Chemical characterization of virgin and recycled polyethylene terephthalate films used for food contact applications

Plastic is commonly used for food packaging, of which plastic polymer polyethylene terephthalate (PET) is widely used in the food and beverage industry. Furthermore, PET is the most suitable and recyclable plastic polymer used in food contact applications due to its functional properties: inertness and low diffusion of gases and migrants. However, using recycled PET (rPET) for food contact applications requires that the rPET is chemically safe. In this study, we use mass spectrometry and spectroscopy-based methods to characterize the chemical composition of virgin PET (vPET) and rPET. The mass spectrometric analysis demonstrated more peaks in rPET and the spectroscopic analysis revealed degradation of the rPET after the recycling process. The tentatively identified peaks in both vPET and rPET were mainly PET oligomers. The present work suggests the importance of testing PET obtained from one or more recycling processes to evaluate the effect on the polymer properties, chemical migration, and chemical safety of rPET for food contact.