The effect of surfactant Tween 80 on the hydrophilicity, water vapor permeation, and the mechanical properties of cassava starch and poly(butylene adipate-co-terephthalate) (PBAT) blend films

In this work, the affinity of water to cassava thermoplastic starch (TPS) and PBAT blend films with the addition of surfactant Tween 80 was investigated. The TPS and PBAT blend films were produced by extrusion with different starch concentrations added with 2% surfactant Tween 80, without surfactant Tween 80 or with 100% starch films (F100) as controls. The sorption isotherms, water vapor permeability (WVP), solubility coefficients, and diffusion coefficients of the films were evaluated. F100 films demonstrated the highest WVP and solubility coefficient values. Addition of the surfactant increased the diffusion coefficient and WVP. Films with the addition of surfactants had lower structural integrity and mechanical resistance than control films. The results indicated that the surfactant increased the free volume between the starch chains, thus, favoring the diffusion of water vapor. The combined effects of solubility coefficients and diffusion coefficients controlled the WVP of the films.