Structure and Properties of Starch/Poly (vinyl alcohol) Film Modificated by Different Inorganic Salts.

In this paper, the regularity of different inorganic salts on the structure and properties of starch/ poly (vinyl alcohol) (PVA) film was studied. The effects of inorganic salts on the structure and properties of starch/PVA film were investigated by scanning election microscope, Fourier transform infrared spectroscopy, X‐ray diffraction, water content test, differential scanning calorimeter, thermogravimetric analysis and tensile test, respectively. The results showed that the plasticizing effect of inorganic salts on starch/PVA composite film was related to the valence and radius of ions. Compared with Li+ and Al3+, the incorporation of Mg2+ significantly improved the compatibility of starch/PVA composite films. Meanwhile, the ability of above three metal chloride salts to destroy the crystal structure of the starch/PVA composite film was essentially the same. When the cation was the same, the effect of inorganic salt containing Cl− on the compatibility of starch/PVA composite film and the destruction of the crystalline structure of starch/PVA composite film were greater than that of NO3−. Among all prepared samples, the magnesium chloride modified starch/PVA composite film has the highest elongation at break and the best flexibility. The modification rule of different inorganic salts on PVA/starch was revealed. The ability of inorganic salts to destroy the crystalline structure of starch/PVA films is related to the valence and ionic radius of anion and cation of inorganic salts. The more the ionic charge of the inorganic salt, the smaller the ionic radius, the easier it is to enter into the starch and PVA molecules, which can destroy the crystal structure of the starch and the PVA molecular chains. [ABSTRACT FROM AUTHOR]