Controlled Transformation Rate Thermal Analysis CRTA Method

Controlled Transformation Rate Thermal Analysis (CRTA) Method [40,43] 

Compared with the conventional thermoana-lytical methods, the CRTA technique can provide 

Plots of ln[l//( )l vs 1/T are constructed for every trial of the mechanism function/( ). The E and A values obtained with the largest linear regression coefficient should be chosen and the corresponding f(a) is the most suitable mechanism function. 

TA measurements are performed at various reaction rates, C, and then many sets of data of T, and C, at a given value are obtained. The plot of In C, vs 1/T, gives the E value. 

The activation energy E can also be determined by the rate-jump method of CRTA. In the rate-jump method, the reaction rate is cycled between two predetermined values by increasing the gas flow towards the exterior of the reaction chamber in that ratio, and by measuring the resulting temperature limits. Each set of two successive rates with the corresponding temperatures allows an independent calculation of from the equation 

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A valuable approach for measuring thermal degradation kinetic parameters is controlled-transformation-rate thermal analysis (CRTA) - a stepwise isothermal analysis and quasi-isothermal and quasi-isobaric method. In this method, some parameters follow a predetermined programme as functions of time, this being achieved by adjusting the sample temperature. This technique maintains a constant reaction rate, and controls the pressure of the evolved species in the reaction environment. CRTA is, therefore, characterised by the fact that it does not reqnire the predetermined temperature programmes that are indispensable for TG. This method eliminates the nnderestimation and/or overestimation of kinetic effects, which may resnlt from an incomplete understanding of the kinetics of the solid-state reactions normally associated with non-isothermal methods. 

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