A new pattern for conductivity of carbon nanofiber polymer composites with interphase and tunneling parameters

In this study, the Weber-Kamal model is advanced to estimate the electrical conductivity of the samples containing polymer and carbon nanofiber (CNF) by the characteristics of the CNF network, interphase, and tunnels, which were disregarded in the original model. The developed model considers the crucial parameters such as interphase depth, contact number (m), contact diameter, polymer tunneling resistivity (ρ), and tunneling distance (λ), along with network portion and interphase concentration. The developed model’s outputs are validated across various levels of these parameters. Furthermore, the developed model’s calculations are associated to the measured conductivity of various examples. Both parametric evaluations and experimental data corroborate the suggested model. The minimum ranges of λ = 1 nm and ρ = 50 Ω.m maximize the conductivity to 0.23 S/m, while an insulative system is observed at high ranges of λ > 6 nm and ρ > 100 Ω.m. Additionally, an insulative system occurs when m < 30 and the waviness factor (u) > 1.4, whereas the top conductivity of 0.036 S/m is reached with the highest number of contacts (m = 100) among the straight CNFs (u = 1).