Evaluation of the Tensile and Morphological Properties of Nanocellulose-Reinforced Polyvinyl Alcohol Films

Nanocellulose has emerged as a high-performance bio-based nanofiller with exceptional reinforcing capability for polymer film matrices due to its high aspect ratio, surface hydroxyl groups, and excellent mechanical properties. This study evaluates the tensile and morphological properties of polyvinyl alcohol films reinforced with nanocellulose isolated from bleached kraft pulp, investigating the potential for biobased packaging film development relevant to Nigerian agricultural produce packaging. Nanocellulose was isolated by sulphuric acid hydrolysis, characterised by transmission electron microscopy, dynamic light scattering, and X-ray diffraction. Composite films were prepared by solvent casting with nanocellulose loadings of 1, 3, 5, and 7 percent by weight, and sorbitol was incorporated as a plasticiser. Tensile strength, elongation at break, Young's modulus, and water vapour permeability were determined following ASTM standard methods. Results demonstrate progressive improvements in tensile strength from 28 MPa for neat polyvinyl alcohol to 54 MPa at 5 percent nanocellulose loading, representing a 93 percent increase. Young's modulus increased by 240 percent at 5 percent loading, reflecting the exceptional reinforcing efficiency of nanocellulose at low volume fractions. Elongation at break decreased with nanocellulose addition due to increased film stiffness. Water vapour permeability declined by 38 percent at 5 percent loading, attributed to tortuous path effects created by nanocellulose network formation. Scanning electron microscopy confirmed uniform nanocellulose dispersion at loadings up to 5 percent, with agglomeration observable at 7 percent. The study demonstrates the viability of nanocellulose as a reinforcing agent for biodegradable packaging films with reduced moisture sensitivity. Keywords: nanocellulose, polyvinyl alcohol, composite film, tensile properties, packaging