The effect of temperature on the service life of stranded carbon fiber composite core conductors was studied based on the kinetic theory of material pyrolysis. The thermal decomposition activation energy calculation for stranded carbon fiber composite cores was carried out by thermogravimetric analysis (TGA). The activation energy E of stranded carbon fiber composites was calculated according to the Flynn-Wall-Ozawa, Kissinger, and Coast-Redfern methods, which were 168.76 kJ/mol, 166.79 kJ/mol, and 160.35 kJ/mol, respectively. The results from these different treatments were within 10% or less, and thus the thermochemical reactions of stranded carbon fiber composite cores were considered to be effective. The life prediction model of the carbon fiber composite core was developed based on the kinetic equation of thermal decomposition. The service life is related to the reaction mechanism function G(α) and the reaction rate parameter k(t). The reaction mechanism function G(α) = ((1 - α)-3.3 - 1)/3.3 and the reaction rate parameter k(t) = 2.14 × 1012exp(E/RT) were obtained by fitting the thermal weight loss data of stranded carbon fiber composite cores. Based on the 5% mass loss criterion for the end of life of stranded carbon fiber composites, the service life of the carbon fiber composite core is given at various operating temperatures.
Keywords: activation energy; carbon fiber composites; life prediction; reaction mechanism function; thermogravimetric analysis.