Oxygen Gas and Water Vapor Permeability of Biaxially Stretched Poly(ethylene terephthalate)/Poly(ethylene-co-vinyl alcohol) and Poly(ethylene terephthalate-co-isophthalate)/Poly(ethylene-co-vinyl alcohol) Blend Films

In this study, poly(ethylene terephthalate)(PET)/poly(ethylene-co-vinyl alcohol) (EVOH) and poly(ethylene terephthalate-co-isophthalate) (PETI)/EVOH (95/5 w/w) blends have been prepared with different types of compatibilizers using a co-rotating intermeshing twin screw extruder. Cast films have been stretched simultaneously and biaxially 2 and 3 times their original dimensions. Scanning electron microscopy, differential scanning calorimetry, oxygen gas and water vapor permeability analyzers have been employed for establishing the relationships among biaxial orientation, crystallinity, morphology, and chemistry on oxygen gas and water vapor permeability. The lowest oxygen gas and water vapor permeability values have been obtained when employed hydroxyl-terminated polybutadiene as the compatibilizer.