TGA kinetics according to McCarty and Green

The McCarty and Green method is of economical interest because only one test run is required for the calculation of reaction kinetics. 

In the evaluation of a decomposition experiment on calcium oxalate monohydrate, the temperatures of the onset and offset points of each of the three consecutive reactions were used as integration limits. The results are shown in Fig. 3-65. These data diverge considerably from those calculated using the Flynn and Wall or the ASTM E 698-79 methods (Table 3-20). Considerable differences in the data are also reported in the literature. Freeman and Caroll 73-34/ reported the following data found by thermogravimetry  

While they do not report any data from references concerning reactions 1 and 2, they cite varying values from references for reaction 3, the removal of CO2 from CaCOj (kJ/Mol) 205.2 145.5 up to 175.9 397.8 171.7 up to 184.2 154.9 up to 163.3 201.0. 

The attraction of this quick evaluation method led to an attempt to calculate the activation energies of evaporation for the series of n-alkanes, but, depending upon the limits of integration chosen, different values showing relatively widespread scattering 

100 % weight onset point 100 % weight onset point 

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