Effect of carbonization time on the structure and electromagnetic parameters of porous-hollow carbon fibres

A series of polyacrylonitrile-based porous-hollow carbon fibres (PAN-PHCFs) were prepared by carbonizing PAN porous-hollow cured fibres at 1073 K for different times in nitrogen. The effects of carbonization time on the structure, electrical volume conductivity and electromagnetic parameters were investigated. Results indicate that the degree of graphitization increases as carbonization time increases. The electrical volume conductivity increases as the degree of graphitization and carbonization time increase. The real and imaginary parts of the complex permittivity (ɛ′ and ɛ″) increase with carbonization time increasing. The values of ɛ′ and ɛ″ of composites of PAN-PHCFs and paraffin are 13.76 and 10.09 when the carbonization time is 240 min, and the electrical volume conductivity of PAN-PHCFs is 190.47 Ω−1 m−1.