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  • 1
    Electronic Resource
    Electronic Resource
    Frequency dependence of the complex dielectric constant of poly(ethylene oxide) under hydrostatic pressure (1994)
    Springer
    Il nuovo cimento della Società Italiana di Fisica 16 (1994), S. 855-864 
    Details
    ISSN: 0392-6737
    Keywords: Polymers, elastomers, and plastics ; Mechanics and rheology of solids ; Conference proceedings
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Summary Electrical-impedance measurements have been made in the frequency range 5 Hz to10 MHz in pure poly(ethylene oxide) having a molecular weight of 600 000 from 254 K nearly up to the melting point of the crystalline phase (about 330 K). As the temperature approaches the melting point there are large increases in the realε′ and imaginaryε″ parts of the dielectric constant. The frequency dependence ofε′ is characterized by a primary-relaxation process, whose frequency increases with increasing temperature as a consequence of decrease of the average structural relaxation time. There is strong evidence that this low-frequency dispersion rises mainly from the diffusive transport of localised charge carriers rather than a purely orientation relaxation process. In addition the effects of hydrostatic pressure (0–25 Gpa) on the frequency dependences of the realε′ and imaginaryε″ parts of the dielectric constant have been measured in the same temperature range.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02456735
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  • 2
    Electronic Resource
    Electronic Resource
    The elastic behaviour under hydrostatic pressure of poly(methyl methacrylate) and its fully deuterated form (1990)
    Springer
    Journal of materials science 25 (1990), S. 4654-4657 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Measurements have been made of the effects of hydrostatic pressure on the velocities of longitudinal and shear ultrasonic waves propagated in a commercial poly(methyl methacrylate) (PMMA) and a fully deuterated PMMA. The experimental results provide a comparison of the bulk and shear moduli and their hydrostatic pressure derivatives for the two polymers. The vibrational anharmonicity of the long wavelength acoustic modes is more pronounced in the deuterated than in the commercial PMMA. ∂B/∂P is 32% larger in the deuterated form than in the undeuterated polymer, a finding which may be understood by including the isotopic mass difference in a simple vibrational model.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01129921
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    Paper (German National Licenses)
    Fulltext
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