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Abstract  

The quality of measurement of heat capacity by differential scanning calorimetry (DSC) is based on the symmetry of the twin calorimeters. This symmetry is of particular importance for the temperature-modulated DSC (TMDSC) since positive and negative deviations from symmetry cannot be distinguished in the most popular analysis methods. Three different DSC instruments capable of modulation have been calibrated for asymmetry using standard non-modulated measurements and a simple method is described that avoids potentially large errors when using the reversing heat capacity as the measured quantity. It consists of overcompensating the temperature-dependent asymmetry by increasing the mass of the sample pan.

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Abstract  

Contrary to the situation in the field of temperature, heat and heat flow rate calibration, so far no generally accepted and easily practicable chemical reaction exists with regard to a kinetic evaluation. A possible reaction would be the well-known first-order cis-trans isomerization of subcooled liquid azobenzene. Surprisingly, the evaluation of measurements performed with a power compensated calorimeter yields activation parameters, which are dependent on the heating rate. The desmearing of the curves does not produce any improvements. However, constant activation parameters are obtained, if a small self-heating of the sample during the exothermic reaction is taken into account.

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302.38 DSC measurements Thermooxidative stability of the samples was studied using the power-compensated calorimeter Perkin Elmer DSC-7 under

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