Electrical characteristics of carbon nanotube doped composites
a National Research University "Moscow Power Engineering Institute", Krasnokazarmennaya st. 14, Moscow, 111250, Russian Federation
b Kintech Lab Ltd., ul. 3-ya Khoroshevskaya 12, Moscow, 123298, Russian Federation
c National Research Centre ‘Kurchatov Institute’, pl. akad. Kurchatova 1, Moscow, 123182, Russian Federation
d Institute of Macromolecular Compounds, Russian Academy of Sciences, Bolshoi prosp. 31, St. Petersburg, 199004, Russian Federation
e University of Perugia, Department of Civil and Environmental Engineering, Via G. Duranti 93, Perugia, 06125, Italy
f Institute of Polymer Science and Technology, ICTP-CSIC, Calle Juan de la Cierva 3, Madrid, 28006, Spain
This paper reviews research into the electrical characteristics that are imparted to composite materials by introducing carbon nanotubes (CNT) into their polymer matrices. Due to the large aspect ratio of CNTs, even a small amount of doping (at a level of 0.01—0.1%) is enough to increase the conductivity of the material by more than ten orders of magnitude, this changing it from an insulator to a conductor. At low doping, charge transfer is of percolation nature in the sense that nanotubes that are in contact with each other form conducting channels in the material. Importantly, the conductivity has a threshold nature, so that the conduction jump occurs at an arbitrarily small increase in doping above the critical value. This paper summarizes experimental data on the position of the percolation threshold and the maximum magnitude of the conductivity for composites obtained using various polymer types and various CNT geometries. Factors affecting the electrical characteristics of composites produced by various methods are analyzed. Methods for and basic results obtained from the simulation of the percolation conductivity of CNT doped composites are discussed. Particular attention is given to contact phenomena that occur at nanotube interfaces and which determine the conductivity of CNT doped composites.