Swelling as a promoter of migration of plastic additives in the interaction of fatty food simulants with polylactic acid- and polypropylene-based plastics

The migration of various plastic additives (antioxidants: BHT, Ionox 220, Irgafos 168; UV absorber: Uvinul 3039; plasticizers: TBAC and TOTM) from polypropylene and polylactic acid was investigated in a series of experiments conducted over a period of 13 days. As fatty food simulants, both ethanol 95 v/v% and isooctane were used. Non-Fickian behaviour was observed on multiple occasions. The kinetic curves of both migration concentrations and swelling were evaluated using variography, to determine objectively the starting points of long-lasting plateaus as well as short halts in the increase. A strong correlation between migration and swelling was observed: the kinetic curves showed that migration always followed swelling. Also, more intensive swelling results in the increased migration of the additivies. Consequently, migration testing can be improved by considering the swelling of the plastic.