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Articles 61 - 73 of 73
Full-Text Articles in Physical Sciences and Mathematics
Solid-State Deuterium Nuclear Magnetic Resonance Of The Methyl Dynamics Of Poly(Alpha-Methylstyrene) And Polymethylphenylsilane, Robert D. O'Connor, Eric J. Ginsburg, Frank D. Blum
Solid-State Deuterium Nuclear Magnetic Resonance Of The Methyl Dynamics Of Poly(Alpha-Methylstyrene) And Polymethylphenylsilane, Robert D. O'Connor, Eric J. Ginsburg, Frank D. Blum
Chemistry Faculty Research & Creative Works
The methyl-d3 dynamics of two relatively similar polymers, poly(alpha-methylstyrene) (PAMS-d3) and polymethylphenylsilane (PMPS-d3), are investigated via deuterium NMR relaxation experiments. Our analysis of the relaxation data uses the entire solid-echo spectra to maximize the precision of the experiments with regard to the information available on the methyl dynamics. The analysis is novel in that it does not use M[infinity] or M0 to fit the relaxation data. Additionally, the three-site symmetric jump model is shown to not have an observable azimuthal angular dependence for T1 relaxation. The methyl dynamics are quantified with taum, sigma, and f which are the log-average correlation …
Dynamics Of Interfacial Polymers In Composites, Frank D. Blum, Wuu-Yung Lin
Dynamics Of Interfacial Polymers In Composites, Frank D. Blum, Wuu-Yung Lin
Chemistry Faculty Research & Creative Works
Much experimental and theoretical work has been done on the behavior of adsorbed polymers. However, not much work has focused on the dynamics, especially segmental dynamics, of the adsorbed polymers. This is especially true of filled polymer or composite systems as the interfacial layers in these systems are difficult to study with most techniques. NMR is not restricted to use in optically clear samples and its use in the characterization in the surface polymers has been reviewed. In our laboratory, we have found that deuterium NMR could be used to probe the segmental dynamics of adsorbed polymers. The position of …
Effect Of Interfacial Mobility On Flexural Strength And Fracture Toughness Of Glass/Epoxy Laminates, T. W. H. Wang, Frank D. Blum, Lokeswarappa R. Dharani
Effect Of Interfacial Mobility On Flexural Strength And Fracture Toughness Of Glass/Epoxy Laminates, T. W. H. Wang, Frank D. Blum, Lokeswarappa R. Dharani
Chemistry Faculty Research & Creative Works
Mechanical testing and surface fractography were used to characterize the fracture of E-glass fiber reinforced epoxy composites as a function of the silane coupling agent used. gamma-Aminopropyltriethoxysilane (APS) and delta-aminobutyltriethoxysilane (ABS) were used because these have been shown to have different interfacial mobilities at multilayer coverage. The values of the properties studied generally increased from untreated c, as determined from a Mode I translaminar fracture toughness tests, for the untreated composites (10.5 ± 0.4 kJ/m2) was lower than that for the ABS-treated composites (14.3 ± 2.1 kJ/m2) which was lower than that for the APS-treated composites (17.1 ± 2.4 kJ/m2). …
Electrodeposition Of Cerium-Based Coatings For Corrosion Protection Of Aluminum Alloys, James O. Stoffer, Thomas J. O'Keefe, Xuan Lin, Eric L. Morris, Pu Yu, Srinivas Pravin Sitaram
Electrodeposition Of Cerium-Based Coatings For Corrosion Protection Of Aluminum Alloys, James O. Stoffer, Thomas J. O'Keefe, Xuan Lin, Eric L. Morris, Pu Yu, Srinivas Pravin Sitaram
Chemistry Faculty Research & Creative Works
A process for enhancing the corrosion resistance of an aluminum-containing component with a cerium based coating. An aluminum-containing cathode and an oxygen- evolving anode are immersed in an electrolyte comprising water, solvent, oxidizing agent and cerium ions. An electrical current is passed through the electrolyte by applying electrical current to deposit a cerium based coating onto the cathode. An electrolyte for use in depositing a cerium based coating. An electrodeposited cerium-based coating. An aluminum aircraft structural component having a cerium-based coating thereon.
Magnetic And Mössbauer Spectral Study Of Mixed Valent La₀.₂Sr₀.₈Cu₀.₂Fe₀.₈O2.68 And Related Perovskites, Gary J. Long, Dimitri Hautot, Amitabh Mohan, Ingeborg Kaus, Harlan U. Anderson, Fernande Grandjean
Magnetic And Mössbauer Spectral Study Of Mixed Valent La₀.₂Sr₀.₈Cu₀.₂Fe₀.₈O2.68 And Related Perovskites, Gary J. Long, Dimitri Hautot, Amitabh Mohan, Ingeborg Kaus, Harlan U. Anderson, Fernande Grandjean
Chemistry Faculty Research & Creative Works
The La0.2Sr0.8Cu1-xFexO 3-δ perovskites are important because they are mixed electron and oxygen anion conductors and thus are able to serve as dense oxygen separation membranes. In order to better understand the mechanism for this separation a Mössbauer spectral study has been carried out to determine the ratio of iron(III) to iron(IV) in these mixed valent compounds. The Mössbauer spectra of La0.2Sr0.8Cu0.2Fe0.8O 3-δ obtained between 4.2 and 78 K reveal that its Néel temperature is ~75 K and the two well-resolved magnetic sextets observed …
Activated Carbon Produced From Agricultural Residues, Daniel W. Armstrong, V. J. Flanigan, William Joseph James, Jui-Lung Li, Kimber L. Rundlett
Activated Carbon Produced From Agricultural Residues, Daniel W. Armstrong, V. J. Flanigan, William Joseph James, Jui-Lung Li, Kimber L. Rundlett
Chemistry Faculty Research & Creative Works
A process for producing activated carbon from agricultural residues by heating the residues to a temperature in the range of about 250° C. to about 550° C. to volatilize organic compounds in the residues and to carbonize the residues and further heating to activate the carbonized residues. Activated carbon produced from agricultural residues.
Thermal Characterization Of Pmma Thin Films On Silica Using Modulated Differential Scanning Calorimetry, Crystal E. Porter, Frank D. Blum
Thermal Characterization Of Pmma Thin Films On Silica Using Modulated Differential Scanning Calorimetry, Crystal E. Porter, Frank D. Blum
Chemistry Faculty Research & Creative Works
The number of studies of thin polymer films has increased over recent years as technological processes incorporate the use of nanomaterials. An enhanced understanding of these films would enable us to predict bound-polymer behavior and thus improve the efficiency of processes and the quality of products. This is especially true as the thickness of the films approach molecular dimensions. The glass transition temperature of a polymer is one of the most important properties for characterization because it indicates how the polymer might perform macroscopically. when a polymer is confined, such as one the surface of a substrate, its behavior is …
Dynamics Of Acrylic Coupling Agents At Interfaces Of Composites, Hyoryoon Jo, Frank D. Blum
Dynamics Of Acrylic Coupling Agents At Interfaces Of Composites, Hyoryoon Jo, Frank D. Blum
Chemistry Faculty Research & Creative Works
Most applications of polymers involve composites, wherein a polymer is used in conjunction with another material, typically a solid fiber or filler. A coupling agent can enhance the adhesion between a polymer matrix and an inorganic filler. Organofunctional silanes, RSiX are often used as coupling agents. The methoxy or ethoxy group, X, can typically be hydrolyzed with water and an acid or a base catalyst in a protic solvent. The silanol groups of a hydrolyzed coupling agent can condense with other silanol groups from a glass surface, while the alkyl group, R, blends physically or bonds chemically to the polymer …
Deuterium Nmr Of Adsorbed Poly(Methyl Acrylate)-D₃, Frank D. Blum, Wuu-Yung Lin
Deuterium Nmr Of Adsorbed Poly(Methyl Acrylate)-D₃, Frank D. Blum, Wuu-Yung Lin
Chemistry Faculty Research & Creative Works
The dynamics of polymers at interfaces are important in a variety of applications, especially where those applications depend on the mechanical or surface properties. Unfortunately, the surface properties of interfacial species like polymers used in composites are not easily measured macroscopically. Microscopic techniques, especially spectroscopic ones, have been successful. In our laboratory we have been successful in applying NMPR to determine the behavior of absorbed polymers. NMR has several advantages for this kind of study, the principal ones being that it can be used on opaque materials, different nuclei can be used as probes, and interfacial material can sometimes be …
Plasma Polymerization Investigated By The Substrate Temperature Dependence., H. Yasuda, Cheng Wang
Plasma Polymerization Investigated By The Substrate Temperature Dependence., H. Yasuda, Cheng Wang
Chemistry Faculty Research & Creative Works
In the reported experiments, plasma polymerization of tetrafluoroethylene (TFE), perfluoro-2-butyl-tetrahydrofuran (PFBTHF), ethylene, and styrene were investigated in various combinations of monomer flow rates and discharge wattages for the substrate temperature range of minus 50 to 80 degree C. The polymer deposition rates can be generally expressed by k//o equals Ae** minus **b**t, where k//o is the specific deposition rate given by k//o equals (deposition rate)/(mass flow rate of monomer), A is the preexponential factor representing the extrapolated value of k//o at zero absolute temperature, and b is the temperature-dependence coefficient. It was found that the value of b is not …
Plasma Polymerization Of Tetrafluoroethylene. I. Inductive Radio Frequency Discharge, H. Yasuda, N. Morosoff, E. S. Brandt, C. N. Reilley
Plasma Polymerization Of Tetrafluoroethylene. I. Inductive Radio Frequency Discharge, H. Yasuda, N. Morosoff, E. S. Brandt, C. N. Reilley
Chemistry Faculty Research & Creative Works
The plasma polymerization of tetrafluoroethylene in an inductively coupled radio frequency glow discharge, using a flow system, was studied. A simple long tube reactor, with the coupling coil placed at the middle of the tube and gas entrance and exit at the respective ends, was used. Deposition rates and the chemical nature of the polymer (as revealed by ESCA spectra and surface energy studies) are obtained as a function of location in the reactor tube with respect to the coupling coil and of applied energy per unit mass of tetrafluoroethylene (W/FM). It was found that a fluorine poor polymer, containing …
Anodic Dissolution Of Beryllium In Anhydrous Media, William Joseph James, Martin E. Straumanis
Anodic Dissolution Of Beryllium In Anhydrous Media, William Joseph James, Martin E. Straumanis
Chemistry Faculty Research & Creative Works
No abstract provided.
The Role Of The Doctor Of Engineering Degree In Graduate Education, Wouter Bosch, Robert E. Carlile
The Role Of The Doctor Of Engineering Degree In Graduate Education, Wouter Bosch, Robert E. Carlile
Chemistry Faculty Research & Creative Works
No abstract provided.