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  • 1
    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: Samples of poly[1-(trimethylsilyl)-1-propyne] were kept for about 4 years in ambient conditions. The permeability and diffusion coefficients were examined and found to be decreased by 1-2 orders of magnitude. To ascertain the nature of the changes underwent during long-term storage of this polymer, several physicochemical methods were applied: positron annihilation, wide-angle X-ray diffraction, spin probe, and density evaluation. These studies indicated that a decrease of free volume and more close chain packing took place during the aging process. IR spectroscopy and 13C-NMR showed that oxygen-containing products appeared in the polymer after long-term storage. This should result in a certain decrease in the rigidity of the backbone chains and more intensive interchain in-teractions, and, hence, in a decrease in the free volume of the aged polymer. © 1993 John Wiley & Sons, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
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  • 2
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Ergebnisse einer Untersuchung orientierter Mischungen, die durch successive Synthese von Polypropylen und Polyethylen mit ZIEGLER-NATTA-Katalysatoren hergestellt wurden, werden dargestellt. Es wird gezeigt, daß wegen der starken Wechselwirkung zwischen Polypropylen und Polyethylen die Polyethylenschmelze orientiert werden kann und unter statischen Bedingungen der orientierte Zustand über längere Zeit erhalten bleibt. Die partiell orientierte Polyethylenschmelze liegt in einem flüssig-kristallinen Zustand vor und kristallisiert mit gestreckten Ketten.
    Notes: The results of a study of oriented blends prepared by the method of successive synthesis of polypropylene and polyethylene with ZIEGLER-NATTA catalysts are presented. It is shown that the strong interaction of polypropylene and polyethylene allows to orient and maintain the oriented state of the polyethylene melt under static conditions for a long period of time. The partially oriented polyethylene melt is in liquid-crystalline state and crystallizes with extended chains.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
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