Compostable biocomposite PLA/PBSA cast films with TPS and lignin: Properties, biodegradation and ecotoxicity assessment

As the agricultural sector strives for sustainable solutions, the use of biodegradable plastic mulch films continues to garner attention over polyethylene (PE) based films. These eco-friendly alternative films can mitigate the drawbacks of PE film disposal after use, while maintaining functionality throughout the field growing season. This research work assessed formulations of films containing thermoplastic starch (TPS) and lignin aimed at enhancing biodegradation of the bioplastic blend containing poly(lactic acid) and poly(butylene succinate-co-adipate). The biodegradation and ecotoxicity of these films were evaluated, which are the key criteria for their potential for mulch film applications, along with mechanical and thermal properties assessment. The findings demonstrated the material was compostable (>80% biodegradation within 90 days), with seedlings growing successfully in the residual compost media (≥81% germination rate). Furthermore, the films were influenced by the inclusion of lignin and TPS, showing reduced mechanical (machine direction tensile strength at yield 17–56% reduction) and thermal characteristics (5 wt% onset degradation lowered between 36 and 97 °C) over the base blend. Overall, this materials screening study demonstrates that these films after further toughness enhancement and field trials have potential use for mulch film applications.