Thermal analysis of WS series cooling agent

Objective: Evaluation of the safety of WS series cooling agents for cigarettes. Methods: In this paper, pyrolysis-gas chromatography-mass spectrometry （Py-GC/MS） and thermogravimetric （TG） methods were used to study the pyrolysis behavior and content distribution of WS series cooling agents in tobacco under different atmospheres. Results: Through TG/DSC analysis, WS-3, WS-5, and WS-23 had only one obvious thermal weight loss stage, and the maximum weight loss rates occurred at 251.8, 281.6, and 206.5 ℃, respectively. The three cooling agents all showed sharp endothermic peaks before weight loss, and a phase transition process of melting occurred. It was speculated that it may be the transformation of crystal form or the dissolution of crystal. Under the atmosphere of 9% oxygen-containing nitrogen-oxygen mixture simulating cigarette combustion, the cracking products and quantities of the three cooling agents increased with the increase of temperature. In comparison, WS-3 and WS-23 were more stable, with less thermal cracking products, while WS-5 was less stable, the heat required for crystal transformation was the lowest and the heat required for complete weight loss was the least, and the thermal cracking products were relatively more. The thermal cracking results of the three cooling agents were mainly prototype transfer, and the normalized percentage content of the peak area of prototype transfer was above 99%. Conclusion: The three cooling agents, WS-3, WS-5, and WS-23, do not appear in the list of HPHCs or SVHC under heating conditions, and can be completely pyrolyzed before 350 ℃, they are all suitable as additives for heating cigarettes.