Fracture behavior and biodegradation characteristics of lignocellulosic-filled polyvinyl alcohol biofilms for green packaging solutions

The development of biodegradable films with enhanced functional performance is essential for replacing petroleum-based packaging materials. This study investigates polyvinyl alcohol (PVA) biofilms reinforced with coconut shell powder (CSP), a lignocellulosic agro-waste, fabricated through a water-based solution casting process. The incorporation of CSP was evaluated for its influence on mechanical, thermal, moisture-resistance, and biodegradation characteristics. Tensile testing showed a substantial improvement in performance, with tensile strength increasing from 54 MPa for neat PVA to 83.6 MPa at 6 wt% CSP, accompanied by an increase in elastic modulus from 1.73 GPa to 2.14 GPa and improved elongation at failure. Multiscale SEM fractography suggested the presence of crack deflection, particle pull-out, and fibrillation, which may contribute to enhanced energy dissipation during fracture. XRD results indicated increased crystallinity with CSP addition, likely due to heterogeneous nucleation, while FTIR spectra showed intensified hydrogen bonding and improved interfacial interactions. Thermal analysis revealed an upward shift in degradation onset and Tmax, indicating partial thermal stabilization of the matrix. Water absorption decreased from 6.4% to 1.5%, and soil biodegradation increased from 10.8% to 21.3% over 30 days, suggesting that CSP may facilitate matrix breakdown through its lignocellulosic nature. The findings demonstrate that CSP can function as an effective reinforcement for PVA films, offering enhanced structural integrity and improved environmental responsiveness for potential packaging applications.