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  • 1
    Electronic Resource
    Electronic Resource
    Time-dependence of crystal orientation in crystalline polymers (1968)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 8 (1968), S. 259-266 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The results of two methods for studying molecular processes accompanying the deformation of polyethylene are described. The examination of spherulite deformation by observing light scattering patters along with measurement of the birefringence, stress and strain during the rapid extension of polyethylene shows that this initial structural deformation is essentially instantaneous. Dynamic x-ray diffraction shows that this is followed by a slower relaxation involving change in the orientation of the crystals by two processes, the lower temperature one involving slipping of lamellae past each other and the higher temperature one involving viscoelastic flow of the crystals.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760080405
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    1969 SPE international award paper. Rheo-optics on two continents - an example of international cooperation in sciencePrepared while the writer was serving as a Fulbright Visiting Professor at Kyoto University, Kyoto, Japan. The work described here has been supported by the Office of Naval Research, the Petroleum Research Fund of the American Chemical Society, and the National Science Foundation. (1969)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 9 (1969), S. 320-330 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Rheo-optical techniques for the study of crystalline polymers, developed primarily in the United States and Japan, include dynamic birefringence, X-ray diffraction, dichroism, light scattering, and fluorescence. These permit the characterization of the rates of orientation of crystals, amorphous regions, and crystalline superstructures. The application of these methods has permitted the formulation of a model for the deformation of crystalline polymers.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760090503
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Structural interpretations of mechanical properties of polycrystalline polymers (1964)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 4 (1964), S. 178-186 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Structural changes are considered in light of the two differing views of the structure of crystalline polymers involving either a two phase structure or a single phase structure involving detects. A compromise picture is proposed which appears consistent with existing experimental evidence. Optical methods are described for analyzing structural changes accompanying deformation of these polymers. These include x-ray diffraction, static and dynamic birefringence measurements and dynamic light scattering studies. The results are consistent with a two stage deformation process involving first the elastic deformation of a spherulitic or crystalline structure followed by an internal rearrangement of crystals within this structure, taking place by a number of mechanisms such as recrystallization, defect migration, plastic flow and crystal rotation. The time dependence of some of these processes is studied and related to structural features.
    Additional Material: 17 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760040308
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    The crystalline morphology of poly(vinylidene fluoride)/poly(methylmethacrylate) blends (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 311-318 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Poly(vinylidene fluoride), PVF2, as well as blends of PVF2 with poly(methyl methacrylate), PMMA, develop a variety of crystalline morphologies at low undercoolings. Both the α and γ crystal forms grow from the melt and the former undergoes a solid-solid phase transition to the latter, though its morphology remains unaltered. Three melting temperatures which decrease with increasing PMMA content are observed. Hoffman-Weeks analysis shows the equilibrium melting points of the blends to be depressed. Using these equilibrium values, the thermodynamic interaction energy density is calculated to go from -5.40 × 106 to -2.96 × 107 j/m3 as the blend composition goes from 40.1 volume percent to pure PVF2. The band periodicity in the α form spherulites increases with crystallization temperature and PMMA content and it appears to be from a lamellar reorientation process with an apparent activation energy of 322 cal/mole. Electron diffraction patterns taken along the radial direction in a given spherulite reveal lamellar twisting which causes the banded appearance. Light scattering results suggest that the lamellar are formed into rod-like structures on a local scale but that on a larger scale they develop a disoriented spherulitic morphology.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760240505
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    Paper (German National Licenses)
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