Natural and Nanomaterial Additives in Biodegradable PLA/PBAT Films: Towards Advanced Packaging Materials

This study reports a systematic, single-additive investigation of biodegradable films based on polylactic acid (PLA) and polybutylene adipate terephthalate (PBAT) blends (T2308 and F2332) from Ecovio^® for packaging applications by incorporating additives such as nisin, essential oils (tea tree, lemongrass, eucalyptus, clove leaves), curcumin, and zinc oxide nanoparticles. Their effects on structure, morphology, thermal behavior, mechanical properties, barrier performance, and optical properties were evaluated by FTIR, SEM with EDX, TGA, DSC, DMA, XPS, mechanical testing, water vapor permeability, moisture absorption, contact angle measurements and UV/visible transmittance. FTIR confirmed additive incorporation with bonding interactions. SEM revealed matrix-dependent morphologies, with T2308 being denser and more heterogeneous, F2332 being more homogeneous and flexible. DSC/TGA showed curcumin markedly reduces crystallinity and melting enthalpy in T2308 (weaker effects in F2332), while oils generally decrease crystallinity and shift Tg depending on molecular structure. Mechanical testing indicated modulus is highly matrix-dependent: curcumin, nisin, and ZnO decrease stiffness in T2308, whereas F2332 shows smaller or opposite trends. UV shielding increases with curcumin and ZnO, and clove oil improves barrier performance. Biodegradation was assessed only for neat films: weight loss averaged ~4-6% after 49 days, with PET/HDPE remaining largely inert. These results illustrate the importance of matrix-additive interactions in enabling tailored biodegradable packaging materials.