Tensile, water vapor barrier and antimicrobial properties of PLA/nanoclay composite films

PLA-based composite films with different types of nanoclays, such as Cloisite Na+, Cloisite 30B and Cloisite 20A, were prepared using a solvent casting method and their tensile, water vapor barrier and antimicrobial properties were tested. Tensile strength (TS). elongation at break (E), and water vapor permeability (WVP) of control PLA film were 50.45 +/- 0.75 MPa, 3.0 +/- 0.1 %, and 1.8 x 10(-11) g m/m(2) s Pa, respectively. TS and E of nanocomposite films prepared with 5 g of clay/100 g of PLA decreased 10-20% and 11-17%, respectively, depending on the clays used. On the contrary, WVP of the nanocomposite films decreased 6-33% through nanoclay compounding. Among the clay types used, Cloisite 20A was the most effective in improving the water vapor barrier property while sacrificing tensile properties the least. The effect of clay concentration tested using Cloisite 20A showed a significant decrease in TS and WVP, with increases in clay content. Among the PLA/clay composite films tested, only PLA/Cloisite 30B composite film showed a bacteriostatic function against Listeria monocytogenes. (C) 2008 Swiss Society of Food Science and Technology. Published by Elsevier Ltd. All rights reserved.