Dielectric relaxation behavior of three-phase MWCNTs-PANI polystyrene nanocomposites

Polymer nanocomposites consisting of multiwalled carbon nanotubes (MWCNTs), poly-
aniline (PANI), and polystyrene (PS) were prepared at different MWCNT weight ratios
and fixed amount of PANI (0.2 wt%). Impedance, dielectric constant, dielectric loss, and
electrical conductivity for these composites were investigated as a function of applied field
and MWCNTs content at room temperature. Obtained results indicated that adding 0.2
wt% PANI polymer to MWCNTs-PS system will enhance electrical conductivity and polar
character while reduce the percolation threshold from 0.8% to 0.2% MWCNTs of
nanocomposites. Relaxation behavior of prepared nanocomposites showed interesting
results. In general, impedance results showed that all samples contain capacitor and
resistor elements. Increasing of MWCNTs amount will reduce the distance between
CNTs–CNTs in the CNTs–polymer network, and the resistor element become more
pronounced. Moreover, at high level of MWCNTs content the relaxation behavior is
mostly due to conductivity relaxation with single value of relaxation time. The addition of
PANI (0.2% PANI) to CNT–polymer or CNT–CNT networks will introduce easy pathway
for carriers to transfer through network leading to increase the electrical conduction for
composites. Relaxation results indicated that the relaxation behavior of prepared nano-
composite is mostly due to conductivity relaxation above 0.2 wt% nanocomposite.