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  • 1970-1974  (3)
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Publisher
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Year
  • 1
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 12 (1974), S. 2091-2110 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A model is proposed to account for the orientation of crystals in spherulites upon deforming a polymer. The model assumes affine deformation of the spherulite accompanied by three processes of crystal reorientation within the spherulite. These are tilting of molecular chains with respect to the plane of the lamellae, characterized by a parameter K, twisting of the lamallae about the spherulite radii described by η, and rotation of the b crystal axis about the c axis characterized by a third parameter, P. Values of these parameters are fitted to measured orientation functions and compared with experimental measurements of the azimuthal variation of the intensities of the 110 and 200 crystal reflections from low-density polyethylene. Good agreement is found between the experimental and theoretically predicted intensity variation. Time-dependent experiments under relaxational and vibrational conditions are also treated by the theory.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 12 (1974), S. 735-761 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A theory is developed by use of the correlation function approach for calculating both the Hv and Vv intensity of scattered light for a concentrated assembly of spherulities. The scattering becomes a function of the radial and tangential polarizabilities of the spherulite αr and αt, the polarizability αm of the medium, surrounding the spherulites, and the volume fraction φs of spherulites. The “effective polarizability of the surroundings” αs, which appeared in previous theories, becomes function of these variables. The theory can explain, for example, why the Vv scattered intensity passes through a maximum during the course of crystallization.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 12 (1974), S. 763-784 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A lattice theory of orientational disorder in two-dimensional spherulites is developed in which the orientation direction of the optic axis in lattice cells is allowed statistically to deviate from its mean value in a manner correlated with the orientation in neighboring cells. The Hv light scattering patterns arising from such disordered spherulites deviate from the patterns for perfect spherulites in that there is excess intensity at both small and large scattering angles and the intensity at the maximum is lower. A comparison of the calculated scattering angular dependence with that which is experimentally measured permits assignment of values of correlation parameters. A consequence of this disorder is that the spherulite birefringence is reduced below that calculated on the basis of perfect crystalline orientation in agreement with experiment.
    Additional Material: 17 Ill.
    Type of Medium: Electronic Resource
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