Effect of dual chemical modification on the properties of biodegradable films from achira starch

The objective of this study was to evaluate the effect of a dual modification (acid hydrolysis and succination) on the structural, mechanical, thermomechanical, and permeability properties of films from achira starch. Micrographs of films revealed a smooth surface and some remnants of starch granules, indicating a partial gelatinization. Tensile strength and percentage of elongation increased in films from double modified starch (10.50 MPa and 42.83%, respectively). The OH groups formed in the amylose and amylopectin chains during the hydrolysis and the alkoxide groups (R-O⁻) generated during the succination resulted in high values of water vapor permeability (3.215 × 10⁻¹⁰ g/s m Pa). The glass transition temperature (T_g) of films from hydrolyzed–succinated starch was decreased due to the reduction of the molecular weight of the polymeric chains and the presence of succinate groups that reduced the molecular interactions of the polymeric chains, increasing the mobility and therefore decreasing the softening temperature.