Effect of Aluminium Nitrate Hydrate on the Crystalline, Thermal and Mechanical Properties of Poly(Vinyl Alcohol) Film

Abstract

The effect of aluminium nitrate hydrate (Al(NO3)3·9H2O) on the crystalline, thermal and mechanical properties of PVA was studied in this paper. The interaction between Al(NO3)3·9H2O and PVA was investigated by Fourier transform infrared (FT-IR) spectroscopy. The influence of Al(NO3)3·9H2O on the crystalline, thermal, and mechanical properties of PVA was studied by X-ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and tensile testing, respectively. The results indicated that Al(NO3)3·9H2O could form interaction with the hydroxyl group on PVA chain. The XRD studies revealed that the crystallites of PVA were destroyed by Al(NO3)3·9H2O. DSC studies showed that Al(NO3)3·9H2O could increase the flexibility of PVA chains and decrease the Tg of PVA. Tensile testing showed that after the addition of Al(NO3)3·9H2O the tensile strength of PVA film decreased and elongation at break increased. All these results show that Al(NO3)3·9H2O has a high plasticizing efficiency for PVA. However, Al(NO3)3·9H2O is a Lewis acid and the acidic property of Al(NO3)3·9H2O would cause the significant decrease of the thermal stability of PVA.