Migration Kinetics of Ethylene Glycol Monomer from Pet Bottles into Acidic Food Simulant: Effects of Nanoparticle Presence and Matrix Morphology

In this study, migration of ethylene glycol from polyethylene terephthalate (PET) bottles (neat PET and PET nanocomposites) into acidic food simulant is investigated. Nanocomposite pellets were prepared by melt blending of PET and TiO2 nanoparticles. The stretch blow molding machine was used to make the preforms and bottles from neat PET and nanocomposites. DSC analyses showed that the presence of nanoparticles at 3 wt % noticeably affected the crystallization temperature, Tc, and the final degree of crystallinity of PET. The incorporation of nanoparticles in the PET matrix leads to a substantial decrease of water vapor permeability. Nanoparticles also decreased the diffusivity of migrants due to the higher degree of crystallinity. The acetic acid samples were stored at 45C for 15 days. Gas chromatography analysis demonstrated that the migration of ethylene glycol from nanocomposite bottles was less than the neat PET. The polymer-specific parameters (AP values) from mathematical migration models were derived from the experimental data. The diffusion coefficients (DP) based on Piringer's model showed a considerable difference between DP of nanocomposites and neat PET. It was concluded that the migration of monomers from food contact materials considerably depends on the structure of the manufactured packaging plastic.