Effect of Cellulose Nanofibrils in Direct Melt-Blending of Poly-(Lactic Acid) and Poly(Butylene Succinate) for 3D-Printing

Biopolymers, especially poly(lactic acid) (PLA), have been among major 3D-printing materials, particularly for fused deposition modelling (FDM) techniques. Blending of PLA with poly(butylene succinate) (PBS) can enhance toughness. The blend can be reinforced by the addition cellulose nanofibrils (CNF), which has been rarely studied. A 1% solution of CNF was added to PLA/PBS with ratio of 70:30 directly during melt-blending into 3D-printing filament, which was fed into a FDM 3D printer. Characterization by Fourier transform infrared spectroscopy revealed successful integration of CNF fillers with more hydroxyl group availability in the composite. The degree of crystallinity of PLA, however, was decreased by addition of CNF fillers. This was also evident by the X-ray diffraction analysis, probably due to reduced chain mobility by entanglement effect. Mechanical performance of the printed samples was studied at 23 °C and at slightly elevated temperature of 40 °C, which revealed improved modulus and elongation stability at 40 °C in PLA/PBS-CNF1% composite. Water absorption study also revealed 50% enhancement with addition of CNF fillers, indicating improved water penetration, which could be beneficial for biodegradability. With good mechanical stability at around 40 °C and good water penetration, PLA/PBS-CNF1% composite could be beneficial in 3D-printing for biomedical application and water treatment.