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Direct Conversion of the TF₆ to TCl₄

Description: The following report provides a general summary of some methods that could be used to convert hexafluoride into tetrafluoride, but is mainly devoted to the work done on the conversion of tetrafluoride to tetrachloride.
Date: September 25, 1945
Creator: Calkins, Vincent P.
Partner: UNT Libraries Government Documents Department

Characterization of polyxylylenes with solid state {sup 13}C nuclear magnetic resonance spectroscopy

Description: Polyxylylenes are thermoplastics used as encapsulants for electronic devices. Five polyxylylenes were prepared by pyrolysis of [2.2]paracyclophanes and characterized by solid state {sup 13}C NMR spectroscopy. The chemical shift data, in combination with interrupted decoupling experiments, allowed assignment of resonances to their carbon sources in the polymers. This confirmed the integrity of the xylylene building block in the polymers and is consistent with linear polymers. No crosslinking could be detected within the NMR sensitivity limits. Residual paracyclophane was detected by {sup 13}C CP MAS NMR spectroscopy in the polyxylylene samples prepared at room temperature; however discrete {sup 13}C resonances due to amorphous and crystalline phases in the polymers were not resolved.
Date: February 1, 1996
Creator: Loy, D.A.; Assink, R.A.; Jamison, G.M.; McNamara, W.F.; Schneider, D.A. & Prabakar, S.
Partner: UNT Libraries Government Documents Department

Densities of Sodium Tetrafluoroborate Aqueous Solutions at 20 Degrees C

Description: Analytical data and plant solution compositions are often reported in molarity units. Densities of salt solutions are needed to convert the concentrations to molal basis in order to utilize physical property data that have been established on a molal basis, for example, solution reaction equilibrium constants or activity coefficients. We report here the densities at 20.0 Degrees C of sodium tetrafluoroborate (NaBF4) solutions from 0.05 molal to 9.0 molal, near saturation of 9.2 molal.
Date: July 9, 2002
Creator: Crooks, W.J. III
Partner: UNT Libraries Government Documents Department

Coefficient of thermal expansion of fluorinert as a function of volume percent absorbed air

Description: The relationship between the coefficient of volumetric thermal expansion of liquid Fluorinert FC-86 and the volume percent of absorbed air was examined experimentally. A special test apparatus was built for this purpose. A floating liquid seal was used to isolate the Fluorinert sample from the atmosphere. This prevented gas absorption during thermal cycling yet allowed the sample to expand and contract freely during testing. It was found that the coefficient of thermal expansion is not influenced by the percentage of absorbed air.
Date: June 1, 1982
Creator: Reilly, J.M.
Partner: UNT Libraries Government Documents Department

Trifluoromethylmetallate anions as components of molecular charge transfer salts and superconductors.

Description: Whereas polymeric and common inorganic anions frequently deprive the synthetic chemist of a chance to modify a charge transfer salt's structure through anion alterations, discrete organometallic anions provide a vast opportunity to probe the structure/property correlations of a material through rational synthetic methods. We have recently undertaken a research effort aimed at the crystallization of conducting charge transfer salts which possess modifiable, organometallic anions as the charge compensating entities. This research has been richly rewarded with the discovery of a new family of bis(ethylenedithio) tetrathiafulvalene (BEDT-TTF or ET) based molecular superconductors. Herein is presented a summary of over twenty {kappa}(ET){sub 2}M(CF{sub 3}){sub 4}(1,1,2-trihaloethane) (M = Cu, Ag, Au) superconducting salts. Three new related salts are also reported: (ET){sub 2} [trans-Ag(CF{sub 3}),(CN){sub 2}], {kappa}{sub L}(BEDT-TSF){sub 2}Ag(CF{sub 3}){sub 4}(TCE), and {kappa}{sub L}(ET){sub 2}Ag(CF{sub 3}){sub 3}Cl(TCE).
Date: October 14, 1998
Creator: Schlueter, J. A.
Partner: UNT Libraries Government Documents Department

THE SLUG-ANNULAR FLOW REGIME TRANSITION AT ELEVATED PRESSURE

Description: The annular slug flow regime has been investigated in vertical upflow without heating through the use of an electrical conductivity probe. The Teflon cladding and seals of the probe were found to work to at least 488 deg F. When the inlet velocity was sufficientiy high, the quality at transition was found to be a constant for each pressure going from 8.6% at215 psia to 17.6% at 615 psia. No fully developed bubbly flow was observed. (auth)
Date: November 1, 1963
Creator: Griffith, P.
Partner: UNT Libraries Government Documents Department

Thermophysical properties of HFC-143a and HFC-152a. Final report, April 1, 1993--June 30, 1994

Description: Numerous fluids have been identified as promising alternative refrigerants, but much of the information needed to predict their behavior as pure fluids and as components in mixtures does not exist. In particular, reliable thermophysical properties data and models are needed to predict the performance of the new refrigerants in heating and cooling equipment and to design and optimize equipment to be reliable and energy efficient. The objective of this fifteen-month project has been to provide highly accurate, selected thermophysical properties data for refrigerants HFC-143a (CH{sub 3}CF{sub 3}) and HFC-152a (CH{sub 3}CHF{sub 2}) and to use these data to fit complex equations of state and detailed transport property models. The new data have filled gaps in the existing data sets and resolved problems and uncertainties that existed in and between the data sets.
Date: July 1, 1994
Creator: Haynes, W. M.
Partner: UNT Libraries Government Documents Department

Synthesis and self-assembly of fluorocarbon- and hydrocarbon-modified hydrophilic polymers. Final report

Description: Over the past 3 years, work was done in several areas: effect of spacer lengths on degree of association of hydrophobically modified polyacrylamides; fluorocarbon mediated association of R{sub F}- substituted polyacrylamide-2-(acrylamido)-2-methyl-propane sodium sulfonate copolymers; hydrophobic association in R{sub F}(R{sub H})-modified poly(N,N-dimethylacrylamide)(PDMA) and polyvinylpyrrolidone; synthesis of R{sub F}-containing poly(N- isopropyl acrylamide)`s; synthesis of HM narrow MWD telechelics PDMA and PDMA block copolymers; and studies of telechelic R{sub F}(R{sub H}) derivatives of polyethyleneglycols. 15 refs, 7 figs, 2 tabs.
Date: November 1, 1996
Creator: Hogen-Esch, T.E.
Partner: UNT Libraries Government Documents Department

Perfluoro(Methylcyclohexane) Tracer Tagging Test and Demonstration

Description: On February 14 and 15, 2000, a demonstration of current perfluorocarbon tagging technology and the future potential of these methods was held at Oak Ridge National Laboratory (ORNL). The demonstration consisted of a brief technical discussion followed by a laboratory demonstration. The laboratory demonstrations included the detection of letters, parcels, briefcases and lockers containing perfluorocarbon-tagged papers. Discrimination between tagged and non-tagged items and between three perfluorocarbon tags was demonstrated along with the detection of perfluorocarbon in a background of non-fluorinated volatile organic solvent. All demonstrations involved real-time detection using a direct sampling ion trap mass spectrometer. The technical results obtained at ORNL during and in preparation for the demonstration are presented in Appendix 1 to assist Tracer Detection Technology Corp. in further evaluating their position on development and marketing of perfluorocarbon tracer technology.
Date: September 26, 2000
Creator: Sigman, M.E.
Partner: UNT Libraries Government Documents Department

Subsurface barrier integrity verification using perfluorocarbon tracers

Description: Subsurface barriers are an extremely promising remediation option to many waste management problems. Gas phase tracers include perfluorocarbon tracers (PFT`s) and chlorofluorocarbon tracers (CFC`s). Both have been applied for leak detection in subsurface systems. The focus of this report is to describe the barrier verification tests conducted using PFT`s and analysis of the data from the tests. PFT verification tests have been performed on a simulated waste pit at the Hanford Geotechnical facility and on an actual waste pit at Brookhaven National Laboratory (BNL). The objective of these tests were to demonstrate the proof-of-concept that PFT technology can be used to determine if small breaches form in the barrier and for estimating the effectiveness of the barrier in preventing migration of the gas tracer to the monitoring wells. The subsurface barrier systems created at Hanford and BNL are described. The experimental results and the analysis of the data follow. Based on the findings of this study, conclusions are offered and suggestions for future work are presented.
Date: December 1, 1996
Creator: Sullivan, T.M.; Heiser, J.; Milian, L. & Senum, G.
Partner: UNT Libraries Government Documents Department

Effect of a fluorinated nickel surface on the decomposition of perfluorodiethoxymethane

Description: Perfluoropolyethers (PFPEs) are a commercial class of lubricants widely used in computer and aerospace industries. This is a study of the degradation of a perfluorinated ether in the presence of a metal fluoride. Perfluorodiethoxymethane (PFDEM) is a PFPE analog. Temperature programmed desorption shows no contribution of PFDEM toward nickel fluoride on an NiF{sub 2} surface obtained by CF{sub 3}I adsorption. Higher coverages of nickel fluoride do not show any evidence of NiF{sub 2} contribution from PFDEM. The results do not agree with the idea that a fluorinated surface might induce decomposition of PFPEs, leading to addition fluoride formation on the surface. The metal fluoride bond strength is not a legitimate concern for decomposition of PFE lubricants. Impurity in PFPEs might be the cause of initial surface fluoridation leading to breakdown of PFPEs which could cause additional metal fluoride formation. It is clear that the reaction of PFPEs with metals does not involve a direct formation of a simple M-F bond; results do not show any C-F bond cleavage of the fluorinated ether and do not support a proposed autocatalytic mechanism.
Date: November 9, 1995
Creator: Sreevidya, S.
Partner: UNT Libraries Government Documents Department

ANTI Preference of the Pyramidalized Radical Center to the Two Fluorines in Difluoro Cyclic Compounds.

Description: An extensive study of disubstituted cycloalkanes like CnH2n where n=3,4,5 and 6 using DFT((U)B3LYP/6-31G(d) and 6-311+G(2df,2p)) calculations is presented focusing on the effect of pyramidalization of the radical center. A potential energy surface (PES) analysis shows that the radical prefers to pyramidalize anti to the two cis fluorines in the disubstituted cycloalkanes. The degree of pyramidalization for 1,2-difluorocyclopropyl radical is 43.9o away from the cis fluorines whereas for 1,3-difluorocyclobutyl radical, 1,3-difluorocyclopentyl radical and 1,3-difluorocyclohexyl radical is 3.8o, 5.4o and 14.5o respectively away from the cis fluorines. The importance of this pyramidality effect in these compounds is discussed in context with the carbon-hydrogen bond dissociation energies (BDE's) because the preference of the radical centers to pyramidalize anti to the fluorines affects the bond dissociation energy. Importance of steric effect and unfavorable electronic interactions have been extensively explored in planar permethylated cyclobutadiene (Me4CBD) and cyclooctatetraene (Me8COT) using ((U)B3LYP/6-31G(d) and 6-311+G(2df,2p)) calculations. It is thought that steric interactions dominate electronic interactions in Me8COT, while this works opposite in case of Me4CBT. Instead, in Me4CBD the number of unfavorable electronic interactions between π bonds and out-of-plane hydrogens plays the dominant role in determining the relative energies. Interactions between the π bonds of CBD and the out-of-plane hydrogens on carbons attached to the four-membered ring becomes very interesting when the ring size changes. With ethano bridge on the cyclobutadiene ring interaction with the diagonal bonds results in non-bonding AOs across the other diagonal having the opposite phase in the highest occupied (HO)MO. If the HOMO and LUMO are switched, bis-ethano-bridged tetrahedrane is formed. It is suggested that bis-ethano-bridged tetrahedrane is thermodynamically more stable than bis-ethano-bridged cyclobutadienes. While the reverse is true for unsubstituted cyclobutadienes. The ability of ethano bridges to reverse the usual order is because it causes the doubly-bonded carbons to pyramidalize.
Date: May 2008
Creator: Tanna, Jigisha
Partner: UNT Libraries

Fluoro-Carbonate Solvents for Li-Ion Cells

Description: A number of fluoro-carbonate solvents were evaluated as electrolytes for Li-ion cells. These solvents are fluorine analogs of the conventional electrolyte solvents such as dimethyl carbonate, ethylene carbonate, diethyl carbonate in Li-ion cells. Conductivity of single and mixed fluoro carbonate electrolytes containing 1 M LiPF{sub 6} was measured at different temperatures. These electrolytes did not freeze at -40 C. We are evaluating currently, the irreversible 1st cycle capacity loss in carbon anode in these electrolytes and the capacity loss will be compared to that in the conventional electrolytes. Voltage stability windows of the electrolytes were measured at room temperature and compared with that of the conventional electrolytes. The fluoro-carbon electrolytes appear to be more stable than the conventional electrolytes near Li voltage. Few preliminary electrochemical data of the fluoro-carbonate solvents in full cells are reported in the literature. For example, some of the fluorocarbonate solvents appear to have a wider voltage window than the conventional electrolyte solvents. For example, methyl 2,2,2 trifluoro ethyl carbonate containing 1 M LiPF{sub 6} electrolyte has a decomposition voltage exceeding 6 V vs. Li compared to <5 V for conventional electrolytes. The solvent also appears to be stable in contact with lithium at room temperature.
Date: September 17, 1999
Creator: NAGASUBRAMANIAN,GANESAN
Partner: UNT Libraries Government Documents Department

Novel Sorption/Desorption Process for Carbon Dioxide Capture (Feasibility Study)

Description: Western Research Institute and the University of Wyoming Enhanced Oil Recovery Institute have tested a novel approach to carbon dioxide capture in power plants and industrial operations. This approach is expected to provide considerable cost savings, in terms of regeneration of the sorbent. It is proposed that low molecular weight, low volatility liquid fluorocarbons be utilized to absorb CO{sub 2} due to their unusual affinity for the gas. The energy savings would be realized by cooling the fluorocarbon liquids below their melting point where the CO{sub 2} would be released even at elevated pressure. Thus, the expense of heating currently used sorbents, saturated with CO{sub 2}, under low pressure conditions and then having to compress the released gas would not be realized. However, these fluorinated materials have been shown to be poor carbon dioxide absorbers under conditions currently required for carbon capture. The project was terminated.
Date: November 1, 2008
Creator: Tuminello, William; Radosz, Maciej & Shen, Youqing
Partner: UNT Libraries Government Documents Department

CHARGE TRANSFER COMPLEXES WITH HEXAFLUDROBENZENE ANDPENTAFLUOROBENZONITRILE AS ACCEPTOR COMPONENTS

Description: Charge transfer associations are a well-established phenomena and a rather extensively investigated one also. Since the acceptor component of such complexes normally does not exist as a liquid under standard conditions, they wish to report on two organic liquids which function as acceptor components with suitable complimentary molecules. As indicated in Figure 1 (the presence of an extended shoulder in the spectra of the mixture), pentafluorobenzonitrile (PFBN) complexes with N,N,N{prime},N{prime}-tetramethyl-p-phenylenediamine (TMPD), with N,N-dimethylaniline (DMA), and with phenothiazine in cyclohexane. In addition, crystalline complexes of TMPN-PFBN and DMA-PFBN are obtained when the pure materials are mixed. These two organic bases also form solid complexes with hexafluorobenzene (HFB) when the materials are mixed in the pure state in a ratio of 1:1. However, new absorption bands are not detected in the spectra (in cyclohexane solutions) of mixtures of TMPD or DMA with HFB. When HFB is used as a solvent for TMPD or DMA, the solutions are visibly yellow. However, with time a reaction occurs as evident by the formation of a black precipitate. The solid complex formed between TMPD-PFBN, which is orange, was analyzed by a combination extraction and spectroscopic method and by vapor phase chromatography and found to contain a ratio of the two components of 1:1 which agrees with an elemental analysis of this complex. Analysis of DMA-PFBN or DMA-HFB complexes were complicated by the presence of excesses of the liquid components on the crystalline complexes. When attempts are made to dry the crystals, the crystals dissociate as the excesses evaporate until the crystals and the two components totally disappear. The TMPD-HFB complex was not analyzed. The complex between phenothiazine and PFBN as not isolated as a crystalline material. The association constants for the TMPD-PFBN and MDA-PFBN complexes were determined according to the method of Hildebrand and Benesi. The ...
Date: October 31, 1967
Creator: Corker, Gerald A. & Calvin, Melvin
Partner: UNT Libraries Government Documents Department