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  • 1
    Electronic Resource
    Electronic Resource
    Dielectric investigation of the glass relaxation in poly(vinyl acetate) and poly(vinyl chloride) under high hydrostatic pressure (1985)
    Springer
    Colloid & polymer science 263 (1985), S. 873-878 
    Details
    ISSN: 1435-1536
    Keywords: Dielectric measurements ; high pressure ; glass relaxation ; poly(vinyl acetate) ; poly(vinyl chloride)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Measurements of the complex relative permittivity of poly(vinyl acetate) from 35 °C to 190 °C and poly(vinyl chloride) from 90 °C to 150 °C in the frequency range 10−2 −107 Hz and the pressure range 1–5000 bar are reported. Details of the pressure generating system and of the dielectric equipment are described.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01469623
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  • 2
    Electronic Resource
    Electronic Resource
    Dielectric relaxation in two liquid crystalline polyacrylates under high hydrostatic pressure (1985)
    Springer
    Colloid & polymer science 263 (1985), S. 895-898 
    Details
    ISSN: 1435-1536
    Keywords: Polymer liquid crystals ; dielectric measurements ; high pressure ; glass relaxation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract For two polyacrylates with p-cyano-phenyl benzoate side groups and different spacer lengths the dielectric relaxation was measured in the nematic and isotropic phase at pressures up to 5000 bar. The relaxation of the cyano groups was observed as a separate relaxation process; it seems to be closely correlated with the glass relaxation. The pressure dependence of the glass temperature and of the clearing temperature could be derived from the experiments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01469626
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  • 3
    Electronic Resource
    Electronic Resource
    Viscoelastic behaviour of model polyurethane networks in the main transition zone (1987)
    Springer
    Colloid & polymer science 265 (1987), S. 8-18 
    Details
    ISSN: 1435-1536
    Keywords: Mechanical measurements ; model networks ; glass relaxation ; unperfect crosslinking reaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Starlike poly (oxypropylene) molecules (M=2630 resp. 710 g/mol), each with three OH-end-groups, are crosslinked with 4,4′-diphenylmethane diisocyanate in one stoichiometric and several nonstoichiometric reactions. Dynamic mechanical (frequency 10−4 to 102 Hz) and also some dielectric (10−2 to 106 Hz) measurements were made on these networks in a wide temperature range. The time-temperature-superposition principle was used to obtain master curves. Two large relaxation processes were detected (separated by many decades of frequency in some samples). The high frequency process seems to correspond to the glass-rubber transition in linear polymers, the low frequency process is probably due to the relaxation of “dangling chains”.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01422657
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  • 4
    Electronic Resource
    Electronic Resource
    Dielectric relaxation of polystyrene with side-chain- and chain-end-labels (1994)
    Springer
    Colloid & polymer science 272 (1994), S. 894-902 
    Details
    ISSN: 1435-1536
    Keywords: Labeled polymer ; dielectric measurements ; glass relaxation ; label relaxation ; glass transition temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Polystyrenes with different concentrations of side groups with cyano groups were prepared and complex dielectric constants were measured in the range of the glass transition temperature and the frequency range of 10−2–107 Hz. The GPC and DSC measurements showed that the molecular weight of these polystyrenes was about 10500 g/mole and the glass transition temperatures were 89.5°C for all samples. The dielectric relaxation spectra obtained for the side group polystyrene labels and also the chain-end polystyrene labels prepared before [9] were analyzed to find out the degree of coupling of the chain-end and side-group labels with the cooperative reorientation of the polymeric matrix. The analysis of the spectra was carried out using the analysis method developed by Mansour and Stoll [6]. The results obtained showed that both end- and side-group labels are strongly coupled with the segmental reorientation and relax with relaxation times longer than that of the segments. The value of Δlogf m = (logf m(label)) − logf m(matrix)) was obtained from the recently designed comparison diagram suggested by Mansour and Stoll [6, 14]. The value of Δlogf m depends on the label length in the case of chain-end labels. It was surprising to find that the side groups relax slower than the segments by only 0.9 decades. These results obtained implied that the label relaxes through a multistep relaxation mechanism of the side and end groups and not through a diffusion mechanism of the whole chain. In addition, the effective lengths of the relaxing units were determined using the empirical equation obtained before in the case of rodlike molecules in polyisoprene [7].
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00658887
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