Addition of α-Tocopherol on Poly(lactic acid): Thermal, Mechanical, and Sorption Properties

This work investigates the effect of the addition of a well-known antioxidant, alpha-tocopherol in poly (lactic acid) flexural and barrier properties. For that purpose, films of poly(lactic acid) enriched with 0, 2.2, and 4.4% of alpha-tocopherol were prepared. Differential scanning calorimetry, thermogravimetric analysis, and dynamic mechanical analysis were used to characterize the changes in the mechanical and thermal properties. The sorption of oxygen and carbon dioxide in the prepared enriched films of poly(lactic acid) was measured at different temperatures between 283 and 313 K and pressures up to atmospheric pressure using a Quartz Crystal Microbalance. Although no significant changes were found in the mechanical and thermal properties, the addition of alpha-tocopherol promotes an increasing in the oxygen sorption and the convex shape of the isotherms indicate a strong interaction gas-polymer. Regarding the sorption of carbon dioxide, no pronounced effect was found. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 119: 2468-2475, 2011