Dielectric characterization of solution intercalation and melt intercalation poly(vinyl alcohol)-poly(vinyl pyrrolidone) blend-montmorillonite clay nanocomposite films

Poly(vinyl alcohol) (PVA)-poly(vinyl pyrrolidone) (PVP) blend-montmorillonite (MMT) clay nanocomposite films up to 10 wt.% clay loading were synthesized by aqueous solution intercalation and melt compounding. Complex dielectric function, alternating current (ac) electrical conductivity and complex impedance of these films have been investigated as a function of clay concentration in the frequency range 20 Hz-1 MHz at 30 degrees C. These films show significant decrease in the real part of relative dielectric function (epsilon') up to 3 wt. % MMT clay loading and at 5 wt.% their epsilon' values are found to be nearly equal to the PVA PVP blend film. It is observed that the epsilon' values of PVA PVP blend MMT clay films are lower than the PVA MMT clay film at the same clay concentration. The ac electrical conductivity of these films increases with increase of frequency. The dc conductivity of these films varies anomalously with increase of clay concentration. The complex impedance spectra suggest that the dielectric properties of these nanocomposite films are independent of electrode polarization effect in the experimental frequency range. A correlation between dielectric function, structural ordering and the effect of preparation route were explored by considering clay intercalation and exfoliation and the interactions between polymer and MMT clay. This study revealed that the dielectric constant values of these organic-inorganic nanocomposite films can be tuned by loading MMT clay in the polymers matrix, which also improves their physical and thermal properties.