Investigation of the thermal decomposition kinetics of bezafibrate

The thermal decomposition kinetics of bezafibrate in a nitrogen atmosphere has been investigated by analyzer DTG-60. The thermal behavior of bezafibrate at the different heating rates 4, 8, 12, 16 and 20 °C min−1 displays two-stage decomposition processes among 500–650 K. The activation energy (E) and pre-exponential factor (A) were calculated to be 128.72 kJ mol−1 and 3.56 × 1010 min−1 by Flynn–Wall–Ozawa, Kissinger–Akahira–Sunose, Doyle, Kissinger and Šatava–Šesták methods for the second-stage decomposition process. The results show that the non-isothermal thermal decomposition mechanism of bezafibrate is classified as three-dimensional diffusion model, and the integral and differential equations are g(α)=[1-(1-α)1/3]2\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$g(\alpha ) = [1 - (1 - \alpha )^{1/3} ]^{2}$$\end{document} and f(α)=321-α231-1-α13-1.\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$f(\alpha ) = \frac{3}{2}\left( {1 - \alpha } \right)^{{{\raise0.7ex\hbox{$2$} \!\mathord{\left/ {\vphantom {2 3}}\right.\kern-0pt} \!\lower0.7ex\hbox{$3$}}}} \left[ {1 - \left( {1 - \alpha } \right)^{{{\raise0.7ex\hbox{$1$} \!\mathord{\left/ {\vphantom {1 3}}\right.\kern-0pt} \!\lower0.7ex\hbox{$3$}}}} } \right]^{ - 1}{.}$$\end{document} The enthalpy (ΔH≠), entropy (ΔS≠) and Gibbs free energy (ΔG≠) were calculated to be 123.74 kJ mol−1, −91.07 J mol−1 K−1 and 178.29 kJ mol−1, respectively.