Mechanism of improving the mechanical and barrier properties of poly(lactide)/poly(butylene adipate-co-terephthalate) blends

Poly(lactide)/poly(butylene adipate-co-terephthalate) (PLA/PBAT) blends containing different amounts of polyethylene wax (PEW) were fabricated via melt-blending, and the effects of PEW on the interfacial morphological evolution and properties of the PLA/PBAT blends were investigated. Scanning electron microscopy (SEM) micrographs show that the compatibility between PLA and PBAT is obviously improved by addition of low contents of PEW. Differential scanning calorimeter (DSC) results indicate that PEW can simultaneously enhance the crystallization ability of PLA and PBAT. Rheological behavior of the blends indicates that PEW has a significant plasticizing effect and can promote the mobility of polymer chains in the blends. More importantly, it is revealed that PEW can effectively improve the mechanical and barrier properties of the blends. Even with a PEW content of only 1 wt%, the elongation at break and notched impact strength of the blend reach 344.1% and 12.55 kJ/m(2), respectively, which are 54% and 140% higher than the blend without PEW. Meanwhile, the water vapor transmission rate (WVTR) and oxygen transmission rate (OTR) of the films containing 1 wt% PEW are decreased from 87.34 to 67.40 g m(-2)<middle dot>24 h(-1) and from 118.26 to 80.94 cm(3) m(-2)<middle dot>24 h(-1), respectively, which are 22.8% and 31.5% lower than those of the PLA/PBAT film.