Ewender Johann, Auras Rafael, Sonchaeng Uruchaya, Welle Frank
Fraunhofer Institute for Process Engineering and Packaging (IVV), 85354 Freising, Germany.
School of Packaging, Michigan State University, East Lansing, MI 48824, USA.
Molecules. 2025 May 6;30(9):2064. doi: 10.3390/molecules30092064.
Poly(lactic acid) (PLA) is one of the most important bio-based and industrial compostable materials in food packaging. Its barrier properties towards oxygen and moisture are well documented. However, data on barrier properties of PLA towards organic molecules are scarce in the literature. This study investigated the diffusion of various organic molecules, including -alkanes, 1-alcohols, 2-ketones, ethers, esters, amines, and aromatics, in two commercial PLA films with thicknesses of 20 µm and 30 µm. The diffusion coefficient () values were determined from lag time in permeation tests conducted at temperatures ranging from 20 °C to 90 °C. The films were also characterized in terms of crystallinity, rigid and mobile amorphous fractions, and molecular weight. Activation energies () were calculated based on the temperature dependence of the using the Arrhenius approach. In total, 290 values for 55 individual substances were determined, and 38 values were derived from these data. The correlated well with the molecular volume of the investigated substances. Moreover, the pre-exponential factor showed a correlation with . These correlations enabled the establishment of diffusion modeling parameters for PLA, allowing the prediction of for untested substances. The diffusion behavior of PLA was further compared with the literature data for polyethylene terephthalate and polyethylene naphthalate, providing insights into the relative performance of these materials.
聚乳酸（PLA）是食品包装中最重要的生物基且可工业堆肥的材料之一。其对氧气和水分的阻隔性能已有充分记载。然而，关于PLA对有机分子阻隔性能的数据在文献中却很稀少。本研究调查了包括正构烷烃、一元醇、二元酮、醚、酯、胺和芳烃在内的各种有机分子在两种厚度分别为20微米和30微米的商业PLA薄膜中的扩散情况。扩散系数（）值是根据在20℃至90℃温度范围内进行的渗透试验中的滞后时间确定的。这些薄膜还通过结晶度、刚性和可移动非晶部分以及分子量进行了表征。基于扩散系数（）对温度的依赖性，采用阿伦尼乌斯方法计算了活化能（）。总共测定了55种单独物质的290个扩散系数（）值，并从这些数据中得出了38个活化能（）值。扩散系数（）与所研究物质的分子体积相关性良好。此外，指前因子与活化能（）也呈现出相关性。这些相关性使得能够建立PLA的扩散建模参数，从而可以预测未测试物质的扩散系数（）。还将PLA的扩散行为与聚对苯二甲酸乙二酯和聚萘二甲酸乙二酯的文献数据进行了比较，从而深入了解这些材料的相对性能。
