Schiessl Stefan, Kucukpinar Esra, Cros Stéphane, Miesbauer Oliver, Langowski Horst-Christian, Eisner Peter
TUM School of Life Sciences, Technical University of Munich, Freising, Germany.
Fraunhofer Gesellschaft FhG, Fraunhofer Institute for Process Engineering and Packaging IVV, Freising, Germany.
Front Nutr. 2022 Mar 7;9:790157. doi: 10.3389/fnut.2022.790157. eCollection 2022.
Materials with high barrier properties against oxygen are required for the packaging of many sensitive foods. Since commodity polymers lack these properties, additional barrier materials are used in plastic-based barrier packaging. These are usually more expensive than commodity polymers and, in higher fractions, also make recycling more difficult. Current developments, therefore, aim at barrier layers that are as thin as possible but retain the barrier properties. One approach is to incorporate nanoparticles into these layers. In this study, the barrier properties of nanocomposite coatings, consisting of unmodified polyvinyl alcohol (PVA), and dispersed stick-shaped halloysite (Hal) or platelet-shaped montmorillonite (MMT) silicate nanoparticles, were investigated. The PVA was dissolved in aqueous nanoparticle dispersions, which were prepared by mechanical shearing, to produce the so-called "nanolacquer." Nanolacquers with nanoparticle concentrations of 7, 30, and 47 vol% with respect to PVA were applied in a single process step with -bar on a polypropylene substrate film. The integration of 30 vol% platelet-shaped MMT enhances the barrier performance in comparison to pure PVA by a factor of 12 and 17 for oxygen and helium, respectively. Scanning electron microscopy (SEM) shows a homogeneous distribution and a parallel alignment of the nanoparticles within the coated layer. An increase in the crystallinity of PVA was observed due to the nanoparticle integration as demonstrated by -ray diffraction (XRD) measurements. The investigation by Fourier transform infrared (FTIR) spectroscopy and the activation energy of the permeation coefficient indicate an interaction between the nanoparticles and the PVA. The theoretically calculated values for barrier enhancement accord well with the experimental values, which emphasizes that the gas barrier improvement for oxygen and helium is mainly dominated by the tortuous path effect.
许多易腐食品的包装需要具有高氧气阻隔性能的材料。由于通用聚合物缺乏这些性能，因此在基于塑料的阻隔包装中会使用额外的阻隔材料。这些材料通常比通用聚合物更昂贵，而且用量较大时也会使回收更加困难。因此，当前的发展目标是制备尽可能薄但仍保留阻隔性能的阻隔层。一种方法是将纳米颗粒掺入这些层中。在本研究中，对由未改性聚乙烯醇（PVA）以及分散的棒状埃洛石（Hal）或片状蒙脱石（MMT）硅酸盐纳米颗粒组成的纳米复合涂层的阻隔性能进行了研究。将PVA溶解在通过机械剪切制备的纳米颗粒水性分散体中，以制备所谓的“纳米漆”。相对于PVA，纳米颗粒浓度分别为7、30和47 vol%的纳米漆通过单次涂布工艺以-bar涂覆在聚丙烯基材薄膜上。与纯PVA相比，掺入30 vol%的片状MMT可使氧气和氦气的阻隔性能分别提高12倍和17倍。扫描电子显微镜（SEM）显示纳米颗粒在涂层内均匀分布且平行排列。如X射线衍射（XRD）测量所示，由于纳米颗粒的掺入，观察到PVA的结晶度增加。傅里叶变换红外（FTIR）光谱研究和渗透系数的活化能表明纳米颗粒与PVA之间存在相互作用。阻隔增强的理论计算值与实验值吻合良好，这强调了氧气和氦气的气体阻隔性能改善主要由曲折路径效应主导。
