Overview

In this Appendix a number of applications of sawtooth modulations are described with modeling and actual results, starting with the sawtooth modulation by utilizing a standard DSC and analysis without Fourier analysis, followed by the analysis of the sawtooth-modulation data after fitting to a Fourier series. Such temperature modulation can be done with any standard DSC which can be programed for a series of consecutive heating and cooling steps.

In the example given, a Perkin-Elmer Pyris-1 ^TM DSC is used with a calibration as described in Sect. 4.3 ^[1]. The modulation is illustrated in Fig. A.13.1. The heavy line represents the change in sample temperature, the dashed lines represent the underlying temperature increase by 1.0 K min ^?1 and the reversing change by 3 K min ^?1. Within each cycle, the upper and lower limits of the heat-flow rates, HF _h and HF _c (proportional to the temperature differences ?T), are read from the measured temperature-difference response, shown in the lower graph of Fig. A.13.2 for an idealized, instantaneously reacting calorimeter and a sample without latent heat contributions. The response HF(t) is represented by the heavy line, jumping from zero to the heating response in heat-flow rate, HF _h, to the cooling response HF _c. If the response were not instantaneous, one would have had to wait until the steady states were reached and then extrapolate the steady-state response back to the beginnings of the heating and cooling segments to...