparaison aux mélanges physiques correspondants (EX SITU). Ce manuscrit présente une étude structurale des différents nanocomposites formés ; par le biais d’analyses DRX, complétées par du SAXS (ligne de lumière SWING à Soleil) et de l’imagerie MET. Des bilans matière sur les différentes synthèses IN SITU sont aussi réalisés pour déterminer les rendements de formation et taux de conversion des précurseurs en matériaux lamellaires. Concernant l’approche EX SITU ; les chaines polymère diffusent entre les plaquettes inorganiques, ceci principalement lié à une réaction d’échange entre les anions acétate des phases lamellaires et les fonctions carboxylates des chaines polymère, conservant l’intégrité des feuillets à par un processus topotactique. L’efficacité du processus d’intercalation a été trouvée décroissante suivant LDH-Zn2Al > LDH- LiAl2 >> LSH-Zn. Dans le cas du LSH-Zn, un ensemble stratifié à plusieurs échelles a été observé alliant charpente inorganique initiale intercalé acétate et une partie diffusée du BOLA, conduisant à une structuration dite biphasique. Contre intuitivement, dans le cas des HDL, la voie EX SITU, basée sur la réaction topotactique d'échange, et la voie IN SITU, basée sur la réaction de templating ont donné dans de nombreux cas des résultats similaires en terme d'états de dispersion, et ceci indépendamment du polymère ou du BOLA utilisé ainsi que de la composition des plaquettes. L’observation de plaquettes isolées LSH-Zn, n’a jamais été reportée dans la littérature, ce qui rend alors le processus de synthèse polyol/IN SITU intéressant pour l’obtention d’état de dispersion exfolié pour ce type de particules. La combinaison polyol/IN SITU permet la génération de plaquette LSH ou LDH de taille latérale comprise entre 10 à 200 nm. Cependant, les plaquettes générées se sont révélées poreuses, un inconvénient pour les propriétés de type barrière. Ce résultat ouvre toutefois des perspectives nouvelles en intégrant ces plaquettes 2D poreuses avec des particules de type 1D pour une approche en architecture « tectonique »Layered particle based nano-composites have recently been shown to impart stone impact resistance to automotive coatings by making use of polymer intercalated Layered Double Hydroxide (LDH) platelets in a variety of different film morphologies. However the LDH particles used were obtained via coprecipitation of the metal salts in the presence of small organic anions in order to render the Layered Hydroxide particles organophilic and to facilitate the intercalation of carboxylate group bearing matrix polymers. Thus anion exchange in the course of colloidal processing and during film formation leads to the release of ionic species which may deteriorate the coatings barrier function. In order to circumvent objectionable counter ions (involved in the synthesis and the coatings formulation), a novel preparation route for layered hydroxide based hybrid phases has been here investigated combining the polyol route with the IN SITU generation of inorganic platelets, in the presence of amphiphilic polymer as well as bola-amphiphiles. The polyol route consists in hydrolysis in an alcoholic medium containing acetate metal cation as precursor(s), to yield LDH (Zn2Al, LiAl2 cation composition) or LSH-Zn (Layered Single Hydroxide). Bola amphiphile descripts as being some hydrophobic polymer segment-telechelic-chains terminated by two anionic hydrophilic end groups, using of volatile ammonium cation as counter ion. The impact of both process conditions as well as the chosen system with regard to the metal hydroxide framework and the organic counter ions on the morphology of the obtained hybrid phases are presented, discussed and compared to corresponding physical mixture. For the EX SITU approach, the diffusion of large cumbersome polymers or amphiphilic bolas between the inorganic platelets was found to be efficient, mostly driven by an anion exchange reaction between interleaved acetate anions and carboxylate functions of the molecular backbones, and keeping intact the inner-sheet integrity through a topotactic process. The efficiency of the intercalation process was found decreasing to range as LDH-Zn2Al > LDH-LiAl2 >> LSH-Zn, more or less regardless of the guest organic species. Aggregation may happen and cannot be discarded especially when using LiAl2 type platelets and non-neutralized bola. In particular with LSH-Zn, a multi stratified assembly has been observed combining acetate pristine structure and partly bola diffused structure, leading to a biphasic structure, aggregated and intercalated. To the best of our knowledge, observation of LSH-Zn single platelets has never been reported, making of the combined process Polyol/IN SITU an interesting new route in reaching exfoliation. Indeed, it yields to the generation of platelets either LSH or LDH of lateral size ranging between 10 up to 200 nm. However, the platelets were found to be porous; it is considered as a drawback for barrier properties. It is our belief that such porosity may open new insights in “tectonic” architecture by intertwining 2D and 1D-type filler. Rather counter intuitively, EX SITU based on topotactic exchange reaction matches the IN SITU templating reaction in many cases as a function of the dispersion state regardless of the polymer or bolas as well as the platelets cation composition
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Garcés, Renata. "Phenomenological theory of chromatin architecture : Liquid-crystalline order induced by nucleosome polarity and chirality correlations." Thesis, Montpellier 2, 2013. http://www.theses.fr/2013MON20132/document.
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Le programme d'expression de gènes dans des cellules eucaryotes dépend fortement de l'état du porteur du génome. L'état physique de la fibre de chromatine est un élément clé de ce programme. Cependant, malgré l'effort considérable fourni pour élucider la structure et les principes physiques de l'organisation de la chromatine, ces principes restent flous. La théorie phénoménologique permet d'analyser l'organisation probable de la chromatine de point de vue thermodynamique. Dans cette thèse, nous étudions l'ordre liquide-cristallin qui résulte de l'équilibre entre le désordre thermique dans la chromatine et les interactions électrostatiques (et mécaniques) de ses constituants. En utilisant les résultats expérimentaux largement acceptés, nous identifions les propriétés robustes mésogènes des nucléosomes (nano-assemblages ADN-protéines) à une petite échelle, et nous montrons comment les corrélations de ces paramètres contrôlent l'ordre qui s'installe dans la chromatine à l'échelle plus grande. Le modèle est basé sur les corrélations des caractéristiques polaires et chirales des nucléosomes. La théorie phénoménologique permet de décrire les phases condensées dans des solutions aqueuses des nucléosomes avec l'ADN linker digéré par des enzymes, aussi bien dans des conditions physiologiques que dans une large gamme de concentration du sel monovalent. Nous utilisons l'hypothèse que pour les mêmes conditions physiologiques les mécanismes physiques qui agissent dans les solutions condensées et dans la fibre sont similaires. Cela nous permet par la suite d'effectuer l'analyse de symétrie, construire le modèle de l'énergie libre, et prédire les états liquide-cristallins hélicoïdaux de la fibre favorisés thermodynamiquement. En plus des modèles de « solénoïde » et de « l'hélice à deux départs » discutés dans la littérature, nous montrons la possibilité des arrangements nucléosomiques « à plusieurs départs » et la biaxialité possible de ces structures. L'effet de l'application d'un champ de force homogène à la fibre de chromatine dans des expériences biochimiques est également étudié. Nous montrons que le déroulement de l'état hélicoïdal est un processus multi-étapes, et nous présentons ses détails structuraux et thermodynamiquesGene expression program in eukaryotic cells is strongly dependent on physical state of the genome carrier. Physical state of the chromatin is a key element in this program. However, despite the efforts to elucidate the structure and the physical principles underlying the organization of chromatin, they remain largely unknown. Phenomenological theory helps to analyze the most probable chromatin organization. In the present work we study liquid-crystalline order in chromatin resulting from the balance of thermal disorder and electrostatic (and mechanical) interactions of its constituents. Using generally accepted experimental facts we identify robust mesogenic parameters of nucleosomes (DNA-protein nano assemblies) at the smaller scale and show how the correlations of these parameters control the ordering into a chromatin structure at the bigger scale. The model is based on correlation of polar and chiral characteristics of nucleosomes. Phenomenological theory allows us to describe the condensed phases in aqueous solutions of nucleosomes with digested linker DNA, both in physiological conditions and in a wide range of monovalent salt concentration. Using the hypothesis of similar physical mechanism acting in condensed solutions and in the fiber in the same physiological conditions, we perform detailed symmetry analysis, construct the free energy model and reveal the thermodynamically favorable helical liquid-crystalline states of the fiber. In addition to « solenoid » and « two-start-helix » models abundantly discussed previously, we show the possibility of multi-start helix arrangements of nucleosomes in the chromatin and possible biaxiality of the structures. The effects of homogeneous mechanical force field applied to the chromatin in biochemical experiments are also studied. We show that helical state unwinding is a multistep process and we give its structural and thermodynamical details
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Qazi, S. Junaid S. "Flow of Colloidal Mesophases." Doctoral thesis, Uppsala universitet, Materialfysik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-152872.
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This dissertation presents new work and results in the flow of complex fluids and experimental methodologies for their investigation. Plate-like colloidal particles of kaolinite and nickel hydroxide are studied. A study of lamellar fragments and their mixture with the nickel hydroxide particles is also presented. The lamellar fragments are self-assembled structures of surfactant molecules that approximate disks. Particles are seen to align with their large faces parallel to the flow direction under shear and elongational strains. Order parameters have been calculated to quantify the extent of preferential alignment and direction of orientation. The experimental data are supported by comparisons with finite-element fluid mechanics calculations that provide estimates of the flow patterns and the strain rates. Elongational strain rates in the range of 5 − 20 s−1 are required to induce a high degree of alignment with the various sizes of the particles whereas about two to three order of magnitude higher shear strain rates are required. The combination of both elongational and shear strain is an effective means to provide a uniform alignment. Comparison of the Peclet numbers calculated for both the shear and elongational flow are presented and this explains that alignment occurs when the energy per particle of the strain is larger than the thermal energy. Mixtures have shown complex behavior: significant changes in the structure are observed that are not seen to the same extent in samples at rest. X-ray diffraction and small-angle neutron scattering techniques are used to characterize the samples and determine the structure in flowing systems. Laboratory X-ray diffraction can be used to characterize dispersed samples. The combination of dynamic light scattering and X-ray diffraction was used to estimate the thickness of the stabilizing layers of the polymer on the colloidal particles. Scattering of synchrotron radiation and neutrons are powerful complementary techniques to provide information about flow and the potential to apply them to systems that are beyond the scope of simple simulations has been demonstrated.
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Brooks, Jason Travis. "Polymers in surfactant mesophases." Thesis, University of Cambridge, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.259541.
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Liu, Chia Hua, and 劉家樺. "Rheological Study of Mesophase Polydiethylsiloxane and Polydimethysiloxane." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/r3mxh2.
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碩士國立臺北科技大學
有機高分子研究所
98
poly(diethylsiloxane) (PDES) is a flexible main-chain isotropic polymer which has columnar mesophase depending on molecular weight. High molecular weight PDES has been shown to crystallize into two different modifications: α and β phase PDES. Preferably kinetic α phase is a monoclinic packing and the thermodynamically more stable β phase has formed tetragonal lattice. A third crystalline modification has been reported for low molecular weight PDES. This modification, designated γ PDES, was found to closely resemble the tetragonal β modification. This study is employed by a parallel plate rheometer to compare the viscosities of mesophase PDES and PDMS under the changes in temperature. An apparent increase in viscosity and dynamic viscoelastic properties were found when PDES was in the isotropic temperature range. It was attributed to the formation of viscoplastic body caused by pseudo crosslinking. In contrast, PDMS demonstrates common shear thinning behavior and its viscoelastic properties are unchanged. Moreover, PDES is performed by differential scanning calorimetry (DSC) and polarizing optical microscope (POM) and parallel plate rheometer (Physica MCR 301) to conform that mesophase temperature range is between 7℃and 17℃. The viscosity and dynamic viscoelastic properties decreased with the climbing percentage of shear strain due to the loosening of pesudo crosslinking networks. The phenomena of amorphous PDES and PDMS do not occur.
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Lu, Chun-huesh, and 盧俊學. "Preparation of refined pitch and its mesophase development." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/55115260922925200807.
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碩士大同大學
材料工程學系(所)
99
This study is divided into four parts the Preparation of refined pitch using solvent method, mesophase to remove edge-particles, Mixture of TI / TS (toluene insoluble / toluene soluble) effects for the mesophase generated and quinoline insoluble (QI) effects for the mesophase pattern generated. Preparation of refined pitch using solvent method in the QI removed use of the china steel chemical corporation Company’s coal tar pitch (Code BP). Solvent method added aromatic wash oil to dilute the pitch viscosity to increase pitch mobility, adding aliphatic solvent to QI easy mutual condensation. Through the standing precipitation and vacuum distillation of separation to obtain refined pitch (code BPT). Self-made bucket under normal pressure heat treatment 400 ℃ to generate Mesophase Pitch. Mesophase pattern observed using polarized light microscopy. Find the best parameters by adjusting the refined pitch process to reduce the mesophase edge-particles. The best parameters to increase the standing time to 24 hours from refined pitch (code BPTT). Toluene filtration separation BPTT, in a mixed soluble and insoluble part after heat treatment generated mesophase under compared different components of the generate rate and pattern of differences. The results showed that with more toluene insoluble (β resin) can be generated in a short period form more mesophase, and is conducive to the formation of fine fibrous structure.Furthermore, separation of coal tar pitch with quinoline insoluble part of the observation by SEM and XRD, added to its insoluble mixture of refined Pitch and heat treatment. Some of it with soluble part after heat treatment compared quinoline insoluble impact on the mesophase. Showed that quinoline insoluble particles may cause the edge-particles appear mesophase. But quinoline soluble heat treatment experiments were also found to have the edge particles. Show part of the quinoline soluble may also be caused by particles has arisen due to the edge-particles.
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JHANG, JHIH-HAO, and 張志豪. "Synthese and mesophase properties of hydroxyl functionalized benzimidazolium salts." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/53317652292046125727.
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Lin, Yan-kuang, and 林彥光. "Implementation of Taguchi Method to the process of mesophase." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/33549194964693974245.
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碩士元智大學
工業工程與管理學系
97
The aim of this thesis is to implement the Taguchi Method to design the experiment for analysis of correlative factor of the mesophase pitch process. According to the physical and chemical changes of the liquid carbonization methods, elemental Analysis, X-ray diffraction, FT-IR Analysis, weight loss, density, soft point and optic organization are considered as quality characteristics. The experimental factors and levels are designed, as follows: speed of the temperature raise（3℃/min,4℃/min,5℃/min）, temperature of the heat treatment（350℃、400℃、450℃）, time of the heat treatment（4hr、8hr、16hr）and atmosphere（pressurized ,fluid , vacuum）. A L9(34) design is used. The first stage of experiment shows that the best parameter combination of various quality characteristics contradicted with each other. After investigating the response of individual quality characteristics, No.9 experiment combination turns out to be the best condition. The responses of quantitative analysis（elemental Analysis, X-ray diffraction, weight loss, density, soft point）all between 3 sigma improved the reproducibility after 5 repetition experiments. In qualitative analysis, optic organization shows liquid carbonization progressed in mesophase stage. The result improves the reproducibility. In FT-IR Analysis, confirmation experiments No.2 has low aromatic functional group. Reexamined the quantitative analysis of confirmation experiments No.2 , it has lower elemental Analysis, X-ray diffraction, density, soft point and higher weight loss. The result reveals that confirmation experiments No.2’s liquid carbonization was insufficient. In conclusion, No.9 experiment combinations is the best parameter of mesophase pitch process in our study.
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Tran, Paul. "Oxidative stabilization of mesophase pitch permeabiltity (sic) measurements and kinetics /." 2007. http://etd.nd.edu/ETD-db/theses/available/etd-11302007-223603/.
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Thesis (Ph. D.)--University of Notre Dame, 2007.Thesis directed by William Strieder and Salma Saddawi for the Department of Chemical and Biomolecular Engineering. "December 2007." Includes bibliographical references (leaves 147-155).
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Lin, Bo-Fan, and 林勃汎. "Preparation of High-Compressive-Strength Carbon Foam Composite Using Mesophase." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/35764165277005272625.
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Liu, Chang. "Mesophase Pitch-based Carbon Fiber and Its Composites: Preparation and Characterization." 2010. http://trace.tennessee.edu/utk_gradthes/816.
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The objective of this study is to investigate the relationship among process, structure, and property of the UTSI pitch-based carbon fibers and optimize carbon fiber’s mechanical properties through the stabilization process. Various analysis techniques were employed throughout these investigations which include the Scanning Electron Microscope (SEM), optical microscope, Dia-stron system, MTS, and ImageJ.
Several fiber process techniques including fiber spinning, stabilization, and carbonization were explored to determine the effect of the thermal process on the fiber yield, fiber diameter, the sheath-core structure of stabilized fibers, the pac-man and hollow core structures of carbonized fibers, and the resulting mechanical properties of the carbon fibers. It was found that stabilization time and the temperature stepping had a great deal on influence on the resulting carbon fibers. Larger diameter fiber is easy to form sheath-core structure in the stabilization process. Pac-man structure was developed at 600°C during the carbonization. Both stabilization duration and the carbonization temperature control the resulting carbon fiber diameter and fiber structure defects such as the pac-man and hollow core defects. Multi-step stabilization can reduce the total stabilization duration and improve the mechanical properties of the resulting carbon fibers.
Fiber structure non-uniformities including fiber diameter distributions for a bundle fiber or along a single fiber, and pac-man angles were determined. Statistical analysis revealed the distribution of the carbon fiber cross-sectional areas and the result is compared against commercial available carbon fibers.
Carbon fiber sandwiched composites (CFSCs) were fabricated with UTSI carbon fiber and commercial PAN-based carbon fibers. Several configurations of sandwich structured composites were explored to test the flexural properties with varying sandwich thickness.
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Techi, Wong, and 翁得期. "Preparation of High Porosity carbons from Mesophase Pitch for Supercapacitor Electrodes." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/08555818768565279345.
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碩士國立成功大學
化學工程學系
88
Abstract Porous carbons with high porosities were prepared from mesophase pitch powder with chemical activation method by using KOH impregnation, which have specific surface area and specific pore volumes higher than 2800 m2/g and 1.6 cm3/g, respectively. But the carbonization method just can produce carbon with specific surface area and specific pore volumes as low as 8 m2/g and 0.01 cm3/g, respectively. Carbons with different physical structure were prepared from mesophase pitch powder by heat treatment and KOH etching at temperature up to 900℃. Though carbon that made by chemical activation have high porosities, but the crystal phase is amorphous. From the result of XRD and TGA data, it shows that mesophase pitch have two different impurity function groups between carbon layers or direct bonded to the aromatic ring. EDLC''s carbon electrodes with different surface were prepared by using chemical activation. The capacitance of single carbon electrode has maximum value 160 F/g in present study. EDLC has stable capacitance and Coulombic efficiency (about 100 %) over 200 cycles. Electrode surface area below 800 m2/g, the capacitance increases dramatically with the specific surface area of electrode. But when electrode surface area higher than 800 m2/g, the capacitance gradually increase with surface area of electrode. According precious paper and this study, the mesopore or large pore size had no significant effect in capacitance. Average pore size distribution probably have bigger surface for electrolyte flowing through, increase double layer capacitance.
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Wang, Guohua. "Molecular composition of needle coke feedstocks and mesophase development during carbonization." 2005. http://etda.libraries.psu.edu/theses/approved/WorldWideIndex/ETD-1154/index.html.
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Chen, Po-yun, and 陳柏勻. "Hexaazatrinaphthaline Polyether-Polymer-Lithium Ion Hybrid: Mesophase Stability and Potential Application." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/97382385169013678573.
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碩士國立中山大學
化學系研究所
104
In this thesis, we synthesized hexaazatrinaphthylene containing six triethylene glycol side chains (HATN-TEG) for application as potential electrolytes for lithium-ion. Our initial studies involved doping different weight percentage of polyethylene glycol having different molecular weight into HATN-TEG and investigate their influence on the mesophase behavior. Interestingly, stable mesophase can be obtained even at high concentration of PEG, showing the compatibility of the TEG-side chains and the impregnation of the PEG along the void of the columnar packing. Furthermore, the hydrophobic liquid crystal HAT-C10, which exhibits similar properties with HATN-TEG, was chosen to compare the phase segregation. It was envisaged that this compound having six polyether side-chain may show special ability to create ion-channels for the lithium-ion. Next, the potential application of HATN-TEG and with PEG were studied as potential electrolyte for lithium ion transport. Interestingly, doping further with lithium salt can also maintain the mesogenic properties. We mixed the different types of HATN-TEG and PEG matrices with lithium perchlorate, and measured the electrochemical impedance to determine their efficiency for lithium ion conductivities.