Mtdsc parameters

Figure 1.20 illustrates how appljdng this correction excellent agreement with the more conventional approach is achieved. The second is that, whilst it is useful to understand the relationships between the results given by MTDSC and the kind of parameters often determined by conventional DSC (such as fictive temperature and enthalpy loss), MTDSC does not afford any advantages over conventional DSC for such studies. Conventional DSC measurements are to be preferred in this case due to shorter measurement times and less data processing [36]. 

Figure 4.34. Multiple melting and crystallisation peaks of indium on MTDSC, 5.87 mg at an underlying heating rate of 0.1 K min k The undistorted sinusoidal sample temperatures are also indicated. The two modulation parameters are as follows A = 1.0 K, / = 60 s, Mettler-Toledo DSC 820, sinusoidally modulated, controlled close to the heater [41].

Different from the other MTDSC techniques is the TOPEM technique, which is based on a quasistochastic temperature modulation superimposed on a conventional DSC temperature program as seen in Fig. 2.90 (Schubnell et al. 2005). This allows separate determination of the reversing and nonreversing heat flows and the quasistatic (zero-frequency) heat capacity, as well as a complex heat capacity (Schawe and Hutter 2005). Since the response at a desired frequency is determined after the run, multiple run parameters can be used to optimize the analysis of different transition regions during a run as noted in text below (see also Fig. 2.91). 

For an MTDSC experiment additional run parameters must be selected when compared with conventional DSC. For TAI modules, these parameters are... 

When deciding what conditions for these parameters to select, one first needs to decide on what type of modulation is desired. MTDSC can be run in a number of modulation modes as noted by Wunderlich and illustrated in Fig. 2.94 (Wunderlich 1997b). 

When attempting to use MTDSC, it should be kept in mind that it is a supplementary technique to traditional DSC and should be considered an extension of conventional DSC. It does not replace it. Before attempting an MTDSC experiment, conventional DSC measurements should first be done to evaluate the need for a modulated run. Care must be taken in a modulated experiment, since the use of modulation adds an additional complication, and any MTDSC experiment, like any DSC experiment, should be verified by other means whenever possible. There are several disadvantages associated with MTDSC. The choice of experimental parameters is difficult, and the use of incorrect parameters could lead to erroneous results. Additionally, interpretation of the heat flow components can be difficult. Finally, speed—MTDSC is usually run at a slower ramp than conventional DSC because of the need to obtain a sufficient number of modulation cycles over a transition region. 

MTDSC Experiments. The selection of experimental parameters is especially important when running MTDSC experiments the underlying... 

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