Influence of 3D-printing deposition parameters on crystallinity and morphing properties of PLA-based materials

Abstract

Morphing effect control is still a major challenge in 4D-printing of polylactic acid (PLA). In this work, the influence of extrusion-based 3D-printing parameters on PLA-based material morphing was studied. A design of experiments was performed, where 5 factors (printing temperature, bed temperature, printing speed, fan speed, and flow) were explored at 2 levels. Crystallinity and morphing properties of each 3D-printed structure were determined and discussed. The crystallinity rates of the PLA-based specimens ranged from ca. 14% up to ca. 71%. The interaction between bed temperature and printing speed showed a significant impact on PLA-based samples crystallinity, where using these two parameters at their higher levels contributed to producing PLA-based specimens with higher crystallinity. When exposed to an external thermal stimulus of 60 °C, all settings were capable of acquiring a temporary shape and recover between ca. 71% and ca. 99% of the original shape, depending on the configurations the recovery times ranged from 8 to 50 s. The configuration that resulted in the highest recovery rate was: printing temperature at 220 °C, bed temperature at 40 °C, printing speed at 80 mm/s, fan speed at 0%, and flow at 100%. Regarding recovery time, the configuration of 180 °C for printing temperature, 80 °C for bed temperature, 10 mm/s for printing speed, 100% for fan speed and 150% for flow resulted in the longest recovery time. Overall, the experimental results clearly showed that the parameters of extrusion-based 3D-printing influence the crystallinity and transformability of PLA-based materials.