Changes in Crystallization Behaviors of Poly(Vinyl Alcohol) Induced by Water Content

Abstract Water as the low‐cost, environmentally friendly, easily obtained plasticizer was used widely in the preparation of poly(vinyl alcohol) (PVA) products. However, few researches were done to investigate the effect of water content on the crystallization behaviors of PVA. The water content in various PVA films was controlled by drying in a vacuum oven at different time and was determined by thermogravimetric analysis. The changes in crystallization behaviors of PVA affected by water content were investigated using differential scanning calorimeter, Fourier transform infrared spectra, and X‐ray diffraction. The wafer thickness and nonisothermal crystallization kinetics of various PVA films were also studied. The corresponding results showed that the crystallinity of various PVA films increased and then stabilized as the drying time increased. The distribution of wafer thickness in PVA films became narrow, and their wafer thickness value became small. The decrease of water content in PVA films promoted the crystallization rate, because the movement ability of PVA molecular chains was enhanced by the decrement in hydration hydrogen bonds in various PVA films.