Analysis of complex thermoanalytical curves: The thermodynamic and kinetic parameters of isopropylammonium nitrate

Kinetic analysis of overlapping multistep thermal decomposition comprising exothermic and endothermic processes: thermolysis of ammonium dinitramide

“…23 When two overlapping mass-loss processes indicate endothermic and exothermic effects, respectively, the apparent kinetic data recorded using differential scanning calorimetry (DSC) are different from those recorded with thermogravimetry (TG), as has been shown for isopropylammonium nitrate decomposition. 24 This type of process with superimposed oppositely signed thermal effects has also been observed during kerogen pyrolysis. 25 Sophisticated kinetic deconvolution technique has been applied to this type of solidstate reaction, as reported for the thermal decompositions of sodium percarbonate 23 and tin(II) oxyhydroxide.…”

“…where Z and g are the contributions of the first reaction step determined on the basis of DTG and DSC curves, respectively: Z = Dm 1 /(Dm 1 + Dm 2 ) and g = Q 1 /(Q 1 + Q 2 ). Schmid et al 24 used these relationships to analyze the consecutive endothermic evaporation and subsequent exothermic vapor decomposition of isopropylammonium nitrate using TG and DSC measurements by combining eqn (3) and (4): 24 PðTÞ…”

“…This study focuses on the establishment of a methodology for kinetic modeling by deconvolution of an overall reaction into exothermic and endothermic reaction steps using simultaneously recorded TG and DSC curves. A deconvolution method using experimental TG and DSC curves is proposed based on the procedure previously reported by Schmid et al 24 The separated kinetic curves of the exothermic and endothermic reaction steps are analyzed as single-step reactions. The results of the kinetic analysis, including the contributions of each reaction step to the overall reaction, are refined by assuming that the kinetic data for the overall reaction process is the sum of the two reaction steps weighed by the contributions of each reaction step.…”

Critical Appraisal of Kinetic Calculation Methods Applied to Overlapping Multistep Reactions

“…In some cases, the respective reaction steps can bring the opposite contributions to the overall process as measured using a TA technique. Experimental studies concerning the overall reaction composed of more than one reaction step with oppositely signed TA signals have been reported, i.e., partially overlapping mass loss and mass gain [3,28,29], or exothermic and endothermic events [30,31,32]. In practice, such complex processes are observed during thermal decomposition of energetic materials [5] and high-temperature operations with ionic liquids [33].…”

“…This particular situation, e.g., two overlapping mass-loss processes corresponding to endothermic and exothermic effects, respectively, educe that the apparent kinetic curves recorded using differential scanning calorimetry (DSC) can be different from that obtained using thermogravimetry (TG). The phenomenon is caused by different nature of these TA signals and was observed experimentally for isopropylammonium nitrate decomposition [30] and kerogen pyrolysis [34]. A sophisticated kinetic deconvolution technique have been applied recently to this type of solid-state reactions, where the kinetic parameters obtained for the constituted single processes have been linked with the physicochemical and physicogeometrical features of the transformations [31,32].…”