Heat flow signal, Fourier transformation

DSC experiment (see below). The averaged signal is subtracted from the raw data and the modulation is then analysed using a Fourier transform procedure to obtain the amplitude and phase difference of the heat flow response at the frequency of the imposed modulation. 

The measured signal of the TMDSC was examined for the case of polymer melting. Fourier transform analysis was used to evaluate the data, the resulting information being the amplitude and the phase shift of the first harmonic of the periodic heat flow component. It was shown that this procedure was not sufficient for quantitative discussions if deviations from the symmetric curve shape occurred in the measured heat flow curves. For polymer melting, it was shown that asymmetric curves would be measured if the experimental temp, amplitude was too large. 15 refs. 

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