Chemistry Commons^™

Excimer Emission From Cathode Boundary Layer Discharges, Mohamed Moselhy, Karl H. Schoenbach

Bioelectrics Publications

The excimer emission from direct current glow discharges between a planar cathode and a ring-shaped anode of 0.75 and 1.5 mm diameter, respectively, separated by a gap of 250 μm, was studied in xenon and argon in a pressure range from 75 to 760 Torr. The thickness of the “cathode boundary layer” plasma, in the 100 μm range, and a discharge sustaining voltage of approximately 200 V, indicates that the discharge is restricted to the cathode fall and the negative glow. The radiant excimer emittance at 172 nm increases with pressure and reaches a value of 4 W/cm² for …

Argon Eximer Emission From High-Pressure Microdischarges In Mental Capillaries, R. Mohan Sankaran, Konstantinos P. Giapis, Mohamed Moselhy, Karl H. Schoenbach

Bioelectrics Publications

We report on argon excimer emission from high-pressure microdischarges formed inside metal capillaries with or without gas flow. Excimer emission intensity from a single tube increases linearly with gas pressure between 400 and 1000 Torr. Higher discharge current also results in initial intensity gains until gas heating causes saturation or intensity drop. Argon flow through the discharge intensifies emission perhaps by gas cooling. Emission intensity was found to be additive in prealigned dual microdischarges, suggesting that an array of microdischarges could produce a high-intensity excimer source.

Fire Retardant Halogen-Antimony-Clay Synergism In Polypropylene Layered Silicate Nanocomposites, Marco Zanetti, Giovanni Camino, Domenico Canavese, Alexander B. Morgan, Frank K. Lamelas, Charles A. Wilkie

Chemistry Faculty Research and Publications

Nanocomposites of polypropylene-graft-maleic anhydride with organically modified clays have been prepared and characterized by X-ray diffraction and transmission electron microscopy. Their combustion behavior has been evaluated using oxygen consumption cone calorimetry. Synergy is observed between the nanocomposite formed and conventional vapor phase fire retardants, such as the combination of decabromodiphenyloxide and antimony oxide. The presence of bromine and antimony does not affect the heat release rate curves of the virgin polymer.

Vibrational Spectra And Assignments Of Cis- And Trans-1,4-Polybutadiene, P. Nallasamy, P.M. Anbarasan, S. Mohan

Turkish Journal of Chemistry

The Raman spectra of cis- and trans-1,4- polybutadiene were recorded in the region 100-4000 cm^{-1} and its infrared spectra were also measured in the wave number range 200--4000 cm^{-1}. The spectra were completely analysed. Probable assignments to observed bands were made with the help of intensities and normal co-ordinate analysis. The calculated normal frequencies were in good agreement with the experimental ones.

Fluorescence And Light Scattering Studies Of Aromatic Polymers Near The Critical Concentration C*, M.Sean Healy

Seton Hall University Dissertations and Theses (ETDs)

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Coating Of Aluminum Powder With Polymers In Supercritical Carbon Dioxide, Li Yuan

Theses

Eleven polymers were used to produce coatings (2-20 nm) on the surface of an aluminum powder to modify its properties. The polymers studied are polyisobutylene (PIB), poly (vinylidene fluoride) (PVF), poly (methyl methacrylate) (PMMA), polystyrene (PS), poly(ethylene terephthalate) (PETP), poly(4-vinylbiphenyl) (PVB), poly(4-vinylpyridine) (PVP), poly(4-bromo styrene) (PBS), poly (vinylidene fluorideco-hexafluoropropylene) (PVFH), poly (styrene-co-methyl methacrylate) (PSMMA), poly (vinyl chloride-co-vinyl acetate) (PVCVA). Supercritical carbon dioxide was used as a solvent and as a transport medium. Coated aluminum powders exhibit enhanced resistance to the dissolution in basic solutions. The protective properties of the polymeric films were quantified based on the dissolution rate. Polymeric films …

Xenon Excimer Emission From Pulsed Microhollow Cathode Discharges, M. Moselhy, R. H. Stark, K. H. Schoenbach, U. Kogelschatz

Bioelectrics Publications

By applying electrical pulses of 20 ns duration to xenon microplasmas, generated by direct current microhollow cathode discharges, we were able to increase the xenon excimer emission by more than an order of magnitude over direct current discharge excimer emission. For pulsed voltages in excess of 500 V, the optical power at 172 nm was found to increase exponentially with voltage. Largest values obtained were 2.75 W of vacuum-ultraviolet optical power emitted from a single microhollow cathode discharge in 400 Torr xenon with a 750 V pulse applied to a discharge. Highest radiative emittance was 15.2 W/cm². The …

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 …

Microhollow Cathode Discharge Excimer Lamps, Karl H. Schoenbach, Ahmed El-Habachi, Mohamed M. Moselhy, Wenhui Shi, Robert H. Stark

Bioelectrics Publications

Microhollow cathode discharges are high-pressure, nonequilibrium gas discharges between a hollow cathode and a planar or hollow anode with electrode dimensions in the 100 μm range. The large concentration of high-energy electrons, in combination with the high-gas density favors excimer formation. Excimer emission was observed in xenon and argon, at wavelengths of 128 and 172 nm, respectively, and in argon fluoride and xenon chloride, at 193 and 308 nm. The radiant emittance of the excimer radiation was found to increase monotonically with pressure. However, due to the decrease in source size with pressure, the efficiency (ratio of excimer radiant power …

Insight Into The Selectivity Of Molecular Imprinted Polymers, Thomas Patrick O'Brien

Seton Hall University Dissertations and Theses (ETDs)

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Generation Of Intense Excimer Radiation From High-Pressure Hollow Cathode Discharges, Ahmed El-Habachi, Karl H. Schoenbach

Bioelectrics Publications

By reducing the diameter of the cathode opening in a hollow cathode discharge geometry to values on the order of 100 μm, we were able to operate these discharges in noble gases in a direct current mode up to atmospheric pressure. High-pressure discharges in xenon were found to be strong sources of excimer radiation. Highest intensities at a wavelength of 172 nm were obtained at a pressure of 400 Torr. At this pressure, the vacuum ultraviolet (VUV) radiant power of a single discharge operating at a forward voltage of 220 V and currents exceeding 2 mA reaches values between 6% …

Fluorinated Polymer Films - Synthesis And Characterization, Anja Ulrike Schnurer

Dissertations and Theses

Three polyfluoroalkyl epoxides, (I OCH2CHCH20CF2CF2S02F, II OCH2CHCH2(CF2)gF and III OCH2CHCH20(CF2)CF(CF3)S02F) were photopolymerized with a cycloaliphatic diepoxide (Cyracure UVR-6110) to form highly crosslinked glassy films. Depth-dependent surface analysis with XPS show that these films are highly enriched with sulfonyl fluoride groups in the outer molecular surface. Film compositions of 17 % wt and more of the fluorinated I and III show surface characteristics of a film composed of 100 % wt of the polymerized sulfonyl fluoride epoxide monomer (at depths for 50 A for each sample). Even films that are prepared with only 1 % wt or less (compound III) of …

Gas Permeation Measurements On Small Polymer Specimens, Karen S. Burns

Chemistry & Biochemistry Theses & Dissertations

Mass spectrometry was used to measure oxygen and nitrogen permeabilities while polarography was used to measure oxygen permeabilities for several contact lens materials. Applicable sample holders were designed and fabricated to accommodate curved and flat specimens with surface areas of 0.5 cm² and 1.0 cm² and thicknesses between 0.025 mm and 0.500 mm. A prepared standard was used to calibrate the mass spectrometric analyses.

The oxygen permeability values determined by mass spectrometry were significantly greater than those determined by polarography. This was attributed to the phase boundary phenomena and the limiting oxygen permeance of water inherent in the …

Molecular Dynamics In Hydrogen‐Bonded Interactions: A Preliminary Experimentally Determined Harmonic Stretching Force Field For Hcn‐‐‐Hf, B. A. Wofford, Shannon Lieb, J. W. Bevan

Scholarship and Professional Work - LAS

Observation of the 2ν₁ overtone band in the hydrogen‐bonded complex HCN‐‐‐HF permits evaluation of the anharmonicity constant X _{1 1}=−116.9(1) cm^{− 1} and determination of the anharmonicity corrected fundamental frequency ω₁. This information, and available data from previous rovibrational analyses in the common and perdeuterated isotopic species of HCN‐‐‐HF, offer an opportunity for calculation of an approximate stretching harmonic force field. With the assumptions f _{1 2}=f _{2 4}=0.0, the remaining force constants (in mdyn/Å) are evaluated as: f _{1 1}=8.600(20), f _{2 2}=6.228(9), f _{3 3}=19.115(40), f _{4 …}

Cyclodimerization Of 1,3-Pentadiene With Homogeneous Nickel Catalyst, Morteza Soltani

Retrospective Theses and Dissertations

Piperylene concentrate is a complex mixture of 5-carbon unsaturated hydrocarbons obtained as by-products when naptha or gas oils are cracked. The major component in this mixture is 1,3-pentadiene. The cyclodimerization of 1,3-pentadience in piperylene concentrate by using a nickel catalyst was studied. Various types of ligands were used in the preparation of the nickel catalyst. The effect of each ligand on activity of the catalyst in dimerization of diene, on conversion, and on yield of reaction were investigated. The effect of reaction conditions, such as temperature, pressure, and reaction time, on conversion of monomer, yield of dimer, and selectivity of …

Isomerization And Dehydrocyclization Of 1,3-Pentadiene, Thomas E. Marcinkowski

Retrospective Theses and Dissertations

Piperylene concentrate is a complex mixture of 5-carbon unsaturated hydrocarbons obtained as a by-product when naphtha or gas oils are cracked. The major component in this mixture is 1,3-pentadiene. During the course of this study, a number of trials, utilizing liquid phase reaction conditions, were made to investigate the geometric isomerization of 1,3-pentadiene and its separation from the piperylene concentrate. Isomerization was accomplished employing catalytic amounts of iodine at temperatures ranging from 0°C to reflux. Using this method, the maximum amount of trans-1,3-pentadiene obtained was 70% as compared to 51% in the piperylene concentrate. Recovery of the product was 90%, …

Preparation Of A Polymer Supported Cobalt (Ii) Schiff Base Catalyst, Susan L. Fuhrman

Retrospective Theses and Dissertations

Polystyrene bis(salicylaldehyde)-propylene-1,3-diiminato Cobalt (II) (salen) and Polystyrene bis(acetylacetone)-propylene-1,3-diiminato Cobalt (II) (BAE) were prepared stepwise from polystyrl chloride. The reaction series included substitution of the chloride with a malononitrile carbanion, reduction to a diamine, condensation to form a Schiff base, and complexation with Co(II) acetate to form the active polymeric material. Optimum conditions with regard to time, temperature, reaction ratios, and solvent were determined for each reaction. The ability of the polymer bound cobalt complex to oxidize 3-methyl indole was measure. The BAE catalyst yielded a large amount of the corresponding o-formylaminoacetophenone. However, the exact yield is not known because product …

The Synthesis Of New Maleimide Addition Polymer Precursors, Richard B. Brown

Chemistry & Biochemistry Theses & Dissertations

1H-2,3-dimethylpyrrolo(1,2-a) benzimidazol-l-one (27) and 1H,9H- 2,3,7,8-tetramethyl-bispyrrolo(1,2-a:6,7-a')benzodiimidazo1-1,9-dione (32) have been synthesized from dimethylmaleic anhydride and o-phenylenediamine and 1,2,4,5-tetraaminobenzene, respectively. The presence of reactive olefinic double bonds in the synthesized compounds was of interest as a site for possible addition polymerization.

The synthetic route involved, in both cases, a simple nucleophilic substitution reaction between the diamine(or tetraamine) and the anhydride to form an intermediate amide-acid-amine which rapidly cyclized to the imide amine. The final ring closure required more rigorous conditions and occurred at melt reaction temperatures.

A Thermogravimetric Study Of Polyvinylidene Chloride In Polymers, Charles Edward Singleton

Master's Theses

In the manufacturing of thin films such as cellophane, polymers employed as coatings greatly improve film functionality. Polymers such as polyvinylidene chloride, polyvinyl chloride, polyvinyl acetate and many others are used as coatings or components of coatings designed to improve the functionality of a film. Selection of polymers with properties that will meet the requirements of the finished film product is a continuing process of film manufacturers. Physical and chemical characterization of the polymer along with coating functionality are the factors involved in the selection. Chemical composition is the most important factor affecting polymer characteristics and must be known if …

Properties Of Chlorophyll Derivatives Bonded To Polymers, Richard Grant Jensen

Theses and Dissertations

Two types of water-soluble complexes of chlorophyll a with organic polymers have been investigated: chlorophyll a coordinately bonded to poly 4-vinylpyridine and a chlorophyll derivative, Mg-chlorin e_6 phytyl methyl ester, covalently bonded to GANTREZ AN (poly (methyl vinyl ether/maleic anhydride) ). The first complex was observed upon dissolving chlorophyll a and poly 4-vinylpyridine in aqueous ethanol solutions. The Mg-chlorin e_6 diester-GANTREZ AN complex (chlorophyll a/polymer) was made by aminolysing the chlorophyll ring V with 1, 6-hexanediamine to give an intermediate product, Mg-chlorin e_6 -6-N-(6' -aminohexyl) carboxamide, phytyl methyl ester. This was attached to GANTREZ AN by linkage of the 6'-amine …