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  • 1
    ISSN: 1572-8943
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Methoden zur Temperatur- und Enthalpiekalibrierung von DSC und DTA Instrumenten werden dargestellt. Dieses Forschungsvorhaben wurde von der Gesellschaft für Thermische Analyse (GEFTA) unterstützt. Gründe werden dargelegt, weshalb die Temperaturkalibrierung auf Referenzsubstanzen abgestützt werden soll, die in der Internationalen Temperaturskala (ITS90) aufgeführt sind. Ebenso wird das schwierige Unterfangen der kalorischen Kalibrierung mit mehreren unterschiedlichen Methoden erlÄutert, und geeignete Referenzsubstanzen werden vorgestellt.
    Notes: Abstract The development of methods for temperature and heat calibration of DSC and DTA supported by the German Society of Thermal Analysis (GEFTA) are presented. Reasons are given for the recommendation of the temperature calibration method, which refers to the valid international temperature scale (ITS 90) and takes into account the fact that the fixpoints of this scale are defined in two phase equilibrium. Furthermore the hard problems with the heat flow and peak area calibration of DSC are described and the methods are presented to come to realistic and sufficient results. Thus both traditional (with the aid ofC p — and enthalpy — reference materials) and electrical calibration are critically discussed. Today's best values of suitable materials for heat calibration are reported.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1572-8943
    Keywords: constraints ; gel-spun UHMW-PE fibers ; hindrance of endothermic transitions ; melting behaviour ; poly(p-xylylene) (PPX) coating ; temperature modulated DSC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The method of temperature modulated DSC has been applied to obtain additional information about the effect of constraints on the melting behaviour of gel-spun ultra high molecular mass polyethylene (UHMW-PE) fibers coated with a high temperature stable poly(p-xylylene) (PPX) polymer. The underlying signal, corresponding to the normal DSC signal, reveals two endothermic peaks for the coated PE fibers. A shift in the underlying and magnitude signal from 142 to 145°C at 0.1 K min–1 , a relative small magnitude signal, together with a vanishing step-like change in the phase signal with increasing PPX coating layer thickness characterize the constraints in terms of a hindrance of the melting of the unconstrained orthorhombic crystal fraction. The time constant of the melting process can be estimated as larger than the reciprocal angular frequency 1/ω=5 s of the modulation.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1572-8943
    Keywords: cold crystallization ; DSC ; heat capacity ; modulated temperature DSC ; poly(ethylene terephtalate)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The modulated temperature differential scanning calorimetric method (MT-DSC) yields three temperature dependent signals, an underlying heat capacity curve from the underlying heat flow rate (corresponding to the conventional DSC signal), and a complex heat capacity curve with a real part (storage heat capacity) and an imaginary part (loss heat capacity). These curves have been measured in the cold crystallization region for poly(ethylene terephtalate) with a modified Perkin-Elmer DSC-7. The underlying curve shows the well known large exothermic crystallization peak. The storage heat capacity shows a step change which reproduces the change in heat capacity during crystallization. This curve may be used as baseline, to separate the crystallization heat flow rate from the underlying heat flow rate curve. The loss heat capacity curve exhibits a small exothermic peak at the temperature of the step change of the storage curve. It could be caused by changes of the molecular mobility during crystallization.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1572-8943
    Keywords: calibration material ; calibration procedure ; DSC ; heat calibration ; heat flow rate calibration ; standards ; temperature calibration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Metrologically based measuring procedures and evaluation methods are recommended as guidance for practical temperature, heat and heat flow rate calibration of DSC instruments which are largely independent of instrumental, test and sample parameters. The relevant terms are defined, the measuring procedures and evaluation methods described, calibration materials and their characteristic data stated and guidance for the sample handling provided. Reference is made to three extended papers on calibration. The recommendations were developed by the working group ‘Calibration of Scanning Calorimeters’ of the German Society of Thermal Analysis (GEFTA).
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1572-8943
    Keywords: copolymers ; degree of crystallinity ; glass transition ; melting behaviour ; terpolymers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Poly(butadiene-alt-1-olefin) copolymers and poly[(butadiene-alt-ethene)-co-(butadiene-alt-1lefin)] terpolymers, and the hydrogenated products too, has been characterized with the aid of differential scanning calorimetry (DSC). Both the glass transition and the melting behaviour of the partial crystallized products has been investigated. From the peak area the degree of crystallinity has been calculated in a first approximation. The results allow to draw conclusions about the crystallization behaviour in relation to the number and length of the side chains and about the course of the synthesis in question.
    Type of Medium: Electronic Resource
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