Modified acacia lignin-reinforced epoxy nanocomposites with PVA assistance for sustainable food packaging

Advanced multifunctional nanocomposite films composed of epoxy-lignin-polyvinyl alcohol (ETOLNPVA) have been created as novel materials for prospective use in food packaging. The films were fabricated using the solvent casting technique, with kraft lignin (LN) derived from Acacia mangium black liquor employed as a filler to improve the structural and functional characteristics of the composite. Epoxy groups derived from epoxidized tung oil were integrated into the PVA utilizing hexamethylene-diisocyanate (HMDI) as a cross-linker to enhance compatibility and performance. The properties of mechanical strength, thermal resistance, UV barrier, antioxidant capacity, water vapor transmission, surface wettability, morphology, oxygen transmission rate, and fire resistance were assessed. The efficacy of nanocomposite films in prolonging the shelf life of food was assessed over a period of 16 days, utilizing grapes as a test fruit. The ETOLNPVA nanocomposite films demonstrated outstanding performance in all assessed properties, including core-shell morphology, semicrystalline structure, improved thermal stability, notable mechanical performance (12.97 N/m²), flame retardancy (23 s), and antioxidant efficiency (89.62 %). Furthermore, they exhibited exceptional water vapor barrier properties (522.35 g/m² per 24 h), outstanding resistance to oxygen transmission (5.455E-12 (cm³·cm/cm²·s·cmHg)), favorable surface wettability (contact angle: 82°), and efficient shielding capabilities against UV-A, UV-B, and UV-C radiation.