Ultra-Slow Thermogravimetric Analyses for Critical Temperature Determination of Novel Materials

Typically, the rate dependence of a material’s decomposition is determined through Differential Scanning Calorimetry (DSC) methods. Common analyses, such as the Flynn-Wall-Ozawa and Kissinger methods, use the exotherm maximum of a decomposition event is used to extrapolate Arrhenius kinetic parameters for the decomposition process. The kinetic parameters are subsequently used to calculate critical temperature (T_crit) values for a given material. While the DSC method is widely used, it provides an incomplete understanding of decomposition, often leading to overestimation of decomposition rates and T_crit values. This is partly because material decomposition often initiates at temperatures far lower than the exothermic maximum, where effects from self-heating are already occurring. This work describes an alternative route for determining the Arrhenius kinetic parameters and T_crit, by utilizing ultra-slow Thermogravimetric Analysis (US-TGA) experiments. US-TGA methods allow for determination of kinetic parameters at the onset of decomposition, thereby eliminating self-heating effects and thermal runaway. This allows for a more accurate calculation of decomposition kinetic parameters, thereby also improving estimates of T_crit for novel materials.