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Theses/Dissertations

Chemical engineering

Retrospective Theses and Dissertations

Chemistry

Articles 1 - 14 of 14

Full-Text Articles in Engineering

Synthesis And Characterization Of Stimuli Responsive Block Copolymers, Self-Assembly Behavior And Applications , Michael Duane Determan Jan 2006

Synthesis And Characterization Of Stimuli Responsive Block Copolymers, Self-Assembly Behavior And Applications , Michael Duane Determan

Retrospective Theses and Dissertations

Water-soluble stimuli responsive block copolymers are a rapidly emerging class of materials with great potential in biomedical and technological applications. In this work a novel class of pentablock copolymers are synthesized via atom transfer radical polymerization techniques and their stimuli-responsive self-assembly properties are characterized. Aqueous solutions of these materials are observed to form micelles and hydrogels in response to changes in both temperature and pH. Cryogenic transmission electron microscopy (cryo-TEM) and small angle neutron and X-ray scattering (SANS and SAXS) techniques are used to investigate the nanoscale structures formed by these pentablock copolymers in solution. The gel structure and mechanical ...


Synthesis And Characterization Of Nanostructured Aluminas , Weihua Deng Jan 2005

Synthesis And Characterization Of Nanostructured Aluminas , Weihua Deng

Retrospective Theses and Dissertations

In the work, mesoporous aluminas were produced by nonionic supramolecular templating and characterized to determine the stability of their physical structure during extended calcination at elevated temperatures. The effect of synthesis temperature on the physical structure of these materials and the resulting thermal evolution from synthesized aluminum hydroxide to transitional alumina was studied using thermogravimetric analysis. A high resolution multiple quantum magic angle spinning NMR spectroscopy method was used to determine quantitatively the evolution of the aluminum coordination during the thermal processing. The mesoporous alumina exhibited high stability upon prolonged heating, which is essential for their future applications in catalytic ...


Interdiffusion Phenomena At Partially Miscible Polymer Interfaces , Erin Lynne Jablonski Jan 2002

Interdiffusion Phenomena At Partially Miscible Polymer Interfaces , Erin Lynne Jablonski

Retrospective Theses and Dissertations

This research is focused on understanding the effect of miscibility on interdiffusion phenomena in bilayers of polystyrene (PS) and the statistically random copolymer, poly (styrene-r-4-bromostyrene) (PBS). Miscibility in such systems can be quantified by N*chi, where N* is an effective degree of polymerization and chi the Flory-Huggins interaction parameter. In the PS/PBS system, miscibility decreases as N *chi increases. The extent of interdiffusion at a bilayer interface is ultimately determined by the miscibility of the system. A description of the effect of miscibility on interdiffusion phenomena, interfacial width, phase behavior, and fracture energy and a relationship between these ...


Investigation Of The Peroxovanadate Sol-Gel Process And Characterization Of The Gels , Craig Joseph Fontenot Jan 2001

Investigation Of The Peroxovanadate Sol-Gel Process And Characterization Of The Gels , Craig Joseph Fontenot

Retrospective Theses and Dissertations

Vanadium oxide gels derived from aqueous solution of V2O 5 and H2O2 have been investigated using in situ 51V NMR and laser Raman spectroscopic techniques. On the basis of this characterization, a pathway for peroxovanadate decomposition has been proposed, including the presence of two peroxovanadate dieters. New Raman bands and assignments for these species are reported. Experimental 51V NMR evidence suggested the VO2+ species was directly involved in the formation of the gel. The vanadia xerogels were studied using 51V and 17O MAS NMR, 17 O 3QMAS NMR, TGA, DSC, XRD, SEM and laser Raman spectroscopy. Based primarily on the ...


Metal Cluster Hydrodesulfurization Catalysts Based On Ternary Molybdenum Sulfides , Robert Kirk Thompson Jan 1999

Metal Cluster Hydrodesulfurization Catalysts Based On Ternary Molybdenum Sulfides , Robert Kirk Thompson

Retrospective Theses and Dissertations

Catalysts based on metal sulfide cluster compounds such as Chevrel phases (MxMo6S8) have been shown to possess high activity and selectivity for hydroprocessing reactions. Previous methods of preparing crystalline Chevrel phases have involved high temperature, solid-state synthetic routes which produce low surface area materials (0.1--1.0m2/gm). In our recent research, lower temperature syntheses via solution precursors have been explored as routes to these materials. The discovery of a new class of compounds, M2x/n n+(Mo6S8)Sx (n = 1--3) has resulted. These new reduced ternary molybdenum sulfides have been shown to have both high activity and selectivity in ...


Triphase Catalysis: Mass Transfer And Kinetic Studies , Holger Jürgen Glatzer Jan 1999

Triphase Catalysis: Mass Transfer And Kinetic Studies , Holger Jürgen Glatzer

Retrospective Theses and Dissertations

The importance of phase transfer catalysis (PTC) in the production of high value chemicals has grown immensely over the past few years. PTC may be a suitable method to synthesize a product whenever each reactant is miscible in a different phase. By addition of a PT catalyst, which functions as a ferrying agent between the phases, significant rate enhancements can be achieved;The PT catalyst (e.g. a quaternary ammonium salt) is usually used in soluble form. Alternatively, it can be bound to a solid support. The latter technique is called triphase catalysis (TPC). It has operational advantages over conventional ...


Process Analysis And Yield Enhancement For The Production Of Beta-Hydroxy-Beta-Methyl-Butyrate (Hmb) , George Barac Jan 1998

Process Analysis And Yield Enhancement For The Production Of Beta-Hydroxy-Beta-Methyl-Butyrate (Hmb) , George Barac

Retrospective Theses and Dissertations

The purpose of this work was to develop an optimum chemical process philosophy for the manufacture of [beta]-hydroxy-[beta]-methyl-butyrate (HMB), using existing synthesis and purification schemes as a starting point. Process analysis and improvement were performed as a means to increase overall efficiency and to address environmental concerns;A protein breakdown suppresser, HMB is used as a nutritional supplement or as a feed additive. The current process which employs reaction of diacetone alcohol and sodium hypochlorite, separation of the product by batch extraction, and crystallization, displays very low efficiency and has to deal with waste disposal issues. Currently ...


A Kinetic Study On The Adsorption And Reaction Of Hydrogen Over Silica-Supported Ruthenium And Silver-Ruthenium Catalysts During The Hydrogenation Of Carbon Monoxide , David Paul Vanderwiel Jan 1998

A Kinetic Study On The Adsorption And Reaction Of Hydrogen Over Silica-Supported Ruthenium And Silver-Ruthenium Catalysts During The Hydrogenation Of Carbon Monoxide , David Paul Vanderwiel

Retrospective Theses and Dissertations

An interesting phenomenon in bimetallic catalysis is the synergistic effect between two metals during CO hydrogenation. For example, addition of Ag to Ru catalysts results in a dramatic decrease in the specific activity of the catalyst, even though Ag alone does not appreciably adsorb H2 or CO. A series of Ag-Ru/SiO2 catalysts containing 0, 3, 10, 20 and 30 atomic percent silver was used to examine the kinetics of the adsorption and reaction of H2 on Ru during CO hydrogenation. CO was saturatively adsorbed at room temperature on each catalyst, followed by subsequent reaction with ambient H2 at 460 ...


Sonochemical Reactions: Mass Transfer And Kinetic Studies Of A Solid-Liquid System , Leigh Christine Hagenson Jan 1997

Sonochemical Reactions: Mass Transfer And Kinetic Studies Of A Solid-Liquid System , Leigh Christine Hagenson

Retrospective Theses and Dissertations

Ultrasound has been shown to have desirable effects on both homogeneous and heterogeneous reactions, such as increasing the conversion, enhancing the selectivity, and improving the yield. Enhancements due to ultrasound may be attributed to chemical effects or mechanical effects, or to both simultaneously. The chemical effects of ultrasound are attributed to the implosion of microbubbles, generating free-radicals with a great propensity for reaction. Mechanical effects are caused by shock waves formed during symmetric cavitation, or by microjets formed when the bubble implodes asymmetrically. Research emphasis in this area attempts to discern the mechanisms behind ultrasound's mechanical effects by selecting ...


Surface Properites Of Coal And Their Effects On The Selective Oil Agglomeration Process , Xiaoping Qiu Jan 1992

Surface Properites Of Coal And Their Effects On The Selective Oil Agglomeration Process , Xiaoping Qiu

Retrospective Theses and Dissertations

The heat of immersion of coal in water and various organic liquids provides a useful means for characterizing the surface of the material, while the oil-water-coal, three-phase contact angle provides a characterization of the coal surface as well as the interactions among oil, water, and coal. Such characterizations may provide an indication of how well the coal will respond to cleaning by the froth flotation and oil agglomeration methods which are controlled by the surface properties of the material;The heat of immersion of two types of coal in water and in several different organic liquids was determined with a ...


Reduced Molybdenum Oxidation States In Hydrodesulfurization Catalysis By Chevrel Phases , Mark Eugene Ekman Jan 1991

Reduced Molybdenum Oxidation States In Hydrodesulfurization Catalysis By Chevrel Phases , Mark Eugene Ekman

Retrospective Theses and Dissertations

The catalytic activities of reduced (relative to Mo[superscript]4+) molybdenum sulfides, known as Chevrel phases, have been evaluated for thiophene and benzothiophene hydrodesulfurization (HDS) and 1-butene hydrogenation (HYD). These materials have been found to have HDS activities comparable to, or greater than, model unpromoted and cobalt-promoted MoS[subscript]2 catalysts; in contrast, Chevrel phases exhibit low activities for 1-butene HYD;X-ray powder diffraction and laser Raman spectroscopy analysis of the used (10 hours of thiophene reaction) catalysts indicated that the bulk structures were stable under reaction conditions. XPS analysis demonstrated that reduced molybdenum oxidation states were present at the ...


A Mathematical Model Of The Chemistry Of The Dump Leaching Of Chalcopyrite, Knona Constance Liddell Jan 1979

A Mathematical Model Of The Chemistry Of The Dump Leaching Of Chalcopyrite, Knona Constance Liddell

Retrospective Theses and Dissertations

No abstract provided.


A Plastic Material Derived Through The Acetylation Of A Lignocellulosic Residue From Hemp Hurds, Bayard King Olmsted Jan 1948

A Plastic Material Derived Through The Acetylation Of A Lignocellulosic Residue From Hemp Hurds, Bayard King Olmsted

Retrospective Theses and Dissertations

No abstract provided.


The Use Of Polymers From Furfural In The Fabrication Of Molded Products , Richard Wedge Bruins Jan 1934

The Use Of Polymers From Furfural In The Fabrication Of Molded Products , Richard Wedge Bruins

Retrospective Theses and Dissertations

No abstract provided.