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

Abstract

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 E a 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 thermogravimetrydifferential 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°C, gases such as CO, CO 2 , amines, and NH 3 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 CO 2, H 2 O, and NH 3 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).

Analysis on the thermal decomposition kinetics and storage period of biomass-based lycorine galanthamine

“…In this work, the thermogravimetric dynamic analysis (TG-DTG) curves and Fourier transform infrared spectroscopy (FTIR) spectra of galanthamine were plotted at different rates of temperature rise, based on the previous studies on the thermal stability of lithophan and ricoramine ( Tian and Xiao, 2012 ; Ling et al, 2022 ). The kinetic parameters of galanthamine pyrolysis and the volatile product characteristics at different stages were calculated using the Kissinger, Ozawa, Achar and Coats-Redfern methods in collaboration.…”

Thermal degradation of naturally aged NBR with time and temperature

“…Jiang et al [16] studied the effects of thermal aging on NBR in hydraulic oil for 70 days at 60 °C and 90 °C, finding that the Shore -A hardness value initially decreased and then increased. Although much research [17][18][19][20][21][22][23] has already been conducted on the thermal decomposition and accelerated aging of NBR, very few studies have been conducted to calculate the activation energy and pre-exponential factors to assess the life of virgin NBR and its comparison with naturally aged NBR under no-load conditions. There are various statistically reliable models; however, the fitted kinetic parameters can differ by a large magnitude, making it difficult to choose an appropriate model.…”