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  • 1985-1989  (7)
  • Polymer and Materials Science  (7)
  • 5-Azacytidine
  • 1
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 27 (1989), S. 807-815 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Polymerization of vinyl acetate initiated by β-picolinium p-chlorophenacylide was carried out at 30, 35, and 40°C, using conventional dilatometric technique. The initiator and the monomer exponent values were 0.80 ± 0.15 and unity, respectively. The polymerization was inhibited in the presence of hydroquinone, but was favored by nonpolar solvent and polymerization temperature. The energy of activation was 90.3 KJ mol-1. An average value of kp2/kt for the present system was found to be 0.37 × 10-2. The results are explained in terms of a radical mode of polymerization with degradative initiator transfer; the principal mode of termination, however, was bimolecular.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 27 (1989), S. 43-51 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The polymerization of vinyl acetate initiated by β-picolinium-p-chlorophenacylide was carried out at 30, 35, and 40°C, using the conventional dilatometric technique. The initiator and the monomer exponent values were 0.80 ± 0.15 and unity, respectively. The polymerization was inhibited in the presence of hydroquinone, but was favored by nonpolar solvent and polymerization temperature. The energy of activation was 90.3 kJ mol-1. An average value of kp2/kt for the present system was found to be 0.37 × 10-2 L mol-1 s-1. The results are explained in terms of radical mode of polymerization with degradative initiator transfer; the principal mode of termination, however, was biomolecular.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 141 (1986), S. 103-111 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die mit α-Picolinium-p-chlorphenacylid initiierte Polymerisation von Methylmethacrylat in Tetrachlorkohlenstoff bei 30, 35 und 40°C und einer Dauer von vier Stunden wurde dilatometrisch untersucht. Die Reaktionsordnungen im Hinblick auf die Konzentration von Ylid und Methylmethacrylat liegen bei 0,22 ± 0,1 bzw. 1,0. Die gesamte Aktivierungsenergie und der mittlere Wert von kp2/kt beträgt 21 kJ · mol-1 bzw. 0,37 · 10-2.Die Ergebnisse wurden als radikalische Polymerisation mit einer initiatorabhängigen Übertragung und einem bimolekularen Abbruch erklärt.
    Notes: The polymerization of methyl methacrylate (MMA) initiated by α-picolinium-p-chlorophenacylide in CCl4 at 30, 35, and 40°C for four h was investigated dilatometrically. The orders of reaction with respect to the concentrations of ylide and MMA are 0.22 ± 0.01 and 1.0, respectively. The overall energy of activation and an average value of kp2/kt are 21.0 kJmol-1 and 0.37 ± 10-2, respectively. The results are explained in terms of radical mode of polymerization with initiator dependent transfer besides bimolecular termination.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 149 (1987), S. 139-150 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die alternierende Copolymerisation von Methylmethacrylat mit Styrol unter Verwendung von β-Picolinum-P-chlorphenacylid als Radikalinitiator bei 55, 60 und 65°C und einer Reaktionszeit von 3 h wurde kinetisch untersucht. Die Copolymerisationsgeschwindigkeit (Rp) ist proportional der Quadratwurzel der Initiatorkonzentration und weist auf einen bimolekularen Abbruch hin. Der durchschnittliche Polymerisationsgrad nimmt mit zunehmender Initiatorkonzentration ab. Die ermittelten Werte für kp2/kt und für die Aktivierungsenergie betragen 1,43 · 10-3 l mol-1 s-1 bzw. 87 kJ mol-1. Die NMR Spektroskopie wurde zur Bestimmung der Struktur, Zusammensetzung und Stereochemie der Copolymeren verwendet.
    Notes: The alternating copolymerization of methyl methacrylate (MMA) with styrene (S) using β-picolinium-p-chlorophenacylide (β-PCPY) as radical initiator at 55, 60, and 65°C for 3 h has been kinetically investigated. The copolymerization rate (Rp) is proportional to the square root of [β-PCPY] and indicates bimolecular termination. The average degree of polymerization decreases as [β-PCPY] increases. The values of kp2/kt and energy of activation have been evaluated as 1.43 · 10-3 l mol-1 s-1 and 87 kJ mol-1, respectively. The NMR spectroscopy has been used to determine the structure, composition, and stereochemistry of copolymers.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 5
    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 oxidative Polymerisation von 2-Methyl,6-isopropyl-phenol mit Mangan-Benzylamin-Komplexen erfolgt nach einem Mechanismus, der einer Michaelis-Menten-Reaktion ähnelt, wobei während der Polymerisation der stationäre Zustand erhalten bleibt. Aus einem Vergleich der kinetischen Parameter wird geschlossen, daß Sauerstoff an dem Reaktivierungsschritt des Katalysators beteiligt ist und so die katalytische Wirkung des Mangankomplexes fördert.
    Notes: With managanese-benzylamine complexes the oxidative polymerization of 2-methyl,6-isopropyl phenol proceeds by a mechanism resembling to that of a Michaelis-Menten-type reaction with the steady state being maintained during the polymerization. From the comparison of the kinetic parameters it was concluded that oxygen takes part in the recyeling step of the catalyst and promotes the catalytic action of the manganese complexes.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Acta Polymerica 37 (1986), S. 193-195 
    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 Polymerisation von Methylacrylat mit Methylnitrilylid als Initiator wird untersucht. Die Polymerisationsgeschwindigkeit ist eine dirkete Funktion der Konzentration des Initiators, des Monomers und eines unpolaren Lösungsmittels. Polare Lösungsmittel und Hydrochinon haben einen umgekehrten Einfluß. Der mittlere Polymerisationsgrad steigt mit der Initiatorkonzentration, ist aber unabhängig von der Polymerisationszeit.
    Notes: The polymerization of methyl acrylate with methyl nitrile ylide as initiator is studied. The rate of polymerization it a direct function of concentration of the initiator, monomer and non-polar solvent, but is affected inversely by polar solvents and hydroquinone. The average degree of polymerization is a direct function of initiator concentration, but independent of the polymerization time.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Acta Polymerica 38 (1987), S. 432-435 
    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 durch Imidazolium-p-chlorphenacylid initiierte Polymerisation von Styren in dem inerten Lösungsmittel Dioxan wurde untersucht. Bei niedriger Styrenkonzentration folgt die Polymerisation des Systems einer idealen radikalischen Kinetik. Bei höherer Styrenkonzentration wurde kein ideales kinetisches Verhalten festgestellt, was auf Basis einer merklichen degradativen Ketten- bzw. Initiatorübertragung erklärt werden konnte.
    Notes: The polymerization of styrene in dioxane as an inert solvent initiated by imidazolium-p-chlorophenacylide is studied. The polymerization of the system follows ideal kinetics at low concentration of styrene. At higher styrene concentration, nonideal kinetics is observed, which is explained on the basis of significant degradative chain (initiator) transfer.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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