Studies of the plasticizing effect of different hydrophilic inorganic salts on starch/poly (vinyl alcohol) films.

The effects of different inorganic salts LiCl, MgCl2·6H2O, CaCl2, and AlCl3·6H2O on the crystalline, thermal, water vapor barrier, and tensile properties of starch/PVA films were studied. The high plasticizing efficiency of all these four inorganic salts for starch/PVA film was confirmed by the obtained results. These four salts all had a good compatibility with starch/PVA within the content of 15 wt% and starch/PVA became completely miscible with the addition of 15 wt% inorganic salts. All these four salts had a strong destroying effect on the crystals of starch and PVA. Among these four salts, AlCl3·6H2O had the largest negative effect on the thermal stability of starch/PVA and LiCl had the largest improving effect on the water sorption rate of starch/PVA film. On the whole MgCl2·6H2O and CaCl2 were the more suitable plasticizer for starch/PVA film among these four inorganic salts. With the addition of 15 wt% MgCl2·6H2O and CaCl2, the elongation at break of starch/PVA film could reach to 418.83% and 434.80%, respectively.