Chemical Engineering Commons^™

Integrating 3d Layered Manufacturing With Photonic Sintering, Precision Machining And Smart Coating Techniques For Rapid Casting Applications, Hemant Bohra

Dissertations

Developments in rapid casting technologies have led to a new era of inclusion of 3D printing. Three-Dimensional (3D) printing provides the flexibility and ease of reproducing a sand mold directly from CAD models, eliminating patterning steps, thus reducing the process time for creating prototypes. In addition to minimizing processing steps, 3D printing provides the advantages of higher precision and the ability to produce complex shaped sand molds, but it simultaneously possesses some limitations and concerns related to throughput, safety and logistics.

This study proposes an alternative method for creating sand molds by introducing a hybrid rapid prototyping approach to overcome …

Replacement Of Solvent Based Ink By Water Based Inks For Gravure Presses With Low Efficiency Ink Driers, Viraj Suresh Dalvi

Masters Theses

Rotogravure printing of decorative laminates, wall coverings, or vinyl floorings process often uses solvent based inks. The main constraining factor with solvent based ink is presence of volatile organic compounds (VOC’s). Due to the environmental norms on Volatile Organic Compounds (VOCs), and restrictions on using solvent based inks, the ink industry came up with water based ink as more environmentally friendly alternative. Organizations which print decorative laminates, wall coverings, or vinyl floorings with solvent based inks have gravure printing infrastructure, which is often equipped with low efficiency driers capable of drying solvent based inks. In order to comply with environmental …

Fluorine Containing Uv-Curable Materials For Advanced Transport Applications, James Thomas Goetz

Dissertations

The characterization of structure, thermal, gas transport, and free volume properties of two unique UV cured polymeric systems are studied and reported. In the initial pursuit of waterproof high water vapor transport membranes, it became apparent that the UV curing of fluorinated materials yielded routes to develop unique materials that fundamentally challenge conventional models for free volume and light gas transport behavior. UV-curing provides a means to rapidly “lock-in” morphologies that are accessible in the small molecule, monomer phase but rapidly become kinetically inaccessible when constraints such as covalent bonding and cross linking limit motion in the polymer system. This …

An Investigation Of Heat Transfer Enhancement In Nanofluids Containing Core And Shell Nanoparticles., Cory Adam Milligan

Electronic Theses and Dissertations

The purpose of this research is to determine the differences in heat transfer enhancement of poly alpha olefin oil after the addition of two types of carbon coated nanoparticles, specifically carbon coated cobalt and carbon coated copper nanoparticles. The carbon shell allows for the nanoparticles to be homogenously dispersed in the oil and remain stable throughout the experimental procedure. The nanofluids were prepared in concentrations of 0.5, 1.0, and 1.5 wt%. A constant surface heat flux testing rig is used to determine the heat transfer coefficients of the base fluids and the nanofluids. Inlet temperatures to the heat transfer section …

Self-Supported Printed Multi-Layer Capacitors, Michael James Joyce

Masters Theses

The increasing demand for miniaturized electronic devices has increased the need for rechargeable micro-power sources. Although lithium and lithium ion batteries have been utilized in these applications since the late 1990s, other energy harvesting technologies, such as thermal, mechanical, and solar, are now being used to augment batteries to enable systems to be self-powered. However, the lifetime of any battery is finite, which may be a major problem when the application is in a permanent structure or medical implant device. For power or significant energy storage applications, printed multilayer capacitors or supercapacitors are being explored as an enhancement, or replacement …

Persistent Hepatic Structural Alterations Following Nanoceria Vascular Infusion In The Rat, Michael T. Tseng, Qiang Fu, Khoua Lor, G. Rafael Fernandez-Botran, Zhong-Bin Deng, Uschi M. Graham, D. Allan Butterfield, Eric A. Grulke, Robert A. Yokel

Chemistry Faculty Publications

Understanding the long-term effects and possible toxicity of nanoceria, a widely utilized commercial metal oxide, is of particular importance as it is poised for development as a therapeutic agent based on its autocatalytic redox behavior. We show here evidence of acute and subacute adverse hepatic responses, after a single infusion of an aqueous dispersion of 85 mg/kg, 30 nm nanoceria into Sprague Dawley rats. Light and electron microscopic evidence of avid uptake of nanoceria by Kupffer cells was detected as early as 1 hr after infusion. Biopersistent nanoceria stimulated cluster of differentiation 3⁺ lymphocyte proliferation that intermingled with nanoceria-containing …

Interfacial Interactions Between Carbon Nanoparticles And Conjugated Polymers, Yanqi Luo

Master's Theses

Conjugated polymer based electronics, a type of flexible electronic devices, can be produced from solution by traditional printing and coating processes in a roll-to-roll format such as papers and graphic films. This shows great promise for the emerging energy generation and conversion. The device performance of polymer electronics is largely dependent of crystalline structures and morphology of photoactive layers. However, the solution crystallization kinetics of conjugated polymers in the presence of electron acceptor nanoparticles has not been fully understood yet. In this study, solution crystallization kinetics of poly (3-hexylthiophene) in the presence of carbon nanotubes and graphene oxide has been …

Fundamental Investigations Of Clay/Polymer Nanocomposites And Applications In Co-Extruded Microlayered Systems, Jeremy John Decker

Dissertations

The second and fourth generations of hydroxylated dendritic polyesters (HBP2, HBP4) were combined with unmodified sodium montmorillonite clay (Na+MMT) in water to generate a broad range of polymer clay nanocomposites from 0 to 100% wt/wt Na+MMT. X-ray diffraction (XRD) and transmission electron microscopy (TEM) were used to investigate intercalation states of the clay galleries. It was shown that interlayer spacings were independent of generation number and changed over the composition range from 0.5 nm to 3.5 nm in 0.5 nm increments that corresponded to a flattened HBP conformation within the clay tactoids.

The HBP4/Na+MMT systems were investigated to study the …

Improved Efficiency Organic Photovoltaic Cells Through Morphology Control And Process Modification, Qi Wu

Dissertations

Organic photovoltaic (OPV) cells have drawn great attention due to the potential to produce flexible, light weight, affordable solar cells using polymer organic photovoltaic materials; however, the current power conversion efficiency achieved for these systems is too low for widespread implementation of the technology. Morphology and phase separation are key factors determining the performance of organic photovoltaic cells. Precise control of the size and distribution of the phase-separated photoactive domains is necessary for optimum photon-electron conversion. Polyhedral oligomeric silsesquioxane (POSS) nanostructered chemicals have the potential to provide enhanced control of morphology, crystallinity, and phase dispersion in polymeric blend systems. In …

Production Of Recombinant Human Coagulation Factor Ix By Transgenic Pig, Weijie Xu

Department of Chemical and Biomolecular Engineering: Dissertations, Theses, and Student Research

Hemophilia B is the congenital bleeding disorder caused by deficiency in functional coagulation factor IX (FIX) and about 28,000 patients worldwide in 2012. And current treatment is restricted to protein-replacement therapy, which required FIX concentrates for patients’ life-time. Approximately 1 billion units FIX were consumed in 2012. However, still about 70-80% patients, mostly in developing countries, received inadequate or no treatment because of the unavailable and/or unaffordable FIX concentrates. Considering safety reasons, e.g. transmission of blood-borne diseases, the recombinant human FIX (rFIX) is recommended other than the plasma-derived FIX. However, only one rFIX is currently available on the market. The …

Opto-Electronic Devices With Nanoparticles And Their Assemblies, Chieu Van Nguyen

Department of Chemical and Biomolecular Engineering: Dissertations, Theses, and Student Research

Nanotechnology is a fast growing field; engineering matters at the nano-meter scale. A key nanomaterial is nanoparticles (NPs). These sub-wavelength (< 100nm) particles provide tremendous possibilities due to their unique electrical, optical, and mechanical properties. Plethora of NPs with various chemical composition, size and shape has been synthesized. Clever designs of sub-wavelength structures enable observation of unusual properties of materials, and have led to new areas of research such as metamaterials. This dissertation describes two self-assemblies of gold nanoparticles, leading to an ultra-soft thin film and multi-functional single electron device at room temperature. First, the layer-by-layer self-assembly of 10nm Au nanoparticles and polyelectrolytes is shown to behave like a cellular-foam with modulus below 100 kPa. As a result, the composite thin film (~ 100nm) is 5 orders of magnitude softer than an equally thin typical polymer film. The thin film can be compressed reversibly to 60% strain. The extraordinarily low modulus and high compressibility are advantageous in pressure sensing applications. The unique mechanical properties of the composite film lead to development of an ultra-sensitive tactile imaging device capable of screening for breast cancer. On par with human finger sensitivity, the tactile device can detect a 5mm imbedded object up to 20mm below the surface with low background noise. The second device is based on a one-dimensional (1-D) self-directed self-assembly of Au NPs mediated by dielectric materials. Depending on the coverage density of the Au NPs assembly deposited on the device, electronic emission was observed at ultra-low bias of 40V, leading to low-power plasma generation in air at atmospheric pressure. Light emitted from the plasma is apparent to the naked eyes. Similarly, 1-D self-assembly of Au NPs mediated by iron oxide was fabricated and exhibits ferro-magnetic behavior. The multi-functional 1-D self-assembly of Au NPs has great potential in modern electronics such as solid state lighting, plasma-based nanoelectronics, and memory devices.

Adviser: Ravi F. Saraf

Catalytic Performance Of An Iron-Based Catalyst In Fischer–Tropsch Synthesis, Majid Sarkari, Farhad Fazlollahi, Hossein Ajamein, Hossein Atashi, William C. Hecker, Larry L. Baxter

Faculty Publications

This paper documents the performance and kinetics of an iron/manganese oxide catalyst in a fixed-bed reactor by Fischer–Tropsch synthesis (FTS) under conditions favoring the formation of gaseous and liquid hydrocarbons (P: 1–12 bar; T: 513–543 K; H2/CO:1, 1.5, 2 mol/mol; gas hourly space velocity: 4200–7000 cm3 (STP)/h/gcat). Based on the hypothesis that water inhibits the intrinsic FTS reaction rate, eight kinetic models are considered: six variations of the Langmuir–Hinshelwood–Hougen–Watson representation and two empirical power-law models. The kinetic expression/mechanism that most precisely fits the data assumes the following: (1) CO dissociation is reversible and does not involve hydrogen; (2) all hydrogenation …

Modeling Of Kinetically Limited Growth Rate For Solution-Synthesized Germanium Nanocrystals, Nicholas Shoop

Chemical and Biological Engineering ETDs

Solution synthesis is a common method of generating semiconductor nanocrystals. For solution synthesis, many studies have assumed that the growth rate is diffusion-limited with an unphysically low diffusion constant. In this thesis, a model is developed that considers both diffusion and surface kinetics. The diffusion coefficient of Ge monomers through the solvent, octadecene, at elevated synthesis temperatures is estimated to be on the order of 10-5 to 10-4 cm2/sec, while the mass transfer boundary layer thickness is estimated to be on the order of a few nanometers, similar to the nanocrystal size. These two realistic conditions strongly suggest that the …

Poly(N-Isopropyl Acrylamide)-Coated Surfaces: Investigation Of Cytotoxicity With Mammalian Cells And The Mechanism Of Cell Detachment, Marta Cooperstein

Chemical and Biological Engineering ETDs

With the increase in life expectancy and with growing numbers of an aging population, there is a rising need worldwide for replacement tissues and organs. One way to address this growing need is through engineered tissues, such as those generated from stimulus-responsive polymers. Stimulus-responsive polymers undergo a physical or chemical change when a stimulus is applied. One such material is poly(N-isopropyl acrylamide), (pNIPAM), which undergoes a conformation change in a physiologically relevant temperature range to release intact mammalian cell monolayers capable of being used to engineer tissues. Two factors currently limit the use of cell sheets for this purpose: 1) …

Nanoparticle Cerium Oxide And Mixed Cerium Oxides For Improved Fuel Cell Lifetime, Stephen Stewart

Chemical and Biological Engineering ETDs

While there is a rich body of literature concerning of properties of bulk cerium oxide and cerium cations in solution, the discussion has been inappropriately applied to nanoscale cerium oxide resulting in many unexpected or unexplained results. In particular, there is very limited understanding about the properties of cerium oxide and its potential use as a radical scavenger, and how the catalytic properties of cerium oxide change as the particle size approaches the nanoscale. For example, the involvement of Ce+4 and Ce+3 cations in reactions such as hydrogen peroxide decomposition have been investigated for both cerium cations and bulk cerium …

Development Of Novel Synthetic Methods For Size-Tunable Synthesis Of Superparamagnetic Iron Oxide Nanoparticles, Erika Vreeland

Chemical and Biological Engineering ETDs

The properties of magnetic nanoparticles vary dramatically with size, so reproducibly controlling size is critical for practical applications. This is particularly true when moving into clinical settings, where regulatory approval requires demonstrated reproducibility in efficacy that can only be achieved with excellent size control. A number of methods for the synthesis of magnetic nanoparticles have been published, although the thermal decomposition of iron(III) precursors in organic solvents has been shown to yield high quality particles with low shape and size dispersity. Currents methods lack reproducibility resulting from non-stoichiometric starting materials, and reliance on reaction parameters, such as temperature ramp rate, …

Fundamental Studies On Copper Zeolites For Catalytic No X Abatement, Anuj Arun Verma

Open Access Dissertations

Stringent regulations in mobile NOx emissions have resulted in the development of Standard Selective Catalytic Reduction (SCR) as the dominant NOx abatement technology in lean burn diesel engines. Standard SCR is a reaction of nitric oxide (NO) with ammonia (NH₃), in the presence of oxygen (O ₂) to form nitrogen (N₂) and water (H₂O). Copper containing zeolites show commercially viable SCR performance. Cu-SSZ-13 (CHA framework), a member of this family, is a preferred catalyst for SCR applications because it shows exceptional hydrothermal stability in addition to commercially viable SCR performance. Our work focuses …

Correlation Between Microstructure And Thermionic Electron Emission From Os-Ru Thin Films On Dispenser Cathodes, Phillip D. Swartzentruber, Thomas John Balk, Michael P. Effgen

Chemical and Materials Engineering Faculty Publications

Osmium-ruthenium films with different microstructures were deposited onto dispenser cathodes and subjected to 1000 h of close-spaced diode testing. Tailored microstructures were achieved by applying substrate biasing during deposition, and these were evaluated with scanning electron microscopy, x-ray diffraction, and energy dispersive x-ray spectroscopy before and after close-spaced diode testing. Knee temperatures determined from the close-spaced diode test data were used to evaluate cathode performance. Cathodes with a large {10-11} Os-Ru film texture possessed comparatively low knee temperatures. Furthermore, a low knee temperature correlated with a low effective work function as calculated from the close-spaced diode data. It is proposed …

Preparation & Characterization Of High Purity Cu2 Znsn(Sxse1-X)4 Nanoparticles, Bethlehem G. Negash

Open Access Theses

Research in thin film solar cells applies novel techniques to synthesize cost effective and highly efficient absorber materials in order to generate electricity directly from solar energy. Of these materials, copper zinc tin sulfoselenide (Cu₂ZnSn(S_xSe_1-x) ₄) nanoparticles have shown great promise in solar cell applications due to optimal material properties as well as low cost & relative abundance of materials.^1,2 Sulfoselenide nanoparticles have also a broader impact in other industries including electronics³, LED ⁴, and biomedical research⁵. Of the many routes of manufacturing these class of semiconductors, …

Solvent System Selection For Xylooligosaccharides Separation By Centrifugal Partition Chromatography Using Conductor-Like Screening Model For Real Solvents, He Zhang

Open Access Theses

The production of value-added, bio-based industrial commodity chemicals is an important area in science right now and this study provides an initial step in the recovery of bio-based chemicals from hemicellulose. Hemicellulose is a long chain polymer mostly consisting of xylose, which is a five-carbon sugar, and a variety of other compounds that are ubiquitous in plant life. The hemicellulose polymer chain can be depolymerized into smaller components, called xylooligosaccharides (XOS) with different chain lengths of xylose linked by beta-1-4 glycosidic bonds, using either hot water, or dilute sulfuric acid. The xylooligosaccharides can then be purified from one another from …