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  • 1
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 26 (1980), S. 881-890 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The objective of this investigation was to study the separation of krypton and xenon from nuclear reactor atmospheres by selective permeation through silicone rubber capillaries. Effective permeability coefficients for pure krypton xenon, nitrogen, and oxygen were determined between 0 and 40°C and at pressure differences across the capillary walls (Δp) of up to 3.45 × 105 N/m2 (50 psi). The silicone rubber capillaries had an O.D. of 635 μm (0.025 in.) and an I.D. of 305 μm (0.012 in.), and were pressurized externally. The effective permeability coefficients decreased with increasing Δp, due to the elastic deformation of the capillaries, in general agreement with a deformation analysis of thick-walled elastic tubes.Gas separation studies were made with a Kr-Xe-N2-O2 mixture in a permeator containing a bundle of silicone rubber capillaries. The permeator had an effective permeation area of 0.480 m2 (5.165 ft2) at a packing density of 4132 m2m3 permeator volume (1260 ft2/ft3), and was operated in a countercurrent mode. The separation studies were conducted at -10 and 20°C and at three Δp values. The separation achieved in the permeator at Δp's of 1.38 × 105 N/m2 (20 Ib/in.2) and 2.07 × 105 N/m2 (30 Ib/in.2) was in good agreement with that predicted from a theoretical model of a permeation stage with countercurrent flow. At 3.45 × 105 N/m2 (50 Ib/in.2), the separation approached that predicted from a “perfect mixing” model. This behavior probably was due to local collapses of the capillaries at weak spots in their walls, as was evidenced also by a sharp increase in the axial pressure drop inside the capillaries.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 13 (1975), S. 2531-2543 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of a series of Polybis(arylamino)phosphazenes is described. The polymers usually were prepared by treatment of polydichlorophosphazene in benzene-tetrahydrofuran with arylamines/triethylamine at reflux for 48-144 hr. The polymers, having viscosities of 0.3-1.4dl/g, are essentially free of active chlorine sites, as shown by elemental analysis and their longterm hydrolytic stability. Thermal analysis revealed glass transition temperatures between 53 and 105°C and decomposition temperatures between 243 and 266°C. Analysis by differential scanning calorimetry revealed no first-order endothermic transitions. For comparison with the arylamino polymers, polydiethylaminophenylaminophosphazene, polybis(benzylamino)phosphazene, and polybis(β-phenethylamino)phosphazene were prepared and are described.
    Additional Material: 1 Ill.
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  • 3
    Publication Date: 2009-02-05
    Description: The heterogeneous reaction of OH radicals with sub-micron squalane particles, in the presence of O2, is used as a model system to explore the fundamental chemical mechanisms that control the oxidative aging of organic aerosols in the atmosphere. Detailed kinetic measurements combined with elemental mass spectrometric analysis reveal that the reaction proceeds sequentially by adding an average of one oxygenated functional group per reactive loss of squalane. The reactive uptake coefficient of OH with squalane particles is determined to be 0.3±0.07 at an average OH concentration of ~1×1010 molecules·cm−3. Based on a comparison between the measured particle mass and model predictions it appears that significant volatilization of a reduced organic particle would be extremely slow in the real atmosphere. However, as the aerosols become more oxygenated, volatilization becomes a significant loss channel for organic material in the particle phase. Together these results provide a chemical framework in which to understand how heterogeneous chemistry transforms the physiochemical properties of particle phase organic matter in the troposphere.
    Electronic ISSN: 1680-7375
    Topics: Geosciences
    Published by Copernicus on behalf of European Geosciences Union.
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  • 4
    Publication Date: 2009-05-18
    Description: The heterogeneous reaction of OH radicals with sub-micron squalane particles, in the presence of O2, is used as a model system to explore the fundamental chemical mechanisms that control the oxidative aging of organic aerosols in the atmosphere. Detailed kinetic measurements combined with elemental mass spectrometric analysis reveal that the reaction proceeds sequentially by adding an average of one oxygenated functional group per reactive loss of squalane. The reactive uptake coefficient of OH with squalane particles is determined to be 0.3±0.07 at an average OH concentration of ~1×1010 molecules cm−3. Based on a comparison between the measured particle mass and model predictions it appears that significant volatilization of a reduced organic particle would be extremely slow in the real atmosphere. However, as the aerosols become more oxygenated, volatilization becomes a significant loss channel for organic material in the particle-phase. Together these results provide a chemical framework in which to understand how heterogeneous chemistry transforms the physiochemical properties of particle-phase organic matter in the troposphere.
    Print ISSN: 1680-7316
    Electronic ISSN: 1680-7324
    Topics: Geosciences
    Published by Copernicus on behalf of European Geosciences Union.
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