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  • 1
    Online Resource
    Online Resource
    Wiesbaden : Springer Fachmedien Wiesbaden | Wiesbaden : Springer Gabler
    Keywords: Cloud Computing ; Leadership ; Management information systems ; Management ; Industrial management ; Business Strategy ; Business IT Infrastructure ; Innovation ; Cloud Computing
    Type of Medium: Online Resource
    Pages: 1 Online-Ressource (IX, 50 Seiten) , 19 Illustrationen
    ISBN: 9783658291013
    Series Statement: essentials
    DDC: 658.4092
    Language: German
    Location Call Number Limitation Availability
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  • 2
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 188 (1987), S. 2865-2873 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A series of rigid rod polyimides 1a-f derived from pyromellitic anhydride (PMDA) and 2,5-di-n-alkoxy-1,4-phenylenediamine containing flexible alkoxy side chains with 4 to 16 carbon atoms was prepared by solution polycondensation. As demonstrated by model experiments full conversion to the imide structure is achieved by reaction of PMDA with 2,5-dialkoxyphenylene diisocyanate, the latter compound being blocked by imidazole. The best solvent for the polycondensation, found in the course of the model reaction, is 1,3-dimethyl-2-oxo-perhydro-pyrimidine together with 4-dimethylaminopyridine as an accelerator. Wide-angle X-ray diffractograms showed that all polyimides under consideration here are highly crystalline at room temperature. The occurrence of a sharp reflection at the region of low angles together with its higher orders demonstrates the presence of a layered structure. The layer spacing was found to increase linearly with the length of the alkyl side chains. Polyimides bearing long side chains (n ≥ 10) exhibit two broad endotherms in the DSC analysis. As is revealed by wide-angle X-ray analysis the first transition is related to a disordering process of the side chains. The second transition leads to a layered high-temperature phase akin to the modification (B) found in a recent study of a similar rigid polyester bearing flexible side chains.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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