Optimization of the ductile properties of poly(lactic acid) (PLA) using green citrate-based plasticizers and itaconic anhydride grafted PLA (PLA-g-IA)

This study investigates the production of poly(lactic acid) (PLA) formulations enhanced with natural plasticizers such as triethyl citrate (TEC) and trihexyl o-butyrate citrate (BTHC). Itaconic anhydride (IA) grafted with PLA (PLA-g-IA) was obtained via reactive extrusion to serve as a compatibilizer. The incorporation of plasticizers notably enhanced the ductility of PLA while simultaneously decreasing its ultimate tensile strength and elastic modulus. Among the plasticizers tested, TEC was more effective in enhancing ductility and energy absorption, as evidenced by increased impact resistance in Charpy tests. The addition of PLA-g-IA further improved the mechanical strength of the plasticized samples without sacrificing ductility. This enhancement is attributed to the higher reactivity of BTHC with itaconic anhydride (IA) groups. The addition of plasticizers lowered the glass transition temperature from 59.6 ºC to as low as 26.6 ºC, increasing chain mobility even at room temperature. Changes in chain mobility were also observed in the thermomechanical properties, resulting in a rubbery state under ambient conditions. Higher plasticizer content improved the speed of recovery immediately after activation. Morphological analyses supported these findings, confirming that combining PLA with natural plasticizers and utilizing PLA-g-IA can effectively tailor material properties. This approach offers a simplified processing method while enhancing performance.