Interfacial Acetalization‐Driven Compatibility: High‐Strength <scp>PLA</scp> /Starch Composites With In Situ Generated <scp>PLA</scp> ‐g‐ <scp>OCS</scp> Copolymers

ABSTRACT This work has developed a polylactic acid/starch composite with enhanced performance and cost‐effectiveness via oxidative modification of starch. Oxidized corn starch (OCS) with different oxidation degrees was prepared using a hydrogen peroxide/copper sulfate pentahydrate catalyst system, and PLA/OCS composites were prepared using melt blending. Tensile test results showed that the tensile strength of the PLA/10OCS4.0 composite (71.2 MPa) was markedly higher than that of the PLA/10CS composite (66.4 MPa) and even surpassed that of neat PLA (68.5 MPa). To probe potential interfacial reactions between the PLA matrix and oxidized starch, Soxhlet extraction followed by FTIR spectroscopy was performed. The results confirmed in situ formation of PLA‐g‐OCS copolymers, evidencing that the CHO groups on the OCS surface acetalization reacted with the terminal ‐OH groups of PLA molecular chains to form covalent linkages. Meanwhile, SEM and DSC results demonstrated that the PLA‐g‐OCS copolymers formed at the two‐phase interface significantly enhanced the interfacial compatibility between the PLA matrix and starch granules, while also improving the crystallization ability of PLA. Furthermore, after introducing triglycidyl isocyanurate (TGIC) into the PLA/10OCS4.0 composite material, the interfacial bonding strength and crystallization ability of the PLA/10OCS4.0/0.5TGIC composite material were further enhanced, with its tensile properties surpassing those of the PLA/10OCS4.0 composite material. The PLA/OCS composite approach proposed in this work not only reduces material costs and enhances tensile properties but is also expected to improve biodegradability, offering a novel technical approach for the application of PLA in the disposable plastics field.