Characteristics of starch-based films produced using glycerol and 1-butyl-3-methylimidazolium chloride as combined plasticizers

The structure and property of cassava starch-based films, produced by using 1-butyl-3-methylimidazolium chloride ([BMIM]Cl) and glycerol as combined plasticizers, were investigated. The combined plasticizers exhibited a stronger effect on the disruption of starch granules compared with glycerol as observed by scanning electron microscopy (SEM). When the mass ratio of [BMIM]Cl/glycerol used was 15/15, all the starch granules were disrupted and transferred to a continuous phase. Due to the strong plasticization effect of [BMIM]Cl, the combined plasticizers contributed to a lower water content, crystallinity, and glass-transition temperature, as well as a higher flexibility when compared with glycerol. Additionally, in spite of the slight decrease in the elongation at break, the combined plasticizers contributed to a higher thermal stability, higher tensile strength, and a lower cost relative to [BMIM]Cl alone, showing excellent potential for practical applications. Therefore, using [BMIM]Cl and glycerol as combined plasticizers to plasticize starch film is effective, practical, and economical, and opens up a new perspective for the plasticization of starch.