Double percolation of multiwalled carbon nanotubes in polystyrene/polylactic acid blends

Selective localization of multi-walled carbon nanotubes (MWCNT) in polylactic acid/polystyrene (PLA/PS) bicontinuous blends is presented in this work. A masterbatch of PS with a 2 wt% content of MWCNT is prepared and then melt mixed with different amounts of PLA. This two-step process results in a double percolated morphology where PS percolates the PLA phase, and MWCNTs percolate the PS phase. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) evidence, respectively, the bicontinuous morphology and the high selectivity of MWCNT localization in the system. Double percolation leads to a very low electrical percolation threshold of about 0.45 vol% MWCNT on total volume and an electrical conductivity of 10(-9) S/cm.