Study on the preferential distribution of acetyl tributyl citrate in poly(lactic) acid-poly(butylene adipate-co-terephthalate) blends

In this work, the preferential distribution of acetyl tributyl citrate plasticiser (ATBC) in poly(lactic acid) (PLA)-poly(butylene adipate-co-terephthalate) PBAT blends has been investigated. Pure plasticised PLA and PBAT blends and their binary blends (PLA/PBAT with 80 wt% of PLA and 20 wt% of PBAT and PBAT/PLA with 80 wt% of PBAT and 20 wt% of PLA) containing different ATBC amount (from 5 to 20 wt%) have been investigated. Dynamic mechanical thermal analysis (DMTA) has been performed in order to evaluate the shift of the glass transition temperature (Tg) in both the polymer systems. The results obtained showed a larger shift for PLA than the PBAT and the calculated plasticiser partition coefficient for both binary blends revealed a preferential distribution of ATBC in the PLA phase rather than PBAT (KA/B = 1.07 for PLA-based system and KA/B = 1.45 for PBAT-based system). The results obtained have also been confirmed by the Hansen Solubility Parameters (HSPs) methodology. The study is finally augmented by the differential scanning calorimetry (DSC) and morphology analysis in order to demonstrate the possible effects of crystallinity on the plasticiser distribution in the binary blends.