Characterization and Properties of High Amylose Mung Bean Starch Biodegradable Films Cross-linked with Malic Acid or Succinic Acid

Because of weak mechanical and highly hydrophilic properties of starch, various applications for starch have been limited. In this study, mung bean starch (MBS), one type of high amylose starch, was chosen for its potential film forming biopolymers. MBS films were prepared and modified by different types and contents of natural di-carboxylic acids, i.e. malic acid (MA) and succinic acid (SA) with different acidity and chemical structures. It was found from FTIR spectra that the extra peak position of 1700cm(-1) were observed, the evidence of ester group formation for MA- or SA- modified MBS films. The incorporation of MA or SA into MBS film also caused the decrease in degree of crystallinity, as confirmed by XRD technique. Additionally, the maximum strain at maximum load was highly improved with the addition of 30% MA or SA. Moreover, swelling power and water vapor permeability (WVP) of MBS film modified by SA were lower than those by MA. Morphology, biodegradability and thermal property of different acid-modified MBS films were also investigated.