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  • 1965-1969  (3)
  • 1
    Electronic Resource
    Electronic Resource
    Characterization studies for polyethylene formed by Co60 γ-radiation under constant conditions in a nonflow system (1965)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 9 (1965), S. 3123-3139 
    Details
    ISSN: 0021-8995
    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: Several properties of polyethylene, synthesized by Co60 gamma radiation have been investigated. The polymerization reactions were carried out in static experiments over a wide range of conditions. Measurements include molecular weight, molecular weight distribution, density, methyl group content, crystalline melting point, and melt index. The density of polyethylene formed at 20°C. was found to be 0.94 g./cc. This value appears to be independent of pressure from 170 to 1700 atm. and radiation intensity from 0.58 × 105 to 4.7 × 105 rads./hr. Increasing temperature results in increasing methyl group content and a decrease in density to 0.91 g./cc. at 200°C. The polymers formed, over the entire range of experimental conditions, were completely soluble in o-dichlorobenzene at 135°C. Intrinsic viscosities were determined and their dependence on temperature, pressure, intensity, and radiation dose are shown. An attempt was made to correlate melt index to molecular weight and molecular weight distribution.
    Additional Material: 20 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1965.070090917
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Co60 γ-radiation-induced copolymerization of ethylene and carbon monoxide (1966)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-1: Polymer Chemistry 4 (1966), S. 29-57 
    Details
    ISSN: 0449-296X
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The γ-radiation-induced free-radical copolymerization of ethylene and CO has been investigated over a wide range of pressure, initial gas composition, radiation intensity, and temperature. At 20°C., concentrations of CO up to 1% retard the polymerization of ethylene. Above this concentration the rate reaches a maximum between 27.5 and 39.2% CO and then decreases. The copolymer composition increases only from 40 to 50% CO when the gas mixture is varied from 5 to 90% CO. A relatively constant reactivity ratio is obtained at 20°C., indicating that CO adds 23.6 times as fast as an ethylene monomer to an ethylene free-radical chain end. For a 50% CO gas mixture, the above value of 23.6 and the copolymerization rate decrease with increasing temperature to 200°C. The kinetic data indicate a temperature-dependent depropagation reaction. Infrared examination of copolymers indicates a polyketone structure containing —CH2—CH2— and —CO— units. The crystalline melting point increases rapidly from 111 to 242°C., as the CO concentration in the copolymer increases from 27 to 50%. Molecular weight of copolymer formed at 20°C. increased with increasing CO, indicating M̄n values 〉20,000. Increasing reaction temperature results in decreasing molecular weight. Onset of decomposition for a 50% CO copolymer was measured at ≈250°C.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1966.150040103
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Radiation-induced copolymerization of ethylene and sulfur dioxide in the liquid and gas phases (1968)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-1: Polymer Chemistry 6 (1968), S. 3201-3215 
    Details
    ISSN: 0449-296X
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The radiation-induced copolymerization of ethylene and sulfur dioxide has been studied in the liquid and gas phases. In the liquid phase, the copolymer composition remained equimolar over a temperature range of 20-160°C. and ethylene pressures of 50-680 atm. The rate of copolymerization in the liquid phase at 680 atm. increased with temperature to a maximum value at ∼80°C. Above this temperature the rate steadily decreased to zero at 157°C. because of temperature-dependent depropagation reactions. In the gas phase, copolymers were formed that contained from 9 to 46 mole-% sulfur dioxide. Under constant conditions of temperature, pressure, and radiation intensity, the copolymerization rate in the gas phase increased with increasing sulfur dioxide in the initial gas mixture. The propagating species for the liquid-phase experiments is considered to consist of an equimolar complex molecule of ethylene and sulfur dioxide. For gas mixtures containing an excess molar concentration of ethylene, the propagating species are ethylene and the complex molecule. Infrared spectra show polysulfone structures. Calorimetric and x-ray diffraction analyses indicate crystalline structures for copolymers in the range 9-50 mole-% sulfur dioxide, although a melt transition temperature could not be observed for copolymer containing 〉31 mole-% sulfur dioxide. Clear uniform film was obtained with copolymers containing up to 31 mole-% SO2.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1968.150061201
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    Paper (German National Licenses)
    Fulltext
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