A combined photoacoustic DSC for simultaneous temperature modulated measurements: does it really work?

• Published in: Thermochimica acta Vol. 330; no. 1; pp. 145 - 154
• Main Author: Vassilev, Tsvetan G
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Amsterdam Elsevier B.V 10.05.1999; Elsevier Science
• Subjects: Analytical chemistry; Chemical and thermal methods; Chemistry; DSC; Exact sciences and technology; Glass transition; Liquid crystal; Phase transition; Photoacoustic; Temperature modulated calorimetry; Photoacoustic; Glass transition; Temperature modulated calorimetry; Liquid crystal; DSC; Phase transition; Differential scanning calorimetry; Coupled method; Dynamic properties; Liquid crystals; Optoacoustic effect; Phase transitions; Specific heat; Phase transformation; Simultaneous measurement; Benzenic compound; Thermal analysis; Thermodynamic properties
• ISSN: 0040-6031; 1872-762X
• DOI: 10.1016/S0040-6031(99)00029-5

Combination of two techniques, photoacoustic (PA) and differential scanning calorimetry (DSC), is a combination of quasi stationary thermodynamic DSC method and nonstationary dynamic PA method. Especially favorable and easy to realize is the combination with power compensated type of DSC. It has several advantages over the use of two techniques separately and allow to perform measurements simultaneously. The most obvious is simultaneous determination of thermodynamic properties such as specific heat, heat of transition and dynamic properties such as effusivity, thermal conductivity at the different phase transitions and complex specific heat at the glass transition. Unlike other temperature modulated techniques PA–DSC is especially suitable for studying polymer materials since their low thermal conductivity is an additional advantage. Conditions for simultaneous measurements are examined. It is proved that the combination of two techniques and necessary changes in construction do not essentially change adequate work of the instrument. A little disbalance of DSC operation due to the construction change can be corrected simply by recalibration. The procedures for testing and calibration for the proper operation of the combined PA–DSC are given together with some details of experimental methodology. Several measurements could serve as examples of widespread applicability of PA–DSC to study different types of phase transitions as well as time dependent processes such as glass transition.