Dielectric properties of LDPE-SiO2 nanocomposites

The dielectric behaviour of nano-SiO₂ filled low density polyethylene is investigated over a frequency range of 10 mHz-10 MHz and for different temperatures from 250 K to 350 K. It is shown that the presence of nanoparticles change significantly the dielectric behaviour of the polymer system. The frequency variations of the permittivity and of the tan delta emphasize a α-relaxation process, for each of the nanocomposite samples. The relaxation is more important and occurs at higher frequencies with the increase of the filler content. The increase of the temperature leads to a shift of the relaxation frequency to higher values. Results from chemiluminescence measurements and from X-ray diffraction analysis are discussed in connection with the dielectric behaviour.