Structure–Property Optimization in High-Barrier Polyglycolic Acid/Polyamide 6 Blends: Achieving Concurrent High Strength and Toughness

Poly(glycolic acid) (PGA), as a biocompatible polyester, is promising for packaging applications due to its excellent gas barrier properties. However, its mechanical brittleness limits its practical use. The blending modification of PGA with polyamide 6 (PA6) was investigated in this study, and the phase structure, rheological properties, thermal behavior, mechanical properties, barrier, and degradation properties of both binary and ternary blends were comprehensively evaluated. The results show that the incorporation of PA6 significantly enhanced the toughness of PGA while maintaining or even improving its tensile strength, overcoming the limitations of conventional PGA toughening methods. The introduction of a chain extender further enhanced the compatibility between PGA and PA6 phases, leading to further improved mechanical properties. Rheological analysis reveals an increased storage modulus and improved processability. Furthermore, the blends exhibit superior oxygen barrier properties compared with neat PGA and neat PA6, attributed to hydrogen bonding at the interface. These findings provide insights into designing hierarchically structured polymer blends for advanced packaging materials combining gas barrier efficacy, mechanical durability, and sustainable processability.