Response surface optimization of acetylated cellulose nanofiber/ZnO-reinforced poly(vinyl alcohol) films with enhanced UV-shielding and water resistance for sustainable packaging

The development of sustainable poly (vinyl alcohol) (PVA)-based packaging films remains challenging due to their high hydrophilicity, poor water resistance, and limited protection against ultraviolet radiation. This study aimed to develop and optimize PVA hybrid films reinforced with acetylated cellulose nanofibers (A-CNF) and zinc oxide (ZnO) nanoparticles using response surface methodology based on a central composite design. The effects of A-CNF and ZnO contents on tensile strength, film thickness, and water contact angle were evaluated to identify an optimum formulation with balanced mechanical and surface properties. The optimized composition contained 8.035 wt% A-CNF and 0.617 wt% ZnO, producing a tensile strength of 39.19 MPa, film thickness of 204.86 μm, and water contact angle of 61.07°. Fourier-transform infrared spectroscopy confirmed successful CNF acetylation and indicated interfacial interactions between PVA, A-CNF, and ZnO. X-ray diffraction and thermogravimetric analyses showed improved structural ordering and thermal stability, while morphological observation supported relatively homogeneous filler dispersion within the PVA matrix. The incorporation of A-CNF improved mechanical reinforcement and reduced hydrophilicity, whereas ZnO enhanced UV-shielding performance while maintaining visible transparency. The main contribution of this work is the integrated optimization of bio-based nanofiber and inorganic nanoparticle reinforcement to improve the multifunctional performance of PVA films. Overall, the optimized PVA/A-CNF/ZnO film demonstrated improved mechanical, thermal, optical, and water-resistance behavior, indicating its potential as a sustainable packaging material.