Biodegradable <scp>PLA</scp> / <scp>PBS</scp> Composite Films Reinforced With Spirulina Powder: Characterization, Degradation Behavior, and Suitability for Seedling Bag Applications

ABSTRACT This study reports the development of biodegradable PLA/PBS/Spirulina composite films for seedling bag applications. Spirulina powder was incorporated at 1 and 3 phr into an optimized PLA/PBS/MA‐g‐PLA/PEG matrix, and the films were characterized for mechanical, thermal, morphological, and degradation properties. Tensile analysis revealed that Spirulina addition reduced tensile strength, with SPR‐1 maintaining acceptable performance (~19 MPa) for agricultural use, while SPR‐3 showed significant loss of strength. Surface properties such as gloss and contact angle improved with Spirulina incorporation. Thermal analysis (DSC and TGA) indicated that Spirulina acted as a nucleating agent, reflected by a slight increase in crystallinity with higher loadings, although accompanied by marginal reductions in thermal stability. XRD patterns of the initial samples further confirmed the enhanced crystalline ordering with Spirulina addition. Soil burial tests demonstrated faster degradation in Spirulina‐filled films, and FESEM micrographs after 60 days revealed surface erosion and crack formation, most pronounced in SPR‐3. These results show that Spirulina improves biodegradability while maintaining sufficient strength at lower loadings, establishing PLA/PBS/Spirulina composites as sustainable alternatives to polyethylene seedling bags.