“The submitted manuscript has been authored by a contractor of the U.S. Government under the contract No. DE-AC05-84OR21400. Accordingly, the U.S. Government retains a nonexclusive, royalty-free license to publish or reproduce the published form of this contribution, or allow others to do so, for U.S. Government purposes”
Abstract
The mathematical equations for step-wise measurement of heat capacity (C p ) by modulated differential scanning calorimetry (MDSC) are discussed for the conditions of negligible temperature gradients within sample and reference. Using a commercial MDSC, applications are evaluated and the limits explored. This new technique permits the determination ofC p by keeping the sample continually close to equilibrium, a condition conventional DSC is unable to meet. Heat capacity is measured at ‘practically isothermal condition’ (often changing not more than ±1 K). The method provides data with good precision. The effects of sample mass, amplitude and frequency of temperature modulation were studied and methods for optimizing the instrument are proposed. The correction for the differences in sample and reference heating rates, needed for high-precision data by standard DSC, do not apply for this method.
Zusammenfassung
Die mathematischen Gleichungen für die stufenweise Messung der Wärmekapazität (C p ) mit modulierter Differential kalorimetrie (MDSC) werden für die Bedingung eines vernachlässigbar kleinen Temperaturgradierten in Probe und Referenzsubstanz diskutiert. Diese neue Technik ermöglicht die Bestimmung vonC p ohne die Probe wesentlich vom Gleichgewicht zu entfernen, eine Bedingung die conventionelles DSC nicht erreichen kann. Die Wärmekapazität is unter “praktisch isothermer Bedingung” gemessen worden (haäfig innerhalb ±1 K). Diese Methode gibt Daten von guter Qualität. Die Effekte der Probenmasse, Amplitude und Frequenz der Temperaturmodulation wurden untersucht und Methoden für die Optimirung des Instruments werden vorgeschlagen. Die Korrekturen für Unterschiede zwischen Proben-und Refernztemparatur aufheizgeschwindigkeiten die für das normale DSC für Daten von hoher Qualität gebraucht werden, sind für diese Methode nicht nötig.
Article PDF
Similar content being viewed by others
Explore related subjects
Discover the latest articles, news and stories from top researchers in related subjects.Avoid common mistakes on your manuscript.
Refereces
A. Mehta, R. C. Bopp, U. Gaur and B. Wunderlich, J. Thermal Anal., 13 (1987) 197.
B. Wunderlich and U. Gaur, ACS Adv. in Chemistry, Series 203, C. D. Craver, ed. Washington DC, p. 195, 1982.
U. Gaur, A. Mehta and B. Wunderlich, J. Thermal Anal., 13 (1978) 71; A. Mehta and B. Wunderlich, Coatings and Plastics Preprints, Am. Chem. Soc., 35 (1975) 393.
B. Wunderlich, J. Thermal Anal., 32 (1987) 1949.
Y. Jin and B. Wunderlich, J. Thermal Anal., 36 (1990) 365; 1519; and 38 (1992) 2257.
S. R. Sauerbrunn, B. S. Crowe and M. Reading, 21st Proc. NATAS Conf. in Atlanta GA, Sept. 13–16, pp. 137–144 (1992); M. Reading, B. K. Hahn, and G. S. Crowe, US Patent 5,224,775 (July 6, 1993).
B. Wunderlich, Y. Jin and A. Boller, Thermochim. Acta, to be published (1994).
M. Reading, D. Elliot and V. L. Hill, J. Thermal Anal. 40 (1993) 949; P. S. Gill, S. R. Sauerbrunn and M. Reading, J. Thermal Anal. 40 (1993) 931; M. Reading, Trends in Polymer Sci., 8 (1993) 248.
P. F. Sullivan and G. Seidel, Phys. Rev., 173 (1968) 679.
G. Dixon, S. G. Black, C. T. Butler and A. K. Jain, Anal. Biochem., 121 (1982) 55.
B. Wunderlich, “Differential Thermal Analysis, A. Weissberger and B. W. Rossiter eds. ‘Physical Methods in Chemistry.’ Vol. 1, Part V, Chapter 8. J. Wiley and Sons, New York, 1971.
B. Wunderlich, ‘Thermal Analysis,’ Academic Press, Boston, MA 1990.
W. Hemminger and G. Höhne, ‘Calorimetry,’ Verlag Chemie, Weinheim, 1984.
J. M. Sturtevant, ‘Calorimetry,’ in A. Weissberger and B. W. Rossiter eds ‘Physical Methods in Chemistry.” Vol. 1, Part V, Chapter 7. J. Wiley and Sons, New York, 1971.
A. Boller, C. Schick and B. Wunderlich, to be submitted 1994.
D. A. Ditmars, S. Ishihara, S. S. Chang, G. Bernstein and E. D. West, J. Research, Natl. Bur. Stand., 87 (1982) 159.
Y. Jin, A. Xenopoulos, J. Cheng, W. Chen, B. Wunderlich, M. Diack, C. Jin, R. L. Hettich, R. N. Compton and G. Guiochon, Mol. Cryst. Liq. Cryst., to be submitted 1994.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Boller, A., Jin, Y. & Wunderlich, B. Heat capacity measurement by modulated DSC at constant temperature. Journal of Thermal Analysis 42, 307–330 (1994). https://doi.org/10.1007/BF02548519
Issue Date:
DOI: https://doi.org/10.1007/BF02548519