Enhancement of 3D Printability by FDM and Electrical Conductivity of PLA/MWCNT Filaments Using Lignin as Bio-Dispersant

To increase the applications of FDM (fusion deposition modeling) 3D printing in electronics, it is necessary to develop new filaments with good electrical properties and suitable processability. In this work, polymer composites filament-shaped with superior electrical performance based on polylactic acid (PLA) carbon nanotubes and lignin blends have been studied by combining solution mixing and melt blending. The results showed that composites achieve electrical percolation from 5 wt.% of nanotubes, with high electrical conductivity. Moreover, the introduction of a plasticizing additive, lignin, improved the printability of the material while increasing its electrical conductivity (from (1.5 +/- 0.9)center dot 10(-7) S center dot cm(-1) to (1.4 +/- 0.9)center dot 10(-1) S cm(-1) with 5 wt.% carbon nanotubes and 1 wt.% lignin) maintaining the mechanical properties of composite without additive. To validate lignin performance, its effect on PLA/MWCNT was compare with polyethylene glycol. PEG is a well-known commercial additive, and its use as dispersant and plasticizer in PLA/MWCNT composites has been proven in bibliography. PLA/MWCNT composites display easier processability by 3D printing and more adhesion between the printed layers with lignin than with PEG. In addition, the polyethylene glycol produces a plasticizing effect in the PLA matrix reducing the composite stiffness. Finally, an interactive electronic prototype was 3D printed to assess the printability of the new conducting filaments with 5 wt.% of MWCNT.

Automated summary

In order to promote the application of FDM 3D printing in electronics, the development of new filaments with excellent electrical properties and processability is crucial. This study focuses on the fabrication of polymer composites filaments based on PLA carbon nanotubes and lignin blends, which exhibit superior electrical performance. The addition of lignin not only improves the 3D printability of the material, but also enhances its electrical conductivity, while maintaining the mechanical properties of the composite. A comparison with polyethylene glycol demonstrates that lignin is a more effective additive in terms of processability and adhesion. The successful 3D printing of an interactive electronic prototype using the new conducting filaments further validates their printability.