Incorporating starch into the poly(butylene adipate-co-terephthalate) (PBAT) polymer by means of blends with high starch contents is a possible option for producing biodegradable packaging using renewable resources and reducing costs. However, the addition of starch increases the water vapour permeability (WVP). The incorporation of substances as lipids and surfactants can reduce the hydrophilicity of films containing starch, favouring their use as packaging. The hydrophilicity of films produced from blends of starch/PBAT with added soybean oil (SO) and tween 80 (TW) was studied. The effects of these substances on the sorption isotherm, on the WVP and on the water vapour diffusion (Dw) and solubility (β) coefficients of the films were evaluated. The water sorption in films with SO, with or without TW, was low. The films with the lowest amount of SO and without TW were the least hydrophilic and less permeable to water vapour. Adding SO reduced the β and Dw values of the starch/PBAT films. This effect was related to the increase in the hydrophobic portions and the compatibility between starch and PBAT in the presence of SO.
Biodegradable polymers; blow extrusion; blends
