Data Analysis Without Fourier Transformation for Sawtooth-type Temperature-modulated DSC |
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Authors: | Hu W Wunderlich B |
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Institution: | (1) Department of Chemistry, The University of Tennessee, Knoxville, TN, 37996-1600;(2) Chemical and Analytical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6197, USA |
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Abstract: | The response of a differential scanning calorimeter (DSC) to sawtooth-type temperature modulation has been analyzed in the
time domain using a standard treatment of the DSC data without Fourier transformation into the frequency domain. This method
has some of the advantages of a temperature-modulated DSC (TMDSC) and may achieve a reasonable accuracy with more transparent
and less time-consuming data analysis than the current TMDSC. The limits of linearity and stationarity of the thermal response,
a prerequisite for the validity of the calculation of the reversing heat capacity by Fourier transformation, can be easily
recognized in standard DSC. In contrast to the common handling of TMDSC, where the non-reversing contributions are calculated
as difference between the total and reversing parts, we define a new, directly measured quantity, called the imbalance in
heat capacity. It represents the difference between heating and cooling due to the non-reversing thermal process. This quantity
is also of value for the representation of irreversible contributions inquasi-isothermal processes, such as cold crystallization
and the annealing of crystallites in the melting range.
This revised version was published online in July 2006 with corrections to the Cover Date. |
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Keywords: | imbalance in heat capacities reversing and non-reversing heat capacities sawtooth modulation standard DSC TMDSC |
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