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  • 1
    Electronic Resource
    Electronic Resource
    Small-angle-X-ray scattering by crystalline polymer fibres 1. Experimental method and investigation of the linear paracrystalline model (1987)
    Springer
    Colloid & polymer science 265 (1987), S. 383-393 
    Details
    ISSN: 1435-1536
    Keywords: Small-angleX-ray ; linearparacrystal ; poly(butylene terephthalate) ; orientedpolymerfibre
    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 Hosemann's formula for X-ray scattering by a linear paracrystal is investigated using the distribution of intensity parallel to the fibre axis of oriented poly(butylene terephthalate). The formula was put into a form suitable for numerical analysis, and a stepping refinement procedure used to adjust the paracrystalline parameters so that the discrepancy between the calculated and measured intensity was minimised. The measured intensity had been corrected for the spread of scattering transverse to the fibre axis before making this comparison. The pin-hole collimation system was designed so that resolution was limited only by the linear position-sensitive detector, and was good enough not to distort the recorded scattering distribution. Although parasitic scatter could not be measured to the same accuracy, it was so small that negligible error was introduced when it was subtracted. “Top-hat”, Gaussian and Reinhold distribution functions for the lengths of the two phases all fitted well in the region of the main peak although detailed analysis suggested significant disagreement on the low-angle side. Only the asymmetric Reinhold function fitted around the third-order peak and beyond. The range of parameter values giving a good fit for this distribution were determined.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01412216
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  • 2
    Electronic Resource
    Electronic Resource
    Crystallization kinetics of amorphous S20Se80 (1990)
    Springer
    Journal of thermal analysis and calorimetry 36 (1990), S. 1481-1486 
    Details
    ISSN: 1572-8943
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Mittels DSC wurde der Einflu\ der Temperatur auf die Kristallisierungskinetik von amorphem S20Se80 untersucht. Unter Verwendung der empirischen Avrami Gleichungen wurde eine Anzahl kinetischer Grö\en ermittelt. Danach ergab sich die Reaktionsordnung n für den Temperaturbereich 340–365 K mit 2.3 und für den Temperaturbereich 370–400 K mit 1.6. Dieses Intervall fürn zeigt, da\ es sich beim Kristallisationsproze\ um ein diffusionsbestimmtes Wachstum mit sinkender Kristallkeimbildungsgeschwindigkeit handelt. Für die Aktivierungsenergie wurde für die gleichen Temperaturbereiche ein Wert von 3 bzw. 1.1 eV gefunden. Ausgehend von den isothermen Ergebnissen im Temperaturbereich 340–400 K wurde eine Zeit-Temperatur-Transformationskurve (TTT) dargestellt, die bei 374 K die Gegenwart eines Minimum aufweist. Auf der Basis derTTT-Kurven konnte für eine 25-, 50-, 75-bzw. 100-prozentige Kristallisation eine kritische Kühlgeschwindigkeit von 2.4, 1.79, 0.72 bzw. 0.42
    Notes: Abstract The effect of temperature on the crystallization kinetics of bulk amorphous S20Se80 has been studied using differential scanning calorimetry. Using the empricial Avrami expressions, a number of kinetic parameters has been determined. The order of the reactionn was found to be 2.3 for the range of temperature 340–365 K and 1.6 in the range of temperature between 370–400 K. This range ofn indicates that the crystallization process is diffusion controlled growth with decreasing nucleation rate. The activation energy was found to be 3, 1.1 ev depending on the same range of temperatures. A time-temperature-transformation (TTT) curves has been plotted from isothermal results over the temperature range 340 K to 400 K showing the presence of minimum at 374 K. From theTTT curves the critical cooling rate required to avoid 25, 50, 75 and 100% crystallization was found to be 2.4, 1.79, 0.72 and 0.42
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01914071
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    Paper (German National Licenses)
    Fulltext
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