Incorporation of Multiwalled Carbon Nanotubes into Electrospun Softwood Kraft Lignin-Based Fibers

Intrinsic properties such as mechanical and electrical conductive properties make carbon nanotubes an ideal nanofiller for reinforcement of polymer materials. In this study, multi-walled carbon nanotubes (MWNTs) were suspended in various fractionated softwood kraft lignin (SKL) concentrations and electrospun into fibers. Solutions prepared from F1-3SKL suspensions contained aggregated MWNTs, which led to spraying and droplet accumulation during fiber formation. By contrast, MWNT suspensions prepared with F4SKL were well dispersed and readily electrospun into fibers. Increasing the F4SKL concentration in the MWNTs' suspension resulted in better electrospinnability. Adding 10mg of F4SKL enabled as much as 18.6mg of MWNTs (or 6wt% based on fiber weight) to be dispersed and electrospun into fibers. The resulting MWNT-reinforced SKL fibers were then thermostabilized and carbonized and the resulting carbon fibers characterized. Unfortunately, the mechanical properties of the fibers did not improve with incorporation of MWNTs. However, the electrical conductivity increased from 2.3 to 3.0 S/cm when incorporating 6wt% MWNTs into the fibers.