DEVELOPMENT OF MASTER CURVES FOR DISCRIMINATING THE MECHANISM OF SOLID-STATE REACTIONS FROM EXPERIMENTAL-DATA OBTAINED BY USING THE CYCLIC AND CONTROLLED RATE THERMAL-ANALYSIS

The cyclic and Controlled Rate Thermal Analysis method (CRTA) has been used. The two rates automatically selected in the cyclic curve are small enough to allow the two states of the sample to be compared have nearly the same re-acted fraction. Thus, the activation energy can be calculated without previous knowledge of the actual reaction mechanism. Provided that the activation energy, E, is known, a procedure has been developed for determining the kinetic law obeyed by the reaction by means of master curves that represent the values of the reacted fraction, alpha, as a function of -E/R(1/T-1/T0.5), T0.5 being the temperature at which alpha = 0.5. This procedure has been tested by studying the thermal decomposition reaction of BaCO3.