Improved flexibility and water resistance of soy protein thermoplastics containing waterborne polyurethane

Abstract

To develop biodegradable material with high performance, waterborne polyurethane (WPU) was used to modify soy protein isolate (SPI) with improved flexibility and water resistance. The blend films were successfully prepared by casting the aqueous dispersions of SPI and WPU. The effect of WPU content on the structure and properties of the resulting films was investigated by scanning electron microscopy, light transmittance, dynamic mechanical thermal analysis, tensile tests and water sensitivity measurements. The blend films exhibited fine compatibility, as a result of the strong hydrogen bonding interactions between SPI and WPU. The flexibility and water resistance of the soy protein based films were improved significantly. Moreover, the incorporation of WPU enhanced the mechanical properties of the blend films in water, leading to the applications under wet conditions. The SPI/WPU blend films exhibited much lower cytotoxicity than WPU. This is a simple pathway for preparation of biodegradable films, which have a potential application as biomedical materials.