Enhanced mechanical, thermal, and barrier properties of poly(lactic acid)/starch composite films using gelatinized starch acetate-functionalized montmorillonite

A nanostructured starch acetate-montmorillonite (SA-Mt) hybrid, where gelatinized SA was attached on the exfoliated Mt through Mt hydration expansion, ion exchange between Mt and quaternary ammonium salt, and SA intercalation, was designed and further used for reinforcing poly(lactic acid)/starch acetate (PLA/SA) composite films. Making use of the synergistic effect of SA and Mt, considerable enhancement in mechanical, thermal, and barrier properties for PLA/SA composite films was achieved. The effect of SA-Mt hybrids on structure-property relationships of PLA/SA composite films was investigated. Under an optimal loading of 7 wt% SA-Mt (SA:Mt = 1:1, w/w), the tensile strength, Young's modulus and elongation at break of SA-Mt-filled composite films were significantly enhanced, about 104%, 73%, and 98% higher than those of PLA/SA, respectively, revealing the synergistic strengthening/toughening effect of SA and Mt; the thermal decomposition temperature and degradation activation energy of such composite film were also enhanced, implying their superior thermal stability. Moreover, the obtained PLA-based composite films with good water/oxygen barrier performance and excellent biodegradability provide a potential for use as packaging materials.

Automated summary

By designing a nanostructured starch acetate-montmorillonite hybrid, remarkable enhancements in mechanical, thermal, and barrier properties of poly(lactic acid)/starch acetate composite films were achieved. The synergistic effect of starch acetate and montmorillonite contributed to the improved performance. The resulting PLA-based composite films showed good water/oxygen barrier performance and excellent biodegradability, making them potential packaging materials.