Impact of incorporating chitosan into starch films: analysis of physicochemical properties and degradability in soil

The aim was to evaluate the effect of incorporating chitosan in films in relation to their characteristics and degradability. The films were developed by the casting method obtaining ten assays (E1 to E10). Films E1 and E3 showed excellent visual characteristics. Opacity was between 3.92 and 6.42 1/mm, while transmittance ranged from 18 to 31 %. The E4 film was thicker, proving to be more resistant and less soluble, around 45 %. Regarding water absorption, all films showed the same absorption behavior in the first 72 h. After 144 h, the E6 film absorbed more water, for relative humidity (RH) of 75 and 85 %, respectively. In the case of the barrier property, the films presented water vapor permeability (WVP) between 0.30 and 1.47 g mm/m² h kPa. Regarding biodegradability, after 7 days, all films had absorbed water, becoming malleable and flexible. Then, after 35 days, the films showed high mass loss, where E2 had the lowest mass loss (27 %) and E6 the highest (40 %). After 67 days, the films were degraded. Based on the above, it was concluded that chitosan improved the homogeneity, continuity, and handling of the E1 film, providing low solubility and permeability to water vapor, and being biodegradable.