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  • 1985-1989  (17)
  • Polymer and Materials Science  (16)
  • Multimorbidity  (1)
  • 11
    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: Molecular weight distributions of branched poly(phenylquinoxa1ines) synthesized by polycondensation of aromatic bis(l,2-diamines) with bis- and tris(l,2-diketones) were calculated based on a special a-priori branching model from gelchromatographic and viscosimetric data. Under the rcactioti conditions considered random reaction of all functional groups is suggested.
    Notes: Die Molmassenverteilungen von durch Polykondensation aromatischer Bis(1,2-diamine) mit Bis- und Tris(1,2-diketonen) synthetisierten verzweigten Polyphenylchinoxalinen wurden auf der Grundlage eines speziellen a-priori-Verzweigungsmodells aus gelchromatographischen und viskosimetrischen Daten berechnet. Damit kann für die angewendeten Synthesebedingungen eine zufällige Reaktion aller funktionellen Gruppen angenommen werden.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 12
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Acta Polymerica 37 (1986), S. 654-655 
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 13
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Acta Polymerica 37 (1986), S. 715-719 
    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 Kinetik der thermischen Polycyclotrimerisierung von 2,2-Bis(4-cyanatophenyl)propan wurde mit Hilfe von DSC und IR-Spektroskopie untersucht. Der autokatalytische Charakter der Reaktion wurde durch Modellierung der Umsatz-Zeit-Kurven bei Zusatz difinierter Mengen der nachgewiesenen Zwischenprodukte aufgeklärt. Weiterhin wurden quantitative Beziehungen zwischen Reinheitsgrad des Dicyanats, Geschwindigkeit der Bruttoreaktion, Lage des DSC-Maximums und B-Zeit gefunden.
    Notes: The kinetics of polycyclotrimerization of 2,2-bis(4-cyanatophenyl)propane was analyzed by differential scanning calorimetry and IR spectroscopy. The autocatalytic character of the reaction was elucidated by modelling the conversion-time curves of systems with definite admixtures of the found intermediate products. Furthermore, quantitative relations between the purity of the dicyanate, the rate of the brutto reaction, the temperature of the DSC maximum, and the B-time of the resin were found.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 14
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Acta Polymerica 38 (1987), S. 655-658 
    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: The average bond lengths and bond angles of the structural units of polycyanurates synthesized by polycyclotrimerization of 2,2-bis(4-cyanatophenyl)propane were measured by single crystal X-ray analysis of model compounds. An off-lattice Monte Carlo model was developed for the simulation of the geometrical structure of cyanurate oligomers with polymerization degrees up to 31. Excluded volume effects were taken into account in the form of hard spheres. The calculated results show that an occurrence of intramolecular cyclizations, which was supposed in the literature, is possible.
    Notes: Die Größen der Bindungsabstände und -winkel der in Polycyanuraten auf Basis von 2,2-Bis(4-cyanatophenyl)propan auftretenden Strukturelemente wurden durch Röntgenkristallstrukturanalyse von Modellsubstanzen ermittelt. Darauf aufbauend wurde ein Monte-Carlo off-lattice Modell zur Simulation der geometrischen Struktur auftretender Oligomere bis zu einem Polymerisationsgrad 31 entwickelt, in dem Effekte des ausgeschlossenen Volumens in Form von hard-sphere Potentialen berücksichtigt sind. Die Ergebnisse belegen unter anderem die aus experimentellen Daten resultierende Vermutung des Auftretens intramolekularer Cyclisierungen.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 15
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Acta Polymerica 38 (1987), S. 16-21 
    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: A Monte Carlo model for the simulation of the process of network building by polycyclotrimerization of difunctional monomers basing on the reaction mechanism of the polycyclotrimerization of aromatic dicyanates was developed. The experimental dependences of the average molar mass, the mass fractions of the first oligomers and of the gel fraction on the conversion of functional groups, measured for the reaction of 2, 2-bis(4-cyanatophenyl) propane in bulk, can be well fitted by the model. Furthermore, the possiblities of the simulation of intramolecular cyclizations and substitution effects are discussed.
    Notes: Auf Basis des Reaktionsmechanismus der Polycyclotrimerisierung aromatischer Dicyanate wurde ein Monte-Carlo-Modell zur Simulation der Netwerkbildung durch Polycyclotrimerisierung difunktioneller Monomere entwickelt. Die experimentell ermittelten Abhängigkeiten der mittleren Molmasse, der Massenanteile der ersten Oligomere und des Gelanteils vom Umsatz der funktionellen Gruppen bei der Reaktion von 2, 2-Bis (4-cyanatophenyl) propan in Schmelze werden durch das Modell gut erfaßt. Weiterhin werden Möglichkeiten der Simulation von intramolekularen Cyclisiierungen und Substituenteneffekten diskutiert.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 16
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Acta Polymerica 39 (1988), S. 548-551 
    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: Unter Zugrundelegung der Kinetik der Hauptreaktionen bis zum Gelpunkt - Polycyclotrimerisierung der Cyanat-gruppe, Einschubreaktion des Glycidethers und Abspaltung eines Phenols - wurde mit Hilf der Kaskadentheorie ein statistisches Strukturmodell der Reaktion von Dicyanaten mit Bisglycidethern entwickelt. Es wurde gefunden, daß die Verschiebung des kritischen OCN-Umsatzes zu höheren Werten im Vergleich zu den klassischen 50% für die reine Polycyclotrimerisation in der Abspaltung eines Phenols mit dem Grundkörper des Cyanatmonomers begründet ist.
    Notes: Basing on the kinetics of the main reactions up to the gelation point - cyclotrimerization of the cyanate, insertion of the glycidylether group and abstraction of a phenol - a statistical structural model for the reaction of a dicyanate with a bisglycidylether was developed using a cascade approach. It was found that the critical OCN conversion shift to higher values compared with the classical 50% for the pure polycyclotrimerization is caused by the abstraction of the phenol with the aromatic rest of the cyanate monomer.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 17
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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