Example:


Figure: Normalized DSC-signals as a function of the temperature for an organic substance. Experimental data are represented as symbols, solid lines represent the calculated signals. The values of the heating rate in °C/min are marked on the curves.


Comments:

Adequate prediction of the investigated reactions requires at least five thermoanalytical measurements carried out with different heating rates, generally in the range of 0.1 to 20 K/min [1-3, 10]. The scans obtained by any thermal technique (such as e.g. DSC, DTA, TG, EGA, TMA), can be applied for the calculations. For open systems (solid gas reactions with open crucibles), the data should be collected under similar experimental conditions because the kinetic parameters of solid-state reactions are not intrinsic properties of an investigated compound but can change depending on the experimental conditions applied [11]. It is usually necessary to correct the measuring values of the baseline for all differential signal types, like DTA and/or DSC measurements. This is especially necessary when the reaction is characterized by the large difference of the specific heats of substrate and product. For DTA and/or DSC scans, a tangential area-proportional baseline correction is carried out during the calculations. AKTS-Thermokinetics Software can also be used for the elaboration of the results obtained by hyphenated techniques such as TA-MS or TA-FTIR. The application of these techniques is widely recognized for the characterization of the degradation of solids [12]. In order to apply correctly the EGA signals for the description of the kinetics of the decomposition of solids, the interrelation between thermoanalytical and mass spectrometric curves in the TA-MS and/or TA-FTIR system has to be known [13]. If the time lag between the thermoanalytical curve (e.g. DTG) and EGA signal is negligible, the spectroscopic signal can be used not only for the qualitative and quantitative [14] analyses of the gaseous products but for the kinetic description of the process as well.

Applying the results obtained by the above thermoanalytical techniques, AKTS-Thermokinetics Software allows accurate prediction of the reaction progress of materials in a broad temperature range and under different temperature modes such as:

· isothermal
· non-isothermal
· stepwise
· modulated temperature or periodic temperature variations
· rapid temperature increase (temperature shock)
· real atmospheric temperature profiles for investigating properties of low-temperature decomposed solids under different climates (yearly temperature profiles with daily minimal and maximal fluctuations)
· adiabatic (safety analysis, storage, scale-up)

The next chapters present the different options for the various temperature modes.