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Full-Text Articles in Physical Sciences and Mathematics

Physical And Mechanical Behavior Of Amorphous Poly(Arylene Ether-Co-Imidazole)S And Poly(Arylene Ether-Co-Imidazole) Modified Epoxies, Patricia D. Roberts-Mcdaniel Jan 1994

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 …


Models For Water Outgassing From Metal Surfaces, Minxu Li Jan 1994

Models For Water Outgassing From Metal Surfaces, Minxu Li

Dissertations, Theses, and Masters Projects

In this study, the outgassing rate from an electropolished stainless steel surface following exposures to H{dollar}\sb2{dollar}O vapor under various conditions was measured. The results of the experiments showed that the outgassing rate is proportional to {dollar}p\sb0\sp{lcub}n{rcub}{dollar}, where {dollar}p\sb0{dollar} is the H{dollar}\sb2{dollar}O exposure pressure and n is about 0.25. The outgassing rate is not as strongly dependent on the system temperature as one would expect if the temperature is kept the same during exposure and pump-down. The outgassing rate is also a function of the exposure time for the first several hours of exposure, indicating that the adsorption saturation time is …


Deuteron Nuclear Magnetic Resonance Studies Of Molecular Motion In Solids, Tak Yan Tse Jan 1994

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 …


Perspectives On Nature: A Comparison Of The Views Of Thomas Jefferson And Henry David Thoreau, Stephanie Brewer Foley Jan 1994

Perspectives On Nature: A Comparison Of The Views Of Thomas Jefferson And Henry David Thoreau, Stephanie Brewer Foley

Dissertations, Theses, and Masters Projects

No abstract provided.


Direct Determination Of Trace Metals In Saline Water Samples Using Gfaas, Michael Joseph Wassell Jan 1994

Direct Determination Of Trace Metals In Saline Water Samples Using Gfaas, Michael Joseph Wassell

Dissertations, Theses, and Masters Projects

No abstract provided.


Characterization And Modeling Of Amino Epoxide Resins, Maria Anastasia Argiriadi Jan 1994

Characterization And Modeling Of Amino Epoxide Resins, Maria Anastasia Argiriadi

Dissertations, Theses, and Masters Projects

No abstract provided.


Toxicity Resistance In Mummichog (Fundulus Heteroclitus) From A Chemically Contaminated Environment, Cynthia A. H. Williams Jan 1994

Toxicity Resistance In Mummichog (Fundulus Heteroclitus) From A Chemically Contaminated Environment, Cynthia A. H. Williams

Dissertations, Theses, and Masters Projects

No abstract provided.


An Investigation Of The Late Quaternary Morphology Of Mobjack Bay, Va And Application Of A Facies Model, Donna Angela Milligan Jan 1994

An Investigation Of The Late Quaternary Morphology Of Mobjack Bay, Va And Application Of A Facies Model, Donna Angela Milligan

Dissertations, Theses, and Masters Projects

No abstract provided.


Great Blue Herons And River Otters: The Changing Perceptions Of All Things Wild In The Seventeenth And Eighteenth-Century Chesapeake, Elise Helene Manning-Sterling Jan 1994

Great Blue Herons And River Otters: The Changing Perceptions Of All Things Wild In The Seventeenth And Eighteenth-Century Chesapeake, Elise Helene Manning-Sterling

Dissertations, Theses, and Masters Projects

No abstract provided.