Effect of crystallinity on the migration of plastic additives from polylactic acid-based food contact plastics

The dependence of swelling and migration on polymer crystallinity was investigated in the case of polylactic acid (PLA)-based plastics. Migration and swelling kinetic experiments were performed at two different temperatures, using plasticized/non-plasticized and annealed/unannealed PLA test specimens. Both swelling and migration proved to be inhibited by the presence of polymer crystals. Crystallization induced clear differences in migration at 40 °C contact temperature, which got more pronounced with the increasing molecular weight (Mw) of additives. At 60 °C the differences diminished, except for Irgafos 168, possibly because of the formation of an inclusion complex type structure. Consequently, to lessen migration, the application of crystallized PLA and high Mw additives in food packaging industry is advantageous. The solvent-induced crystallization of PLA in ethanol 95 v/v% was also confirmed, therefore this alternative food simulant should be used with restrictions in the migration testing of PLA-based plastics. •Crystallized structure inhibits both swelling and migration.•At 40 °C, crystallinity has notable effect on the extent of swelling and migration.•At 60 °C, the rate of swelling and migration decreased due to crystallization.•Solvent-induced crystallization of PLA in ethanol 95 v/v% food simulant was proved.•Migration from PLA-based plastics can be reduced by post-production annealing.