Advancements in the integration and understanding of the Sestak–Berggren generalized conversion function for heterogeneous kinetics

Kinetic models are relevant to describe heterogeneous kinetic processes; a number of kinetic models and their mathematical expressions have been reported in the literature, many of these based on idealistic conditions in terms of geometrical constrain and driving forces. Alternatively, the semi-empirical Sestak–Berggren (SB) conversion function, which was proposed as a general equation, encompasses a large variety of equations corresponding to different kinetic models. Despite the fact that the SB equation does not provide any physical meaning, it is extremely useful for kinetic analysis as it offers a good fit to experimental data even when they do not follow the ideal conditions assumed for the conventional kinetic models. One limitation of the SB kinetic model is the fact that its conversion function cannot be analytically integrated to provide an exact solution; thus, it cannot be directly applied in kinetic integral methods. The objective of this study aims to propose some solutions for some specific cases, while the mathematical limits for the values of the kinetic exponents m , n , p of the SB model and their validity are also explored. Further ideas for improving the SB equation or finding an alternative for a superior conversion function were explored in this work.