Résumé
The identification of contaminants on postconsumer food packaging is crucial for developing/adapting decontamination technology of closed-loop mechanical recycling. So far, almost all contamination studies were conducted on PET bottles, with results extrapolated to other polymers. This work investigates the sorption mechanisms of three contaminants (Benzophenone, Ferulic acid and Irganox 1076), with different molecular weights and polarity, on the biodegradable polymer PHBV. Characterization of their respective partition coefficient (K-P/L) and diffusion coefficient (D), under realistic conditions of use (contact with food simulants), allowed the modeling of their concentration profile in the thickness of the material. The results show a sorption in the core of PHBV of these three molecules, reached after a few hours/days. On the contrary, the same model applied to PET reveal a very slow sorption (several years), and only at the surface of the material. This study highlights the impact of polymer structure (chain mobility, polarity horizontal ellipsis ) on contaminant sorption. The behavior of each polymer towards contaminants is directly related to its structure under given conditions of use, and it is a mistake to continue to address the decontamination processes of all polymers, based on the nature and level of contamination of PET.