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  • 1
    Electronic Resource
    Electronic Resource
    Hydrogen/liquid vapor radio frequency glow discharge plasma oxidation/hydrolysis of expanded poly(tetrafluoroethylene) (ePTFE) and poly(vinylidene fluoride) (PVDF) surfaces (1991)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 555-570 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Modification of fluorine-containing polymers has recently received much attention due to new chemistries allowing for refunctionalization of these materials, especially their surfaces. In this article results are discussed which demonstrate various interesting modifications (including incorporations of —OH and oxygen comprised functionality) to expanded poly(tetrafluoroethylene) (ePTFE) surfaces. This is effected through the use of low damage, radio frequency glow discharge (RFGD) processes. The low damage conditions, which preserve the original pore structure/morphology of these RFGD treated materials, are supported by Scanning Electron Microscopy (SEM) while the resulting atomic and molecular effects are investigated through other surface analytical methodology. All materials reported in this investigation have been subjected to intensive structural analyses utilizing Electron Spectroscopy for Chemical Analysis (ESCA), Attenuated Total Reflectance Fourier Transform Infrared spectroscopy (ATR-FTIR), and wettability profiles obtained through contact angle measurements using a large series of liquids having varying surface tensions and surface reactive functionality. Through this multitechnique analysis of both expanded PTFE and poly(vinylidene fluoride) (PVDF) treated surfaces, a model is supported which illustrates surfaces possessing both high and low energy regions comprising both oxygen and fluorine functionality in close molecular proximity.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1991.080290412
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  • 2
    Electronic Resource
    Electronic Resource
    Nitro- and fluoropolyformals. II. Novel polyformals from α, ω-fluoro- and nitrodiols (1991)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 719-727 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The scope of polyformal formation from nitro- and fluorodiols has been explored further with a series of α, ω-diols. Polymers with M̄ns of 2000-4000 were generally obtained but M̄ns approaching 10,000 are possible in some cases. Effects of monomer structure and reaction parameters on polymer molecular weight are described. The polymers were characterized by GPC, 1H-NMR, and DSC analysis.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1991.080290514
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  • 3
    Electronic Resource
    Electronic Resource
    A multitechnique surface analytical study of a segmented block copolymer poly(ether-urethane) modified through an H2O radio frequency glow discharge (1991)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 535-545 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Recent work in our laboratories has fully characterized the surface region of a segmented poly(ether-urethane) (PEU) extending from the air/polymer interfacial region through bulk depths in the micron range. This characterization utilized energy and angle dependent Electron Spectroscopy for Chemical Analysis (ESCA), Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy (ATR-FTIR), and Comprehensive Wettability Profiling (contact angle using a homologous series of liquids) as defined by Zisman. In this study this same multi-analytical-technique approach is used to elucidate changes in these PEU surfaces induced through an H2O Radio Frequency Glow Discharge (RFGD) plasma. This investigation reports both qualitative and quantitative changes due to the modification treatments as well as the permanency of the changes effected on these surfaces through the plasma treatment. From our analyses, the amount of surface residing polyurethane (hard segment) is observed to increase due to a proposed plasma etching mechanism. Further, the addition of oxygen containing functionality is detected at the modified surfaces unique with respect to the unmodified PEU. These surface modifications which show large increases in wettability, are finally observed to be semi-permanent over a time period of 6 months.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1991.080290410
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  • 4
    Electronic Resource
    Electronic Resource
    Synthesis and polymerization of racemic and optically active substituted β-propiolactones. VI. α-Phenyl β-propiolactoneReferences 2, 3, 4, 5, and 28 are Parts I, II, III, IV, and V of this series, respectively. (1991)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 1281-1291 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis and optical resolution of α-phenyl β-amino-ethylpropionate led to the preparation of optically active α-phenyl β-propiolactones (PhPL) of different optical purities. The enantiomeric excess of PhPL was determined using 200 MHz 1H-NMR spectroscopy, after complexation with tris[3-(trifluoromethyl hydroxymethylene)-d-camphorato]europium III. It was then polymerized, in bulk and in solution, using a potassium acetate/crown ether complex as initiator. The optically active poly(PhPL)s thus obtained are insoluble in most organic solvents, whereas atactic poly(PhPL)s are soluble in CCl4, CHCl3, and dichloroethane. Several differences are observed between the physical properties of optically active and atactic poly(PhPL)s. However, atactic poly(PhPL)s are semi-crystalline polymers, similar to poly(α-disubstituted β-propiolactone)s, but in contrast with poly(α-methyl β-propiolactone). Melting (Tf) and glass transition temperatures, as well as enthalpy of fusion (ΔH), vary with the optical purity of the polymers. For example, atactic poly(PhPL) exhibits a Tf = 94°C and ΔH = 9 J/g as compared to Tf = 119°C and ΔH = 37 J/g for a poly(PhPL) having an enatiomeric excess of 50%.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1991.080290907
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  • 5
    Electronic Resource
    Electronic Resource
    Electrocatalytic Hydride-Forming Compounds for rechargeable batteries (1991)
    Weinheim : Wiley-Blackwell
    Advanced Materials 3 (1991), S. 343-350 
    Details
    ISSN: 0935-9648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A New class of highly electroactive hydride-forming compounds is described as well as simple metallurgical methods for producing these materials. The new type of metal alloys consist of two different crystallographic phases. The bulk phase is responsible for hydrogen storage and is formed by the stable multicomponent “standard alloy” of the AB5 type. The second phase homogeneously decorates the surface of the bulk phase and ensures a high electrocatalytic activity. In composing this second phase no precious metals are required, but carefully selected combinations of transition metals can be used. Very high overall exchange currents and discharge efficiencies are obtained, even at low temperature. Cycle life and storage capacities are comparable with the values found for the standard alloy. Substituting small amounts of B-metals with highly electrocatalytic elements was also found to be effective in improving the electroactivity of AB5 compounds. However, a drawback of this method is that significant improvements are obtained only when precious metals are incorporated. Double-phase materials must therefore be considered as more serious candidates for use in future nickel/metal-hydride batteries with high charge/discharge capability.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/adma.19910030704
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  • 6
    Electronic Resource
    Electronic Resource
    Deuterium Isotope Effects during RDX Combustion: Mechanistic burn rate-controlling step determination (1991)
    Weinheim : Wiley-Blackwell
    Propellants, Explosives, Pyrotechnics 16 (1991), S. 279-286 
    Details
    ISSN: 0721-3115
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: High pressure (500 psig/3.55 MPa and 1000 psigl6.99 MPa) burn rate comparisons from the combustion of solid RDX (hexahydro- 1.3,.5-trinitro-1,3,5-triazine) and perdeuterio-labeled RDX-dh cylindrical pressed pellets reveals a large kinetic deuterium isotope cffect (KDIE). This experimental KDIE confirms that chemical reaction kinetics are a significant mechanistic factor in controlling the inherent RDX burn rate and further shows the six-membered RDX hcterocycle's rate-controlling mechanistic step during com- bustion is the same as that previously reported for its larger eight-membered HMX (octahydro-l.3,5,7-tetranitro-l.3.5,7 tetrazocine) homologuc. As with HMX. This experimental KDTE approach also demonstrates a direct mechanistic relationship between RDX's higher order cornbustion regime and its ambient pressure thermochemical decomposition process.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prep.19910160605
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