Crystallization behavior and water vapor permeability of poly(lactic acid) nanocomposite under oscillatory shear

ABSTRACT The crystallization behavior and water vapor permeability of a poly(lactic acid) (PLA) nanocomposite containing 5 wt % organic montmorillonite (OMMT) under oscillatory shear were investigated. Under the oscillatory shear, OMMT platelets exhibited a better intercalated structure and oriented along the flow direction, some of the OMMT platelets are exfoliated and dispersed in the form of single or few‐layer platelets. These well‐dispersed OMMT platelets acted as more effective nucleating and accelerating agent for the crystallization of PLA, as a result, the cold crystallization enthalpy was significantly decreased, the cold crystallization temperature was much closer to the melting temperature and the crystallinity is dramatically increased, which are observed for the first time. Moreover, the water vapor permeability is decreased by 36% due to the barrier effect of the well‐dispersed OMMT and the increased crystallinity of PLA, which increase the tortuous path that water molecules required to permeate. The mechanical properties are also enhanced owing to the well‐dispersed OMMT and increased crystallinity. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42321.