Food packaging requires long shelf life and the monitoring of safety and quality based on international standards. In the past decade, polymer nanocomposites have emerged as a new class of food packaging materials, because they have several advantages, such as enhanced mechanical, thermal, and barrier properties. The larger surface area of nanoparticles compared with their microscale counterparts favours filler-matrix interactions and the performance of the resulting material. A new technology is accepted by the community once it has been tested for its effects on health. There have been some studies on the migration of nanoparticles from packaging material into food/food simulants during storage. It is very important to evaluate the safety of nanocomposite packaging materials used for food products. This review summarizes the characteristics and properties of nanocomposite packaging materials along with their safety problems for food consumers.

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Poly(ethylene terephthalate) (PET)/clay nanocomposite samples were prepared by melt blending PET and Cloisite 20A nanoparticles. A stretch blow‐moulding machine was used to produce bottles from neat PET and PET nanocomposite. Tests were performed on the migration of aluminum and silicon from PET nanocomposite bottles into acidic food simulant. The samples were stored at room temperature (about 25°C) and 45°C for time durations ranging from 7 to 90 days. A specific surface of sheets (prepared from PET/clay nanocomposite) immersed in acidic food simulant, and two‐sided migration of Al and Si was investigated. According to X‐ray diffraction analysis, the nanoclays show intercalated structure in the PET matrix. Transmission electron microscopy and atomic force microscopy micrographs displayed both intercalation and exfoliation morphology for PET/clay nanocomposites. Inductively coupled plasma was used to quantify amounts of Al and Si that had migrated into the acidic food simulant. It was observed that the migration process is dependent on storage time and temperature, and the molar ratio of aluminum and silicon in the acidic aqueous solution (Al/Si)aq to the ratio in the solid phase of prepared nanocomposites (Al/Si)solid was about 23% higher in the samples stored at 45°C. Copyright © 2013 John Wiley & Sons, Ltd.

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Abstract:Two types of polymers were tested in this study; poly(ethylene terephthalate) (PET) as a synthetic example and poly(lactic acid) (PLA) as a natural polymer. DSC analyses showed that the use of nanofiller increased the degree of crystallinity (X c ) of both PET and PLA polymers, but the effect was more noticeable on PET nanocomposites. The crystallization of PLA and PET nanocomposites occurred at higher temperatures in comparison to neat polymers. According to dynamic mechanical-thermal analysis (DMTA), the damping factor of PET/TiO 2 nanoparticles decreased compared to the neat matrix, but for PLA nanocomposites the opposite trend was observed. Results of the mechanical test showed that for both PET and PLA nanocomposites, the most successful toughening effect was observed at 3 wt% loading of TiO 2 nanoparticles. SEM micrographs revealed uniform distribution of TiO 2 nanoparticles at 1 and 3 wt% loading levels. The results of WAXD spectra explained that the polymorphs of PLA and PET was not affected by TiO 2 nanoparticles. UV-visible spectra showed that TiO 2 nanocomposite films had high ultraviolet shielding compared to neat polymer, but there was significant reduction in transparency.

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