Material Properties and Molecular Aspects of Highly Acetylated Starch-Based Films

Properties of starch triacetates films from different origins were evaluated. Tensile and barrier properties, glass transition temperatures and moisture uptake were measured, and the molecular structure was characterised. High amylose starches were good film formers, normal potato starch formed decent films and potato amylopectin formed very brittle films even after plasticisation. Barley amylopectin did not form continuous films. Different plasticisers were studied and diacetin was shown to perform better than the standard plastizicer triacetin. All films were water resistant, and the best films gave water vapour barriers in the range as films of polylactic acid, cellulose acetates and gluten. The inherent oxygen barrier of native starches was lost when the starches were highly acetylated. Starch triacetates are commonly dissolved in organic solvents such as chloroform. When testing different approaches to dissolve the triacetates it was found that acetic acid as well as acetylacetone were good solvents without imposing negative effects on material properties.