Studies on the properties of poly(vinyl alcohol) film plasticized by urea/ethanolamine mixture

Abstract This study investigated the effects of urea/ethanolamine mixture (UE) on the crystallinity, thermal, and mechanical properties of poly(vinyl alcohol) (PVA) films. PVA films were prepared from solutions containing PVA, urea, ethanolamine, and water by casting and evaporating at 50°C for 12 h. The plasticization efficiency of UE was compared with that of glycerol (GL), the conventional plasticizer for PVA. The properties of PVA films plasticized by UE and GL, abbreviated to UE‐plasticized PVA film and GL‐plasticized PVA film, respectively, were investigated by Fourier‐transform infrared spectroscopy, X‐ray diffraction, differential scanning calorimetry, thermogravimetric analysis, and mechanical testing. It was proved that UE could form more stable hydrogen bonding with the hydroxyl group of PVA molecule and was more effective in breaking the hydrogen bonds between the hydroxyl groups. Thus, the crystallinity of UE‐plasticized PVA films was lower than that of GL‐plasticized PVA films. The melting temperatures of UE‐plasticized PVA films were lower than those of GL‐plasticized PVA films. It was found that UE‐plasticized PVA film showed a higher degradation temperature compared with GL‐plasticized PVA film. The degree of swelling of UE‐plasticized PVA film was higher than that of GL‐plasticized PVA film but solubility (S) of UE‐plasticized PVA film was lower in aqueous solution. Furthermore, UE‐plasticized PVA films show lower tensile strength and higher elongation at break (E) than those of GL‐plasticized PVA films. The tensile strength, E, and Young's modulus of PVA film containing 30% UE mixture reached 50.78 MPa, 591.19% and 76.9 MPa, respectively. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012