Cold plasma treatment to improve the adhesion of cassava starch films onto PCL and PLA surface

Since starch hydrophilicity makes it difficult to be used as packaging material, its combination with synthetic biodegradable polymers is an alternative of interest. In this work, atmospheric air cold plasma was used as an adhesion improver between polycaprolactone (PCL) or poly(lactic acid) (PLA) and starch layers, in order to produce multilayer films. For this, a barrier dielectric discharge plasma reactor was used, at ambient temperature and atmospheric pressure. The treatment of PCL and PLA films resulted in increase of the surface roughness and decrease of the water contact angle. Multilayer films (PCL-, PLA-starch) were produced after plasma treatment. Adhesion of starch films onto both PCL and PLA surfaces was improved with plasma treatment, and the delamination resistance increased with treatment time. The best adhesion was obtained for PLA-starch film with 10 min of plasma treatment, resulting in no delamination. The water vapor barrier of the multilayer films was significantly higher than of starch films, while the mechanical properties were similar to those found for PCL/PLA films, showing that these multilayer films are promising for package applications.