Fatty Acid Esterification of Bamboo Flour Toward Thermoplastic Biomass‐Based Toughening of Polylactic Acid

ABSTRACT Polylactic acid (PLA) is a bio‐based and biodegradable polymer, but its inherent brittleness limits its applications requiring high deformation capability. In this study, thermoplasticized bamboo flour was developed as a biomass‐derived deformable modifier for PLA through long‐chain fatty acid esterification. Among the modified products, decanoic acid‐modified delignified bamboo flour (DBF‐C10) showed the most favorable thermoplastic processability, with an elongation at break of approximately 160%. PLA/DBF‐C10 blends containing 10–50 wt% DBF‐C10 were prepared by melt processing, and their structure, thermal properties, mechanical properties, and fracture behavior were investigated. FTIR and 13 C‐NMR confirmed the coexistence of PLA and DBF‐C10 after processing without new covalent bond formation. Increasing DBF‐C10 content decreased the crystallinity and slightly reduced the glass transition temperature of the PLA phase, while the melting temperature remained nearly unchanged. Although tensile strength and storage modulus decreased, the elongation at break of TPLA‐50 was approximately twice that of neat PLA. DMA and SEM revealed that DBF‐C10 facilitated deformation and crack propagation through interfacial debonding, fibrous drawing, plastic deformation, and crack deflection. These results demonstrate the potential of thermoplasticized bamboo flour as a deformable biomass modifier for toughening PLA.