Thermogravimetric infrared analysis for the pyrolysis mechanism and shelf life of lycoramine hydrobromide

Thermal decomposition curves of lycoramine hydrobromide were obtained in the nitrogen by thermogravimetry coupled with infrared spectroscopy (TG‐FTIR). Four thermal analysis kinetic methods, for example, Achar, Coats–Redfern, Kissingers, and Ozawa methods were used to speculate the probable mechanisms of the thermal decomposing reaction and the kinetic parameters (apparent activation energy Ea and preexponential factor A). The shelf life of lycoramine hydrobromide at room temperature was calculated by the kinetics parameters. According to the theoretical calculations of thermogravimetry–differential thermal analysis (TG‐DTG), infrared spectra, and bond levels, the decomposition of lycoramine was divided into three stages. The first stage started from 227.3 to 312.3°C, chemical bonds between oxygen atoms and carbon atoms cracked and released alcohol material. The most acceptable mechanism is a chemical reaction control mechanism, which conforms to the reaction series equation, with f(α) = 2(1 − α)3/2. In the second stage, starting from 312.3 to 392.3℃, gases such as CO, CO2, amines, and NH3 produced by lycoramine hydrobromide decomposition were released. The most expected mechanism is a chemical reaction, F3, deceleration type α–t curve, which meets the three‐stage function, f(α) = 1/2(1 − α)3. In the third stage, the residual molecular skeleton (toluene) was thermally cracked deeply from 392.3°C to the end and the gases such as CO2, H2O, and NH3 were released. According to the kinetic parameters of thermolysis at the first stage, the shelf life of lycoramine hydrobromide was inferred, which was 4–5 years at room temperature (25°C).