Naturally occurring eugenyl acetate as biobased plasticizer for sustainable polylactide formulations with improved toughness.

In this study, we explore the potential of eugenyl acetate (EAc), a naturally occurring ester of eugenol, as a biobased plasticizer to overcome the intrinsic brittleness of polylactide (PLA) derived from starch. A theoretical assessment of the miscibility between PLA and EAc is carried out. Our findings demonstrate that EAc shows exceptional miscibility with PLA, as confirmed by their similar solubility parameters (EAc-19.83 MPa, and PLA-20.66 MPa), and an interaction parameter of χ = 0.39. The incorporation of EAc improves the ductility of PLA, with strain at break increasing to 427.7 % at 20 wt% EAc, compared to a brittle 10.2 % for neat PLA. The plasticizing effect of EAc also leads to a considerable reduction in the glass transition temperature of PLA, from 60.4 °C to 35.7 °C at 20 wt% EAc. Scanning electron microscopy reveals no phase separation and the development of plastic deformation in PLA formulations with 15-20 wt% EAc. Additionally, all plasticized formulations exhibit full biodegradation in controlled compost conditions in <8 weeks. These results contribute to advancing PLA-based formulations that are both high-performance and eco-friendly, supporting the broader goals of sustainable development in polymer science.