Multi-functional medical grade Polyamide12/Carbon black nanocomposites in material extrusion 3D printing

[Display omitted] •Multifunctional Polyamide 12/Carbon black nanocomposites in 3D printing.•Nanocomposites are prepared with a thermomechanical process.•Electrically conductive and electrothermal multi-functional nanocomposites.•Mechanical and thermal properties investigation (international standards).•Fracture mechanisms investigated through SEM.•The filler effect on the matrix was thoroughly investigated. Carbon black (CB) modified polyamide 12 (PA12) nanocomposites (PA12/CB) were fabricated through melt mixing extrusion for a range of different filler weight-to-weight ratios (0.1%, 0.5%, 1.0%, 2.5%, 5.0%, and 10.0%). Filaments fabricated via thermomechanical extrusion, were employed to manufacture electrothermally conductive nanocomposites, through 3D Printing Fused Filament Fabrication (FFF). Mechanical performance was assessed, whilst, the electrical percolation threshold was identified, with the nanocomposites exhibiting electrical conductivity for a filler ratio of 2.5 wt% and above. Scanning Electron Microscopy (SEM) was conducted to reveal nanocomposite’s fracture mechanisms. Dynamic Mechanical Analysis (DMA) tests revealed a stiffening mechanism, while the antibacterial response of the nanocomposites for two bacteria was also investigated through a screening process, i.e., Escherichia coli (E. Coli) and Staphylococcus aureus (S. aureus). The highest reinforcement was observed at the PA12/CB 5.0 wt% nanocomposite material. The increase of the nanofiller concentration increased the electrical conductivity and the antibacterial performance of the nanocomposites. A better biocidal response was found against the S. aureus bacterium than the E. Coli bacterium. The studied nanocomposites, exhibited multifunctional behavior, suitable for various applications requiring enhanced mechanical performance, such as free-of-shape and stretchable conductors, circuitry resistors, Joule-heating elements, piezoresistive sensors, etc., as well as medical supplies.