Improved thermal stability of polylactic acid (PLA) composite film via PLA-β-cyclodextrin-inclusion complex systems

The effects of the incorporation of PLA-beta-cyclodextrin-inclusion complex (IC) and beta-cyclodextrin (beta-CD) on biopolyester PLA films were investigated. Thermal stability, surface morphology, barrier, and mechanical properties of the films were measured at varying IC (1, 3, 5, and 7%) and beta-CD (1 and 5%) concentrations. The PLA-IC-composite films (IC-PLA-CFs) showed uniform morphological structure, while samples containing beta-CD (beta-CD-PLA-CFs) showed high agglomeration of beta-CD due to poor interfacial interaction between beta-CD and PLA moieties. According to the thermal property analysis, the 5% IC-PLA-CFs showed 6.6 times lower dimensional changes (6.5%) at the temperature range of 20-80 degrees C than that of pure PLA film (43.0%). The increase of IC or beta-CD content in the PLA-composite films shifted the glass transition and crystallization temperature to higher temperature regions. The crystallinity of both composite films improved by increasing IC or beta-CD content. Both composite films had higher oxygen and water vapor permeability as IC or beta-CD content increased in comparison to pure PLA film. All the composite films had less flexibility and lower tensile strength than the pure PLA film. In conclusion, this study shows that the IC technique is valuable to improve the thermal expansion stability of PLA-based films. Published by Elsevier B.V.