Combined kinetic analysis of solid‐state reactions: The integral method (ICKA)

Abstract

In this work, we propose the first Integral method for the Combined Kinetic Analysis (ICKA) of solid-state reactions typically performed in a thermogravimetric analyzer. The ICKA method prevents the systematic inaccuracies inherent to all the differential methods, including the standard CKA method. Two main achievements have been made for implementing the method: (1) the most accurate approximation for the general temperature integral yet developed, and (2) a general integral form of the kinetic model of the type g (α) = (abcZ) −1 [1 − (1 − α a) b ] c , where Z is a parameter evaluated together with the preexponential factor and a, b, and c are fitting parameters. This expression allows any known kinetic model to be exactly or very closely reproduced. Together, the two developments yield an equation for the conversion, α, that has been successfully fitted to simulated conversion values of single-step reaction processes following different kinetic models. The curve fitting resulted in the same values of the kinetic and model parameters as those from which the simulated conversion curves were originally built, proving the validity of the ICKA method.

Synthesis, Characterization, and Thermal Decomposition Kinetics of Nitrogen-Rich Energetic Biopolymers from Aminated Giant Reed Cellulosic Fibers

“…The observed dependency is in accordance with the concept of kinetic analysis in the solid-phase reaction, where Arrhenius parameters are a function of temperature and extent of reaction. 40,76 Furthermore, the obtained results reveal that the used integral methods give close values and similar evolution trend of the Arrhenius parameters for each investigated sample, except for the it-FWO model, which presents relatively low kinetics values. This expectation is due to the fact that the it-FWO procedure, unlike the other models, uses only the first approximation of the temperature integral.…”

Correct Use of the Bhatia and Perlmutter Random Pore Model under Nonisothermal Conditions

“…The fundamental kinetic equation for any solid-state process that can be reasonably approximated as single-step kinetics can be written as normald α normald t = italicAf ( α ) e − E / RT where f (α) is the so-called conversion function . For nonisothermal integral methods of kinetic analysis, it is useful to also define the integral form of the conversion function as g ( α ) = ∫ 0 α normald α f ( α ) = ∫ 0 t A normale − E / italicRT d t For decades, the RPM has been used under nonisothermal conditions with the following definitions for these functions f ( α ) = ( 1 − α ) 1 − ψ 0.25em ln ( 1 − α ) g false( α false) = − ln false( 1 − α false) false( normal f o r 0.25em ⁢ ψ = 0 false) g...…”

“…The fundamental kinetic equation for any solid-state process that can be reasonably approximated as single-step kinetics can be written as where f (α) is the so-called conversion function. 12 For nonisothermal integral methods of kinetic analysis, it is useful to also define the integral form of the conversion function as For decades, the RPM has been used under nonisothermal conditions with the following definitions for these functions Here, it has been proven that the random pore model can actually be used under nonisothermal conditions. Let us now check whether the aforementioned functions are actually valid.…”

“…where f(α) is the so-called conversion function. 12 For nonisothermal integral methods of kinetic analysis, it is useful to also define the integral form of the conversion function as…”

Non-Isothermal Crystallization Kinetics and Activation Energy for Crystal Growth of Polyamide 66/Short Glass Fiber/Carbon Black Composites

“…Table 8. Algebraic expressions of gX(T) and fX(T) for the most common reaction mechanisms of the solid-state process [33,59,78].…”