Water vapor permeability, morphological properties, and optical properties of variably hydrolyzed poly(vinyl alcohol)/linear low-density polyethylene composite films

Poly(vinyl alcohol) (PVA)/ linear low-density polyethylene (LLDPE) composite films were prepared using PVAs of various molecular weights and degrees of hydrolysis. The crystallinity, water permeability, mechanical properties, and optical properties of the composite films were analyzed based on the absorption properties of the different PVAs. The formation of the composite film became increasingly difficult with increase in the molecular weight and the degree of hydrolysis of PVA, because the resulting crystallinity increased the intramolecular hydrogen bonding of the hydroxyl groups on the main chains of PVA. The 4-98/LLDPE composite film absorbed water gradually and continuously for a long time, and its water vapor absorption rate was similar to that of the 4-88/LLDPE film but lower than that of the PVA 205/LLDPE film. The mechanical properties of the 4-98/LLDPE film were slightly better than those of the 4-88/LLDPE film but inferior to those of the PVA 205/LLDPE film.