A strategy for achieving low percolation and high electrical conductivity in melt-blended polycarbonate (PC)/multiwall carbon nanotube (MWCNT) nanocomposites: Electrical and thermo-mechanical properties

In this work, polycarbonate (PC)/multiwall carbon nanotube (MWCNT) nanocomposites were prepared by simple melt mixing at a temperature (similar to 350 degrees C) well above the processing temperature of PC, followed by compression molding, that exhibited percolation threshold as low as of 0.11 wt% and high electrical conductivity of 1.38x10(-3) S.cm(-1) at only 0.5 wt% MWCNT loading. Due to the lower interfacial energy between MWCNT and PC, the carbon nanotubes are excellently dispersed and formed continuous conductive network structure throughout the host polymer. AC electrical conductivity and dielectric permittivity of PC/MWCNT nanocomposites were characterized in a broad frequency range, 10(1)-10(7) Hz. Low percolation threshold (p(c)) of 0.11 wt% and the critical exponent (t) of similar to 3.38 was resulted from scaling law equation. The linear plot of log sigma(DC) vs. p(-1/3) supported the presence of tunneling conduction among MWCNTs. The thermal property and storage modulus of PC were increased with the incorporation of little amount of MWCNTs. Transmission electron microscopy (TEM) and field emission scanning electron microscopy (FESEM) confirmed the homogeneous dispersion and distribution of MWCNTs throughout the matrix phase.