Barrier and functional enhancement of PLA films incorporating curcumin and modified cellulose nanocrystals

Polylactic acid (PLA) has attracted considerable attention for food packaging applications due to its biodegradability and high transparency; however, its practical application is limited by insufficient barrier performance, poor UV resistance, and a lack of inherent antioxidant activity. In this study, PLA-based nanocomposite films incorporating 1 wt% silane-modified cellulose nanocrystals (SCNC) and curcumin (0.5 and 1 wt%) were prepared via a solution-casting method to overcome these limitations. SEM analysis indicated a relatively uniform dispersion of curcumin and SCNC within the PLA matrix. Both additives served as heterogeneous nucleating agents, increasing the degree of crystallinity. From an optical perspective, curcumin induced a light yellow coloration and provided effective UVA blocking while maintaining relatively high transparency in the visible region. The simultaneous incorporation of curcumin and modified nanocellulose significantly reduced the water vapor permeability (WVP) of the PLA films, particularly in the ternary film containing 1 wt% curcumin and 1 wt% SCNC. The mechanical properties showed a moderate increase in yield stress without a significant change in elastic modulus. In addition, despite the low curcumin release, the ternary nanocomposite films exhibited good antioxidant activity, primarily governed by curcumin content. Overall, the developed PLA films demonstrated improved barrier and functional properties along with maintained mechanical performance, highlighting their potential for active food packaging applications.