Development and characterization of starch films prepared by extrusion blowing: The synergistic plasticizing effect of water and glycerol

Herein, we have investigated the synergistic plasticizing effect of water (W) and glycerol (G) on the physicochemical and structural properties of starch-based films prepared by extrusion blowing. Fourier transform infrared spectroscopy (FT-IR) revealed that glycerol could act as a typical plasticizer in the presence of sufficient amounts of water (approximately 15%). All the films exhibited a B +V-type crystalline structure by X-ray diffraction (XRD). We hypothesize that there were two stages for the effect of plasticizer on the mechanical properties of the composite film. The crystallinity, thermal stability, and water vapor permeability (WVP) of the film initially decreased and then increased with increasing water content from 0 to 20%. The opposite trends were observed for surface smoothness and surface hydrophobicity. Moreover, the addition of 15% G-15% W coplasticizers was optimal for film blowing, which can substantially reduce the cost of producing starch-based films.