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  • Physics  (5)
  • Wiley-Blackwell  (5)
  • American Geophysical Union
  • Nature Publishing Group
  • Springer Nature
  • 1980-1984  (5)
  • 1
    Electronic Resource
    Electronic Resource
    Copolymerization of isobutene and α-methylstyrene as a function of reaction conditions (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 20 (1982), S. 1517-1532 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The influence of reaction conditions (solvent, Lewis acid, temperature) on the cationic copolymerization of isobutene and α-methylstyrene was investigated. The crude product consists of low molecular nonprecipitable oligomers, polyisobutene, and poly(isobutene-co-α-methylstyrene). The amount of poly(α-methylstyrene) formed under the reaction conditions used was negligible. The degree of charge separation in the propagating cationic intermediate determines the selectivity of the reaction; that is, incorporation of monomer units into the polymer, ratio of different product fractions, and microstructure. Molecular weight distribution, copolymerization parameters, and sequence-length distribution functions were determined. The softening range of the copolymers depended on their isobutene content but appeared to be constant up to 15% isobutene in copolymers. The degradation temperature of the copolymers was between 340 and 390°C.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1982.170200613
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  • 2
    Electronic Resource
    Electronic Resource
    On the structure of polyurethane hard segments based on MDI and butanediol-1,4: X-ray diffraction analysis of oriented elastomers and of single crystals of a model compoundDedicated to Professor Herbert Grunewald on the occasion of his 60th birthday. (1984)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 22 (1984), S. 163-173 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Single-crystal x-ray diffraction analysis is performed on a model compound (bisurethane of diphenylmethane-4-monoisocyanate and butanediol-1,4) for the thermoplastic polyurethane (TPU) hard segment formed from diphenylmethane-4,4′-diisocyanate and butanediol-1,4. The resulting structure is compared to structure models of corresponding TPU hard segments, especially to the structure proposed by Blackwell and Ross. Our results confirm this structure model showing a planar zigzag of the (CH2)4 group and planar hydrogen bonding between the urethane groups of adjacent molecules. X-ray diffraction analyses of polymeric TPU hard segments and of TPU elastomers with noncrystallizing soft segments lead to a revision of the dimensions of the proposed lattice cell, resulting in a more plausible value of 1.3226g/cm3 for the crystal density.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1984.180220202
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  • 3
    Electronic Resource
    Electronic Resource
    Comparison of the rheological properties of linear and star-branched polyisoprenes in shear and elongational flows (1983)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 21 (1983), S. 2287-2298 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The rheological properties of narrow-molecular-weight-distribution linear and star-branched polyisoprenes have been determined using both shearing and stretching deformations. At all strain rates studied the tensile stress measured under transient and steady-state conditions did not increase above the linear viscoelastic value. The absence of an enhanced tensile stress for the branched polymer is in contrast to what is observed for branched low-density polyethylene. An explanation for the difference is proposed. Additional remarks are made about the broad distribution of relaxation times observed for star-branched polyisoprenes and about the approach to steady state in constant-strain-rate and constant-stress tests.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1983.180211106
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  • 4
    Electronic Resource
    Electronic Resource
    Polymer-bound flavins. I. Influence of polarity of the polymer chain on properties of bound flavin (1984)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 22 (1984), S. 705-719 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The preparation of flavin-containing, water-soluble terpolymers with varying contents of quaternary ammonium and neutral monomer units is described. The composition of the polymer, that is, the polarity of the polymer chain, affects the UV/VIS absorbance spectrum of the bound flavin moiety by influencing the flavin-solvent interaction. Aerobic oxidation of 1-benzyl-1,4-dihydronicotinamide (BNAH) is accelerated as much as 17-fold by polymer-bound flavins, compared with free flavin. Depending on the ratio of polar/nonpolar groups in the flavin polymer and the 2-propanol content of the aqueous reaction medium (pseudo) first-order or Michaelis-Menten type kinetics were observed as a function of substrate concentration. The influence of the polymer composition on flavin/BNAH complex formation (Km-1) and rate-limiting hydride transfer step (k2) is discussed. Accumulation of the substrate in the polymer domain due to apolar interactions is one of the major factors that determine the observed rate enhancements.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1984.170220319
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  • 5
    Electronic Resource
    Electronic Resource
    Polymer- bound flavins. III. Effects of coil dimension and substrate structure on reaction kinetics in water/2-propanol mixtures (1984)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 22 (1984), S. 2169-2180 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The strong influence of medium composition (water/2-propanol mixtures) on the rate of oxidation of 1-substituted dihydronicotinamides by a flavin-containing polyelectrolyte was studied. We found that the coil dimensions of the corresponding copolymer of styrene and vinylbenzyltriethylammoniumchloride without flavin groups dramatically depend on the solvent. Viscometric measurements revealed compact coil conformations in solvents of both high water and high 2-propanol content, but pronounced coil expansion in intermediate mixtures. These changes of polyelectrolyte coil dimensions are related to changes in electrostatic potential of the microreactors. Addition of 2-propanol also results in decrease of substrate enrichments, caused by weakening of nonpolar polymer-substrate interactions, as was demonstrated for 1-carbamoylmethyl-, 1-benzyl-, and 1 decyl-substituted 1,4-dihydronicotinamide substrates. The enormous decrease in rate constant for oxidation of DNAH by 2 upon increasing the 2-propanol content from 10 to 40% (v/v), from k = 3120 to 21 M-1 s-1, can thus be explained as a cooperation of both effects. Evidence for the formation of a charge transfer complex between the polyelectrolyte-bound flavin and the dihydronicotinamide having a long-wavelength absorption is also presented.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1984.170220918
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