Effect of average functionality on properties of UV-curable waterborne polyurethane-acrylate

A series of ultraviolet (UV) curable waterborne polyurethane-acrylate (WPUA) with different average functionalities were synthesized in new methods. The chemical structures of WPUA were confirmed by Fourier-transform infrared spectroscopy (FT-IR) and the effect of average functionality on properties of WPUA was systemically investigated. It was found that the average functionality had a positive effect on the water resistance and tensile strength of WPUA, to make optimal formation of WPUA molecule chains available, whereas the increasing of average functionality decreased the viscosity and extension of WPUA samples. Besides, through the investigation on the UV curing kinetics, it was found that the average functionality too high or too low was unfavorable for the increase of unsaturation conversion. The morphology and microstructure of WPUA films were also comprehensively discussed with WAXD patterns and fractured surface observed from SEM images.