Department of Packaging and Materials Technology, Faculty of Agro-Industry, Kasetsart University, Bangkok 10900, Thailand; Center for Advanced Studies for Agriculture and Food, Kasetsart University Institute for Advanced Studies, Kasetsart University, Bangkok 10900, Thailand.
Department of Packaging and Materials Technology, Faculty of Agro-Industry, Kasetsart University, Bangkok 10900, Thailand; Center for Advanced Studies for Agriculture and Food, Kasetsart University Institute for Advanced Studies, Kasetsart University, Bangkok 10900, Thailand; Center for Advanced Studies in Nanotechnology and Its Applications in Chemical, Food and Agricultural Industries, Kasetsart University, Bangkok 10900, Thailand.
Int J Biol Macromol. 2020 Oct 1;160:506-517. doi: 10.1016/j.ijbiomac.2020.05.178. Epub 2020 May 25.
The objective of this study was to improve the compatibility between poly(lactic acid) (PLA) and thermoplastic starch (TPS) in PLA/TPS blown films by incorporating oligo(lactic acid)-grafted starch (OLA-g-starch) as a compatibilizer. OLA-g-starch with a degree of substitution of 1.2 and degree of polymerization of 2.0 was synthesized via a ring-opening polymerization of lactide initiated by hydroxyl groups of starch. The PLA/TPS blends containing OLA-g-starch were prepared using a twin-screw extruder with a constant weight proportion of PLA to TPS of 50:50 and various concentrations of OLA-g-starch, i.e., 1, 2, 3, and 5%. The obtained blends were blown into thin films using a blown film extruder. SEM confirmed the droplet/matrix morphology of the PLA/TPS blends both with and without OLA-g-starch. Incorporating OLA-g-starch improved the compatibility between the TPS dispersed phase and PLA matrix, as evidenced by the smaller size and better distribution of the TPS phase. As a result, the blends containing OLA-g-starch exhibited up to 280% greater extensibility as well as enhanced water vapor and oxygen barrier properties, water resistance, melt flowability, and thermal stability. The T, T, and T of PLA in the blends shifted to higher temperatures when OLA-g-starch was incorporated. The obtained PLA/TPS blown film containing OLA-g-starch has the potential to be used as flexible packaging.
本研究旨在通过添加寡乳酸接枝淀粉（OLA-g-starch）作为增容剂来改善聚乳酸（PLA）与热塑性淀粉（TPS）在 PLA/TPS 吹塑薄膜中的相容性。OLA-g-starch 的取代度为 1.2，聚合度为 2.0，是通过淀粉上的羟基引发丙交酯开环聚合合成的。将 PLA/TPS 共混物用双螺杆挤出机制备， PLA 与 TPS 的重量比为 50:50，OLA-g-starch 的浓度分别为 1%、2%、3%和 5%。使用吹膜挤出机将所得共混物吹成薄膜。SEM 证实了含有和不含有 OLA-g-starch 的 PLA/TPS 共混物的液滴/基质形态。添加 OLA-g-starch 提高了 TPS 分散相与 PLA 基质之间的相容性，这表现在 TPS 相的尺寸更小且分布更好。因此，含有 OLA-g-starch 的共混物表现出高达 280%的延展性，以及增强的水蒸气和氧气阻隔性能、耐水性、熔体流动性和热稳定性。当添加 OLA-g-starch 时，共混物中 PLA 的 T、T 和 T 向更高的温度移动。含有 OLA-g-starch 的 PLA/TPS 吹塑薄膜具有用作柔性包装的潜力。
