Piezoelectric and Dielectric Characterization of MWCNT-Based Nanocomposite Flexible Films

PZT-epoxy-multiwalled carbon nanotube (MWCNT) flexible thick film actuators were fabricated using a sol-gel and spin coat and deposition process. Films were characterized in terms of their piezoelectric and dielectric properties as a function of MWCNT volume fraction and polarization process. Correlations between surface treatment of the MWCNTs and composite performance were made. The surface morphology and filler distribution were observed with the aid of SEM and TEM images. The volume fraction of PZT was held constant at 30%, and the volume fraction of MWCNTs varied from 1% to 10%. Two forms of dielectric polarization were compared. Corona discharge polarization induced enhanced piezoelectric and dielectric properties by a factor of 10 in comparison to the parallel-plate contact method (piezoelectric strain coefficient and dielectric constant were 0.59 pC/N and 61.81, respectively, for the parallel-plate contact method and 9.22 pC/N and 103.59 for the corona polarization method, respectively). The percolation threshold range was observed to occur at a MWCNT volume fraction range between 5% and 6%.