Sustainable polysaccharide reinforcements: Cellulose-rich micro- and nanofibers from kimchi cabbage byproducts for tunable mechanical and barrier properties in biocomposites

Polysaccharide-based cellulose-rich fibers (CRFs) and cellulose nanofibers (CNFs) were extracted from kimchi cabbage leaf byproduct (KCLB) and applied as sustainable reinforcements in poly(butylene adipate-co-terephthalate) (PBAT) composites. Structural characterization confirmed that CRFs and CNFs exhibit higher aspect ratios, increased oxygen-to-carbon ratios, and enhanced hydroxyl group exposure compared with bulk KCLB, indicating successful isolation of well-defined cellulose structures. The PBAT/CRF/CNF hybrid composite with 1.0 wt% CNFs exhibited a maximum Young’s modulus of ∼369 MPa, significantly higher than that of neat PBAT (149.40 MPa). This enhancement is attributed to synergistic interactions within the polysaccharide network, in which CNFs function as an interfacial regulator and secondary nucleating agent, leading to refined crystalline morphology and increased tortuosity that effectively suppress oxygen and water vapor permeation. These results demonstrate that KCLB-derived bio-fillers provide an effective strategy for sustainable waste valorization and endow tailored structural and barrier properties in sustainable packaging materials.