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Full-Text Articles in Engineering
Nanofibrils As The Basic Building Blocks Of Spider Silk, Qijue Wang
Nanofibrils As The Basic Building Blocks Of Spider Silk, Qijue Wang
Dissertations, Theses, and Masters Projects
Spider silk is a natural high-performance biopolymer with superior mechanical properties, resulting from its hierarchical structure. With protein nanofibrils observed in various spider and silkworm silks, the critical role of nanofibrils in achieving the silk's mechanical behavior has been widely suggested by both experimental observations and numerical simulations. However, a close review of available evidence of silk nanofibrils reveals many crucial aspects are still largely ambiguous or unknown. This further hinders the development of advanced silk-based materials. The simple structure of the ribbon-like recluse (Loxosceles) silk provides an ideal opportunity to investigate silk nanofibrils. By studying the surface and internal …
Growth And Properties Of Vapor Diffused Nb3sn Coating For Superconducting Radiofrequency Accelerator Cavity Applications, Uttar Last Pudasaini
Growth And Properties Of Vapor Diffused Nb3sn Coating For Superconducting Radiofrequency Accelerator Cavity Applications, Uttar Last Pudasaini
Dissertations, Theses, and Masters Projects
The desire to reduce construction and operating costs of future SRF accelerators motivates the search for higher-performing alternative materials. Nb3Sn (Tc ~ 18.3 K and Hsh ~ 425 mT) is the front runner. The tin vapor diffusion process is currently the technique of choice to produce promising Nb3Sn-coated cavities. Understanding Nb3Sn nucleation and growth in this process is essential to progress. Samples representing different stages of Nb3Sn formation have been produced and studied to elucidate the effects of nucleation, growth, process conditions, and impurities. Nb3Sn films with thickness …
Boron Nitride Nanotubes (Bnnts) For Thermal Management And Structural Reinforcement, Mahmoud Samy Mohamed Fahmy Amin
Boron Nitride Nanotubes (Bnnts) For Thermal Management And Structural Reinforcement, Mahmoud Samy Mohamed Fahmy Amin
Dissertations, Theses, and Masters Projects
Boron nitride nanotubes (BNNTs) are a fascinating material that has a lot of potential applications due to its outstanding physical and chemical properties. BNNTs synthesized using different high- and low-temperature methods, unfortunately, contain 30-70% impurities. To maximize the potential of BNNTs, new characterization techniques and purification methods are needed, especially with respect to industrial applications. Research groups have used different characterization techniques to monitor the synthesis and purity of BNNTs. Quantitative and qualitative characterization of the tubes for quality or purity control has not been previously described in the literature. In this work, we created a comprehensive set of thermogravimetric …
Optical Characterization Of Dynamic Exchange Coupling Interaction In Ferromagnetic Heterostructures, Xiao Liu
Optical Characterization Of Dynamic Exchange Coupling Interaction In Ferromagnetic Heterostructures, Xiao Liu
Dissertations, Theses, and Masters Projects
This thesis presents the optical characterization of interfacial exchange coupling interaction in ferromagnetic bilayer heterostructures. Both static and dynamic magnetic response are investigated in the exchange-coupled Co2FeAl/(Ga,Mn)As bilayer system using static magneto-optical Kerr effect (MOKE) and time-resolved magneto optical Kerr effect (TRMOKE) techniques. The goal of this thesis is to understand the underlying physics of the interfacial exchange coupling effect on the ultrafast spin dynamics in a ferromagnetic metal/ferromagnetic semiconductor bilayer heterostructure. Our finding provides a viable pathway for designing advanced semiconductor spintronic devices for ultrafast low-power spin manipulation. First, a significant enhancement of the excitation efficiency of coherent magnetization …
Surface Modification Of Synthetic And Natural Polymers Using Deep Uv (172 Nm) Irradiation, Lopamudra Das
Surface Modification Of Synthetic And Natural Polymers Using Deep Uv (172 Nm) Irradiation, Lopamudra Das
Dissertations, Theses, and Masters Projects
The ability to modify the surfaces of polymers and impart desirable functionalities without affecting the bulk-mediated physical properties is vital for advanced materials development. Photochemical approaches to surface modification are particularly attractive as they minimize the need for use of hazardous materials used in conventional wet chemical technologies, and are relatively faster, efficient and convenient to use. In this research, we undertook a combined experimental and computational approach to understand the effect of deep UV irradiation on a broad range of polymeric materials, and develop a scalable and deployable surface modification strategy that could be extended to all. Four polyesters, …
Surfactant Free Emulsion Polymerization Of Poly(Styrene-Co-Methyl Methacrylate): Correlation Of Microsphere Characteristics With Monomer Reactivity And Water Solubility, Samantha Applin
Dissertations, Theses, and Masters Projects
Polymeric microspheres have been used in a broad range of applications from chromatographic separation techniques to analysis of air flow over aerodynamic surfaces. The preparation of microspheres from many polymer families has consequently been extensively studied using a variety of synthetic approaches. Although there are a myriad of polymeric microsphere synthesis methods, free-radical initiated emulsion polymerization is one of the most common techniques. In this work, poly(styrene-co-methyl methacrylate) microspheres were synthesized via surfactant-free emulsion polymerization. The effects of the co-monomer composition and addition time on particle size distribution, particle formation, and particle morphology were investigated. Particles were characterized using dynamic …
The Thin Ribbon Silk Of The Brown Recluse Spider: Structure, Mechanical Behavior, And Biomimicry, Sean Robert Koebley
The Thin Ribbon Silk Of The Brown Recluse Spider: Structure, Mechanical Behavior, And Biomimicry, Sean Robert Koebley
Dissertations, Theses, and Masters Projects
Silk has enormous potential as a next-generation material: it is a biopolymer spun from protein at ambient temperature and pressure, and the best spider silks are as strong as steel and tougher than Kevlar. Because of its green production, mechanical robustness, and biocompatibility, silk has been researched for use in a range of engineering and biomedical applications. However, despite exciting recent advances in artificial silk fabrication via recombinant techniques, reserachers remain unable to fully replicate the complex assembly and hierarchical structure of native silks. Herein, we describe our morphological and mechanical characterization of a uniquely simple model silk system that …
Canary Red: Preserving Cochineal And Contrasting Colonial Histories On Lanzarote, Sarah Mattes
Canary Red: Preserving Cochineal And Contrasting Colonial Histories On Lanzarote, Sarah Mattes
Dissertations, Theses, and Masters Projects
No abstract provided.
Magneto-Optics And Magneto-Transport Studies On Thin Films For Sensor Applications, Kaida Yang
Magneto-Optics And Magneto-Transport Studies On Thin Films For Sensor Applications, Kaida Yang
Dissertations, Theses, and Masters Projects
Recent progress and interest have bought considerable effort to bear on the synthesis and opportunities of magnetic thin films in different fields. There are applications in many fields, including remote sensing, waveguide applications, hard drive applications, etc. at the College of William and Mary, we have focused on utilizing magnetic thin films in some of these applications and are deeply involved in the optimization process of the thin films.
Superconducting Thin Films For Srf Cavity Applications: A Route To Higher Field Gradient Linacs, Wiliam Michael Roach
Superconducting Thin Films For Srf Cavity Applications: A Route To Higher Field Gradient Linacs, Wiliam Michael Roach
Dissertations, Theses, and Masters Projects
Many linear accelerator (linac) applications rely on the use of superconducting radio frequency (SRF) cavities. In order to overcome the current field gradient limits imposed by the use of bulk niobium, a model involving the deposition of alternating superconducting-insulating-superconducting (SIS) thin films onto the interior surface of SRF cavities has been proposed. Since SRF performance is a surface phenomenon, the critical surface of these cavities is less than 1 micron thick, thus enabling the use of thin films. Before such approach can successfully be implemented fundamental studies correlating the microstructure and superconducting properties of thin films are needed. to this …
Nonlinear Optical Studies Of Photoelastic Effect And Magneto-Plasmonics, Wei Zheng
Nonlinear Optical Studies Of Photoelastic Effect And Magneto-Plasmonics, Wei Zheng
Dissertations, Theses, and Masters Projects
Nonlinear optical (NLO) processes are optical phenomena involving a nonlinear response to an applied light field. Two kinds of nonlinearities are studied in this dissertation: magnetic-induced second-harmonic generation (MSHG) interacting with surface plasmon, called "nonlinear magnetoplasmonics" (NMP), and the nonlinear index induced by a strong pump beam in Titanium doped sapphire crystal, referred to as population-induced nonlinear index effect.;The fundamentals of the major effects involved are discussed, which include: surface plasmon and its field enhancement effect, MSHG technique and phenomenological calculations, the contrast ratio of magnetic switching, the calculation of lensing effects, population induced strain, and photoelastic effect. Furthermore, the …
Optical Characterization Of Magnetism In Magnetic/Nonmagnetic Heterostructures, Yichun Fan
Optical Characterization Of Magnetism In Magnetic/Nonmagnetic Heterostructures, Yichun Fan
Dissertations, Theses, and Masters Projects
This thesis focuses on the study of the static and dynamic magnetic interactions in ferromagnetic/nonmagnetic heterostructures using interface-specific and time-resolved optical techniques. The goal of this thesis is to elucidate the interface exchange coupling, magnetic anisotropy, and coherent spin dynamics in these advanced material systems, crucial to the realization of high performance spintronic devices.;First, a pronounced exchange bias (EB) phenomenon is observed in Fe/MgO (001) by magnetic second harmonic generation. The bulk magnetization does not, in marked contrast to typical systems where EB is manifested only in the net magnetization. The magnitude of the exchange bias varies with interface oxygen …
Surface Impedance Of Superconducting Radio Frequency (Srf) Materials, Binping Xiao
Surface Impedance Of Superconducting Radio Frequency (Srf) Materials, Binping Xiao
Dissertations, Theses, and Masters Projects
Superconducting radio frequency (SRF) technology is widely adopted in particle accelerators. There remain many open questions, however, in developing a systematic understanding of the fundamental behavior of SRF materials, including niobium treated in different ways and various other bulk/thin film materials that are fabricated with different methods under assorted conditions. A facility that can measure the SRF properties of small samples in a range of 2∼40 K temperature is needed in order to fully answer these questions. The Jefferson Lab surface impedance characterization (SIC) system has been designed to attempt to meet this requirement. It consists of a sapphire-loaded cylindrical …
Microscopic Dynamics And Transport Of Hydrogen In Proton Conducting Oxides, Erik J. Spahr
Microscopic Dynamics And Transport Of Hydrogen In Proton Conducting Oxides, Erik J. Spahr
Dissertations, Theses, and Masters Projects
The microscopic motion of hydrogen in solid oxides plays an important role in defect migration and reaction processes. Understanding the vibrational dynamics associated with both hydrogen-oxygen (O-H) bonds and the surrounding ionic environment allows one to better characterize these fundamental interactions. This thesis presents a comprehensive investigation into the vibrational decay dynamics of O-H and O-D stretch modes in crystalline oxides using time-resolved infrared pump-probe spectroscopy.;Measurements of the vibrational lifetimes of hydrogen related local modes in potassium tantalate (KTaO3) and titanium dioxide (TiO2 ) show that the localized O-H vibration is very closely tied to proton transport. In KTaO3 we …
Thin Film And Chemical Ordering Effects On The Magnetic Anisotropy In Binary Alloys, Jonathan Ronald Skuza
Thin Film And Chemical Ordering Effects On The Magnetic Anisotropy In Binary Alloys, Jonathan Ronald Skuza
Dissertations, Theses, and Masters Projects
This dissertation presents various investigations into the structure-property correlations in highly anisotropic FePt and FePd thin films and nanostructures. These binary alloy thin films may exhibit long-range chemical ordering (e.g. L10), which induces a strong uniaxial magnetic anisotropy whose orientation is dependent on the ordering direction in the thin film. The chemical ordering, and hence the magnetic anisotropy, in these thin films can be controlled and tailored through sputter deposition and ion implantation conditions followed by subsequent processing. Two novel fabrication methods, x-ray rapid thermal annealing (XRTA) and heavy ion implantation, successfully demonstrate the ability to obtain highly anisotropic nanometer-sized …
Enhanced Field Emission From Vertically Oriented Graphene By Thin Solid Film Coatings, Michael Bagge-Hansen
Enhanced Field Emission From Vertically Oriented Graphene By Thin Solid Film Coatings, Michael Bagge-Hansen
Dissertations, Theses, and Masters Projects
Recent progress and a coordinated national research program have brought considerable effort to bear on the synthesis and application of carbon nanostructures for field emission. at the College of William and Mary, we have developed field emission arrays of vertically oriented graphene (carbon nanosheets, CNS) that have demonstrated promising cathode performance, delivering emission current densities up to 2 mA/mm2 and cathode lifetime > 800 hours. The work function ( & phis;) of CNS and other carbonaceous cathode materials has been reported to be &phis;∼4.5-5.1 eV. The application of low work function thin films can achieve several orders of magnitude enhancement of …
First-Principles Calculations Of Nuclear Magnetic Resonance Chemical Shielding Tensors In Complex Ferroelectric Perovskites, Daniel Lawrence Pechkis
First-Principles Calculations Of Nuclear Magnetic Resonance Chemical Shielding Tensors In Complex Ferroelectric Perovskites, Daniel Lawrence Pechkis
Dissertations, Theses, and Masters Projects
Nuclear magnetic resonance (NMR) spectroscopy is one of the most important experimental probes of local atomistic structure, chemical ordering, and dynamics. Recently, NMR has increasingly been used to study complex ferroelectric perovskite alloys, where spectra can be difficult to interpret. First-principles calculations of NMR spectra can greatly assist in this task. In this work, oxygen, titanium, and niobium NMR chemical shielding tensors, s&d4; , were calculated with first-principles methods for ferroelectric transition metal prototypical ABO3 perovskites [SrTiO3, BaTiO 3, PbTiO3 and PbZrO3] and A(B,B')O3 perovskite alloys Pb(Zr1/2Ti1/2)O3 (PZT) and Pb(Mg1/3Nb2/3)O3 (PMN). The principal findings are 1) a large anisotropy between …
The Functionalization Of Carbon Nanosheets, Ronald A. Quinlan
The Functionalization Of Carbon Nanosheets, Ronald A. Quinlan
Dissertations, Theses, and Masters Projects
Carbon nanosheets are a novel two-dimensional nanostructure made up of 2-20 graphene atomic planes oriented with their in-plane axis perpendicular to the growth substrate. Previous efforts in developing nanosheet technology have focused on the characterization of the system and their development as an electron source due to the high atomic enhancement factor (beta) and low turn on field. Further investigation of nanosheets as high surface area electrodes revealed poor wetting by polymeric material and extreme hydrophobic behavior.;Because nanosheet technology has promise as a high surface area electrode material, this thesis research has focused on three areas of interest: the enhancement …
Time-Resolved Magnetic Flux And Ac-Current Distributions In Superconducting Yttrium Barium Copper Oxide Thin Films And Multifilaments, Ran Yang
Dissertations, Theses, and Masters Projects
Time-resolved magneto-optical imaging (TRMOI) technique allows dynamic ac transport measurements on superconductors. The high time and spatial resolutions of the measurements also offer good quantitative data analysis of the MO images. YBa2Cu 3O7-delta (YBCO) was discovered as a high-temperature superconductor (HTSC) which has wide applications due to its high critical temperature of Tc = 91 K, and high critical current density Jc in the order of 106-7 Acm-2. Many of the applications require high ac current load and a high magnetic field. We study the interaction behavior of YBCO thin films in an ac transport current and a dc magnetic …
Synthesis And Field Emission Properties Of Carbon Nanostructures, Kun Hou
Synthesis And Field Emission Properties Of Carbon Nanostructures, Kun Hou
Dissertations, Theses, and Masters Projects
This dissertation focuses on developing carbon nanostructures for application as the electron emissive material in novel back-gated triode field emission devices. The synthesis, characterization, and field emission properties of carbon nanostructures, including 1-D carbon nanofibers (CNF), 2-D carbon nanosheets (CNS), and chromium oxide coated carbon nanosheets (CrOx-CNS), are presented in this work.;First, we have fabricated aligned carbon nanofiber based back-gated triode field emission devices and confirmed the operation of these devices. 1-D carbon nanofibers were directly synthesized on blank TiW substrates using direct current plasma enhanced chemical vapor deposition. It was found that the morphology of carbon nanofibers could be …
Field Emission Study Of Carbon Nanostructures, Xin Zhao
Field Emission Study Of Carbon Nanostructures, Xin Zhao
Dissertations, Theses, and Masters Projects
Recently, carbon nanosheets (CNS), a novel nanostructure, were developed in our laboratory as a field emission source for high emission current. to characterize, understand and improve the field emission properties of CNS, a ultra-high vacuum surface analysis system was customized to conduct relevant experimental research in four distinct areas. The system includes Auger electron spectroscopy (AES), field emission energy spectroscopy (FEES), field emission I-V testing, and thermal desorption spectroscopy (TDS). Firstly, commercial Mo single tips were studied to calibrate the customized system. AES and FEES experiments indicate that a pyramidal nanotip of Ca and O elements formed on the Mo …
Silicon Oxynitride: A Field Emission Suppression Coating, Nimel D. Theodore
Silicon Oxynitride: A Field Emission Suppression Coating, Nimel D. Theodore
Dissertations, Theses, and Masters Projects
We have studied coatings deposited using our inductively-coupled RF plasma ion implantation and desposition system to suppress field emission from large, 3-D electrode structures used in high voltage applications, like those used by Thomas Jefferson National Accelerator Facility in their DC-field photoelectron gun. Currently time and labor-intensive hand-polishing procedures are used to minimize field emission from these structures. Previous work had shown that the field emission from polished stainless steel (27 muA of field-emitted current at 15 MV/m) could be drastically reduced with simultaneous deposition of sputtered silicon dioxide during nitrogen implantation (167 pA of field-emitted current at 30 MV/m). …
Photochemical Modification Of Polyethylene Terephthalate Surface, Zhengmao Zhu
Photochemical Modification Of Polyethylene Terephthalate Surface, Zhengmao Zhu
Dissertations, Theses, and Masters Projects
The prospect of obtaining desired surface-mediated characteristics while retaining bulk-mediated physical properties and avoiding potential environmental issues with wet chemical technology lends considerable appeal to photochemical approaches to surface modification.;We undertook a combined experimental and computational approach to investigate the effect of deep UV irradiation on the polyethylene terephthalate (PET) surface. its response to 172 nm UV from a xenon examiner lamp in the absence of oxygen was characterized with X-ray Photoelectron Spectroscopy (XPS), Time of Flight/Secondary Ion Mass Spectrometry (ToF/SIMS), transmission infrared spectroscopy (IR), and Atomic Force Microscopy (AFM). The surface chemistry details suggested that the primary photochemical reactions …
Vibrational Lifetimes Of Hydrogen And Oxygen Defects In Semiconductors, Baozhou Sun
Vibrational Lifetimes Of Hydrogen And Oxygen Defects In Semiconductors, Baozhou Sun
Dissertations, Theses, and Masters Projects
Characterization of defect and impurity reactions, dissociation, and migration in semiconductors requires a detailed understanding of the rates and pathways of vibrational energy flow and of the coupling mechanisms between local modes and the phonon bath of the host material. Information on the inelastic microscopic interaction can be obtained by measuring the lifetime of local vibrational modes. This dissertation presents lifetime measurements of hydrogen and oxygen defects in semiconductors by means of time-resolved infrared pump-probe spectroscopy.;First, we measured the vibrational lifetime of H- and D-related bending modes in Si and other semiconductors. Time-resolved pump-probe and linewidth measurements reveal that the …
Electron Stimulated Desorption Of Hydronium Ions From Chromium Oxide Surfaces, Charles Randal Cole
Electron Stimulated Desorption Of Hydronium Ions From Chromium Oxide Surfaces, Charles Randal Cole
Dissertations, Theses, and Masters Projects
The mass spectral peak observed at 19 amu in residual gas analyzers at very high (<10-6 Torr) and ultrahigh vacuum (<10 -9 Torr) has often been attributed to fluorine. Using Fourier Transform Mass Spectrometry, the hydronium ion, H3O+, has been fully resolved from F+ and its correlation to water vapor concentration was determined to be linear as expected for a gas phase process. The comparison of the mass 19 signals for a conventional quadrupole mass spectrometer and a Fourier transform mass spectrometer on the same vacuum chamber indicated hydronium was the source of mass 19.;The partial pressures of H2O in the very high vacuum range and higher suggest there is sufficient H2O density for the hydronium ions to form through ion-molecule interactions because hydronium formation was found to directly correlate with the H2O partial pressure. However, in a QMS at UHV, formation of H3O+ appears to occur principally by electron stimulated desorption (ESD). Introducing hydrogen into the system from 1 Langmuir exposure to saturation (1 x 10-6 Torr for 8 hours) increased the H3O + ESD yield detected by the QMS by as much as a factor of 10. The initial hydronium ESD cross section from a hydrogen saturated grid was estimated to be sigma ∼ 1 x 10-19, cm2.;TOF-SIMS sputter yields from the stainless steel grid of a quadrupole mass spectrometer also showed small signals of H3O+, as well as its constituents (H+, O+ and OH) and a small amount of fluorine as F-, but no F+ or F+ complexes (HF+, etc.). Using x-ray photoelectron spectroscopy, a small amount (0.4%) of fluorine was found in the surface of stainless steel. Electron bombardment reduces the fluorine bound in surface complexes, but not metal halides found below the surface. However, heating the sample eliminated the F 1s signal entirely, indicating that fluorine is not likely to be the source of mass 19 in residual gas analysis. Also, changes in the spectral shoulders on the O 1s and Cr 2P3/2 peaks show that hydrogen dosing stainless steel and chromium increases the amount of hydroxides at the surface, while heating and electron bombardment reduce them.
Characterization Of Ionic, Dipolar And Molecular Mobility In Polymer Systems, Zhenrong Guo
Characterization Of Ionic, Dipolar And Molecular Mobility In Polymer Systems, Zhenrong Guo
Dissertations, Theses, and Masters Projects
Changes in the ionic and dipolar molecular mobility in a polymer system are the basis for the changes in the dielectric mechanical properties of polymer materials. Frequency Dependent Dielectric Measurements (FDEMS) and Ion Time-of-Flight (ITOF) are two important techniques to investigate ionic and dipolar molecular mobility in polymer systems. The results can be related to the macro- and molecular dielectric, electrical and dynamic properties of polymeric materials. The combination of these two methods provides a full view of electric, dielectric and dynamic behavior for the systems as they undergo chemical and/or physical changes during polymerization crystallization, vitrification, and/or phase separation.;The …
Ultrasonic Signal Detection And Recognition Using Dynamic Wavelet Fingerprints, Jidong Hou
Ultrasonic Signal Detection And Recognition Using Dynamic Wavelet Fingerprints, Jidong Hou
Dissertations, Theses, and Masters Projects
A novel ultrasonic signal detection and characterization technique is presented in this dissertation. The basic tool is a simplified time-frequency (scale) projection which is called a dynamic wavelet fingerprint. Take advantage of the matched filter and adaptive time-frequency analysis properties of the wavelet transform, the dynamic wavelet fingerprint is a coupled approach of detection and recognition. Different from traditional value-based approaches, the dynamic wavelet fingerprint based technique is pattern or knowledge based. It is intuitive and self-explanatory, which enables the direct observation of the variation of non-stationary ultrasonic signals, even in complex environments. Due to this transparent property, efficient detection …
Solid State Nmr Characterization Of Conductive Polyanilines, Yanina Anatolievna Goddard
Solid State Nmr Characterization Of Conductive Polyanilines, Yanina Anatolievna Goddard
Dissertations, Theses, and Masters Projects
Different forms of ring deuterated polyaniline with different conductivity have been characterized by solid state deuteron nuclear magnetic resonance.;Quadrupole echo (QE) spectra of all forms of polyaniline consist of a superposition of lineshapes for nearly rigid aromatic rings and a small fraction of rings which undergo fast 180?? flips. The intensity of the fast flipping component is temperature dependent and different for conductive emeraldine salt (ES) and non-conductive emeraldine base (EB). This is a manifestation of the different structure and morphology of these polymers.;Simultaneous measurements of QE lineshapes and the relaxation time anisotropies allowed an accurate description of motion in …
Dual Energy Scanning Beam X -Radiography, Randolph Frank Wojcik
Dual Energy Scanning Beam X -Radiography, Randolph Frank Wojcik
Dissertations, Theses, and Masters Projects
Dual energy X-radiography is a method first developed in the mid-1970's by which one uses the information contained in the energy spectrum of the transmitted X-ray flux through an object. With this information one can distinguish the types of materials present in a radiograph and thus allow a computer to subtract them from the image enhancing the contrast of the remaining materials. Using this method, one can see details, which would have been hidden by overlying structures of other materials such as seen in radiographs of parts, made up of mixtures of metals and composites. There is also great interest …
Synthesis And Characterization Of Polyimide Residuum, Friable Balloons, Microspheres And Foams, Erik Saul Weiser
Synthesis And Characterization Of Polyimide Residuum, Friable Balloons, Microspheres And Foams, Erik Saul Weiser
Dissertations, Theses, and Masters Projects
In order to meet requirements of future NASA systems for advanced polymeric cellular materials, research was undertaken to develop the next generation of polyimide foams which could be utilized as a reusable structural insulation on future Reusable Launch Vehicle (RLV) Programs. This research activity focused on developing polyimide foam and foam structures which were made using monomeric solutions or salt solutions formed from the reaction of a dianhydride and diamine dissolved in a mixture of foaming agents and alkyl alcohols. This process produced a precursor solid residuum which could then be manufactured into foams, friable balloons and microspheres. Polyimide foams …