The plasticizing effect of calcium nitrate on poly(vinyl alcohol)



Calcium nitrate (Ca(NO3)2) was used as the plasticizer to improve the properties of Poly(vinyl alcohol) (PVA). The interaction between Ca(NO3)2 and PVA was investigated by Fourier transform infrared (FTIR) spectroscopy. The influence of Ca(NO3)2 on the crystalline, thermal, and mechanical properties of PVA was studied by X-Ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), and tensile testing, respectively. FTIR studies showed that Ca(NO3)2 could strongly interact with PVA molecule and reduce the intensity of the hydrogen bonding between PVA molecules. The crystallization of PVA was interrupted and the degree of crystallinity of PVA decreased due to the strong interaction between Ca(NO3)2 and PVA. DSC studies showed that the glass transition temperature of PVA decreased with the addition of Ca(NO3)2. However, the thermal stability of PVA decreased with the addition of Ca(NO3)2. The mechanical properties of PVA was improved with the addition of Ca(NO3)2, PVA film became soft and ductile, with lower tensile strength and higher elongation at break compared with original PVA. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers