Mitigating plasticizer migration in bio-based PLA by constructing a physical barrier-chemical anchoring dual inhibition system

To address the prevalent issue of PEG migration in polyethylene glycol/polylactic acid (PEG/PLA) plasticized systems, this study employs SiO 2 as a physical barrier and the chain extender ADR 4370 as a chemical anchoring agent to fabricate ADR/SiO 2 /GA composites via melt blending and hot-pressing, and aims to suppress PEG migration within the PLA matrix by leveraging the physical confinement of SiO 2 and the chemical fixation of ADR. The results demonstrated that the synergy between SiO 2 and ADR significantly enhanced mechanical properties. Specifically, the elongation at break of the 1.0 SiO 2 /GA reached 409.48% (approximately 40% higher than the GA composites), further increasing to 423.06% for the 1.0 ADR/SiO 2 /GA composites. Appropriate SiO 2 content increased crystallinity, while ADR regulated the crystallization behavior. Crucially, the synergistic modification effectively suppressed PEG migration. After thermal aging at 80 °C for 35 days, the migration ratio of the GA composites was 11.48%, whereas 0.5–1.5 SiO 2 /GA showed lower mass losses (8.12%, 8.31%, and 8.54%, respectively). The ADR/SiO 2 /GA composites exhibited even lower losses than that of the SiO 2 /GA composites, with the 1.0 ADR/SiO 2 /GA achieving the minimum (approximately 14% reduction). Additionally, the composites exhibited excellent optical performance and optical stability, with the T 660 of the SiO 2 /GA remaining at 77.8% after thermal aging. This work provides a reliable theoretical basis and technical reference for the design and preparation of high-stability, low-migration biodegradable packaging composites, which is conducive to promoting the practical application of PLA-based flexible materials in food packaging.