Abstract: The plasticized poly(vinyl alcohol)(PVA) films were prepared by the casting method using magnesium chloride(MgCl₂) as the plasticizer. The interaction between MgCl₂ and PVA was analysised by Fourier transform infrared(FTIR) spectroscopy. The change of the crystalline and thermal properties of PVA with the content of MgCl₂ were measured by X-ray diffraction measurements(XRD), differential scanning calorimetry and thermogravimetric analysis(TGA) respectively. The mechanical properties were measured as a function of MgCl₂ content. It was found that MgCl₂ could form considerable interaction with PVA and form a complex. The XRD showed that the crystallinity of PVA film decreased with the content of MgCl₂, which would be ascribed to the interaction of MgCl₂ with PVA molecules, causing the destroying of the intra/inter molecular hydrogen bonding between PVA chains. The glass transition temperature of PVA also decreased with the content of MgCl₂. The TGA results show that the thermal stabilities of PVA decreased with the addition of MgCl₂ and the thermal degradation process was changed. The mechanical testing showed that PVA become soft, with lower tensile strength and higher elongation at break after modification.

Key words: Poly(vinyl alcohol), Plasticization, Magnesium chloride, Crystallinity, Thermal stability