Transfer of a low‐molecular‐weight compound between two immiscible polymers

ABSTRACT We investigated plasticizer transfer between poly(ethylene‐co‐vinyl acetate) (EVA) and poly(lactic acid) (PLA) and its temperature dependence using laminated films comprising EVA and PLA, each containing equal amounts of a plasticizer [i.e., diethyl phthalate (DEP) or dibutyl phthalate (DBP)]. Because the miscibility between PLA and DEP is better than that between EVA and DEP, a large amount of DEP was detected in the PLA film after annealing the laminated films at 80 °C; that is, some DEP moved from the EVA film to the PLA film. Furthermore, more DEP migrated to the PLA film at 130 °C, suggesting that the difference in the interaction parameter with DEP between PLA and EVA is more pronounced at higher temperatures. In laminated films containing DBP, the DBP content in each film was almost equal after annealing at 80 °C, although DBP migrated from the PLA film to the EVA film at 130 °C. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47386.