Biodegradable packages development from starch based heat sealable films

Heat sealing capacity of native and acetylated corn starch based films was evaluated to develop biodegradable packages, such as bags. Thermo-mechanical properties were analyzed since they condition their handling and applications. Acetylated starch addition reinforced 80% sealing resistance of starch films. Unplasticized heat-sealed films presented adhesive failures while those containing glycerol showed a rupture near the zip. Unplasticized films exhibited a single relaxation (at around 60 °C), detected by DMA and conventional DSC, which was not affected by the acetylated starch content. DMA curves of plasticized films showed two relaxations, one close to −50 °C associated to the glass transition of the plasticizer-rich phase, and other around 60 °C, attributed to the starch-rich phase. This last transition was also observed using MTDSC. Glycerol addition decreased the relaxation temperature of the starch-rich phase being this effect more marked in native starch films, about 28%. A relation between film composition, microstructure, mechanical behavior, and dynamic mechanical thermal analysis was established.