Percolation in a nanotube–polymer system and its lumped-circuit modeling

Electrical properties of composites composed of polyurethane polymer and multi-walled nanotubes are reported. Samples with different nanotube volume fractions are prepared, and an impedance spectroscopy technique in the frequency range from 10 mHz to 10 MHz is used to characterize the properties of the samples. It is observed that the resistivity of the mixture can be varied widely, from ∼10 MΩm to ∼1 Ωm, just by slightly altering the volume fraction of nanotubes. A lumped-circuit model illustrated that the micro-scale morphology between nanotube-clusters influences the resistive relaxation in the composite system. The investigations show that the presented binary mixture has a potential to be utilized in conductive electrical components (flexible electrodes), electromagnetic shielding, and electrostatic and field grading materials for electronic and high voltage insulation technologies.