Effects of Polyethylene Glycol ( PEG ) on the Structure and Properties of Flexible PEG / PLA Composite Films

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To enhance the toughness of polylactic acid (PLA) films, the polyethylene glycol (PEG)/PLA films were prepared via the film‐blowing process. The effects of PEG molecular weight, content, storage environment, and degradation time on the mechanical, thermal, optical, and degradation properties of the films were systematically investigated. The results showed that PEG significantly enhanced the elongation at break of the films. Low molecular–weight PEG outperformed high molecular–weight PEG in toughening of the films. Outdoor environment exposure drastically reduced the elongation of the films, while indoor/refrigerated storage maintained their stability. PEG promoted PLA crystallization and lowered its glass transition temperature. High‐content PEG modified films exhibited excellent UV shielding performance, and their transparency did not show a significant decline. Soil degradation tests revealed that the films modified with low molecular–weight PEG had a faster rate of mass loss. In all, PEG can markedly improve the toughness of PLA, but it necessitates carefully optimizing the molecular weight and content of PEG to balance the mechanical stability, optical performance, and environmental durability of the PEG/PLA films for practical applications. Moreover, to maintain the performance of the PEG/PLA films and for subsequent processing, storing them in the refrigerator is the best storage environment.