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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 …