Materials Science and Engineering Commons^™

Synthesis Of Nanostructured Conducting Polymers And Their Application As Gas Sensors, Zhe-Fei Li

Masters Theses

"A single-step, bottom-up technique based on a nanostructured conducting polymer has been used to fabricate sensors. Small amounts of aqueous solutions of aniline, a dopant, and an oxidant were placed on an interdigitated electrode array. Ultraviolet (UV)-irradiation of the solutions enhanced polymerization, yielding a highly porous film of polyaniline nanofibers with mean diameters of around 100 nm and lengths on the order of 1 µm. Solutions that were not irradiated formed bulk-like polyaniline films. Nanofibers and bulk polyaniline sensors were exposed to vapors in an argon carrier gas including: chloroform, a weak proton donor; toluene, a vapor that causes polymer …

Friction Stir Spot Welding Of Aluminum Alloys, Wei Yuan

Masters Theses

"Efforts to reduce vehicle weight and improve safety performance have resulted in increased application of light-weight aluminum alloys and a recent focus on the weldability of these alloys. Friction stir spot welding (FSSW) is a solid state welding technique (derivative from friction stir welding (FSW), which was developed as a novel method for joining aluminum alloys). During FSSW, the frictional heat generated at the tool-workpiece interface softens the surrounding material, and the rotating and moving pin causes material flow. The forging pressure and mixing of the plasticized material result in the formation of a solid bond region. The present work …

Development Of Knowledge Base Of Concrete Bridge Maintenance System, Bahre Karam

Masters Theses

Bridges are the key elements of any transportation system of a country. Bridges are expensive structures and therefore, it's essential to maintain and repair them on regular basis. Almost one third of the bridges in United States are reported to be in some what deteriorated conditions. This Research presents the development of knowledge base for decision support system for concrete bridges.

During this research various concrete bridge problems are investigated including COlTosion, delamination, cracks, spalling and scour etc. The inspection tools and techniques are addressed in order to identify these problems both for above and below water surface. The various …

Properties Of Alkaline-Resistant Calcium-Iron-Phosphate Glasses, Jiawanjun Shi

Masters Theses

"The physical properties and alkaline corrosion resistant properties of calcium-iron-phosphate glasses were studied. The addition of Fe₂O₃ decreases the thermal expansion coefficient and increases the glass fiber's Young's modulus in comparison with the addition of CaO. Bulk glass dissolution behavior in alkaline Lawrence solution was studied by weight loss experiments, Raman spectroscopy, and analytical scanning electron microscopy. The corrosion of glass powder in NaOH solution was studied by X-ray diffraction, infrared spectroscopy and high pressure liquid chromatography. The results show that the dissolution rate decreases when the phosphate chain length decreases. Calcium oxide can improve the glass durability in high …

Age Strengthening Of Gray Cast Iron: Alloying Effects And Kinetics Study, Thottathil Viswanathan Anish

Masters Theses

"Age strengthening of gray cast iron has become a critical issue with metal casters trying to optimize their process for the closest conformance to properties. This necessitated more robust and precise methods to predict age strengthening. Most foundries use age strengthening behavior to cast at hight carbon equivalents to facilitate smaller gating systems. Also, it is well known in the casting industry that the tool life improves with aging. Hence these foundries require a model to predict aging behavior and accelerate the mechanism from days to hours. This research focuses on the methods of composition adjustments to control aging properties, …

Process Development And Applications Of A Dry Film Photoresist, Phaninder R. Kanikella

Masters Theses

"In this study, dry film photoresist was patterned using UV lithography and the sidewall profile was optimized to achieve vertical sidewalls. Sidewall verticality of dry film is very important for better pattern transfer"--Abstract, page iv.

Friction Stir Processing Of Cast Magnesium Alloys, Timothy A. Freeney

Masters Theses

"This thesis investigates the feasibility and benefits of using friction stir processing as a thermo-mechanical microstructural modification tool for local property enhancement or casting repair of magnesium alloys, specifically high strength EV31A and WE43"--Abstract, page iv.

Direct Microstructure Deposition By Micromirror Direct Patterning And Laser Sintering Of Nanoparticles, Weiya Fang

Masters Theses

"The emerging demand for low cost, medium volume production and flexible micro-fabrication techniques has been advanced by the development of MEMS and limitations of the existing technique. As a promising building block for future MEMS and IC industry, nanoparticles are attracting more and more attention due to their interesting electronic, catalytic and optical properties, which can be finely tuned by varying their size. A novel process for the manufacturing of functional microstructures by modulated laser direct patterning and curing of nanoparticles is presented.

The first part of the thesis aims to understand the possibility and process of using modulated laser …

Microwave Pretreatment Of Corn Stover For Anaerobic Digestion, Abhishek D. Saxena

Masters Theses

Anaerobic digestion is one of the several technologies used for biomass conversion to electricity or heat. This thesis focused on microwave irradiation of corn stover as a pretreatment for anaerobic digestion, and studies its impact on methane production.

The first run comprised three sets of stover soaked overnight in water, dilute sulfuric acid and dilute acetic acid, and each treated to three different levels of microwave irradiation. The results indicated a high variability in the data of the water set, which showed that there was no clear impact of microwave pretreatment on methane production. The dilute sulfuric acid and dilute …

Investigation Of Electrical Properties And Structure Of Vacuum Evaporated C60 Films, Angiras D. Pandya

Masters Theses

C₆₀ is an important electronic material and its properties can be tuned by thermal annealing process and solid phase crystallization process. These properties were investigated as a function of thermal annealing temperature and solid phase crystallization. However there is no systematical study on annealing effect and Solid Phase Crystallization of C₆₀ films. In this study, the effect of thermal annealing on formation of nanocrystalline C₆₀ thin films were investigated for annealed samples and solid phase crystallized samples. The C₆₀ films described here were prepared by vacuum thermal evaporation method. The structural properties of C₆₀ films …

Hot Melt Inks For Rotogravure-Formulation, Printability And Rheology, Hrishikesh Shreeram Bhide

Masters Theses

A new generation of "Hot melt inks for Rotogravure" was formulated. They melt during heating and reach printable viscosity between 75° C and 130° C, depending on formulation. After printing onto substrate, they solidify. Selections of the best formulations were done based on ink rheology, and print analysis. The formulated inks were also printed on the Moser sheet-fed proofing press .. The rheological data indicated that hot melt inks (without viscosity modifier) have viscosity in the range of 10°-10¹ Poise at 95°C. After printed on a laboratory gravure K-Proofer, the inks showed good reflective density (0.90 - Yellow, 1.30 …

The Effect Of Non-Stoichiometry On The Structure Of La-Ni And La-Ni-Ga Alloys, Pertrice Auguste Wethey

Masters Theses

Non-stoichiometric samples of the AB₅ system defined by the formula La_1-yNi_5+2y and LaNi_5+2xGa_1-x were cast using an arc-melting furnace. The samples were then analyzed to determine their lattice parameters and phases present using XRD. They were then heat-treated to produce homogeneous compounds and quenched with the intention of retaining high temperature compositions. Following the heat-treatment, the alloys underwent XRD again as well as SEM/EDS. The XRD information was analyzed using Rietveld refinement and the elemental data derived from the EDS was used to ascertain the compositions were statistically akin to the weighed values. …

Texture And Residual Stresses On Nanocomposite Coatings, Hussam E. Aikhasawneh

Masters Theses

Nickel was electroplated on cold-rolled 2024-T3 aluminum. The coating was done with reinforcement by nanoparticles of y-alumina or silicon carbide. For comparison, nickel-only coatings were done too. Rectangular samples were coated in nickel sulfamate bath with no particles to determine the optimum coating conditions. The optimized parameters were the current density, time of coating, and agitation rate. After coating conditions were established, composite samples were coated using these conditions. The coated layer was characterized by measuring: thickness, residual stresses, and crystallographic preferred orientation. The coated layer was tested by SEM for evaluation of the quality of the coatings. The presence …

Effect Of Modified Clay-Zeolite Pigment On The Viscoelastic, Optical, And Printing Properties Of A Lwc Gravure Coating, Lokendra Pal

Masters Theses

This study investigates the influence of modified clay- zeolite pigment on the viscoelastic, optical, and printing properties of a LWC coating. Currently, lightweight, coated papers have experienced problems with mottle, distortion, fiber puffing and poor print quality when printed with water-based inks. However, water-based inks represent a proven solution to reducing volatile organic compound (VOCs) emissions. Poor wetting and ink spreading on the paper surface constitute the majority of print quality issues associated with the water-based printing of LWC papers.

Similar problems are encountered during the printing of ink jet papers due to high percentage of water contained in these …

Development Of Water-Based Ink System For Braille Printing, Saurabh Varma

Masters Theses

The most commonly used system of writing by and for blind persons is called Braille, named after its French inventor, Louis Braille (1809-1952). Braille is comprised of a rectangular six-dot cell on its end, with up to 63 possible combinations using one or more of the six dots. Braille is the only reliable method of literacy for blind persons, because it enables them to read and write by touch¹.

Currently, Braille is printed by special embossers that serve as a printing press. These embossers create Braille output when it is attached appropriately to computers. The speed of these …

Metastable Phases Of Mgo-Tio2 Solid Solutions, Liang-Chieh Ma

Masters Theses

Magnesium titanium oxide powders were synthesized by the sol-gel method using alkoxides of magnesium and titanium with different ratios. Matastable phases of qandilite, Mg₂TiO₄, were found with Mg:Ti ratios down to 1.52:1 in lower temperature 600 °C than in the equilibrium condition which is above 1200 °C. Powder samples were examined by neutron powder diffraction and X-ray photoelectron spectroscopy (XPS) for analysis of structure and oxidation states. Also, samples were tested for the Mg:Ti ratios by induced coupled plasma atomic emission spectrometry. The structure refinements of the samples were done by General Structure Analysis System (GSAS) …

Iron Phosphate Glass For The Vitrification Of Ineel Sodium Bearing Waste And Hanford Low Activity Waste, Robert Douglas Leerssen

Masters Theses

"The current study investigates the feasibility of using iron phosphate glass for the immobilization of nuclear wastes that have limited solubility in the current borosilicate glass used for vitrification. These wastes contain elements such as sulfur and phosphorus, which have proven problematic (causing phase separation at >1 wt%) for vitrification in borosilicate glasses, as well as having a high soda content (50-75 wt%) which also limits wasteloading"--Abstract, page iv.

Lateral Migration Of A Solid Particle In Shear Flow, Wutthapong Jiraporncharoen

Masters Theses

Lateral migration of solid particles in shear flow is observed in various industrial applications. Suspensions in a blade coater, a device used to apply coating pigment to a base paper to improve paper properties, is an example. Particle hydrodynamics will affect the quality of coated paper and runnability of the coater especially when the speed of the coating machine is very high or the pigment concentration is increased.

Many factors will affect the particle migration. The wall repulsion or lubrication effect forces the particle away from a wall to the channel center. The inertial effects are increased by increasing the …

Effects Of Compression Processing Parameters And Antioxidants On Molecular Degradation Of Biodegradable Poly-L-Lactide (Plla), Thomas J. Hannan Jr.

Masters Theses

The purpose of this research was to find a combination of poly (L-lactic acid), also known as poly-L-lactide or (PLLA) and antioxidants that would, together, produce a product whose degradation rate would be advantageous for use in biodegradable medical implants. Intrinsic viscosity tests were conducted on compression molded samples of PLLA that were molded at various processing parameters in order to find optimal parameters. The optimal processing parameters were found to be time 10 minutes, temperature 220°C, and pressure 1000 psi.

The molecular weight of PLLA sample was taken while pressure, time, and temperature were varied. As pressure increased, no …

Effect Of Antioxidants On Ultra High Molecular Weight Polyethylene (Uhmwpe), Clifford Schrader

Masters Theses

This thesis presents a study on the effects of antioxidants on the oxidative induction time (OIT), thermal behavior, and hardness property of ultra high molecular weight polyethylene (UHMWPE). The antioxidants were dissolved into methanol alcohol before the solution was mixed with UHMWPE powder. The mixture was degassed under vacuum, and then compression-molded into disks 1.25 in. in diameter.

Different antioxidants were evaluated at concentrations up to 0.6 percent. A 0.6 percent concentration was used to screen the effectiveness of various antioxidants. Effect of antioxidant concentration was investigated in the range between 0 and 0.6 percent. OIT was evaluated on UHMWPE …

An Analysis Of Texture Resulting From Thermomechanical Processing Of Ti-6al-V, David J. Brock

Masters Theses

An investigation of texture and microstructure formation in Ti-6Al-4V after thermomechanical processing and heat treating was performed. X-ray diffraction was used to measure prismatic and pyramidal pole figures. These pole figures were used to calculate basal pole figures, which showed significant changes in texture from heavy rolling and near or above β-transus heat treatments. Primary texture components were found to be strengthened by near β-transus heat treatments. For heavily rolled material, above β-transus heat treatments were found to reverse the primary texture components order of dominants. Heavy rolling was found to reduce the RD component and strengthen the TD.

The Effects Of Machining On Structure And Tribological Properties Of Ultra High Molecular Weight Polyethylene For Artificial Joint Prostheses, Jinshan Song

Masters Theses

Understanding the effect of machining on the structure and property of subsurface layer of ultra high molecular weight polyethylene (UHMWPE) can significantly facilitate the increase in longevity of artificial joints. This study was performed to investigate the machining effects on the polymeric structure and tribological properties. Machining parameters include cutting speed, tool feed rate and depth of cut. Temperature rise was studied during machining to assess the extent of thermal degradation due to machining. Polymeric structure of the semicrystalline polymer was characterized using differential scanning calorimetry (DSC) in terms of melting enthalpy, crystallinity and melting temperature. Surface texture and hardness …

Mechanical And Tribological Properties Of Composites Of Recycled High Density Polyethylene And Recycled Rubber, Jason G. Boulanger

Masters Theses

This thesis presents a study on the mechanical and tribological properties of composite materials of recycled high density polyethylene (HDPE) and recycled rubber tire particles. The materials were compounded by extrusion and formed into test specimens by injection molding.

The first experiment studied the effect of recycled rubber percentage on mechanical properties of composites of recycled HDPE and recycled rubber. The mechanical properties included tensile strength, percent elongation, hardness, and impact resistance. Recycled rubber concentrations of 0, 5, 10, 15, 20, 25, and 30 percent were tested. The second experiment investigated the tribological properties of recycled HDPE and recycled rubber …

Study On Rheological Behavior Of The Composites Of Recycled Hdpe With Recycled Tire Rubber Particles, Yanze Li

Masters Theses

This study was mainly concerned with rheological properties of composites of recycled high density polyethylene (HDPE) with recycled tire rubber particles at shear rates from 1.167 to 116.7 s^-1. The viscosity was investigated in terms of effects of shear rate, shear stress, temperature, concentration of recycled tire rubber particles and heating duration. The temperature was in the range from 160 to 250 °C and the rubber particle concentration was between 0 and 25%. The heat duration for the composites was up to 240 minutes before testing.

The viscosities of composites were decreased with increase in shear rate and …

Thermoplastic Composites Of Recycled High Density Polyethylene And Recycled Tire Particles, James N. Mckirahan Jr.

Masters Theses

This study identified the mechanical properties and processibility of composite materials of recycled high density polyethylene (HDPE), recycled rubber tire particles, and/or ethyl co-vinyl acetate and poly (e-caprolactone). The composites were processed using a single screw extrusion system.

Three groups of experiments were conducted, on the composites in their extruded form to investigate the mechanical properties of ultimate tensile strength, percent elongation, and hardness. The first experiment investigated the effect of recycled rubber particle concentration in the composites up to 25 percent. The second experiment investigated the effect of recycled rubber particle size on the composites of recycled HDPE and …

Nonlinear Finite Element Micromechanic Analysis Of Thermoplastic Composite Of Recycled High Density Polyethylene Reinforced With Short Glass Fibers, Qiming Lou

Masters Theses

This thesis studied the nonlinear micromechanic behavior of thermoplastic composite of recycled high density polyethylene (HDPE) reinforced with short glass fibers using finite element method. The composite material was modeled using a micromechanic unit cell to simulate the stress distribution between the plastic matrix and the fiber in the composite. Nonlinear behavior of recycled HDPE and imperfect bonding between the fiber and matrix were investigated. Load-bearing capability of the fiber was evaluated using stress partition ratio (SPR) in the composite models. The effect of fiber aspect ratio on the stress distribution of the composite was studied to optimize the material …

Iron Phosphate Glasses As A Potential Nuclear Waste Disposal Medium, Melissa G. Mesko

Masters Theses

”Phosphate glasses containing large amounts of Fe₂O₃ (up to 43wt%) were studied to determine their potential suitability as nuclear waste disposal glasses for high level radioactive wastes containing large concentrations of iron oxide, phosphate, and fluoride compounds. Glass formation and chemical durability was the prime focus of this study, while properties such as density, thermal expansion, dilatometric softening temperature, and devitrification temperature were examined as well. It was found that large amounts of simulated nuclear waste material (up to 44.4wt% Cs₂O or 37.5wt% SrO) could be incorporated into the base iron phosphate glass while retaining …

Effect Of Poly Acrylate Addition On Coating Color Rheology, Water Retention And Coating Performance, Shambhu Nath

Masters Theses

Five polyacrylate samples were used to study their effects on coating color rheology, water holding and runnability. The Cylindrical Laboratory Coater was used to apply the coatings and study the runnability of the coating colors. The healing tendencies of the coatings were studied by inducing a scratch under the blade. The higher acid level and degree of crosslinking of the polyacrylate gave higher viscosity and the higher acid level also gave higher water retention. Coating colors containing polyacrylates were less prone to dilatancy at high shear. The addition of polyacrylate reduced the healing of coating colors, but for the same …

An Investigation Of Recycled High Density Polyethylene Reinforced By Short Glass Fibers, Tony Lynn Alwardt

Masters Theses

The mechanical properties of recycled high density polyethylene (HDPE) reinforced by short glass fibers were investigated. The composites formed by an injection molding process were examined in terms of tensile strength, percent elongation, and hardness. Recycled HDPE was compared to virgin HDPE regarding the effects of fiber concentrations, types, sizes, and treatments. The addition of three coupling agents at different concentrations was investigated.

The virgin HDPE composites slightly outperformed their recycled HDPE counterparts; having higher tensile strength and hardness, but were less ductile. Increase in fiber concentration generally increased the tensile strength and hardness, but the concentration of fibers was …

Silicon Carbide/Electroless Nickel Composite Plating For Aluminum Substrates, Ben Charbit

Masters Theses

The effectiveness of producing a composite coating by suspending micron-sized particles in an electroless nickel bath while plating a 2024T4 aluminum alloy part was studied. The variation in the count of particles trapped in the nickel coating due to changes in the particle size, concentration of the particles in the bath, and the substrate surface texture was also studied. Particle sizes of 1 micron and 10 microns, concentrations of 15 gr/lt and 30 gr/lt, and polished and blasted textures were used. It was found that this technique is an effective way to produce composite coatings rendering a high number of …