Determination of the partition and diffusion coefficients of five chemical additives from polyethylene terephthalate material in contact with food simulants

What is it about?

An investigation on the migration of five chemical additives from polyethylene terephthalate (PET) into food simulants was undertaken to determine the partition and diffusion coefficients between PET/food simulants. The migration tests were carried out using three simulants (20%, 50% ethanol and isooctane) in contact with PET samples at different time-temperature conditions, the concentration of additives in polymer matrix and food simulants were analyzed by high-performance liquid chromatography (HPLC). The results confirmed that the partitioning of plastic additives was affected significantly by the temperature and simulants’ properties, the polarity and molecular weight of substances can also have influence. The diffusion coefficients of plastic ad- ditives were spread between 9.8 ×10 -15 and 1.4 × 10 -8 cm 2 s -1 , which deviated from the calculated values by Piringer model and Welle model. The obtained activation energies of five additives were close to or smaller than 100 kJ mol -1 . It indicated that the PET samples in the experiments were influenced (swelling for example) by the food simulant, especially at high temperature. In this situation, the derived diffusion coefficients might be greater than the actual values. The influence of food substance on plastic additives’ partition and diffusion should be pay more attention in future work.

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