Toughening polylactic acid by melt blending with polybutylene adipate‐co‐terephthalate and natural rubber, and the performance of the resulting ternary blends

Abstract Polylactic acid (PLA) is one of the most commercially potential bio‐based and biodegradable materials recently used to partially replace non‐biodegradable petroleum‐based plastics; however, PLA's innate brittleness limits its practical applications. The present work aims to reduce the brittleness and improve the toughness of PLA by blending it with polybutylene adipate‐co‐terephthalate (PBAT) and natural rubber (NR). PLA/PBAT/NR ternary blends were prepared by a melt blending process, using both an internal mixer and a twin‐screw extruder, and were converted into test specimens using an injection molding machine. The weight ratio of PBAT:NR was kept constant at 1:1, while the amounts of PBAT/NR blend were varied at 14, 26, and 38 wt%. SEM confirmed the incompatibility among PLA, PBAT, and NR, as island‐like NR phases and oval PBAT phases were dispersed in the PLA matrix. Compared with neat PLA, the PLA/PBAT/NR ternary blends exhibited increased elongation at break from 6.2% to 21.0% (up to 240%), improved impact strength from 36.6 to 85.0 J/m (up to 130%), decreased density from 1.254 to 1.159 g/cm 3 (approximately 7.6%), enhanced thermal stability and water resistance, and reduced shear‐dependent behavior. The obtained PLA/PBAT/NR blends have potential for the production of injection‐molded articles such as biomedical devices, toys, agricultural supplies, office supplies.