Estimation of contact resistance and its effect on electrical conductivity of CNT/PEEK composites

The contact resistance between carbon nanotube (CNT)-carbon nanotube (CNT) in polymers reinforced with CNTs is known to consist of the resistance due to direct contact between the CNTs and a tunneling resistance across a thin polymeric layer. By fitting experimental data on electrical conductivity of Poly Ether Ether Ketone (PEEK) reinforced with CNTs with Holm–Kirschstein equation, Simmons’ equation and Kovacs’ equation, both the contact resistance and the thickness of the tunneling layer were determined. The tunneling distance corresponding to the percolation threshold for this composite system was found to be about 1.7 nm. This is in agreement with the distance obtained by simulation in a previous research.