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Articles 61 - 85 of 85
Full-Text Articles in Engineering
Influence Of Material Selection And Fabrication Process Repeatability On Mechanical Properties Of Glass-Polymer Matrix Composite Structures, Charles Edwards
Influence Of Material Selection And Fabrication Process Repeatability On Mechanical Properties Of Glass-Polymer Matrix Composite Structures, Charles Edwards
All Theses
This study has aimed to evaluate property uniformity from data obtained utilizing one design of a single layup composite plaque, three sources of glass fibers and a single, industry accepted resin to produce a repeatable fabrication process. This thesis has investigated the following:
1. Whether the type of glass (E-Glass, S-Glass, and R-Glass) influences the property values of individually tested samples compared between glass types.
2. Whether the type of glass influences the property uniformity throughout the set of tested samples.
3. Whether the composite plaque design and resulting performance, as defined by ASTM Standards or industry accepted parameters, is …
Optimizing The Mechanical Properties Of Partially Yttria Stabilized Zirconia With Alumina Additions, Ramanaganapathy Kandaswamy
Optimizing The Mechanical Properties Of Partially Yttria Stabilized Zirconia With Alumina Additions, Ramanaganapathy Kandaswamy
All Theses
Zirconia is one of the extensively studied solid oxide ceramics with respect to its use in various industrial applications like electrolyte in fuel cells, sensors, refractories and exhaust chamber in automobile industry. It can be found from the literature 1-4 that are contradictory results on the mechanical properties when alumina is added. There are several factors like microstructure, phase composition and method of processing that affects the mechanical properties of the material. The focus of this research is to examine how hardness, tensile strength and other properties varies with alumina content and deduce the optimal amount of alumina that is …
Microstructure Modification Of Cu0.2ag2.8sbsete2 Through, Sloan Lindsey
Microstructure Modification Of Cu0.2ag2.8sbsete2 Through, Sloan Lindsey
All Theses
Cu0.2Ag2.8SbSeTe2 is new potential thermoelectric compound that exhibits very low thermal conductivity and a region of glass-like thermal conductivity. The compound phase segregates into AgSbTe2 and Ag2Te phases with Se and Cu acting as isoelectronic dopants. Backscatter SEM imaging is used to study the resulting microstructure. Normally cast samples exhibit cracks forming near the interfaces of the two phases. In this work we show that the cracks are caused by a low temperature monoclinic to cubic phase transition that occurs in the Ag2Te phase. We demonstrate that through rapid quenching we can control the size and shape of the phase …
Fabrication Of Fluorescent Nanoparticle-Polymer Composites For Photoactive-Based Materials, Brett Ellerbrock
Fabrication Of Fluorescent Nanoparticle-Polymer Composites For Photoactive-Based Materials, Brett Ellerbrock
All Theses
Nanocomposites of nanoparticles dispersed throughout a polymer matrix have been studied to great length to improve the overall polymer properties. These enhancements are observed in the thermal, physical, and/or optical characteristics. Being able to harness nanoparticles in such a way may help improve fiber technology into the 21st century.
This work was geared toward synthesizing rare earth doped lanthanum fluoride (LaF3) nanoparticles because good separation in the absorption and emission bands of the material and it fluoresces in the visible to near-infrared range. Terbium ions were added to a LaF3 crystal because of their distinct visible green …
Surface Characterization And Electrochemical Behavior Of Colloidal Particles, Cinta Pepin
Surface Characterization And Electrochemical Behavior Of Colloidal Particles, Cinta Pepin
All Theses
There is an ongoing interest in research focused on developing polymeric organic-light-emitting-devices (OLED) to replace inorganic devices. Compared to inorganic devices, OLEDs could present better properties such as higher efficiency, lower cost and simpler device fabrication. In an attempt to get a device with high efficiency, the hole transporting group and the electron transporting group were combined into a polymer to make an individual 'particle device'. The idea was to create a polymer particle containing both charge transporting moieties via emulsion polymerization. In this presentation, different techniques will be described that were used to determine the stability and the surface …
Influence Of Iso-Structural Substitutions On Properties Of Ge(As,Sb)(S,Se) Glasses, Guillaume Guery
Influence Of Iso-Structural Substitutions On Properties Of Ge(As,Sb)(S,Se) Glasses, Guillaume Guery
All Theses
Chalcogenide glasses possess exceptional infrared transparency, large non-linear refractive indexes and low phonon energies, making them good candidates for infrared optical applications. Previous studies in the Ge-Sb-S glass system have shown an increase in the nonlinear refractive index with an iso-structural substitution of two- coordinated selenium (Se) for sulphur (S) and variation of other physical properties with substitution of other iso-structural species such as three-coordinated arsenic (As) for antimony (Sb). The role of such iso-structural exchange on properties important to the thermo-, visco- and mechanical attributes of glasses in the Ge-As/Sb-S/Se system has not been thoroughly evaluated and form the …
Kinetic And Finite Element Modeling For Firing Brick, Daniel Mckinney
Kinetic And Finite Element Modeling For Firing Brick, Daniel Mckinney
All Theses
Kinetic modeling and simulation were used to optimize the firing cycle for brick. This was done to develop a tool for the brick industry to reduce fuel consumption and emissions during firing. A kinetic model was built using shrinkage data from dilatometer measurements and mass loss data from thermogravimetry measurements in order to predict the density as a function of temperature and time. The density of brick was related to the absorption coefficient (C/B), an ASTM standard which is related to the durability of the brick. The kinetic model was used to optimize the firing curve using a rate controlled …
Biodegradable Polymer Blends And Composites From Proteins Produced By Animal Co-Product Industry, Bernice Nzioki
Biodegradable Polymer Blends And Composites From Proteins Produced By Animal Co-Product Industry, Bernice Nzioki
All Theses
ABSTRACT
Development of new green materials from by-products of animal rendering industries would provide a substantial economic return to animal rendering processors. Meat and bone meal (MBM), one of the products of the rendering industry, has potential for numerous bio-based applications. This research focuses on fabrication of plastics blends made of MBM (Meat and bone meal) and UHMWPE (ultra high molecular weight polyethylene). We investigated thermal, morphological, water absorption and mechanical properties of the plastics. The plastics were compression molded and their properties were examined.
DSC thermographs of the blends indicated that the thermal properties of UHMWPE did not change …
Characterization And Modification Of Helmet Padding System To Improve Shockwave Dissipation, Katelyn Howay
Characterization And Modification Of Helmet Padding System To Improve Shockwave Dissipation, Katelyn Howay
All Theses
Currently soldiers are being exposed a much higher number of improvised explosive devices (IEDs) and the resulting shockwaves. These shockwaves can cause traumatic brain injuries (TBIs) even without the occurrence of ballistic impact. The focus of this research was to reduce the amount of shockwaves soldiers are exposed to by inserting fibers and woven fabrics into a foam padding system. These fibers and fabrics facilitate the dissipation of the shockwave energy before it is able to penetrate the padding and cause TBIs.
The sound velocity of high-performance fibers, commodity fibers and woven fabric was measured using a Dynamic Modulus Tester. …
Investigation Of The Thermoelectric Behavior Of Cu-Doped Pbteagxse, Ben Ma
Investigation Of The Thermoelectric Behavior Of Cu-Doped Pbteagxse, Ben Ma
All Theses
Sustainable energy research is currently on the forefront of scientific exploration thus a major effort is devoted to the development of new energy conservation and production techniques. Thermoelectric materials can play a significant part both in energy conservation and energy production via the Seebeck effect (heat to electric power) and the Peltier effect (electricity to cooling power), since they can convert wasted heat to useful electrical energy.
Presented herein are the measured electrical and thermal transport properties and phenomenal analysis of the PbTeAgxSe (x=1.9, 2.0, 2.01) system. First, it would lead to a significant reduction in the thermal conductivity and …
Investigation Of The Thermoelectric Behavior And Structure Formation Of (Pbte/Agsbte2)-Silver Chalcogenide Mixtures, Yisha Wang
All Theses
Sustainable energy research is currently on the forefront of scientific exploration and energy conservation and the development of new energy production techniques are both crucial for our long lasting stable future. Accordingly, thermoelectric materials will be a significant energy conservation and production source. The state-of -the-art thermoelectric materials can be used to collect the wasted heat and converted to power, which is the future for the green power generation.
PbTe is considered a state-of-the-art thermoelectric material, which has been extensively studied. It forms in the NaCl structure and it is a semiconductor with a room temperature gap value of 0.29 …
Mechanical And Chemical Characterization Of Biological Composite Structures, Bonnie Zimmerman
Mechanical And Chemical Characterization Of Biological Composite Structures, Bonnie Zimmerman
All Theses
A better understanding of the bioresponse of naturally occurring systems will help
to optimize the engineering of synthetic biomaterials. The aim of this thesis was to
characterize the mechanical and chemical behavior of two distinct biological composite
systems, human teeth and wool fibers. These mechanical and chemical properties were
also studied as a function of natural structure and environmental conditions.
Human teeth are composite systems consisting primarily of hydroxylapatite and
protein. This project investigated how the use of clinical dental treatments and
procedures, such as whitening and etching, affects mechanical properties. Analysis of
nanoindentation with the Oliver-Pharr model provided elastic …
Electrodeposition Of Nanocrystalline Ni-Based Alloys, Hanseung Park
Electrodeposition Of Nanocrystalline Ni-Based Alloys, Hanseung Park
All Theses
Nanocrystalline materials can often process superior properties, but they are generally unstable against grain growth. Addition of a dopant can stabilize nanocrystalline alloys by decreasing the excess grain boundary energy as the thermodynamic driving force for grain growth and reducing grain boundary mobility via a kinetic effect of solute drag. In this thesis study, eight Ni-based alloys (Ni-W, Ni-P, Ni-Mo, Ni-Cu, Ni-B, Ni-Mg, Ni-Zn and Ni-Co) and pure Ni were made using an electrodeposition method. It is concluded that the use of different dopant can drastically affect the deposition mechanism as well as the morphology of resultant films. Ni-W and …
Thermal And Structual Properties Of Candidate Moldable Glass Types, Scott Gaylord
Thermal And Structual Properties Of Candidate Moldable Glass Types, Scott Gaylord
All Theses
This thesis contains results of our efforts to develop a method for defining key glass material properties that must be known and modeled for the design and experimental validation of a precision glass molding (PGM) process for optical glasses. Viscosity, calorimetric, and thermal expansion properties of two commercial glass types N-BK7 and P-SK57 of SCHOTT were characterized to establish a proof-of-concept protocol for the experimental determination of meaningful material properties. Experimental results were determined in order to be incorporated into a computational model predicting final glass size and shape following a molding cycle. Experimental methods were confirmed on the two …
The Role Of Crystallographic Relationships Between Alpha(Α) And Beta(Β) Phases On The Elevated Temperature Isothermal Phase Transformation Kinetics In Timetal Lcb (Ti-6.5mo-4.5fe-1.5al), Basak Kokuoz
All Theses
This investigation has examined the mechanisms controlling the precipitation of various alpha (α) phase morphologies which form during the elevated temperature beta(β)beta(β)+alpha(α) phase transformations in TIMETAL LCB (Ti-6.8Mo-4.5Fe-1.5Al, in wt.%).
Alpha (α) phase precipitation was promoted by aging the TIMETAL LCB specimens in the α+β two phase region. The temperature range considered was between 700-745oC.The specimens were isothermally aged for successively increasing times, starting at 30 seconds until the equilibrium microstructure was achieved. Solution treated and aged TIMETAL LCB specimens were investigated using x-ray diffraction (XRD), optical (OM) and scanning electron microscopy (SEM), electron backscattered diffraction (EBSD) and quantitative image …
Protein Interactions With Mixed Poly(Ethylene Glycol)/Polyacrylic Acid Brushes, Zhenqing Li
Protein Interactions With Mixed Poly(Ethylene Glycol)/Polyacrylic Acid Brushes, Zhenqing Li
All Theses
Tethered polymer chains that are grafted to a solid substrate by one chain end (polymer brushes) may be distinguished from other anchored polymer layers by the relatively high grafting densities gained. Potential uses of polymer brushes for interfacial modification to regulate interactions between proteins and substrates, such as drug delivery and protein separation, are widely recognized. Therefore, it is important to investigate interactions between proteins and surfaces modified with a polymer brush.
In this study, the 'grafting-to' method has been used to graft mixed poly(ethylene glycol) (PEG) and polyacrylic acid (PAA) brushes onto poly(glycidyl methacrylate) (PGMA)-modified silicon wafers/glass slides to …
Synthesis And Dielectric Properties Of Nanocrystalline Barium Titanate And Silver/Barium Titanate Particles, Hiroki Maie
Synthesis And Dielectric Properties Of Nanocrystalline Barium Titanate And Silver/Barium Titanate Particles, Hiroki Maie
All Theses
The increasing needs for further functionality, higher performance, and miniaturization of electronic devices have highly demanded down-size and volume-efficiency of electronic components such as multilayer ceramic capacitors (MLCCs). To meet this demand, the use of high dielectric constant material with nanometer size and spherical shape is considered as requirements. Embedded capacitors are an important emerging technology for meeting the performance and functionality requirements of next-generation electronic devices. One major obstacle for implementing this technology is the scarcity of dielectric materials with appropriate dielectric and mechanical properties was mainly discussed
Considering these backgrounds, this research is devoted to synthesis of high …
Surface Functionalized Colloidal Particles And Polymer Synthesis For Led Based Applications, Zachary Hunt
Surface Functionalized Colloidal Particles And Polymer Synthesis For Led Based Applications, Zachary Hunt
All Theses
Over the last decade atom transfer radical polymerization, ATRP, has become a commonplace route by which tailored polymers can be synthesized. The advent of this polymerization mechanism has enabled the controlled synthesis of block and multi-block polymer systems that maintain a terminal bromine functionality that adds further versatility to the synthesized polymers.
Additionally, in the last few years 'click' chemistry has come to light as an efficient method of selectively linking molecules under mild conditions (e.g. room temperature and aqueous systems). In particular, the copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) reaction has become more and more popular, and provides another route by …
Laser-Assisted Synthesis And Optical Properties Of Bismuth Nanorods, Jason Reppert
Laser-Assisted Synthesis And Optical Properties Of Bismuth Nanorods, Jason Reppert
All Theses
Bismuth in the bulk form is a semimetal with a rhombohedral structure. It has a small band overlap between the conduction and valence bands and a highly anisotropic electron effective-mass tensor. Thermoelectric materials, in which one of the three dimensions is in the nanometer regime, exhibit unique quantum confinement properties and have generated much interest in recent years. Theoretical investigations have suggested that nanowires with diameters <10 nm will possess a figure-of-merit ZT>2. Prior to this research, it has been shown by the Dresselhaus group at MIT that Bi nanowires with small enough diameters (~50 nm), prepared via the template-method, undergo a transition from a semimetal …
Study Of Structure Development During Melt Spinning Of Isotactic Polypropylene Fibers Using Raman Spectroscopy And Wide Angle X-Ray Diffraction Simultaneously , Dushyanth Pandana
Study Of Structure Development During Melt Spinning Of Isotactic Polypropylene Fibers Using Raman Spectroscopy And Wide Angle X-Ray Diffraction Simultaneously , Dushyanth Pandana
All Theses
ABSTRACT
Isotactic polypropylene (iPP) fibers have a wide variety of applications. Specific end-use applications require specific properties, which are dependent on the polymer morphology produced during processing. Therefore, the final properties of a material are dependent on the processing parameters. iPP fibers are produced mainly by melt spinning. The important processing parameters in the melt spinning process include, the extrusion temperatures, the throughput and shear rates, the rate of cooling, and the feed and draw roll take-up velocities. An understanding of how the morphology develops along the spinline, and the effect of processing parameters on the morphology is crucial in …
Synthesis And Photocatalysis Study Of Brookite Phase Titanium Dioxide Nanoparticles, Radhika Bhave
Synthesis And Photocatalysis Study Of Brookite Phase Titanium Dioxide Nanoparticles, Radhika Bhave
All Theses
Titanium dioxide is used in variety of applications like photocatalysis, self-cleaning coatings, fog proof glass and water purifier. A lot of research is being done in synthesis and applications of TiO2. Titanium dioxide or TiO2 mainly exists in three phases namely anatase, brookite and rutile. Current studies relate to synthesis of brookite phase TiO2 nanoparticles by ambient condition sol (ACS) process and characterization of these particles for phase purity, morphology and surface area analysis. The photoactivity of these particles was investigated and absorption in the visible light region was detected. This implies brookite to have good potential to be used …
Optimizing Production Methods For Artifical Silk Proteins Through Bioreactor And Purification Studies Of Recombinant Proteins Expressed From Pichia Pastoris, Aaron Ramey
All Theses
Advancements in the field of biomaterials are being made to produce an artificial silk fiber. A gene was constructed which utilized components from both the dragline silk of Nephila clavipes and nematode collagen. For this engineered protein, the yeast strain Pichia pastoris was chosen to be the host organism. Previous research has shown P. pastoris to have comparatively low amounts of specific protein productivity. Therefore, this problem must be compensated for by obtaining extremely high cell densities. The main focus of this study was to optimize the fermentation parameters of transgenic yeast cultures within a bioreactor in order to increase …
Influence Of Temperature And Polymer/ Mold Surface Interactions On Micro-Feature Replication At Ambient Pressure In Micro Injection Molding, Varun Thakur
All Theses
This study assesses micro-feature replication at elevated mold temperature and ambient pressure using a variety of polymers. Moldings were made on the surface of stainless steel and silicon wafers containing features as small as 130 nm under isothermal conditions in a heated chamber by allowing polymer to spread over the features at ambient pressure. Feature replication was analyzed via AFM and SEM. Polymer behavior was characterized via melt contact angle and melt viscosity. While feature detail was well replicated, the moldings exhibited poor dimensional accuracy due to shrinkage. In general, polymers with low viscosity and surface tension comparable to the …
Dielectric Properties And Method Of Characterizing Ceramic Powders And Multiphase Composites, Ravi Kiran Kota
Dielectric Properties And Method Of Characterizing Ceramic Powders And Multiphase Composites, Ravi Kiran Kota
All Theses
Barium Titanate was the first developed ferroelectric ceramic material and even today it is widely used. It is also a well-known material used for capacitors. The only reason behind a wide range of applications is that barium titanate boasts of high dielectric properties. A phase transition from cubic to tetragonal at normal working temperatures provides enhanced dielectric properties in this electronic material. For any application and design, the most inquired property is the dielectric constant. Predicting the dielectric constant is very much required as it is the pre-requisite. This is the major objective of the present work. To estimate the …
Study Of Parameters Affecting Performance Of Automotive Transmission Filters, Debra Cauthen
Study Of Parameters Affecting Performance Of Automotive Transmission Filters, Debra Cauthen
All Theses
Modified isocyanate binders have been introduced as a possible alternative to phenolic resins for bonding nonwovens in automatic transmission filtration. The Occupational Safety and Health Administration (OSHA) and the American Conference of Governmental Industrial Hygienists (ACGIH) have placed restrictions on worker exposure to phenol-formaldehyde due to toxicological and ecological concerns. Modified isocyanates are unproven for bonding needlefelts in this application.