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, T-c, 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 (A(P) values) from mathematical migration models were derived from the experimental data. The diffusion coefficients (D-P) based on Piringer's model showed a considerable difference between D-P 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. Practical ApplicationsPolyethylene terephthalate (PET) nanocomposite pellets containing 3% wt TiO2 nanoparticles were prepared by melt blending and PET bottles were made by injection stretch blow molding. The results showed that incorporation of TiO2 nano-fillers in PET matrix considerably increased crystallinity and rigidity of PET packaging material and decreased the amorphous region in the polymer matrix. TiO2 nanoparticles with uniform distribution in the polymer matrix created a tortuous path, leading to reduce in monomer migration from packaging material into food simulant. Mathematical model used in this study was a practical tool for better understanding of migration process. Improved barrier properties and lower monomer migration from PET bottles into food could increase the application of PET nanocomposites in food packaging.