A Detailed Comparison of First Order Transitions by DSC and TMC |
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Authors: | Boller A Ribeiro M Wunderlich B |
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Institution: | (1) Department of Chemistry, The University of Tennessee, Knoxville, TN, 37996-1600 |
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Abstract: | Indium was analyzed with both, standard differential scanning calorimetry (DSC) and temperature-modulated DSC (TMDSC) using
sinusoidal and saw-tooth modulation. Instrument and sample effects were separated during nucleated, reversible melting and
crystallization transitions, and irreversible crystallization with supercooling. The changes in heat flow, time, and sample
and reference temperatures were correlated as functions of heating rate, mass, and modulation parameters. The transitions
involve three regions of steady state (an initial and a final region before and after melting/crystallization, a region while
melting/crystallization is in progress) and one region of approach to steady state (melting peak to final steady state region).
Analyses in the time domain show promise when instrument lags, known from DSC, are used for correction of TMDSC. A new method
of integral analysis is introduced for quantitative analysis even when irreversible processes occur in addition to reversible
transitions. The information was derived from heat-flux calorimeters with control at the heater block or at the reference
temperature sensor.
This revised version was published online in July 2006 with corrections to the Cover Date. |
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Keywords: | frequency domain heat-flux calorimeter indium integral analysis melting transition pseudo-isothermal analysis quasi-isothermal measurement reversible melting saw-tooth modulation sinusoidal modulation temperature-modulated calorimetry time-domain |
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