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  • 1
    Electronic Resource
    Electronic Resource
    An analysis of the secondary relaxation in isochronal measurement of glasses (1986)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 24 (1986), S. 2655-2668 
    Details
    ISSN: 0887-6266
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A method by which the occurrence of a secondary relaxation can be deduced from the isochronal dielectric and mechanical loss data of amorphous and crystalline materials is given. The method eliminates the complexity arising from the frequency-independent, temperature-dependent background loss in solids.It is shown that the relaxation rate measured at a fixed frequency by varying the temperature substantially differs from that measured at a fixed temperature by varying the frequency when the strength of the relaxation is temperature dependent. This discrepancy leads to a different value of activation energy and of preexponential factor when the strength increases with temperature. The results are discussed in terms of the temperature dependence of the strength of relaxation and its distribution parameter.The method of analysis has been applied to the data for a molecular and a polymeric glass and shows the occurrence of a β process which is otherwise not detected in their tan β isochrones. Experimental data on a wide variety of glasses also show that the activation energies and relaxation rates obtained from isochrones differ from those obtained from the isothermal spectrum.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1986.090241205
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    An analysis of ionic conductivity in polymer electrolytes (1994)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 32 (1994), S. 2733-2741 
    Details
    ISSN: 0887-6266
    Keywords: polymer electrolytes ; ionic conductivity ; Vogel-Tammann-Fulcher equation ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Conductivities for a wide variety of ionically conducting polymer electrolytes with a range of salt compositions have been investigated over the temperature region Tg to 370 K. When the conductivity data are analyzed as a function of temperature using the empirical Vogel-Tammann-Fulcher (VTF) equation a common trend is observed in that deviations in the fits to the data invariably occur in the temperature range 1.2 Tg to 1.4 Tg for all of the samples investigated. This deviation is interpreted as a decoupling of the ions from polymer segmental motion. Recent 23Na NMR and 22Na positron annihilation studies of sodium salt-based polymer electrolytes support this interpretation with evidence of a change in dynamics at about 1.2Tg. © 1994 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1994.090321619
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  • 3
    Electronic Resource
    Electronic Resource
    Ionic conduction in composite polymer electrolytes at subambient temperatures (1996)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 34 (1996), S. 2911-2917 
    Details
    ISSN: 0887-6266
    Keywords: composite polymer electrolytes ; conduction mechanism ; glass transition temperature ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The majority of investigations carried out on polymer(SINGLEBOND) salt systems have been on polyether electrolytes at moderate temperatures where such electrolytes exhibit macroscopic uniformity. Relatively little attention has been paid to the subambient temperature region where composite electrolytes based on polyethers exhibit much higher conductivities than their pure polyether electrolyte analogues. For all of the composite systems studied the conduction mechanism changes from one in which the ions are coupled to the polymer segmental relaxations to one in which the ions are decoupled and thermally activated ionic hopping produces higher conductivities than would be expected from ion-segmental coupling and higher than observed for the base polyether(SINGLEBOND) salt system. This change has been observed at temperatures between 10 and 80°C above the respective glass transition temperatures. The relationship between this interaction and these higher conductivities at subambient temperatures is explored and discussed. © 1996 John Wiley & Sons, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 4
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    Single-Particle Measurements of Midlatitude Black Carbon and Light-Scattering Aerosols from the Boundary Layer to the Lower Stratosphere (2006)
    In:  Other Sources
    Details
    Publication Date: 2019-07-19
    Description: A single-particle soot photometer (SP2) was flown on a NASA WB-57F high-altitude research aircraft in November 2004 from Houston, Texas. The SP2 uses laser-induced incandescence to detect individual black carbon (BC) particles in an air sample in the mass range of approx.3-300 fg (approx.0.15-0.7 microns volume equivalent diameter). Scattered light is used to size the remaining non-BC aerosols in the range of approx.0.17-0.7 microns diameter. We present profiles of both aerosol types from the boundary layer to the lower stratosphere from two midlatitude flights. Results for total aerosol amounts in the size range detected by the SP2 are in good agreement with typical particle spectrometer measurements in the same region. All ambient incandescing particles were identified as BC because their incandescence properties matched those of laboratory-generated BC aerosol. Approximately 40% of these BC particles showed evidence of internal mixing (e.g., coating). Throughout profiles between 5 and 18.7 km, BC particles were less than a few percent of total aerosol number, and black carbon aerosol (BCA) mass mixing ratio showed a constant gradient with altitude above 5 km. SP2 data was compared to results from the ECHAM4/MADE and LmDzT-INCA global aerosol models. The comparison will help resolve the important systematic differences in model aerosol processes that determine BCA loadings. Further intercomparisons of models and measurements as presented here will improve the accuracy of the radiative forcing contribution from BCA.
    Keywords: Meteorology and Climatology
    Type: Journal of Geophysical Research Atmospheres (ISSN 0148-0227); 111
    Format: text
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