Properties of 3D Printable Poly(lactic acid)/Poly(butylene adipate-co-terephthalate) Blends and Nano Talc Composites

Abstract

Biodegradable poly(lactic acid) (PLA) filaments have been widely used in the fused deposition modeling (FDM) 3D printing technology. However, PLA has low toughness and low thermal resistance that affects printability and restricts its industrial applications. In this study, PLA was compounded with 0 to 40 wt% of poly(butylene adipate-co-terephthalate) (PBAT) and varied content of nano talc at 0 to 40 wt% in a twin screw extruder. The compounds were reextruded to filaments using a capillary rheometer. PLA/PBAT blends and their composite filaments were printed with a FDM 3D printing machine. Morphology, rheological behaviour, thermal characteristic, surface roughness, and mechanical property of 3D printing of the blends and the composites were investigated. Complex viscosity of the blends and the composites increased with increase of the PBAT and the nano talc contents. The incorporation of the nano talc enhanced crystallization temperature and reduced the coefficient of volume expansion of the composites. It was found that the PLA/PBAT blends and composites were excellent in both printability and dimension stability at PBAT content 10-30 wt% and nano talc up to 10 wt%. Interestingly, it was possible to print the composite filaments at an angle up to 75° during the overhang test without a supporter. From the vertical specimens, the surface roughness improved due to the incorporation of the nano talc. Tensile strength of the blends and the composites decreased, whereas elongation at break increased when the PBAT and the nano talc contents were increased. The reduction of tensile strength was attributed to agglomeration of the PBAT dispersed phase and less adhesion between the nano talc and the matrix. It can be noted that the composite 3D printing product showed superior elongation at break up to 410% by adding nano talc 1 wt%. This result suggests that the ductile 3D printable PLA/PBAT blend and the PLA/PBAT-nano talc composite products can be prepared, which shows potential for the commercialized scale.