Engineering Commons^™

Nanostructured Morphologies In Glassy Polymer Networks, Brian Greenhoe

Dissertations

The body of this work describes a novel approach for the dispersion of multi-walled carbon nanotubes in a high T_g epoxy prepolymer matrix using a twin screw high-shear continuous reactor. The method demonstrated improves on previous dispersion methods in several ways. It offers increased efficiency through excellent heat transfer, while being solvent-less, scale-able, and tailorable to drive dispersion states to judiciously chosen dispersion states. Furthermore, it was shown that dispersion state and agglomerate morphology can be directed, in several ways, through processing conditions and also by controlling the matrix viscosity profile through cure. Broadband dielectric spectroscopy, optical hot-stage microscopy, …

Confinement Effects And Magnetic Interactions In Magnetic Nanostructures, Kristen Lee Stojak Repa

USF Tampa Graduate Theses and Dissertations

Multifunctional nanocomposites are promising for a variety of applications ranging from microwave devices to biomedicine. High demand exists for magnetically tunable nanocomposite materials. My thesis focuses on synthesis and characterization of novel nanomaterials such as polymer nanocomposites (PNCs) and multi-walled carbon nanotubes (MWCNTs) with magnetic nanoparticle (NP) fillers.

Magnetite (Fe₃O₄) and cobalt ferrite (CoFe2O4) NPs with controlled shape, size, and crystallinity were successfully synthesized and used as PNC fillers in a commercial polymer provided by the Rogers Corporation and poly(vinylidene fluoride). Magnetic and microwave experiments were conducted under frequencies of 1-6 GHz in the presence of …

Atomistic And Mesoscopic Simulations Of Heat Transfer Across Heterogeneous Material Interfaces, Sridhar Sadasivam

Open Access Dissertations

The study of heat transfer and the associated thermal interface resistance at heterogeneous material interfaces is over 70 years old since the first measurements of thermal interface resistance by Kapitza in 1941. However, recent developments in experimental metrology techniques that enable spectrally-resolved phonon transport measurements at the nanoscale along with the development of high-fidelity simulation methods have provided a renewed interest in the fundamental physics of heat transfer across interfaces. Miniaturized electronic devices and nanostructured materials for energy applications are among technologies that would benefit from a fundamental understanding of interfacial thermal transport. This dissertation focuses on the study of …

Investigation Of Cnt-Induced Escherichia Coli Lysis And Protein Release, Abdollah Mosleh

Graduate Theses and Dissertations

This research investigated the use of carbon nanotubes (CNTs) as a treatment to increase the permeability of a bacterial cell wall. Recombinant Escherichia coli BL21 (DE3) containing a plasmid that expressed Green Fluorescent Protein (GFP) and -lactamase were exposed to CNTs under various levels of agitation for different times. Fluorescence assay for GFP, optical absorbance for -lactamase activity, and Transmission Electron Microscopy (TEM) were used to determine the amount of released protein, and visually examine the permeability enhancement of the cells, respectively. It was found that more -lactamase was present in the culture fluid after treatment with CNTs in a …

Nonlinear Dynamics Of Electrostatically Actuated Nanotweezers, Bin Liu

Theses and Dissertations

Bin Liu, Nonlinear Dynamics of Electrostatically Actuated Nanotweezers. Master of Science (MS), May 2016, 77 pp, 6 tables, 59 figures, references, 25 titles. The amplitude-frequency response of electrostatic nanotube nanotweezer device system is investigated; soft alter current was setting at near half natural frequency impulse on nanotubes which are referred to as two arms, parametric and primary resonances will be shown in the results, respectively. Firstly we are using the Method of Multiple Scales (MMS) analytical model; results will be compared with Reduced Order Model (ROM). By variation and comparison of multiple parameters including van der wall molecular forces, electrostatic …

Carbon And Boron Nitride Nanotube Fabricated Supercapacitors, Derek Christian Demuth

Electrical & Computer Engineering Theses & Dissertations

The fabrication of supercapacitor devices consisting of boron nitride nanotubes (BNNTs) and carbon nanotubes (CNTs) has great theoretical capabilities of high specific capacitance, energy density, and power density. Various methods of dispersion and deposition are utilized to optimize such supercapacitors with BNNTs and CNTs, and also to produce devices with only CNTs to use as a benchmark. In addition to capacitance measurements, BNNTs that were exposed to nitric acid were compared to fabricated devices without acid exposure.

Dispersion has been accomplished through the trial of many solvents and surfactants for both CNTs and BNNTs. Deposition techniques that are utilized rely …

Electro-Mechanical Characterization Of Carbon Nanotube Sheets In Simulated Space Environments: The Dawn Of “Carbon Spacecraft”, Jacob W. Singleton

Theses and Dissertations

Carbon nanotube (CNT) materials are exciting candidates for spacecraft by virtue of their unprecedented specific mechanical and electrical properties. Analysis in this thesis identifies 14 types of CNT-sheets with distinct variables, and discovers the mechanisms controlling macroscopic properties. Specimen variables include acid treatment, polymer coatings, production method, and combinations. Mechanical testing includes tensile-tests and investigation with scanning electron microscopy and energy-dispersive x-ray spectroscopy. Physical properties testing include electromagnetic interference (EMI) shielding effectiveness (SE) and electrical conductivity. This research also highlights the resilience of CNT-sheets to atomic oxygen and thermal fatigue qualifying them for performance in space. EP CNT-sheets have decreased …

Removal Of Perfluorooctanoic Acid From Water Using Primitive, Conventional And Novel Carbonaceous Sorbent Materials, Christopher K. Brown

Theses and Dissertations

Polyfluoroalkyl Substances (PFAS), like perfluorooctanoic acid, have been used for the last 50 years in a wide variety of industrial processes and consumer-based products, including polymer additives, lubricants, fire retardants and suppressants, pesticides, and surfactants (Buck et al. 2015). The Department of Defense (DoD) has used PFAS-based Aqueous Film Forming Foam (AFFF) at fire training facilities and aircraft hangars. AFFF has contaminated approximately 600 sites classified as fire training facilities with PFAS (Huang, 2013).

This study focused on testing the most likely carbonaceous adsorbent compounds to remediate PFAS-contaminated sites on Air Force installations. Batch tests were performed to determine the …

The Effects Of Carbon Nanotubes On Cells In A Synthetic Oxygen Carrier Enriched Alginate Scaffold, Joshua Paul Tate

LSU Master's Theses

Abstract Huge progress has been made in the development of three dimensionally printed tissue structures. With the use of cells, three dimensional printers, and CAD drawing software, donor identical structures can be fabricated. However, cell scaffolds currently lack significant mechanical integrity which can result in reduced cellular survival, attachment, and nutrient delivery. For this reason, multiple strategies have been developed to increase and improve mechanical stability within engineered constructs without having to sacrifice cell viability. The hypothesis of this paper was that incorporating Perfluorotributylamine (PFTBA), a greenhouse gas, with single walled carbon nanotubes (SWCNT), a allotrope of carbon with a …

Degradation And Exciton Energy Transfer Studies In Single-Walled Carbon Nanotube Bundles, Abhishek Gottipati

Legacy Theses & Dissertations (2009 - 2024)

Single walled carbon nanotubes (SWNTs) due to their unique optical behavior, large surface area, robust mechanical strength and electrical properties make them one of the ideal candidates for sensing and opto-electronic applications. In this work, we explore the energy transfer (exciton energy transfer-EET) phenomena occurring between nanotubes in bundles, using resonance Raman spectroscopy.