Cassava starch films containing acetylated starch nanoparticles as reinforcement: Physical and mechanical characterization

• Nanoparticles (NPAac) were obtained by nanoprecipitation from acetylated starch.
• Nanoprecipitation process increases thermal stability of acetylated starch.
• NPAac were essentially amorphous when compared with acetylated starch.
• Films with low amounts of NPAac showed improved mechanical, thermal and barrier properties.
• Films containing NPAac have potential use as active packing.

This paper reports the use of acetylated starch nanoparticles (NPAac) as reinforcement in thermoplastic starch films. NPAac with an average size of approximately 500 nm were obtained by nanoprecipitation. Fourier transform infrared (FTIR) and thermogravimetric analysis (TGA) indicated that NPAac are more thermally stable and essentially amorphous when compared with acetylated starch. Thermoplastic starch films with different proportions of NPAac (0.5, 1.0, 1.5, 10.0%, w/w) were obtained and characterized by scanning electron microscopy (SEM), water vapor permeability (WVP), adsorption isotherms, TGA and mechanical tests. The inclusion of reinforcement caused changes in film properties: WVP was lowered by 41% for film with 1.5% (w/w) of NPAac and moisture adsorption by 33% for film with 10% (w/w) of NPAac; and the Young's modulus and thermal stability were increased by 162% and 15%, respectively, for film with 0.5% (w/w) of NPAac compared to the starch film without the addition of NPAac.