Study on 3D printability of PLA/PBAT/PHBV biodegradable blends for packaging applications

Additive manufacturing offers a fast and cost-effective pathway to develop new sustainable, multifunctional packaging prototypes. However, the range of biodegradable polymers suitable for this technology is still critically narrow. Poly (3-hydroxybutyrate-co-3-hydroxy valerate) (PHBV) possess favorable barrier, mechanical properties and biodegradability; however, its low thermal stability and poor melt strength pose severe challenges in 3D printing process. On their side, PBAT-rich Ecovio blends provide high ductility and thermal stability but suffer from buckling issues due to excessive flexibility of the filaments. To address these concerns, this study systematically evaluates the role of PHBV in Ecovio-based blends for 3D printing, providing new insights into the relationship between blend composition, processability and dimensional stability, for the development of new packaging prototypes using fused deposition modeling (FDM). The printing temperature (from 200 to 250 °C) and the blends composition (up to 40 % PHBV concentration) were optimized to enhance the printability, the dimensional accuracy and the mechanical properties of the specimens for the target application, based on preliminary characterization of chemical, thermal, rheological and morphological investigations. Results showed that the incorporation of PHBV into the blends at concentrations ≥20 % ensured a decrease in viscosity and adequate rigidity to guarantee successful 3D printing, while Ecovio increased the thermal stability of PHBV and expanded the processing window, enabling the blends to be printed up to 250 °C. Among all, the Ecovio/PHBV 70/30 blend printed at 230 °C demonstrated to be best combination of composition and temperature to achieve better compactness, flexural properties and optimized processability, while minimizing warpage, shrinkage and degradation phenomena, making it a promising candidate for the realization of novel, sustainable packaging prototypes. Finally, overall migration tests demonstrated the compliance of the developed packages to the limits of Regulation (EU) No October 2011 for food contact applications.