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  • 1985-1989  (2)
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  • 1
    Electronic Resource
    Electronic Resource
    Infrarotspektroskopische Untersuchungen an Harnstoff-Formaldehyd-Feststoffen (1987)
    Weinheim : Wiley-Blackwell
    Acta Polymerica 38 (1987), S. 574-579 
    Details
    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: Urea formaldehyde particles formed by acid-catalyzed condensation were investigated by infrared spectroscopy. Depending on the composition three different structures were found. At molar ratio F/H 〈 1.25 linear crystalline methylene ureas were obtained, at F/H 〉 1.25 dimethylene ether linkages, and only when the reaction is carried out under strong acid conditions cyclic structures (urons) are formed.
    Notes: Durch säurektalysierte Polykondensation hergestellte feinverteilte Harnstoff-Formaldehyd-Feststoffe wurden infrarotspektroskopisch untersucht. In Abhängigkeit von der Zusammensetzung wurden drei verschiedene Strukturen gefunden. Bei einem Molverhältnis F/H 〈 1,25 wurden lineare kristalline Methylenharnstoffe erhalten, bei F/H 〉 1,25 Dimethylenetherstrukturen und nur unter stark sauren Bedingungen cyclische Strukturen (Urone).
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/actp.1987.010381007
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  • 2
    Electronic Resource
    Electronic Resource
    Zur Katalyse der Polyesterbildung durch Metallalkoxide (1988)
    Weinheim : Wiley-Blackwell
    Acta Polymerica 39 (1988), S. 315-320 
    Details
    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: Based on kinetic and non-kinetic methods, the metalalkoxide catalysis in the formation of polyesters was examined. The microkinetic rate constants for several polyester/catalyst systems were determined by polycondensation in thin layers of the melt. Spectroscopic investigations of benzoic acid esters/metalalkoxide model systems showed that no direct interactions between metal and ester groups are possible. The catalysts influence the inter- and intramolecular hydrogen bridge bonds of the ω-hydroxyalkylester groups. The polycondensation reaction was activated by alkoxid acids. These acids were formed from metal alkoxids and the hydroxyalkyl ester groups contained in the system.
    Notes: Die metallalkoxid-katalysierte Polyesterbildung wurde mittels kinetischer und nichtkinetischer Methoden untersucht. Die mikrokinetischen Geschwindigkeitskonstanten werden aus Polykondensationsversuchen in dünnen Schmelzeschichten erhalten. Spektroskopische Untersuchungen von Benzoesäureester-Metallalkoxid-Modellsystemen zeigten keine direkten Wechselwirkungen des Metalls mit den Estergruppen an. Die Katalysatoren beeinflussen die inter- und intramolekularen Wasserstoffbrückenbindungen der ω-Hydroxyalkylestergruppen. Die Aktivierung der Polykondensationsreaktion erfolgt durch Alkoxosäuren, die aus den Metallalkoxiden und den im System vorhandenen Hydroxyalkylestergruppen gebildet werden.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/actp.1988.010390611
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    Paper (German National Licenses)
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