Conductivity and Dielectric Response of Carbon- Based Composites in a Broad Frequency Range

Composites formed by a dielectric ceramic or polymer matrix and a conductive filler are very interesting materials since their physical properties, such as optical, electrical and magnetic properties as well as tribological, corrosion-resistance and wear properties can be tailored, which makes them attractive for many new electronic, optical, magnetic and structural applications. In particular, the introduction of carbon based nanoparticles, such as CNTs or CNFs, in polymeric or ceramic matrices has led to the development of materials for a wide variety of new applications [1], and devices based on tunable electrical conductivity [2], piezoresistivity [ 3 ], magnetoresistivity [ 4 ] or electromagnetic shielding [5]. CNTs are subject to much stronger Van der Waals forces than CNFs, so it becomes necessary to disperse or functionalize CNTs, increasing production costs. Unlike conventional composites, the electrical percolation threshold in these systems is more complex. To determine percolation and dielectric dispersion studies have focused as a rule in the frequency range up to 10 Hz, where standard capacitance and impedance measurements can be carried out.