Biodiesel is produced from vegetable oils through transesterification. Triglyceride mixtures extracted from oilseed feedstocks are upgraded by reaction with an alcohol in the presence of a catalyst to produce fatty acid esters. This reaction produces a mixture of esters, glycerin, alcohol, and catalyst. Separation of the fatty acid esters (biodiesel) and glycerin can be accomplished through liquid-liquid extraction by water addition. Designing liquid-liquid extraction with water as the solvent requires ternary liquid-liquid equilibrium data for mixtures of water, glycerin, and fatty acid esters. Ternary mixture LLE data have been experimentally measured for several of these systems. Those measured include mixtures with the methyl esters of lauric, myristic, palmitic, stearic, and oleic acids. Data were collected at atmospheric pressure and 60°C. These ternary systems have been correlated using the NRTL equation. These data and correlation parameters can be used to improve separations efficiency in trans-esterified biodiesel fuels.

Rocketry employs cryogenic refrigeration to increase the density of propellants, such as oxygen, and stores the propellant as a liquid. In addition to propellant liquefaction, cryogenic refrigeration can also conserve propellant and provide propellant subcooling and densification. Previous studies analyzed vapor conditioning of a cryogenic propellant, which occurred by either a heat exchanger positioned in the vapor or by using the vapor as the working fluid in a refrigeration cycle. This study analyzes the refrigeration effects of a heat exchanger located beneath the vapor-liquid interface of liquid oxygen. This study predicts the mass liquefaction rate and heat transfer coefficient for liquid oxygen using two different models, a Kinetic Theory Model and a Cold Plate Model, and compares both models to experimental data. The Kinetic Theory Model overestimated the liquefaction rate and heat transfer coefficient by five to six orders of magnitude, while the Cold Plate Model underestimated the liquefaction rate and heat transfer coefficient by one to two orders of magnitude. This study also suggested a model to predict the densification rate of liquid oxygen, while the system is maintained at constant pressure. The densification rate model is based on transient heat conduction analysis and provides reasonable results when compared to experimental data.

With exploding growth of information exchanges between people, display has become indispensable in our daily lives. After decades of intensive research and development in materials and devices, and massive investment in manufacturing technologies, liquid crystal display (LCD) has overcome various obstacles and achieved the performance we need, such as wide viewing angle, high contrast ratio, and high resolution, etc. These excellent performances make LCD prevailed in every perspective. Recently, with the demands of energy conservation, a greener LCD with lower power consumption is desired. In order to achieve this goal, new energy-effective driving methods, such as field sequential color display, have been proposed. However, in order to suppress color breakup the LC response time should be faster than 1 ms. To overcome this challenge, various fast-response liquid crystal modes, such as thin cell gap, low viscosity materials, overdrive and undershoot voltages, polymer stabilization, and ferroelectric liquid crystal, are under active investigations. Among these approaches, blue phase liquid crystal (BPLC) shows a greater potential with less fabrication limitations. In this dissertation, the feasibility of polymer-stabilized blue phase liquid crystal for display applications is explored starting from the building blocks of the material system, polymer-stabilization processes, test cell preparations, electro-optical (EO) properties, to suggested approaches for further improvements. iv Because of the nature of blue phase liquid crystals, delicate balance among system components is critically important. Besides the properties of each composition, the preparation process also dictates the EO performance of the self-assembled nano-structured BPLC composite. After the preparation of test cells, EO properties for display applications are investigated and results described. Approaches for further improvements of the EO properties are also suggested in the final part of this dissertation.

Dual frequency liquid crystal (DFLC) exhibits a positive dielectric anisotropy at low frequencies and negative dielectric anisotropy at high frequencies. The frequency where dielectric anisotropy is zero is called crossover frequency. DFLC can achieve fast rise time and fast decay time with the assistance of applied voltage. However, one drawback of DFLC is that it has dielectric heating effect when driven at a high frequency. Thus, the first part of this dissertation is to develop low crossover frequency DFLC materials. The dielectric relaxation and physical properties of some single- and double-ester compounds were investigated. Experimental results indicate that the double-ester compound exhibits a ~ 3 X lower dielectric relaxation frequencies and larger dielectric anisotropy than the single ester, but its viscosity is also higher. More generally, ten groups of dual frequency liquid crystals were compared in terms of dielectric relaxation frequency and dielectric anisotropy. The dielectric relaxation theory was discussed at last. To realize fast response time, high birefringence and low viscosity LC are required. From these two aspects, firstly four new high birefringence laterally difluoro phenyl tolane liquid crystals with a negative dielectric anisotropy were studied. These materials are used to enhance the birefringence of DFLC. They have a fairly small heat fusion enthalpy (~3000 cal/mol) which improves their solubility in a host. We dope 10 wt% of each compound into a commercial negative mixture N1 and measured their birefringence, viscoelastic constant and figure of merit. Birefringence varies very little among homologues while viscoelastic constant increases as alkyl chain length increases. Secondly, we studied the effects of six diluters for lowering the viscosity while stabilizing the vertical alignment (VA) of the laterally difluoro terphenyl host mixture at elevated temperatures. The pros and cons of each diluter are analyzed. These lateral difluoro terphenyls exhibit a high birefringence, fairly low viscosity, and modest dielectric anisotropy, but their molecular alignment in a VA cell is gradually deteriorated at elevated temperatures as their concentration increases. As a result, the device contrast ratio is decreased noticeably due to the light leakage through the crossed polarizers. Finally, liquid crystal doped with metallic nanoparticles, such as Pd, Ag, or Ag-Pd, which are protected with ligand molecules, such as nematic liquid crystal were studied. The metal nanoparticles doped LC exhibit a frequency modulation (FM) electro-optical (EO) response in the millisecond to submillisecond range together with the ordinary root-mean-square voltage response.

<p> The spectra of depolarized light scattered from Isotropic and anisotropic liquids were Investigated In order to obtain information on both the reorientational and collisional motions of the liquid molecules. </p> <p> The liquid spectra taken at 22°C on a Coderg spectrometer (1 cm. ^-1 slits) were decomposed into relaxational and collisional components using least squares fitting techniques. Integrated Intensities and depolarization ratios in the zero em -1 (1 cm ^-1= 3 x 10^10 hz.) frequency sjift region as well as in the less than 5 cm^-1 region are reported. </p> <p> The Isotropic liquid spectra from 5 cm ^-1 consisted of a narrow Lorentz and a broader coliisional component which was exponential at shifts > 10 cm^-1. The anisotropic spectra also consisted of relaxational and collisional components; however, the Integrated Intensity of the relaxational and the collisional components Increased by a factor of 20 and 10 respectively from the isotropic liquids. </p> <p> A simple model based on frame distortion Induced anisotropy was constructed to predict the relative Intensity ratios of the collisional component for both Isotropic and anisotropic liquids. </p> <p> The relaxation time of the Lorentz component was Interpreted for both isotropic and anisotropic liquids as being the average time between collisions. It was, found to vary as μ^((3/4)/p), where μ is the reduced mass of two colliding molecules and p the liquid density.</p> <p> The line width parameter 1/vo for all the collisional components was interpreted as being a measure of the duration of a collision and was found to vary as μ^1/2 independent of the density P. </p> / Thesis / Master of Science (MSc)

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