Caprolactam is the monomer typically used for the production of polyamide 6 films. Originating from incomplete polymerization reactions, caprolactam can remain part of the final food packaging and has the potential to migrate from the plastic packaging into the packed good. For film and food producers as well as for end users, it is of great interest that the conformity of a film with migration limits is ensured over its lifetime and that environmental conditions do not affect the migration behavior inadequately. In this work, we have investigated the long‐term storage characteristics of a polyamide/polyethylene (PA/PE) film over a storage period of 40.5 months with respect to the specific migration rate of caprolactam. Within statistical indicators, this rate is stable over the complete storage period. Different exposure conditions were applied to the same PA/PE film to accelerate the aging process. Alterations under forced aging conditions (elevated temperature and ultraviolet radiation) were studied by Fourier transform infrared (FTIR) spectroscopy to detect possible chemical changes in the polymer bulk and, by the use of the attenuated total reflection method, on the sample surface. The film was subjected to an extraction study to verify the results obtained using FTIR. Additionally, mechanical tensile tests were carried out. Indication for alterations regarding caprolactam under the different storage conditions were found. The results clearly show that photo‐oxidative conditions led to changes in the chemical and mechanical properties of the film. New chemical species occurred caused by degradation of the polymers and their contribution to chemical migration is discussed.

中文翻译：

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在使用前长期储存的条件下，食品包装用聚酰胺/聚乙烯复合薄膜的己内酰胺比迁移和红外特性

己内酰胺是通常用于生产聚酰胺6薄膜的单体。由于不完全的聚合反应，己内酰胺可以保留在最终食品包装中，并有可能从塑料包装迁移到包装食品中。对于电影和食品生产商以及最终用户，人们非常感兴趣的是确保电影在整个使用期限内都具有迁移极限，并且环境条件不会对迁移行为产生不适当的影响。在这项工作中，我们研究了相对于己内酰胺的特定迁移率，聚酰胺/聚乙烯（PA / PE）膜在40.5个月的存储期内的长期存储特性。在统计指标范围内，该速率在整个存储期间都是稳定的。将不同的曝光条件应用于同一PA / PE膜以加速老化过程。通过傅立叶变换红外（FTIR）光谱研究了在强制老化条件下（高温和紫外线辐射）的变化，以检测聚合物本体中可能的化学变化，并通过使用衰减全反射法检测样品表面上的化学变化。对该膜进行提取研究以验证使用FTIR获得的结果。另外，进行了机械拉伸试验。发现了在不同储存条件下己内酰胺发生变化的迹象。结果清楚地表明，光氧化条件导致薄膜的化学和机械性能发生变化。