Development of Toughened Blends of Poly(lactic acid) and Poly(butylene adipate-co-terephthalate) for 3D Printing Applications: Compatibilization Methods and Material Performance Evaluation

The research presented in this article discusses the subject of poly(lactic acid) (PLA) modification via reactive mixing with the poly(butylene adipate-co-terephthalate) (PBAT) copolymer for 3D printing applications. Filaments suitable for fused deposition modeling were prepared from blends of PLA containing 10, 20, and 30% by weight of PBAT. Mechanical testing clearly indicated that the blending with PBAT effectively increases the impact strength of PLA, from an initial value of approximately 30 J/m to more than 700 J/m for the optimized PLA/PBAT (30%) chain extender-modified blend. The addition of the multifunctional chain extender (ESA) also has a positive effect on the rheological profile of the PLA/PBAT materials, which facilitates both the production process of the extruded filament and the maintenance of a stable width of the printed material path. Despite the use of a significant PBAT content, the analysis of thermomechanical properties did not show any significant deterioration in the thermal resistance of the materials, while a detailed differential scanning calorimetry analysis indicates a small tendency to nucleate the PLA structure by PBAT inclusions. The structural analysis of scanning electron microscopy clearly indicates a change in the mechanism of deformation from a brittle fracture for pure PLA to a more favorable shear yielding for PBAT-rich blends. The comparison of the properties of printed and injected PLA/PBAT blends indicates the possibility of obtaining similar or in some respects better mechanical properties, especially for ESA-modified samples.