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Fabrication And Characterization Of Novel Polymer-Matrix Nanocomposites And Their Constituents, Rui Ding Jan 2016

Fabrication And Characterization Of Novel Polymer-Matrix Nanocomposites And Their Constituents, Rui Ding

Graduate Theses and Dissertations

Two main issues for the wide application of polymer-matrix nanocomposites need to be addressed: cost-effective processing of high-performance nanomaterials, and fundamental understanding of the nanofiller-polymer interaction related to property changes of nanocomposites.

To fabricate inexpensive and robust carbon nanofibers (CNFs) by the electrospinning technique, an organosolv lignin for replacing polyacrylonitrile (PAN) precursor was investigated in this work. Modification of lignin to its butyl ester alters the electrospinnability and the thermal mobility of the lignin/PAN blend precursor fibers, which further affect the thermostabilization and carbonization processes of CNFs. The micromorphology, carbon structure, and mechanical properties of resultant CNFs were evaluated ...


The Effect Of Macrophage Phenotype And Surface Modification Of Liposomes On Internalization, Lilusi Ma Jan 2016

The Effect Of Macrophage Phenotype And Surface Modification Of Liposomes On Internalization, Lilusi Ma

Graduate Theses and Dissertations

The effects of surface modifications on liposomes using a library of arginine derivatives for improved drug delivery were examined. Encapsulating either fluorescein or doxorubicin, both unmodified liposome and modified liposomes were tested for their drug delivery properties and propensity for internalization with macrophages. The modified liposomes were characterized by dynamic light scattering (DLS) and zeta potential. The resulting liposomes were able to encapsulate doxorubicin with a loading efficiency greater than 90% and cumulative releases of less than 15% after 144 h. The internalization of these particles was examined by loading the liposomes with fluorescein or doxorubicin to test internalization through ...


Oxidation Of Zirconium Diboride Based And Molybdenum Based Ultra-High Temperature Ceramics, Gaoyuan Ouyang Jan 2016

Oxidation Of Zirconium Diboride Based And Molybdenum Based Ultra-High Temperature Ceramics, Gaoyuan Ouyang

Graduate Theses and Dissertations

Designing resilient high temperature alloys has been a long-standing engineering challenge. The driver for high temperature material research ranges from the need of developing robust thermal protection systems for hypersonic vehicles to increased operating temperatures (and hence Carnot efficiencies) of gas turbines. Ni based superalloys have been widely used in a variety of high temperature applications, but these alloys are limited by the melting temperature of Ni3Al and a variety of topologically close-packed phases that melt in the 1200 - 1300°C range. Transitioning to higher temperatures call for materials with high thermal stability. Hence, ceramics such as silicides, borides, nitrides ...


Altering Macrophage And Fibroblast Responses With Biomaterials For Drug Delivery, Wound Healing, And Tissue Engineering, Hannah Bygd Jan 2016

Altering Macrophage And Fibroblast Responses With Biomaterials For Drug Delivery, Wound Healing, And Tissue Engineering, Hannah Bygd

Graduate Theses and Dissertations

Even with significant advances in the development of biomaterials for drug delivery, tissue engineering scaffolds, artificial organs, and other medical devices, one obstacle that remains is a limited understanding of material biocompatibility. Ultimately, the success or failure of these biomaterials depends on the extent of the wound healing and foreign body response following implantation. As macrophage phenotype is dynamic throughout the course of these processes, this research targets these cells to engineer improved materials for modern healthcare applications, and to better understand the material parameters that influence biocompatibility. Evidence shows that polymeric systems can influence the function of macrophages, but ...


Polymer Nanodielectrics And Sensors For Capacitor And Cable Applications, Weixing Sun Jan 2015

Polymer Nanodielectrics And Sensors For Capacitor And Cable Applications, Weixing Sun

Graduate Theses and Dissertations

Capacitive polymer-matrix composites (PMCs) were fabricated with various nanofillers, defined as nanodielectrics. Surface modification of nanofillers was conducted to improve the homogeneity of nanocomposites. A capacitive sensor was designed and fabricated to measure dielectric properties of thermally aged cable jackets for the purpose of nuclear power plant (NPP) cable status monitoring.

Silanized-Si/epoxy nanocomposites were studied for structural capacitors. The surface treatment of Si nanoparticles by silane coupling agents was achieved to improve dispersion of nanofillers in an epoxy matrix. The nanocomposite shows an increase of dielectric breakdown strength and dielectric constant with no significant increase in loss tangent at ...


Tailoring Device-Scale Properties In Organic Electronics: Morphological, Optical And Electrode-Interface Related Approaches, Moneim Reda Ismail Jan 2015

Tailoring Device-Scale Properties In Organic Electronics: Morphological, Optical And Electrode-Interface Related Approaches, Moneim Reda Ismail

Graduate Theses and Dissertations

In era of dwindling fossil fuel supplies, increasing energy demand and high rates of carbon emission, investment in the clean and renewable-energy market is now the goal of many governments. This global prospect pushes the countries to consolidate new policies and rules to increase the production of cost-effective resources and grow the deployment in renewable energy. Sunlight, wind, waves and geothermal heat are the natural energy resources that strongly contribute to our global energy consumption. Organic materials - restricted to those that have conjugated structure and exhibit semiconducting properties - have gained intense interest in research and academia, leading to efficient and ...


Design And Development Of High-Performance Lead-Free Piezoelectric Ceramics, Xiaoming Liu Jan 2015

Design And Development Of High-Performance Lead-Free Piezoelectric Ceramics, Xiaoming Liu

Graduate Theses and Dissertations

Piezoelectric ceramics have been widely used in the commercial applications of actuators, sensors, etc. Nowadays, Pb(Zr,Ti)O3-based (PZT) ceramics, which contain ≥ 60 wt.% of lead, dominate the market due to their excellent electromechanical properties. The large electric field induced polarization and strain developed in PZT piezoceramics are intimately related to the morphotropic phase boundary (MPB). This has been attributed to the coexistence of tetragonal and rhombohedral perovskite phases. However, toxic lead severely threatens the environment and human health, as a significant amount of lead is released into the air during the fabrication and disposal. Thus, there is an ...


Physical Properties Of Various Conductive Diborides And Their Binaries, Austin Harold Shaw Jan 2015

Physical Properties Of Various Conductive Diborides And Their Binaries, Austin Harold Shaw

Graduate Theses and Dissertations

Hard, wear-resistant materials have potential utility as both coatings and bulk components in wear-prone applications. First-principle calculations performed by other investigators indicated that TaB2 and WB2 could be in the class of ultra-hard materials (hardness > 45 GPa), while MoB2 could be slightly less hard, but still in the "super-hard" range (hardness >30 GPa). However, relatively little empirical work has been done to confirm or refute such ultra-hard/super-hard expectations for the materials, and they have seen essentially no engineering use.

In this study, research was performed to determine whether:

 MoB2, NbB2, TaB2, and WB2 have high hardness.

 These borides have ...


Computational Design Of New Scintillator Chemistries And Defect Structures, Hyung Jin Kim Jan 2015

Computational Design Of New Scintillator Chemistries And Defect Structures, Hyung Jin Kim

Graduate Theses and Dissertations

The focus of this thesis is computationally designing inorganic scintillators previously predicted by informatics, which have not been validated computationally. Density Functional Theory (DFT) calculations were performed to (1) select garnet host lattices that are good scintillators, thereby down selecting from compounds previously identified via informatics, and (2) identify co-dopant chemistries in perovskites which enhance scintillator property. In this thesis, the property of focus is bandgap, which in general has an inverse correlation to light yield. The total energy code Cambridge Sequential Total Energy Package (CASTEP) was used for performing DFT calculations, taking advantage of its speed in modeling the ...


Mechanochemical Synthesis Of Hydrogen-Storage Materials Based On Aluminum, Magnesium And Their Compounds, Ihor Z. Hlova Jan 2015

Mechanochemical Synthesis Of Hydrogen-Storage Materials Based On Aluminum, Magnesium And Their Compounds, Ihor Z. Hlova

Graduate Theses and Dissertations

Over the last few decades, interest in hydrogen-storage materials as an alternative high-efficiency and safe, green energy carriers is steadily increasing. Among numerous hydrides scrutinized for the purpose over the past 10-15 years, aluminum- and magnesium-based systems attract continued attention, mainly because of their high gravimetric capacity and low cost. However, difficulties associated with facile synthesis and hence the reversibility, relatively high desorption temperatures, and sluggish kinetics in many of these systems are still of great concern and hold them back from broad, large-scale applications, e.g. in automotive industry.

Our research was devoted to studies of mechanochemical activation and ...


Structure-Property Relationships In An Al Matrix Ca Nanofilamentary Composite Conductor With Potential Application In High-Voltage Power Transmission, Liang Tian Jan 2015

Structure-Property Relationships In An Al Matrix Ca Nanofilamentary Composite Conductor With Potential Application In High-Voltage Power Transmission, Liang Tian

Graduate Theses and Dissertations

This study investigated the processing-structure-properties relationships in an Al/Ca composites using both experiments and modeling/simulation. A particular focus of the project was understanding how the strength and electrical conductivity of the composite are related to its microstructure in the hope that a conducting material with light weight, high strength, and high electrical conductivity can be developed to produce overhead high-voltage power transmission cables. The current power transmission cables (e.g., Aluminum Conductor Steel Reinforced (ACSR)) have acceptable performance for high-voltage AC transmission, but are less well suited for high-voltage DC transmission due to the poorly conducting core materials ...


Dielectric Properties And Degradation Monitoring In Polymer-Matrix Structural Composites, Connor Daily Jan 2015

Dielectric Properties And Degradation Monitoring In Polymer-Matrix Structural Composites, Connor Daily

Graduate Theses and Dissertations

Polymer-matrix composites (PMCs), material systems made of two or more phases, are increasingly being utilized in aerospace applications due to their high strength-to-weight ratios and corrosion resistance. The present reasearch investigates two different types of PMCs: particle-reinforced and fiber-reinforced.

To adequately describe some surprising properties that are observed in polymer-matrix composites reinforced with nanoscale filler particles, a three-phase theoretical model is proposed that is suitable for describing the effective permittivity of polymer-matrix composites containing spherical nanoparticles. The model accounts for the presence of an interphase region, which takes on a dominant role in influencing properties of nano-filled composites due to ...


Effects Of Alloying Elements On The Microstructure And Fatigue Properties Of Cast Iron For Internal Combustion Engine Exhaust Manifolds, David Jon Eisenmann Jan 2015

Effects Of Alloying Elements On The Microstructure And Fatigue Properties Of Cast Iron For Internal Combustion Engine Exhaust Manifolds, David Jon Eisenmann

Graduate Theses and Dissertations

In the design of exhaust manifolds for internal combustion engines the materials used must exhibit resistance to corrosion at high temperatures while maintaining a stable microstructure. Cast iron has been used for manifolds for many years by auto manufacturers due to a combination of suitable mechanical properties, low cost, and ease of casting. Over time cast iron is susceptible to microstructural changes, corrosion, and oxidation which can result in failure due to fatigue. This thesis seeks to answer the question: “Can observed microstructural changes and measured high temperature fatigue life in cast iron alloys be used to develop a predictive ...


Evaluation Of Titanium Carbide Metal Matrix Composites Deposited Via Laser Cladding, Daniel Thomas Cavanaugh Jan 2015

Evaluation Of Titanium Carbide Metal Matrix Composites Deposited Via Laser Cladding, Daniel Thomas Cavanaugh

Graduate Theses and Dissertations

Metal matrix composites have been widely studied in terms of abrasion resistance, but a particular material system may behave differently as particle size, morphology, composition, and distribution of the hardening phase varies. The purpose of this thesis was to understand the mechanical and microstructural effects of combining titanium carbide with 431 series stainless steel to create a unique composite via laser cladding, particularly regarding wear properties. The most predominant effect in increasing abrasion resistance, measured via ASTM G65, was confirmed to be volume fraction of titanium carbide addition. Macrohardness was directly proportional to the amount of carbide, though there was ...


Invariant And Univariant Eutectic Solidification In Ternary Alloys, Irmak Sargin Jan 2015

Invariant And Univariant Eutectic Solidification In Ternary Alloys, Irmak Sargin

Graduate Theses and Dissertations

While solidification structures with a large variety of morphologies and scales continue to be promising candidates for advanced applications in addition to the conventional ones, solidification science has been focused on understanding and building the bridges between theory and application, aiming to describe the solidification process at all length scales and enabling enhanced control over the final microstructure and resulting material properties. The knowledge of solidification built over the decades has been mostly based on simple cases like single phase formation one or two component or coupled growth in peritectic or eutectic alloys, whereas the understanding on much more complex ...


Vacuum Insulation Panel Core Materials And Modelling The Thermal Conductivity Of Granular Materials, Boyce Sek Koon Chang Jan 2015

Vacuum Insulation Panel Core Materials And Modelling The Thermal Conductivity Of Granular Materials, Boyce Sek Koon Chang

Graduate Theses and Dissertations

A majority of the energy consumed by the average household is used for space heating and cooling. Typically, these buildings are equipped with fiberglass and polystyrene foam insulation. In order to reduce energy consumption, vacuum insulation panels (VIP) were developed. Although VIPs provide high performance heat insulation, they are much more expensive relative to traditional insulation mainly due to the use of fumed silica as the core material. Hence, the goal of this research is to devise a low cost core material, which would allow widespread implementation of VIPs. Diatomaceous earth and glass bubbles were studied for their potential as ...


Structure-Property Relationships In Rare Earth Intermetallic Compounds Rfe4ge2 And R117m52+Xx112+Y, Jing Liu Jan 2014

Structure-Property Relationships In Rare Earth Intermetallic Compounds Rfe4ge2 And R117m52+Xx112+Y, Jing Liu

Graduate Theses and Dissertations

Rare earth-based intermetallic compounds continue to draw considerable attention due to their fundamental importance in understanding structure-property relationships and potential for practical applications based on a variety of phenomena. The focus of this project is to employ two rare earth intermetallic systems: RFe4Ge2 and R117M52+xX112+y ternary intermetallic systems as model candidates to uncover the underlying electronic, atomic and microscopic interactions that result in a strong coupling between the crystallographic and magnetic sub-lattices.

A systematic investigation of the structure, magnetic and thermal properties of DyFe4Ge2 has been performed. Magnetization of DyFe4Ge2 measured as a function of temperature in 1 ...


Novel Plant Oil-Based Thermosets And Polymer Composites, Kunwei Liu Jan 2014

Novel Plant Oil-Based Thermosets And Polymer Composites, Kunwei Liu

Graduate Theses and Dissertations

Because of the continuously increasing price of petroleum resources and an increase in environmental awareness, researchers are actively trying to produce polymers based on biorenewable resources to replace the traditional petroleum-based plastics. This presentation will discuss: (1) a novel thermoset based on acrylated epoxidized soybean oil (AESO) and methacrylated eugenol (ME); (2) a biocomposites from tall oil-based polyamide (PA) with lignin-cellulose fiber (LCF) as fillers.

Project 1: A biorenewable thermoset was prepared by copolymerizing AESO/ME via free radical polymerization. Both of the starting materials, soybean oil and eugenol, are biorenewable. The thermal, mechanical, and rheological properties of this thermoset ...


Objective Forensic Analysis Of Striated, Quasi-Striated And Impressed Toolmarks, Ryan Edward Spotts Jan 2014

Objective Forensic Analysis Of Striated, Quasi-Striated And Impressed Toolmarks, Ryan Edward Spotts

Graduate Theses and Dissertations

Following the 1993 Daubert v. Merrell Dow Pharmaceuticals, Inc. court case and continuing to the 2010 National Academy of Sciences report, comparative forensic toolmark examination has received many challenges to its admissibility in court cases and its scientific foundations. Many of these challenges deal with the subjective nature in determining whether toolmarks are identifiable. This questioning of current identification methods has created a demand for objective methods of identification - "objective" implying known error rates and statistically reliability. The demand for objective methods has resulted in research that created a statistical algorithm capable of comparing toolmarks to determine their statistical similarity ...


The Clamping Force Of Heat Shrinkable Fittings, David K. Rehbein, B. J. Skillings, J. F. Smith, Donald O. Thompson Jan 1983

The Clamping Force Of Heat Shrinkable Fittings, David K. Rehbein, B. J. Skillings, J. F. Smith, Donald O. Thompson

Review of Progress in Quantitative Nondestructive Evaluation

A number of alloys exhibit a phenomenon which has come to be known as ‘shape memory’. Without exception these alloys undergo a rather special type of martensitic transformation which results from one or another of the elastic constants1–7 weakening with changing temperature to the point that at the transformation temperature the transforming phase becomes both mechanically and thermodynamically unstable. ‘Shape memory’ is exhibited in the following way. A specimen at a temperature above the martensitic transformation is shaped to some desired form. The specimen is then cooled below its transformation temperature and deformed. Subsequent heating of the specimen through ...