Resistors: Theory of Operation, Behavior and Safety Regulations

The conductivity, temperature behavior and thermal cycling stability of resistive materials, based on multi-walled carbon nanotube networks with and without polymer or epoxy matrixes, has been investigated. Pure carbon nanotube networks and polyethylene/CNT based composites require a prolonged burn-in procedure for the stabilization of the electrical characteristics while, in the case of epoxy/carbon nanotube compounds, a low resistivity, perfect ohmic behavior and an excellent long-term stability has been achieved for temperatures up to 160°C for samples with a rather low carbon nanotube concentration. It has been demonstrated, that the epoxy matrix based carbon nanotube network resistors can be used as electrical heating elements and temperature sensors. Low frequency noise spettroscopy, applied to the characterization of carbon nanotube based resistors, enabled a more detailed modelling of the temperature dependence of the conductivity.