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  • 1
    Electronic Resource
    Electronic Resource
    Estimation of the rate constant of termination by the monomer in the anionic polymerization of methyl methacrylate (1974)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 175 (1974), S. 497-505 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Unter der Voraussetzung, daß der Abbruch bei der anionischen Polymerisation von Methylmethacrylat in Tetrahydrofuran mit Cumylcäsium als Initiator ausschließlich durch das Monomere verursacht wird, wird die Abbruchsgeschwindigkeitskonstante kt± für die Ionenpaare des Polymethylmethacrylcäsiums aus der Molekulargewichtsverteilung von Polymeren, die bei verschiedenen Temperaturen unter sonst gleichen Bedingungen hergestellt wurden, abgeschätzt. Die Abbruchreaktion hat eine Aktivierungsenergie von etwa 11 kcal/mol (46 kJ/mol). - Die relativ große Breite der Verteilung der nicht desaktivierten Ketten („interne Uneinheitlichkeit“) zeigt deutlich die Existenz von verschieden reaktiven Ionenpaararten.
    Notes: Based on the assumption that the termination reaction in the anionic polymerization of methyl methacrylate in THF with cumyl cesium as initiator is exclusively caused by the monomer, the termination rate constant kt(±) for the ion-pairs of polymethylmethacrylcesium is estimated by analyzing the molecular weight distribution (MWD) of polymer samples prepared at different temperatures under otherwise identical reaction conditions. The activation energy of the termination reaction of the ion-pairs is found to be about 11 kcal/mol (46 kJ/mol). - The relatively broad MWD of the non-deactivated chains (the so called internal nonuniformity) reveals the existence of ion-pairs with different reactivity.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1974.021750213
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  • 2
    Electronic Resource
    Electronic Resource
    Influence of aging and crystallinity on the molecular motions in bisphenol-A polycarbonate (1996)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 34 (1996), S. 2863-2879 
    Details
    ISSN: 0887-6266
    Keywords: semicrystalline polymers ; polycarbonate ; TSDC ; rigid amorphous phase ; glass transition ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Thermally Stimulated Depolarization Current technique, Differential Scanning Calorimetry, and Dynamic Mechanical Analysis have been applied to amorphous and semicrystalline bisphenol-A polycarbonate with crystallinity degrees up to 21.8%, in a temperature interval covering the α and β relaxations. The secondary β transition is found to be the sum of three components whose variations in aged and annealed specimens have shown the cooperative character of the β1 and β2 modes, contrary to the localized nature of the β3 component. A Tg decrease was observed by both TSDC and DSC as a function of Xc and has been related to the possible confinement of the mobile amorphous phase in regions whose sizes are smaller than the correlation lengths of the cooperative movements that characterize the motions occurring at Tg. The α relaxation intensity variations with crystallinity show the existence of an abundant rigid amorphous phase in the semicrystalline material. The relaxation parameters deduced from the Direct Signal Analysis of the α relaxation for the mobile amorphous phase do not show significant deviations from those found for the amorphous material. The existence of the rigid amorphous phase has been associated to the ductile-to-brittle transition experienced by the material at low crystallinity levels. © 1996 John Wiley & Sons, Inc.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 3
    Electronic Resource
    Electronic Resource
    Ternary ABC block copolymers based on one glassy and two crystallizable blocks: polystyrene-block-polyethylene-block-poly(ε-caprolactone) (1998)
    Weinheim : Wiley-Blackwell
    Macromolecular Chemistry and Physics 199 (1998), S. 1063-1070 
    Details
    ISSN: 1022-1352
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The hydrogenation of polystyrene-block-polybutadiene-block-poly(ε-caprolactone) SBC triblock copolymers was performed in the presence of the Wilkinson catalyst RhCl(P(C6H5)3)3. Reaction conditions (hydrogen pressure, temperature and reaction time) were varied to ensure quantitative hydrogenation without detectable side reactions. Gel permeation chromatography showed no broadening of the molecular weight distribution during hydrogenation. The efficiency of the catalyst is markedly influenced by the molecular weight of the copolymer. Due to the presence of the polyethylene (PE) block, the resulting polymers exhibit a reduced solubility in comparison to the starting materials. Using differential scanning calorimetry (DSC), preliminary results about the crystallization and melting behavior of the PE-block were obtained. In the triblock copolymers, the PE-block showed a marked depression of the melting point and crystallinity when compared to pure hydrogenated polybutadiene of equivalent molecular weight and microstructure or to a comparable PE-block within a polyethylene-block-poly(ε-caprolactone) diblock copolymer. A fractionated crystallization process of the PCL-block was observed when the PCL component in the hydrogenated triblock copolymers was present as a minor phase.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Kinetische Untersuchung zur Hydratisierung von Acrolein (1991)
    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 63 (1991), S. 733-735 
    Details
    ISSN: 0009-286X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cite.330630714
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  • 5
    Electronic Resource
    Electronic Resource
    Kinetics of the anionic polymerization of methyl methacrylate in 1,2-dimethoxyethane (1980)
    Basel : Wiley-Blackwell
    Die Makromolekulare Chemie, Rapid Communications 1 (1980), S. 363-368 
    Details
    ISSN: 0173-2803
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/marc.1980.030010603
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