The Effect of glycerol on the crystalline, thermal, and tensile properties of CaCl ₂ ‐doped starch/ PVA films

Starch/poly(vinyl alcohol) (PVA) films with the addition of 10 wt% CaCl ₂ and various content of glycerol were prepared. The effect of glycerol on the crystalline, thermal, and tensile properties of CaCl ₂ ‐doped starch/PVA films was studied by X‐ray diffraction, thermogravimetric analysis (TGA), and tensile testing, respectively. The effect of glycerol on the miscibility of CaCl ₂ ‐doped starch/PVA films was studied by scanning electron microscopy. The CaCl ₂ ‐doped starch/PVA film became more homogeneous after the addition of glycerol. The addition of glycerol would increase the crystallinity of CaCl ₂ ‐doped starch/PVA film. With the addition of 10 wt% glycerol and 10 wt% CaCl ₂ , the starch/PVA film showed the highest degree of crystallinity. The TGA results show that the thermal stability of CaCl ₂ ‐doped starch/PVA film increased after the addition of glycerol. The toughness of CaCl ₂ ‐doped starch/PVA films was enhanced with the addition of glycerol. The starch/PVA film with the addition of 10 wt% CaCl ₂ and 20 wt% glycerol showed the tensile strength of 17 MPa and the elongation at break of 428%. Moreover, the water sorption of CaCl ₂ ‐doped starch/PVA film decreased after the addition of glycerol at the low and intermediate relative humidity of 33 and 54%. POLYM. COMPOS., 37:3191–3199, 2016. © 2015 Society of Plastics Engineers