Degree of conduction transfer through incomplete interphases controlling the conductivity of carbon nanofiber composites

Assuming an incomplete interphase in carbon nanofiber (CNF)/polymer composites (PCNFs), the conduction transfer amount from the CNF to the polymer media, denoted as Y , is determined by the CNF length and the minimum length required for effective conduction transfer to the matrix ( L c ). The real inverse aspect ratio, actual CNF volume fraction, percolation threshold, and the amount of network are all influenced by Y . Additionally, the Kovacs model is extended for PCNF conductivity to incorporate network concentration, real inverse aspect ratio, and tunneling resistance. The effects of parameters on the Y , percolation threshold, and composite conductivity are illustrated and analyzed. The calculated conductivity is compared with the measured conductivity of multiple samples to validate the proposed model. Shorter L c , longer and thinner CNFs, and higher interphase conductivity lead to increased values of Y . Furthermore, a higher Y results in an inferior percolation and a greater network portion. For instance, when Y = 1, the percolation threshold reaches a maximum of 0.009, whereas for Y > 15, the percolation threshold decreases to 0.006, and the network fraction increases to 0.155 at Y = 21. Moreover, maximum values of Y = 20 and a 4 vol.% CNF can enhance the nanocomposite conductivity to 0.13 S/m, highlighting the direct influence of Y on the PCNF conductivity.