Preparation and properties of cellulose nanocrystals-reinforced Poly (lactic acid) composite filaments for 3D printing applications

In this work, the composite filaments containing different cellulose nanocrystals (CNCs) were successfully fabricated by using a single screw extruder and used to 3D print. The influence of CNCs contents (0, 0.75, 1, and 2 wt%) on the properties of the filaments and 3D printed samples were evaluated. The properties of the filaments and 3D printed samples were characterized by using SEM, FT-IR, XRD, DSC, TGA, and tensile tests. Results revealed that no chemical changes occurred in the presence of CNCs but improved crystallinity was found. The presence of 2 wt% CNCs slightly improved the thermal stability of the neat PLA filament and 3D printed sample. The tensile strength of the neat PLA filament was enhanced by 18.2% by adding up to 1 wt% CNCs but reduced at 2 wt% CNCs content. For the 3D printed samples, the tensile strength of the neat PLA was improved by 11% with the introduction of 0.75 wt% CNCs and decreased for further CNC addition. In addition, compared with the 3D printed samples, the filaments exhibited a higher tensile strength for all CNCs contents. Furthermore, the water absorption of the composite filaments was increased with increasing the CNCs contents. On the other hand, the 3D printed samples containing CNCs showed a lower water absorption than the neat PLA.