Oxygen-barrier properties of poly(lactic acid)/poly(vinyl acetate-co-vinyl alcohol) blends as biodegradable films

The oxygen-barrier properties of poly(lactic acid) (PLA)/poly(vinyl acetate-co-vinyl alcohol) [P(VAc-co-VA)] were investigated. P(VAc-co-VA)s with vinyl alcohol (VA) contents of 5, 10, and 15 mol % were prepared with the acid-catalyzed hydrolysis of poly(vinyl acetate). The obtained copolymers with various contents of VA were blended with PLA at 5/95, 10/90, and 15/85 compositions. Films of the blends were prepared by a solution-casting method with chloroform as the cosolvent. Although the blend with 5% VA in the copolymer appeared to be miscible, the blends with 10 and 15% VA content in the copolymer were immiscible, as verified by dynamic mechanical analysis. The oxygen-barrier properties of the PLA films were enhanced when they were blended with P(VAc-co-VA). There was a reduction of about 40% in permeability with the addition of only 5% P(VAc-co-VA). The reduction in the permeability was more noticeable at higher VA contents. Also, the incorporation of P(VAc-co-VA) into PLA improved the elongation at break of the films significantly. (C) 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012