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Dissertations / Theses on the topic 'Crystalline mixtures'
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1
Sarkar, Sudipta Kumar. "Phase transition in Binary Liquid Crystalline Mixtures." Thesis, University of North Bengal, 2017. http://hdl.handle.net/123456789/2674.
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2
Pramanik, Anamika. "Investigations on the physical properties of some liquid crystalline compounds and multi-component mixtures." Thesis, University of North Bengal, 2015. http://hdl.handle.net/123456789/1876.
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3
Pribyla, Karen J. "Thermochemical Study of Crystalline Solutes Dissolved in Ternary Hydrogen-Bonding Solvent Mixtures." Thesis, University of North Texas, 2001. https://digital.library.unt.edu/ark:/67531/metadc2783/.
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The purpose of this dissertation is to investigate the thermochemical properties of nonelectrolyte solutes dissolved in ternary solvent mixtures, and to develop mathematical expressions for predicting and describing behavior in the solvent mixtures. Forty-five ternary solvent systems were studied containing an ether (Methyl tert-butyl ether, Dibutyl ether, or 1,4-Dioxane), an alcohol (1-Propanol, 2-Propanol, 1-Butanol, 2-Butanol, or 2-Methyl-1-propanol), and an alkane (Cyclohexane, Heptane, or 2,2,4-Trimethylpentane) cosolvents. The Combined NIBS (Nearly Ideal Binary Solvent)/Redlich-Kister equation was used to assess the experimental data. The average percent deviation between predicted and observed values was less than ± 2 per cent error, documenting that this model provides a fairly accurate description of the observed solubility behavior. In addition, Mobile Order theory, the Kretschmer-Wiebe model, and the Mecke-Kempter model were extended to ternary solvent mixtures containing an alcohol (or an alkoxyalcohol) and alkane cosolvents. Expressions derived from Mobile Order theory predicted the experimental mole fraction solubility of anthracene in ternary alcohol + alkane + alkane mixtures to within ± 5.8%, in ternary alcohol + alcohol + alkane mixtures to within ± 4.0%, and in ternary alcohol + alcohol + alcohol mixtures to within ± 3.6%. In comparison, expressions derived from the Kretschmer-Wiebe model and the Mecke-Kempter model predicted the anthracene solubility in ternary alcohol + alkane + alkane mixtures to within ± 8.2% and ± 8.8%, respectively. The Kretschmer-Wiebe model and the Mecke-Kempter model could not be extended easily to systems containing two or more alcohol cosolvents.
4
Flood, Joseph. "Solution and liquid crystalline properties of sodium lauroyl methyl isethionate/water mixtures." Thesis, University of Manchester, 2015. https://www.research.manchester.ac.uk/portal/en/theses/solution-and-liquid-crystalline-properties-of-sodium-lauroyl-methyl-isethionatewater-mixtures(d9f043f2-3ca6-4a13-b3f0-d5d5eae83bfc).html.
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The project contributes to the general theme of complex chemical systems and strengthens ties with Innospec, a multi-national chemical company. Sodium lauroyl methyl isethionate (SLMI. Trade name “Iselux”) is a newly developed surfactant with attractive product properties for personal care applications. Little is known about the fundamental surface and solution properties of SLMI, and it is not currently possible to use information on available surfactants to predict phase behaviour. We characterise the solution and liquid crystalline phase behaviour of the SLMI/water system using a combination of optical microscopy, X-ray scattering and differential scanning calorimetry techniques. SLMI is synthesised using a batch process that leads to variable component concentrations. Preliminary studies conducted by Innospec indicate that the presence of particular process components has a significant influence on SLMI formulation rheological properties. We investigate the effects of synthesis-derived components on the rheological properties of the SLMI/sodium {(3-(dodecanoylamino)propyl)(dimethyl)ammonio)}acetate/water system using rheology and light scattering (static and dynamic) techniques. SLMI is often formulated into personal care products on mixing aqueous formulation components. Micelle growth occurs via a mechanistic process that is not understood and the equilibrium viscosity is attained at a time after mixing that ranges from seconds to weeks. Developing an improved understanding of the micelle growth mechanism is of both academic and industrial value. We utilise static light scattering and nuclear magnetic resonance techniques to probe a range of samples in the viscoelastic region of the SLMI/(carboxymethyl)hexadecyldimethyl ammonium hydroxide/water system. Experimental findings improve our current understanding of micelle growth process and provide a platform for future research on non-equilibrium mixing kinetics. In the final section we investigate salt-induced cloud point and precipitation phenomena in the SLMI/salt/water system. The cloud point is commonly observed in surfactant and protein systems by increasing the solution temperature above a critical value, resulting in phase separation of solute-rich and solute-depleted layers. Cloud point induced phase separation may also be prompted by addition of salt. The mechanistic process driving electrolyte-induced cloud point phenomena is not understood. We use a combination of turbidimetry measurements and lightscattering (static and dynamic) techniques to measure cloud point curves andcharacterise micellar behaviour prior to clouding.
5
Sánchez, González Sandra. "The swelling pressure of bentonite and sand mixtures." Thesis, KTH, Skolan för kemivetenskap (CHE), 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-158511.
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The compacted bentonites are used as buffer and backfill materials for engineering barriers for high-level nuclear waste repositories located underground. For this purpose, it is very important to evaluate the swelling characteristics of this clay. The swelling capacity is one of the most important properties of the bentonite clay. The swelling behaviour is due two mechanisms, the crystalline swelling and the osmotic swelling. These mechanisms produce an increase in the distance between the layers of montmorillonite which is one component of bentonite. The result of the swelling capacity is the swelling pressure. It has been studied in several investigations. The results of experimental tests have been collected and compared in this thesis, considering only the Na-dominant bentonite and sand and distilled water as test solution. The experimental tests show that there is only an unique relation between different bentonites in the Na-dominant bentonite and sand mixture swollen depending on its final dry density. Also, the relation between the swelling pressure and the clay void ratio shows the mechanism of the swelling pressure. On the other hand, a mechanistic model is used to predict the swelling pressure of fully saturated bentonite and sand mixture in distilled water. Firstly, it has been compared with the results of experimental tests and it should be pointed out that the model gives good predictions. In addition, the model has been used to make sensitivity analysis with different parameters of bentonite. The most important conclusions in this section show that the swelling pressure mainly depends on the distance among particles. Also, the sensitivity analyses indicate which parameters should be fitted more carefully for future studies to validate this model with different bentonites.
6
Merchan, Alvarez Lina Paola. "Alkane fluids confined and compressed by two smooth gold crystalline surfaces: pure liquids and mixtures." Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/47551.
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With the use of grand canonical molecular dynamics, we studied the slow ompression(0.01m/s) of very thin liquid films made of equimolar mixtures of short and long alkane chains (hexane and hexadecane), and branched and unbranched alkanes (phytane and hexadecane). Besides comparing how these mixtures behave under constant speed compression, we will compare their properties with the behavior and structure of
the pure systems undergoing the same type of slow compression. To understand the arrangement of the molecules inside the confinement, we present segmental and molecular density profiles, average length and orientation of the molecules inside well layered gaps. To observe the effects of the compression on the fluids, we present the number of confined molecules, the inlayer orientation, the solvation force and the inlayer diffusion coefficient, versus the thickness of the gap. We
observe that pure hexadecane, although liquid at this temperature, starts presenting strong solid-like behavior when it is compressed to thicknesses under 3nm, while pure hexane and pure phytane continue to behave liquid-like except at 1.3nm when they show some weak solid-like features. When hexadecane is mixed with the short straight hexane, it remains liquid down to 2.8nm at which point this mixture behaves solid-like with an enhanced alignment of the long molecules not seen in its pure form; but when hexadecane is mixed with the branched phytane the system does not present the solid-like features seen when hexadecane is compressed pure.
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Ozturk, Hale Bahar. "Mechanical And Thermal Properties Of Thermotropic Liquid Crystalline Copolyester (tlcp) And Its Mixtures With Poly(ethyleneterephthalate) And Denture Base Poly(methyl Methacrylate)." Master's thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/12605205/index.pdf.
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In this study, the thermal and mechanical properties of poly(ethylenetheraphthalate) (PET)-thermotropic liquid crystal polyester (TLCP), mixtures and poly(methyl methacrylate) (PMMA)-TLCP mixtures were studied. The curing of PMMA-TLCP mixtures was done by heat, gamma radiation and microwave. The amount of TLCP in mixtures was % 0.5, 2 and 5 TLCP by weight.
TLCP was synthesized by melt-acidolysis system, and PET-TLCP mixtures were prepared by using lab scale batch mixer. PMMA samples were prepared according to denture manufacturer&rsquos procedure. The characterization of polymer samples and mixtures were carried by FT-IR, NMR, DSC, DMA, tensile, impact, three point bending tests and light microscopy. The mixing of TLCP with PMMA yielded heterogeneous dispersions. This was observed from light micrographs. The mechanical and rheological properties of all polymers were not positively affected by inclusion of TLCP. It is also worthwhile to note that weakening of PET-TLCP mixtures were due to the thermal degradation as the thermal age of the mixtures is much higher.
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Leal, Ronan. "Epitaxial growth of silicon by PECVD from SiF4/H2/Ar gas mixtures for photovoltaics." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLX038.
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Cette thèse de doctorat évalue le potentiel de la croissance épitaxiale à basse température (200-300°C) par dépôt chimique en phase vapeur assisté par plasma à partir de SiF4/H2/Ar pour la formation de l’émetteur dans des cellules solaires de type nPERT. La première partie concerne l’identification et l’optimisation des conditions de dépôt pour réaliser des couches épitaxiées faiblement contraintes avec une interface epi/wafer de bonne qualité. La perte d’épitaxie a également été étudiée et nous avons mis en évidence que la formation de macles au cours de la croissance était responsable de la dégradation de la cristallinité. Ensuite, l’étude des mécanismes de croissance a été menée et l’analyse des phases initiales de croissance a permis d’identifier un mode de croissance de type Volmer-Weber.Les conditions de dépôt ont ensuite été transférées à un réacteur PECVD semi-industriel de 6 pouces. Les problèmes d’homogénéité et de vitesse de croissance ont été abordés par le design d’une nouvelle « shower head » grâce aux simulations d’écoulement du gaz. Des couches épitaxiées dopées bore avec un dopage de type p de 4.1019 cm-3 et une efficacité de dopage jusqu’à 70% ont ainsi été fabriquées à seulement 300°C. La vitesse de croissance dans ces conditions atteint 1.1 Å/s, i.e. 15 fois plus rapide que les premiers résultats obtenus. Enfin, la passivation des couches épitaxiées a été étudiée et un temps de vie de 160 μs a été obtenu sur des couches intrinsèques de 200 nm d’épaisseur passivées avec 10 nm d’oxyde d’aluminiumThis doctoral work aimed to assess the potential of low-temperature (200-300°C) epitaxy by plasma-enhanced chemical vapor deposition (PECVD) using SiF4/H2/Ar gas mixtures for the emitter formation in nPERT solar cells. The first part of this PhD thesis concerned the identification and the optimization of the process conditions to perform lowly strained intrinsic epi-layers with a smooth epi/wafer interface. We also investigated the causes of epitaxy breakdown and found out that a twinning-induced mechanism was responsible. Subsequently we focused on the growth mechanisms by studying the initial stages of growth and a Volmer-Weber growth mode has been highlighted. Finally, the process conditions for intrinsic epitaxy were transferred from a researchPECVD reactor to a 6 inch semi-industrial one. Inhomogeneity and growth rate issues have been tackled by fluid dynamics simulations resulting in the design of a new shower head. Boron-doped epi-layers grown at 300°C with an as-deposited hole concentration of 4.1019 cm-3 and a doping efficiency up to 70 % have been achieved keeping a low mosaicity and a low variation of the lattice parameter. The growth rate in these conditions reached 1.1 Å/s, i.e 15 times higher than what obtained at the beginning of this PhD for boron-doped epi-layers. Finally, the passivation of epitaxial layers has been investigated and lifetimes up to 160 μs for a 200 nm thick intrinsic layer passivated with
9
Камінський, Андрій Тарасович. "Ремонтні суміші з підвищеними експлуатаційними властивостями на основі лужного портландцементу." Diss., Національний університет "Львівська політехніка", 2021. https://ena.lpnu.ua/handle/ntb/56764.
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Pratibha, R. "Investigation on liquid crystalline mixtures." Thesis, 1988. http://hdl.handle.net/2009/2940.
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11
Chou, Yu-Chiang, and 周予強. "Synthesis and Study of Blue Phase Liquid Crystalline Mixtures Consisting of H-Bonded Bent-Core Diads." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/22898214472535945594.
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碩士國立交通大學
影像與生醫光電研究所
100
We synthesized a series of pyridine-based molecules and carboxylic acid molecules. The chemical structures of these compounds were characterized by H1-NMR and EA. They consisted of hydrogen bonding supramolecular diad mixtures. The liquid crystalline phases and mesomorphic behavior of all compounds were identified from the results of POM and Electro-optical measurement. Pyridyl molecules connected to a simple carboxylic acid molecule by a hydrogen bond have a nematic phase. The F functional group in carboxylic acid-based molecules affects their supramolecular liquid crystal temperature range. As the carboxylic acid molecules have chiral structure, the nematic phase switches to the chiral nematic phase. Next, we mixed pyridine-based molecules with carboxylic acid molecules with chiral structures and F functional groups in different molar percentage blends. In the case of excess carboxylic acid molecules, the carboxylic acid molecules will form a rod-like structure with another via a hydrogen bond. This series of C9IIIPy-A2F * and C7IIIPy-A2F * have blue phase (BPI /II). The series of C9IIIPy-A2F * have blue phase when carboxylic acid molecules are 60 mol% to 80 mol%. The blue phase temperature range is about 8℃. The series of C7IIIPy-A2F * also have blue phase when carboxylic acid molecules are 60 mol% to 70 mol%. The blue phase temperature range is about 7℃.
12
楊李涵. "Synthesis and Study of Blue Phase Liquid Crystalline Mixtures Consisting of Rod-Like and H-Bonded Bent-Core Dimers." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/69585897539158074469.
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13
Wei-ChihCheng and 鄭偉志. "Study on the selective routes of liquid crystalline organizations and azimuthal orientation of Poly(3-hexylthiophene) backbones in hypo-eutectic mixtures." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/13366178527879309820.
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碩士國立成功大學
材料科學及工程學系碩博士班
101
The delocalization of π-electron has been acknowledged as a basic feature for charge transport within thin film of conjugated molecules. For the intermolecular charge transportation through π-π stacking, the spread of ordered and amorphous domains within thin film is critical. However, for most studied electro-optic conjugated polymers, the assembly and crystal growth mechanisms within thin film remains unclear. The limited control on molecular packing, domain morphology and distribution unavoidably results in the defects able to traps the electrons, significantly lowering the performance of organic thin film. It is needed to explore new understanding on low dimensional polymer physics for enhancing and tailoring molecular organization. Via homogeneous mixing with hexamethylbenzene (HMB), binary eutectic systems of poly(3-hexylthiophene) (P3HT) has been achieved. Based on the variation of melting points with mixing ratio, the eutectic temperature and phase diagram was disclosed. During cooling from molten state, the continuous crystalline network of small organic molecules developed first and subsequently initiated epitaxial crystallization of conjugated polymers. The routes of liquid crystalline (LC) organization of P3HT below eutectic temperature were studied as a consequence of dissolution in mixing constituent HMB. Regarding the successive molecular organization process within studied binary mixtures, the encountered degree of supercooling were found influential to the organization orientation of conjugated backbone relative to substrate. While 45 degrees of supercooling is created, face-on organization is dominant and featured with layer stacking of organized thiophene stems alternatively with loosely-aggregated regions by a nanometer scale of stacking periodicity. Differently, under only few degrees of undercooling below the eutectic temperature, edge-on organization preferably progressed, which results in the anisotropic platelets extending along the chain direction. Regarding these prompt epitaxial LC organizations of conjugated polythiophene on HMB crystals, the association of bead-like or worm-like fringe micelles in molten state emerges as the elucidative background for both structural and morphological features. Further annealing treatment is able to cause the transformation of prior face-on liquid crystalline phase to the edge-on crystalline packing. With the incorporation of graphene nanocrystals within this binary system, only edge-on organization is able to develop. Nevertheless, on the crystalline surface of dichlorobenzene (DCB), molecular organization only adopts face-on orientation. In summary, these binary systems unveil the substrate and mixing effect on introducing new routes of molecular organization with selective backbone orientation relative to substrate.
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"MECHANICAL AND THERMAL PROPERTIES OF THERMOTROPIC LIQUID CRYSTALLINE COPOLYESTER (TLCP) AND ITS MIXTURES WITH POLY(ETHYLENETEREPHTHALATE) AND DENTURE BASE POLY(METHYL METHACRYLATE)." Master's thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/12605205/index.pdf.
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Liao, Chun-Yen, and 廖俊彥. "Synthesis and Study of Hydrogen-Bonded Bent Core Liquid Crystalline Mixtures Containing C60 Surface-Modified with Single and Double Benzoic Acid Surfactants." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/09027417812510703974.
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碩士國立交通大學
材料科學與工程學系所
102
In this study we prepared novel composites materials from the hydrogen-bonded bent-core liquid crystal (LC) host and different mole ratios (0–90 mol%) of the surface-modified fullerenes(C60). The chemical structures of these compounds were characterized by 1H-NMR, 13C-NMR, IR spectra, MS as well as elemental analysis, and the liquid crystalline phases and mesomorphic behavior of all the compounds were identified from the results of DSC, POM, electro-optical measurement and XRD. The mesomorphic properties of the composites, including their mesophasic types and ranges, values of Ps, and saturated electric field were adjustable by varying the doping concentrations of fullerenes. By increasing the concentration of fullerenes, the polarity of the SmCP phase in the composite varied sequentially from anti-ferroelectricity to ferroelectricity. Futhermore, adding a little amount of surface-modified fullerenes make the mixtures possesses the best Ps value and saturated electric field.
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Wang, Shiu-fan, and 王秀帆. "Study of Hydrogen Bonding Effects on Bent-core and Rod-like Liquid Crystalline Mixture Containing Amide Functional Group." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/75462512767146170153.
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