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TEX is a thermostable compound and less sensitive to external stimuli. It sublimates and decomposes at high temperature. The influence of DSC and TG measurement conditions and substance mass on the thermal decomposition of TEX was determined. It was observed that substance mass, pan type and fulfillment degree of pan influence the thermal decomposition and kinetic parameters of TEX decomposition. Sublimation of the sample was the main observed process; thermal decomposition was the secondary process during the heating of TEX in open pans. With increasing substance mass, the participation of thermal decomposition of TEX increased. Uncontrolled thermal decomposition was observed for larger mass of a sample. The sublimation and decomposition processes were confirmed by FT-IR method. Thermal decomposition was the main process observed during heating the sample of TEX in hermetic pans. Sublimation of a sample was marginal. The sublimation effect decreased with increasing the degree of fulfillment pan. The kinetic parameters were determined with the Friedman's isoconversional method. The conversion, mass of sample and the type of pan caused the large changes in the values of kinetic parameters. The apparent activation energy varied from 128 to 355 kJ mol -1 and logA varied from 9.95 to 30.64 in initial step (a = 0.02) for different condition of measurements. The low values of apparent activation energy (about 130 kJ mol -1 ) were associated with sublimation process and the high values (about 340 kJ mol -1 ) with the decomposition process.

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