Model-free Kinetics Analysis of Thermal Degradation of Polysiloxane Lubricant

I. Mohorič, M. Krajnc and U. Šebenik

Abstract
The object of this study was to investigate the thermal stability and degradation kinetics of polysiloxane material used as lubricant in the die casting process of aluminium alloys. The degradation of dried polysiloxane emulsion was studied by thermal gravimetric analysis (TGA) using nitrogen atmosphere. Several non-isothermal experiments at different heating rates and isothermal experiments were performed. The isoconversional kinetic analysis using the integral procedure was applied to the non-isothermal TGA results. The apparent activation energy was calculated by the Flynn-Wall-Ozawa method as a reliable way of determining the kinetics parameters. Based on the determined apparent activation energy isothermal degradation behavior of the lubricant at different temperatures was predicted. The efficiency of the predictions was verified and confirmed by isothermal TGA experiments.

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Keywords
Polysiloxanes, thermogravimetric analysis, isoconversional methods, model-free kinetics