Dielectric Response of Onion-Like Carbon-Based Polymethyl Methacrylate Composites

The dielectric properties of polymethyl methacrylate films with embedded onion-like carbon particles have been studied from 20 Hz to 1 MHz to investigate the structural relaxations of the composite material by varying the temperature between 240 and 520 K. The temperature behaviour of the complex permittivity at a given frequency is found to be strongly dependent on the nanocarbon concentration. A small effect of the onion-like carbon concentration on the beta transition of the polymer composite has been observed, which indicates that the included onion-like carbon particles do not block the rotational degrees of freedom of the ester groups along the polymer chains. By contrast, it has been found that embedding the nanocarbon fillers to the polymethyl methacrylate matrix changes significantly the alpha transition and the melting temperatures in a non-monoto-nous way.