Creating poly(lactic acid)/carbon nanotubes/carbon black nanocomposites with high electrical conductivity and good mechanical properties by constructing a segregated double network with a low content of hybrid nanofiller

Conductive biodegradable polymer composites have broad application prospects, but obtaining composites with high electrical conductivity and good mechanical properties at low filler content has been an important challenge. In this work, we melt blended poly(lactic acid) (PLA) and one-dimensional (1D) carbon nanotubes (CNTs) and found that CNTs can form part of the conductive network in the polymer matrix to improve its electrical conductivity. However, to achieve high electrical conductivity, PLA should be mixed with large amounts of CNTs, which inevitably impairs its mechanical properties. When carbon black (CB) was mechanically mixed with PLA/CNTs particles with sizes less than 200 mu m, it not only formed a conductive network structure by itself but also interconnected with the CNTs network within the PLA/CNTs composites. Ultimately, a segregated double filler (0D CB-1D CNTs) network structure was constructed in PLA nanocomposites. The resulting nanocomposites achieved good electrical conductivity, tensile strength, flexural strength, and impact toughness of 9.8 x 10(-2) S/m, 70.1 MPa, 91.3 MPa, and 2.8 kJ/m(2) at the addition of 1 phr CNTs and 1 phr CB, respectively. These results demonstrate that PLA-based composites with high electrical conductivity and good mechanical properties could be prepared using this technique at low filler content. This extends the application scope of PLA composites.