Open Access. Powered by Scholars. Published by Universities.®
Physical Sciences and Mathematics Commons™
Open Access. Powered by Scholars. Published by Universities.®
Articles 31 - 60 of 63
Full-Text Articles in Physical Sciences and Mathematics
The Promotion Of Poly(Methyl Methacrylate) Depolymerization By Metal-Based Initiators, Jason Andrew Macko
The Promotion Of Poly(Methyl Methacrylate) Depolymerization By Metal-Based Initiators, Jason Andrew Macko
Dissertations, Theses, and Masters Projects
No abstract provided.
Characterization Of Epoxy-Amine Systems And Nylon-11 And Pvdf Degradation, Wendy Raquel Mahler
Characterization Of Epoxy-Amine Systems And Nylon-11 And Pvdf Degradation, Wendy Raquel Mahler
Dissertations, Theses, and Masters Projects
No abstract provided.
Microstructural Characterization Of An Ultra-High-Performance Polyimide, April Heather Baugher
Microstructural Characterization Of An Ultra-High-Performance Polyimide, April Heather Baugher
Dissertations, Theses, and Masters Projects
The motivation for this study was to further characterize a relatively new high-temperature polymer for application as a matrix resin for carbon fiber composites. The two primary questions addressed in this study dealt with the structural and chemical changes occurring in these polymers on exposure to high temperature.;To investigate the structural changes in the heat-treated samples, a positron annihilation lifetime spectrometer was designed, built and optimized. Because the lifetime of a positron in a material reflects the electronic structure of the material in which it annihilates, measurements by positron annihilation lifetime spectroscopy can be used to investigate changes in a …
The Synthesis, Characterization, And Molecular Modeling Of Cyclic Arylene Ether Oligomers, Sheeba Ahmed
The Synthesis, Characterization, And Molecular Modeling Of Cyclic Arylene Ether Oligomers, Sheeba Ahmed
Dissertations, Theses, and Masters Projects
Cyclophanes are a family of bridged cyclic aromatic compounds that have found extensive applications in host-guest chemistry, molecular recognition, biomimetics and most recently as precursors in ring-opening polymerizations.;This research presents the synthesis of several novel cyclic arylene ether oligomers, based on 1,3-bis(4-fluorobenzoyl) benzene and 3,3{dollar}\sp\prime{dollar}-methylene diphenol and 3,3{dollar}\sp\prime{dollar}-(ethylene dioxy) diphenol, and their characterization by LC-MS/MS, 1-D {dollar}\sp1{dollar}H-NMR and x-ray crystallography. Electrospray ionization (ES) along with MS/MS was used to characterize cyclic oligomers of molecular weight up to 1600 Da. The thermal properties of these cyclic oligomers were studied by differential scanning calorimetery (DSC) and thermal gravimetric analysis (TGA).;These cyclic oligomers …
A Study Of Poly(Vinyl Chloride) Microstructure, Vadim Guennadievich Zaikov
A Study Of Poly(Vinyl Chloride) Microstructure, Vadim Guennadievich Zaikov
Dissertations, Theses, and Masters Projects
High-field {dollar}\sp{lcub}13{rcub}{dollar}C and {dollar}\sp1{dollar}H NMR spectroscopies were used to investigate some unusual features of the molecular microstructure of poly(vinyl chloride) (PVC).;Several model monochloroalkenes were synthesized in order to determine {dollar}\sp{lcub}13{rcub}{dollar}C shift increments for the replacement of H by Cl at positions that are near an isolated internal double bond. These increments then were used to predict the {dollar}\sp{lcub}13{rcub}{dollar}C shifts of the internal allylic chloride structure in PVC. The predictions were not satisfactory, because, as expected, the increments were not additive.;It was shown that during conventional VC polymerization, the chloroallylic chain end (-CH{dollar}\sb2{dollar}CH=CHCH{dollar}\sb2{dollar}Cl) does not copolymerize with the monomer and is …
Microstructures Of Poly(Vinyl Acetate) Studied By Nuclear Magnetic Resonance Spectroscopy, Hongyang Yao
Microstructures Of Poly(Vinyl Acetate) Studied By Nuclear Magnetic Resonance Spectroscopy, Hongyang Yao
Dissertations, Theses, and Masters Projects
Carbon-13 NMR spectroscopy was used to investigate the microstructures of poly(vinyl acetate) prepared by solution polymerization in benzene. A series of aromatic compounds was synthesized in order to model the structures formed via chain transfer to solvent. The peaks near 126.5 and 128.5 ppm in the spectra of the polymer samples were assigned to a 1-phenyl-(2n + 1)-multi-acetoxyalkane (where n = 1, 2, 3, etc.) microstructure. The concentration of that structure obtained from NMR spectra was correlated with the concentration calculated from reported kinetic data.;Chain transfer to benzene was shown to occur by addition of the macroradical to benzene, followed …
The Synthesis Of Reflective And Electrically Conductive Polyimide Films Via An In Situ Self-Metallization Procedure Using Silver(I) Complexes, Robin Elaine Southward
The Synthesis Of Reflective And Electrically Conductive Polyimide Films Via An In Situ Self-Metallization Procedure Using Silver(I) Complexes, Robin Elaine Southward
Dissertations, Theses, and Masters Projects
Optically reflective polyimide films have been prepared by the incorporation of silver(I) acetate and a {dollar}\beta{dollar}-diketone solubilizing agent, hexafluoroacetylacetone (HFAH), into a dimethylacetamide solution of the poly(amic acid) formed from {dollar}3,3\sp\prime,4,4\sp\prime{dollar}-benzophenonetetracarboxylic acid dianhydride (BTDA) and {dollar}4,4\sp\prime{dollar}-oxydianiline {dollar}(4,4\sp\prime{dollar}-ODA). Optically reflective and conductive polyimide films have been prepared by replacing the {dollar}\beta{dollar}-diketone (HFAH), with the less substituted {dollar}\beta{dollar}-diketone, trifluoroacetylacetone (TFAH). The former system has been both cast directly from the poly(amic acid) resin and cast from the poly(amic acid) resin onto a fully imidized {dollar}\rm BTDA/4,4\sp\prime{dollar}-ODA base (forming a metallized topcoat). Thermal curing of the silver(I)-containing poly(amic acid) leads to imidization with …
The Influence Of Microstructure On The Thermal Degradation Behavior Of Poly(Vinyl Chloride), Hoang Vi Tran
The Influence Of Microstructure On The Thermal Degradation Behavior Of Poly(Vinyl Chloride), Hoang Vi Tran
Dissertations, Theses, and Masters Projects
No abstract provided.
Synthesis And Characterization Of Boron-Containing Polymeric Materials For Neutron Shielding Applications, Michael B. Glasgow
Synthesis And Characterization Of Boron-Containing Polymeric Materials For Neutron Shielding Applications, Michael B. Glasgow
Dissertations, Theses, and Masters Projects
The development of boron-containing polymeric materials for neutron shielding applications was undertaken. Three types of materials were characterized for physical and thermal properties: boron powder-filled epoxy composites, carborane polyamides having boron chemically bonded into the polymer, and boron-loaded polyimide thin films. Addition of amorphous submicron boron powder did not affect significantly the thermal performance of the epoxy. The 17% boron loading produced a 26% increase in compressive failure strength and a 68% increase in the compressive modulus. 0.125 inch thick specimens containing 17% boron absorbed 92% of incident neutrons from a 5-Curie Pu/Be source compared with {dollar}<{dollar}1% for the neat epoxy. Dispersion of the boron in the epoxy was improved with the addition of larger size crystalline boron powders. Carborane polyamides containing up to 35% boron were thermally stable up to 400{dollar}\sp\circ{dollar}C in air. The polymers had hydrogen/boron ratios from 2.0 to 3.8 and were soluble in several organic solvents. Polymer solutions were processed into clear, colored thin films. Boron-filled polyamic acid solutions of a PMDA-ODA polyimide containing up to 10% boron were processed into thin films. Neutron absorption of the opaque films measured in a 5-Curie Pu/Be neutron source was linear with boron concentration and film thickness. The fraction of neutrons absorbed varied linearly with boron concentration and film thickness. The applicability of boron-containing materials to the aerospace, nuclear power and accelerator industries was investigated.
Low-Valent Metal Complexes As Reductive Coupling Agents For Smoke Suppression In Poly(Vinyl Chloride), Panagiotis Ioannou Kourtesis
Low-Valent Metal Complexes As Reductive Coupling Agents For Smoke Suppression In Poly(Vinyl Chloride), Panagiotis Ioannou Kourtesis
Dissertations, Theses, and Masters Projects
No abstract provided.
Characterizing The Degradation Of Nylon-11 And Pvdf In A Flexible Oil Pipe And Cure Monitoring Of Chemflake Vinylester, John Chen Yang
Characterizing The Degradation Of Nylon-11 And Pvdf In A Flexible Oil Pipe And Cure Monitoring Of Chemflake Vinylester, John Chen Yang
Dissertations, Theses, and Masters Projects
No abstract provided.
Metallization Of Polyimide Films To Enhance Dimensional Stability And To Achieve Reflective And Conductive Surfaces, David Scott Thompson
Metallization Of Polyimide Films To Enhance Dimensional Stability And To Achieve Reflective And Conductive Surfaces, David Scott Thompson
Dissertations, Theses, and Masters Projects
No abstract provided.
Characterization Of Nylon-11 Degradation, Leslie Christian Mccullough
Characterization Of Nylon-11 Degradation, Leslie Christian Mccullough
Dissertations, Theses, and Masters Projects
No abstract provided.
The Synthesis, Characterization, And Application Of Ether-Containing Polymides, Catharine Croall Fay
The Synthesis, Characterization, And Application Of Ether-Containing Polymides, Catharine Croall Fay
Dissertations, Theses, and Masters Projects
Polyimides are a family of heterocyclic polymers that have received extensive evaluation as adhesives, fibers, films, moldings, composite matrices, insulators, coatings, membranes, and resists. their outstanding thermal stability, excellent mechanical and electrical properties, and chemical resistance make them attractive for many applications.;This research developed ether-containing polyimides for three applications: liquid crystalline polyimides as processing aids, polyimides for microelectronic applications, and polyimides for harsh environments. The approach consisted of three primary activities: (1) developed novel diether dianhydrides for polyimide fabrication, (2) designed, characterized, and evaluated polyimide architectures based on the material application requirements, and (3) provided extensive structure-property relationships utilizing a …
Characterization Of Pr500 For Use In Resin Transfer Molding, Rhonda Michelle Barksdale
Characterization Of Pr500 For Use In Resin Transfer Molding, Rhonda Michelle Barksdale
Dissertations, Theses, and Masters Projects
No abstract provided.
Mechanisms Of Poly(Vinyl Chloride) Fire Retardance And Smoke Suppression Induced By Copper Additives, Jong Paul Jeng
Mechanisms Of Poly(Vinyl Chloride) Fire Retardance And Smoke Suppression Induced By Copper Additives, Jong Paul Jeng
Dissertations, Theses, and Masters Projects
The purpose of this study was to elucidate the mechanisms of PVC fire retardance and smoke suppression induced by copper additives.;The experimental approaches involved: (1) the use of activated copper (Cu{dollar}\sp0{dollar}) to study PVC model-compound reactions and the crosslinking of PVC and (2) the pyrolysis of PVC model compounds in the presence of several copper additives in order to examine all of the possible chemical reactions involved in the formation of heavy products.;The results obtained from experiments with activated copper and allylic chloride model compounds suggest that the reductive coupling mechanism is a viable process in PVC. The Cu{dollar}\sp0{dollar} that …
Calculations Of The Interactions Of Energetic Ions With Materials For Protection Of Computer Memory And Biological Systems, Myung-Hee Y. Kim
Calculations Of The Interactions Of Energetic Ions With Materials For Protection Of Computer Memory And Biological Systems, Myung-Hee Y. Kim
Dissertations, Theses, and Masters Projects
Theoretical calculations were performed for the propagation and interactions of particles having high atomic numbers and energy through diverse shield materials including polymeric materials and epoxy-bound lunar regolith by using transport codes for laboratory ion beams and the cosmic ray spectrum. Heavy ions fragment and lose energy upon interactions with shielding materials of specified elemental composition, density, and thickness. A fragmenting heavy iron ion produces hundreds of isotopes during nuclear reactions, which are treated in the solution of the transport problem used here. A reduced set of 80 isotopes is sufficient to represent the charge distribution, but a minimum of …
Deuteron Nuclear Magnetic Resonance Studies Of Molecular Motion In Solids, Tak Yan Tse
Deuteron Nuclear Magnetic Resonance Studies Of Molecular Motion In Solids, Tak Yan Tse
Dissertations, Theses, and Masters Projects
$\sp2$H-NMR is a powerful spectroscopic technique for investigating dynamics in solids. to extend the range of motional rates that can be quantitatively investigated, a new approach for measuring the quadrupolar spin-lattice relaxation time $T\sb{1Q}$ was developed. This uses a Broadband Jeener-Broekaert (BBJB) sequence with echo-detection, which avoids the frequency-discriminated excitation profile and spectral baseline distortion intrinsic to the conventional Jeener-Broekaert (JB) experiment. By combining the BBJB experiment with an Inversion-Recovery sequence with Quadrupole-Echo detection (IRQE), two independent longitudinal relaxation times, $T\sb{1Q}$ and $T\sb{1Z}$, can be measured. Spectral densities of motion $J\sb1(\omega\sb{o}$) and $J\sb2(2\omega\sb{o}$) are extracted from these relaxation times. The …
Physical And Mechanical Behavior Of Amorphous Poly(Arylene Ether-Co-Imidazole)S And Poly(Arylene Ether-Co-Imidazole) Modified Epoxies, Patricia D. Roberts-Mcdaniel
Physical And Mechanical Behavior Of Amorphous Poly(Arylene Ether-Co-Imidazole)S And Poly(Arylene Ether-Co-Imidazole) Modified Epoxies, Patricia D. Roberts-Mcdaniel
Dissertations, Theses, and Masters Projects
Due to the high crosslink density of cured epoxy resins they generally lack damage tolerance. A significant amount of research has been expended to improve the toughness of epoxies. Research into the area of thermoplastic epoxy modifiers has begun to overcome some of the limitations of early methods of epoxy toughening (i.e. lower modulus and thermal stability).;This study examines the physical and mechanical properties of random poly(arylene ether-co-imidazole) (PAE-co-Is) and the characterization of epoxies modified with poly(arylene ether-co-imidazole)s.;Poly(arylene ether-co-imidazole)s exhibited the highest solubility in N,N,N{dollar}\rm\sp\prime,N\sp\prime,{dollar}-tetraglycidyl- 4,4{dollar}\sp\prime{dollar} diaminodiphenyl methane (TGMDA) based resins. The high molecular weight polymers caused significant decreases in …
Characterization And Modeling Of Amino Epoxide Resins, Maria Anastasia Argiriadi
Characterization And Modeling Of Amino Epoxide Resins, Maria Anastasia Argiriadi
Dissertations, Theses, and Masters Projects
No abstract provided.
Characterization Of Epoxy Resins For Use In The Resin Transfer Molding Process, Christina Kaye Short
Characterization Of Epoxy Resins For Use In The Resin Transfer Molding Process, Christina Kaye Short
Dissertations, Theses, and Masters Projects
No abstract provided.
A Study Of Molecular Order And Motion In Nematic Liquid Crystal Mixtures, Jon Michael Goetz
A Study Of Molecular Order And Motion In Nematic Liquid Crystal Mixtures, Jon Michael Goetz
Dissertations, Theses, and Masters Projects
Materials which flow like fluids, but possess anisotropic properties like molecular crystals, are called 'liquid crystals'. Studies of liquid crystals contribute to our understanding of how molecular orientation influences macroscopic properties. This thesis presents experimental and theoretical investigations of molecular order and dynamics in nematic liquid crystal systems. First, deuterium nuclear magnetic resonance is used to determine the degree of orientational order of both components of a liquid crystal mixture simultaneously. The temperature dependence of the four order parameters is interpreted using a newly developed mean field theory of nematic binary mixtures composed of biaxial molecules. Next, mean field theory …
Cross-Linking Additives As Smoke Suppressants For Poly(Vinyl Chloride), Steven Alfred Terranova
Cross-Linking Additives As Smoke Suppressants For Poly(Vinyl Chloride), Steven Alfred Terranova
Dissertations, Theses, and Masters Projects
No abstract provided.
Intelligent Processing Of Pmr-15, Sean Michael Hart
Intelligent Processing Of Pmr-15, Sean Michael Hart
Dissertations, Theses, and Masters Projects
No abstract provided.
The Imidization Reactions Of Pmr-15 Polyimide, Kerri Ann Robillard
The Imidization Reactions Of Pmr-15 Polyimide, Kerri Ann Robillard
Dissertations, Theses, and Masters Projects
No abstract provided.
The Effects Of The Exposure Of Atomic Oxygen On Polymeric Material: I Siloxane Modified Epoxy Resins Ii Polyetherimide Films With Additives, Eugene Canlas Aquino
The Effects Of The Exposure Of Atomic Oxygen On Polymeric Material: I Siloxane Modified Epoxy Resins Ii Polyetherimide Films With Additives, Eugene Canlas Aquino
Dissertations, Theses, and Masters Projects
No abstract provided.
The Imidization Of Pmr-15 Aromatic Thermosetting Polyimide, Thomas Clifton Prettyman
The Imidization Of Pmr-15 Aromatic Thermosetting Polyimide, Thomas Clifton Prettyman
Dissertations, Theses, and Masters Projects
No abstract provided.
Dielectric And Kinetic Analysis Of Thermosetting Polyester Resin, Patricia Haverty Tully
Dielectric And Kinetic Analysis Of Thermosetting Polyester Resin, Patricia Haverty Tully
Dissertations, Theses, and Masters Projects
No abstract provided.
Monitoring Environmental Effects On High Performance Tetraglycidyl Methylenedianiline Epoxy And Pmr-15 Polyimide, William Robinson Hayes Clark
Monitoring Environmental Effects On High Performance Tetraglycidyl Methylenedianiline Epoxy And Pmr-15 Polyimide, William Robinson Hayes Clark
Dissertations, Theses, and Masters Projects
No abstract provided.
Non-Lattice Monte Carlo Simulations Of Polymer Motion, David Albert Eichinger
Non-Lattice Monte Carlo Simulations Of Polymer Motion, David Albert Eichinger
Dissertations, Theses, and Masters Projects
No abstract provided.