Evaluation of the Efficiency of a Biobased Reactive Plasticizer on the Morphology and Properties of Sustainable Flexible Films Based on Poly(Lactic Acid) (PLA) Produced by Blown Film Extrusion

In the present work, sustainable bio-based films are successfully developed at a pilot scale after a careful screening phase, demonstrating thermal and mechanical properties comparable to conventional petrochemical plastics. The starting blend, used as a reference, consists of poly (lactic acid) (PLA), acetyl tributyl citrate (ATBC), and poly (butylene adipate-co-terephthalate) (PBAT). The matrix was melt-mixed with epoxy-functionalized plasticizers derived from cardanol, acting as plasticizers and compatibilizers. A comparative investigation of two epoxy additives (NC513 and NC514s) clarified their distinct roles: NC513 mainly acts as a plasticizer, reducing viscosity and enhancing ductility, whereas NC514s promotes reactive interactions, increasing melt strength and stiffness. A nucleating agent and a melt strength enhancer were subsequently optimized to improve processability. The most promising formulations were scaled up using a semi-industrial twin-screw extruder and processed via blown film extrusion, confirming technological feasibility. The resulting films exhibited tensile strengths of 27–29 MPa and elongation at break above 300%, with tear resistance comparable to LDPE films of similar thickness. These results demonstrate that low amounts (1–3 wt.%) of bio-based epoxy-functionalized cardanol enable the production of compostable flexible films as sustainable alternatives to petrochemical-based packaging materials.