Cellulose Nanofiber-Reinforced PVA Films Incorporated with Moringa oleifera Leaf Extract: Mechanical, UV-Shielding, and Structural Properties

Abstract

Polymer films that combine mechanical durability with ultraviolet (UV) protection are needed for sustainable packaging. In this study, polyvinyl alcohol (PVA) films reinforced with cellulose nanofibers (CNF) and incorporated with Moringa oleifera leaf extract (MLE) were prepared by solution casting at combined loadings of 1–4 wt% CNF and 0.5–2 wt% MLE. The tensile properties, UV–visible transmittance, and crystalline structure of the films were evaluated, and the tensile data were analyzed by one-way ANOVA followed by Duncan’s multiple range test (p < 0.05). Tensile strength and tensile modulus increased significantly with increasing CNF–MLE loading. The P-CNF4/MLE2 film exhibited the highest tensile strength (75.47 ± 2.89 MPa) and tensile modulus (654.04 ± 14.96 MPa), corresponding to increases of 118.4% and 116.8%, respectively, relative to neat PVA. Although elongation at break decreased at the lowest loading, both elongation at break and toughness increased at higher loadings, reaching 334.43 ± 6.90% and 227.96 ± 15.43 MJ m⁻³, respectively, for P-CNF4/MLE2. All composite films strongly attenuated UV radiation; films containing at least 2 wt% CNF and 1 wt% MLE transmitted less than approximately 1% of the incident light across the 200–400 nm range, whereas visible-light transmittance at 600 nm decreased from approximately 92% for neat PVA to 45% for P-CNF4/MLE2. X-ray diffraction confirmed that the semicrystalline structure of PVA was retained without the formation of a new crystalline phase, while the crystallinity index increased from 71.79% to 87.91%. The combined incorporation of CNF and MLE therefore produced strong, tough, and UV-shielding PVA films with potential application as light-protective packaging materials.