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.