Study of Pyrolysis Kinetics of Silicone Rubber Composite Insulators by Thermogravimetric Analysis
The pyrolysis kinetics of silicone rubber insulators(SiR)in nitrogen(N2)and air environments were studied by thermogravimetric analysis(TGA).Three transformation models,Flynn-Wall-Ozawa(FWO),Kissinger-Akahira-Sunose(KAS),and Friedman(FR)methods,were applied to calculate activation energy and pre-exponential factors.The average activation energies of FWO,KAS,and FR methods under N2 atmosphereare were 421.46,431.60,433.98 kJ/mol,respectively.The pre-exponential factor ranged from 109 to 1016,which illustrated that the pyrolysis was independent of surface area.Under the air atmosphere,the average activation energies of FWO,KAS,and FR methods were 127.21,120.93,123.38 kJ/mol,respectively.The value of pre-exponential factor ranged from 108 to 109,and pyrolysis was controlled by surface area.The thermodynamic properties of the reaction under N2 atmosphere,such as enthalpy changes(ΔH),Gibbs free energy(ΔG)and entropy change(ΔS)were much higher than that under air atmosphere,confirming the complexity of the reaction in N2.The results of the study contribute to a deeper understanding of the combustion mechanism of SiR and provide a reference for its feasibility as a more effective high-temperature resistant material.
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