Solution chemistry-assisted preparation of ZnO NPs–PLA nanocomposites and their filaments for fused filament fabrication 3D printing process

Nanocomposite filament preparation is still a technological challenge in fused filament fabrication (FFF) 3D printing process. Herein, the results of the preparation of zinc oxide nanoparticles (ZnO NPs)–Polylactic acid (PLA) nanocomposite of different weight percentages of ZnO (2.5 and 5 wt. %) and with 10 wt. % plasticizer through a chemical mixing process and the results of filament preparation with the length of 3–5 m and average diameters of 1.6–1.9 mm through extrusion process at processing temperature range of 140–155 °C with their 3D printability are presented. Initially ZnO nanoparticles of average size of 10–20 nm were synthesized using the facile co-precipitation technique. The investigations on structural, thermal, morphological, and mechanical properties of the prepared nanocomposite filaments were carried out. X-ray diffraction studies revealed the presence of crystalline ZnO NPs within PLA matrix. Fourier-transform infrared (FT-IR) spectroscopy results revealed the presence of various functional peaks, which indicated the generation of nanocomposite. Scanning electron microscopy (SEM) images of the prepared filaments exhibited uniformly dispersed ZnO NPs within the PLA matrix. A decreasing trend in tensile properties and flexibility for filaments with ZnO powder content from 2.5 to 5 wt.% in PLA matrices was observed. Plasticizer addition was effective in improving the mechanical behavior of the prepared composite polymer. Thermal stability of the nanocomposites was found to be decreased with the filler concentration in the nanocomposites as compared to the pristine PLA indicating their inferior thermal stability.