Preparation of ultrafine tobacco stalk with co-milling and its incorporation for biodegradable mulch film production

Conventional plastic mulch films contribute to persistent soil pollution due to their poor biodegradability. To address this issue, this study developed a biodegradable mulch film with improved overall performance using co-milling technology and an ionic cross-linking strategy. Ultrafine tobacco stalk powder (TSC) was efficiently prepared through co-milling with calcium carbonate, reducing particle size to approximately 25.41 μm. Composite films were fabricated by incorporating TSC into a polyvinyl alcohol (PVA) matrix plasticized with glycerol, followed by Fe 3 ⁺ cross-linking treatment. The optimal TSCF 30 -Fe film exhibited a well-balanced combination of strength, flexibility, and stiffness, with a tensile strength of 11.8 MPa, elongation at break of 123%, and Young's modulus of 42.1 MPa. The Fe 3 ⁺ coordination formed a cross-linked network that enhanced mechanical strength and water resistance, accompanied by a reduced swelling ratio. Furthermore, the composite films demonstrated excellent UV-shielding capability, with strong UV-shielding capability across the 200–400 nm range. Surface hydrophobicity increased with increasing TSC content, which was attributed to the presence of lignin hydrophobic groups. Soil burial tests confirmed biodegradability, showing progressive surface erosion, pore formation, and a continuously increasing degradation rate, whereas commercial films remained intact. This study presents a sustainable approach for valorizing agricultural waste and offers a sustainable strategy for agricultural waste valorization and provides useful insight into the development of biodegradable mulch film materials.