Biodegradable polylactic acid blends with gelatin and acetyl tributyl citrate: Improving mechanical properties and...

Polylactic acid (PLA) is a promising biodegradable polymer, but its brittleness, relatively high cost, and poorly controlled degradation limit its applications. In this study, PLA/gelatin (GEL)/acetyl tributyl citrate (ATBC) blends were prepared by melt blending to simultaneously improve mechanical properties and regulate degradation behavior. ATBC, an environmentally friendly plasticizer, improved the compatibility between PLA and GEL and reduced the brittleness of PLA, whereas GEL, a hydrophilic biopolymer, modified the degradation behavior of PLA and contributed to reinforcing the blends. Mechanical tests showed that GEL increased bending strength, while ATBC markedly enhanced ductility, thereby balancing stiffness and flexibility. For the formulation containing 15 phr GEL and 20 phr ATBC, the elongation at break reached 344.25% (47.6 times higher than neat PLA), and the bending strength was 37.13 MPa (5.95 times higher than the corresponding blend without GEL). Raman spectroscopy revealed that during the "brittle-to-ductile transition" process, ATBC transformed from a dispersed phase to a continuous phase within the blends, elucidating the toughening mechanism. In alkaline solution, the blends containing 15 phr GEL and 20 phr ATBC completely degraded within 6 days, whereas neat PLA and the PLA/ATBC blends containing 20 phr ATBC showed mass losses of only 23.8% and 4.76%, respectively. Under composting conditions, the cumulative biodegradation degree of the blends containing 15 phr GEL and 20 phr ATBC was 54.53% higher than that of neat PLA, confirming its excellent biodegradability. Overall, the PLA/GEL/ATBC blends exhibited balanced mechanical properties, providing a practical route for controlled degradation and expanded PLA applications.