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  • 1
    Electronic Resource
    Electronic Resource
    Surface enrichment in thin films of PVC and PMMA (1996)
    Weinheim : Wiley-Blackwell
    Acta Polymerica 47 (1996), S. 234-242 
    Details
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The surface enrichment in thin bilayer films of poly(vinyl chloride) (PVC) and deuterated poly(methyl methacrylate) (PMMAd) was studied by neutron reflectometry, X-ray photoelectron spectroscopy (XPS) and static secondary ion mass spectrometry (SSIMS). In a layer system, where the PVC film is placed on top of a thin PMMA film, the PMMA chains migrate to the surface, although annealing of the films is performed below the glass transition temperature of PMMA. In addition, the surface segregation in blends of these materials was studied by XPS and SSIMS. In all cases PMMA is enriched at the surface. Results from the different techniques, probing different, sample depths, are consistent, if an exponential concentration profile of PMMAd at the surface is assumed. Concentration profiles at the surface are discussed with respect to theoretical models and diffusion coefficients are estimated.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/actp.1996.010470508
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  • 2
    Electronic Resource
    Electronic Resource
    An estimation of the number of tie molecules in semicrystalline polymers by means of neutron scatteringThe neutron scattering experiments were partly carried out at the ILL, Grenoble, France. (1984)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 22 (1984), S. 1491-1513 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A new method for the evalution of neutron scattering data from semicrystalline polymers is proposed for small and intermiediate q [q = (4π/λ)sinθ/2]. It is based on the assumption that, in general, a molecule cryustallizes in various lamellae. Within one lamella the crystalline stems connected by loop or folds from intramolecular “clusters,” which are connected by tie molecules. Without further assumptions the method yields in a straightforward manner the following quantities: (i) the average number of clusters per molecule, from which the number of tie molecules can be estimated; (ii) the radius of gyration 〈R2∝〉 of the centers of the stems belonging to one cluster; and (iii) the radius of gyration 〈R2ρ〉 of the cluster centers with respect to the center of the molecule the method was successfully tested using experimental data obtained from poly(ethylene oxide), polyethylene, and isotactic polypropylene.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1984.180220813
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  • 3
    Electronic Resource
    Electronic Resource
    Determination of elastic shear constants of polyethylene at room temperature by inelastic neutron scattering (1984)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 22 (1984), S. 1515-1527 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The elastic shear constants of both the amorphous and crystalline regions of polyethylene have been measured at room temperature. A newly developed method is used which allows the determination of elastic constants from the coherent inelastic neutron scattering of polycrystals. A deuterated and partially oriented sample is investigated on a triple-axis spectrometer and a time-of-flight instrument. The elastic constants of the crystalline regions of polyethylene are c44 = 2.1 ± 0.3, c55 = 2.2 ± 0.3, c66 = 1.8 ± 0.2, and c′ = 1/4(c11 + c22 - 2c12) = 0.92 GPa. The shear modulus of the amorphous regions is obtained as G = 0.55 ± 0.03 GPa. In connection with other experimental results the elastic constant matrix is given and compared with theoretical estimates. With simple models, macroscopic moduli are calculated which are in good agreement with published experimental data.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1984.180220814
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  • 4
    Electronic Resource
    Electronic Resource
    Influence of the conformation of polyethylene on wide-angle neutron scattering patterns (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 235-244 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Wide-angle neutron scattering investigations of mixtures of deuterated and nondeuterated chains are well suited to detect sequences of regular adjacent reentry folding of a polymer chain in particular crystallographic directions. It is shown that the diffuse neutron scattering intensity is peaked at large scattering angles for (100) and (010) folding, whereas (110) folding is difficult to detect. Detailed calculations indicate that the position, intensity, and half-width of the diffuse peak depend strongly on the mode of folding as well as on the number of adjacent stems. By a comparison with experimental data adjacent reentry folding in (100) and (010) crystallographic planes with more than five adjacent stems can be excluded. The implications for other folding models containing regular folded chain sequences are discussed.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1982.180200206
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  • 5
    Electronic Resource
    Electronic Resource
    Packing and state of order in conducting polymers. The structure of [(CH)(SbF6)0,06]x (1985)
    Basel : Wiley-Blackwell
    Die Makromolekulare Chemie, Rapid Communications 6 (1985), S. 425-431 
    Details
    ISSN: 0173-2803
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/marc.1985.030060610
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  • 6
    Electronic Resource
    Electronic Resource
    Temperature evolution of the structure of a thermotropic main-chain liquid crystalline copolyester (1994)
    Weinheim : Wiley-Blackwell
    Acta Polymerica 45 (1994), S. 196-203 
    Details
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: X-ray diffraction, differential scanning calorimetry and dynamic mechanical analysis are used to study the temperature evolution of the structure of the thermotropic copolyester poly[(phenyl-pphenylene)-co-(terephthalate)-co-(p-hydroxybenzoate)] (PES) prepared from terephthalic acid, phenyl-hydroquinone and p-hydroxybenzoic acid (molar ratio 45/45/10). Needle-like crystals are developed in the quenched as-spun fibers despite the random sequence of the monomers of the copolyester. Moreover, two other crystalline phases are observed at elevated temperatures, which may be explained by a phase separation process. X-ray diffraction experiments show a significant temperature dependence of structural features, indicating some conformational disorder and mobility in this class of “rigid-rod” liquid crystalline polymers. Changes in the X-ray pattern are observed on heating, starting immediately above the glass transition temperature of the copolyester. Melting of PES reveals a two-step character with transitions at 300 °C and 320 °C. The material becomes isotropic at 400 °C or higher.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/actp.1994.010450310
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