TMDSC calibration with

Measurements at different heating rates may lead to different amounts of instrument-lag, i.e., the temperature marked on the DSC trace can only be compared to a calibration of equal heating rate and baseline deflection. A simple lag correction makes use of the slope of the indium melting peak when plotted vs. sample temperature as a correction to vertical lines on the temperature axis, hi some commercial DSCs this lag correction is included in the analysis program. It must be considered, however, that different samples have different thermal conductivities and thermal resistances so that different lags are produced as shown, for example, in Fig. 4.94, for an analysis with TMDSC. 

Considerable calibration and care are needed not to exceed the conditions of steady state and negligible temperature gradients within the sample for the standard DSC, as discussed in Sect. 4.3.4-7. For TMDSC, additional points must be considered, as discussed in Sect. 4.4.3. The conditions of steady state may be relaxed to some degree, as long as linearity and stationarity are kept. Calibrations and checks of compliance with those conditions, thus, are also key to good TMDSC. 

The TMDSC enables another elegant possibility of Cp (magnitude) determination from the amplitude of the modulated part of the measured heat flow rate function both in the isothermal and. scanning modes of operation. This method is especially advantageous in cases of noisy signals with low sample masses or low heating rates. Precise calibration of the heat flow rate amplitude is a prerequisite for obtaining reliable results [43]. 

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