Controlled rate thermal analysis (CRTA) and controlled mass normalized rate thermal analysis (CMNRTA)

摘要

Controlled Rate Thermal Analysis (CRTA) was developed by Jean Rouquorol in 1969. In this technique, the ambient gas pressure, temperature, or some other rate-forcing factor is regulated so as to maintain a constant or a stepping rate of weight loss. This will tend to keep the total flux of gases escaping from the surface of the material constant. However the special utility of CRTA has been restricted thus far as it applies directly only to reactions where the substrate maintains a constant surface area and the flux through this surface limits the kinetics. A modification of this technique was introduced by Flynn in 1976, called, here on, Controlled Mass Normalized Rate Thermal Analysis (CMNRTA). Here the rate of change of the logarithm of the remaining sample mass [(I/m)(dm/dt) = d(ln m)/dt] is controlled so that the flux into or from the sample will be proportional to its dwindling mass. It is suggested that this technique is more appropriate for reaction kinetics where the rate limiting steps are bulk phase phenomena.