Abstract:
Aiming at the problem of uncertain mechanism of kinetics of thermal decomposition of fluorinated graphite and insufficient information of kinetic prediction, the dynamic mechanism of (CF)
n thermal decomposition reaction was analyzed by measuring multiple sets of non-isothermal thermogravimetric curves and using model-free kinetics. The thermogravimetric curve shows that (CF)
n thermal decomposition undergoes one step of weight loss, resulting in an average gas phase composition of CF
2.95. The results of kinetic analysis show that the mechanism function changes with the conversion rate:
α < 0.1, the mechanism function is JMA equation
f(
α)=1.5(1-
α)-ln(1-
α)
1/3; 0.15 <
α < 0.3, the mechanism function is two-dimensional Avrami-Erofeyev equation
f(
α)=2(1-
α)-ln(1-
α)1/2;0.3 <
α < 0.8, the mechanism function is Šesták-Berggren equation
f(
α)=7.5
α1.2(1-
α)2; 0.85 <
α, the mechanism function is the one-dimensional Avrami-Erofeyev equation
f(
α)=(1-
α). The recommended kinetic prediction parameter activation energy is 264.23±7.82 kJ/mol, and the pre-exponential factor is (8.70±0.21)×10
14/s. In addition, the kinetic mechanism reflects the existence of carbon chain chain growth and interaction with the branching chain in the (CF)
n decomposition process, which may be an important factor in the formation of amorphous structural carbon in the reaction product.