Melt processing of poly(vinyl alcohol) through adding magnesium chloride hexahydrate and ethylene glycol as a complex plasticizer

The melt processing of poly(vinyl alcohol) (PVA) was achieved using magnesium chloride hexahydrate (MgCl₂·6H₂O) and ethylene glycol as a complex plasticizer. The interaction between the complex plasticizer and PVA was studied by Fourier transform infrared spectroscopy (FT‐IR). The PVA films were characterized using X‐ray diffraction (XRD), differential scanning calorimetry, thermogravimetric analysis (TGA), scanning electron microscope, and dynamic thermomechanical analysis (DMA) techniques. The band shift of the observed peak around 3335 cm^?1 in the FT‐IR spectra indicates that the complex plasticizer MgCl₂·6H₂O and ethylene glycol could form strong interactions with PVA and thus interrupt the intermolecular and intramolecular hydrogen bonding in PVA. The XRD results show that the addition of the complex plasticizer would significantly destroy the crystallites of PVA and result to the decrease of the degree of crystallinity of PVA. The melting point was reduced from 229°C of pure PVA to around 170°C after the plasticization. The TGA studies show that with the complex plasticizer, the thermal stability of PVA is improved. PVA plasticized by 30 wt% MgCl₂·6H₂O and 10 wt% ethylene glycol shows the tensile strength of 33 MPa and the elongation at break of 362%. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers