Advanced Kinetic Analysis: The Vyazovkin Method

Theoretical Introduction

Isoconversional kinetic analysis is a powerful method used to study the kinetics of transformations without assuming a specific reaction model. The core principle is that the reaction rate at a constant extent of conversion (α) is only a function of temperature. This allows for the determination of the activation energy (Ea) as a function of α.

The Vyazovkin method is a highly accurate, non-linear isoconversional technique. For a set of experiments at different heating rates (βi), the activation energy for any given conversion (Eα) is the value that minimizes the function:

Ψ(Eα) = ∑i=1nj ≠ in I(Eα, Tα,i) βj I(Eα, Tα,j) βi

Here, Tα,i is the temperature for conversion α at heating rate βi, and I(E, T) is the numerically calculated temperature integral. A dependency of Eα on α indicates a complex, multi-step reaction. From these kinetics, one can predict the material's lifetime, such as the Td24: the temperature at which it takes 24 hours to reach a small, critical degree of conversion (e.g., 5%).

1. Load DSC Data

Upload three DSC files (.txt or .csv). The parser will read column 3 for Temperature (°C) and column 4 for Heat Flow (W/g). Other columns are ignored. Text headers are automatically skipped.