Abstract: Rod-like nano-sized zinc oxide (ZnO) was prepared by liquid phase precipitation method with Zn(NO₃)₂•6H₂O,aqueous ammonia and sodium hydroxide solution as raw materials.Influence of synthesis conditions,such as initial ammonia concentration,dropping rate,and heating way,on the morphology and size of ZnO nanoparticles were investigated.Results indicated that the synthesized ZnO nanoparticles were rod-like in morphology and dispersed uniformly with slenderness ratio of 11 when the initial ammonia concentration was 5%（mass fraction）,dropping rate was 60 g/h,and two stage heating way (nucleation growth temperature is 60 ℃ and aging temperature is 80 ℃) was adopted.Nano-sized ZnO had good antibacterial effect to colon bacillus.When 1.5% (mass fraction) rod-like nano-sized ZnO was incorporated into waterborne polyurethane composite,tensile strength was increased from 2.7 MPa to 4.5 MPa.Furthermore,UV absorbance in the wavelength of 250~400 nm was observed. 

Key words: nano-sized zinc oxide, waterborne polyurethane, ultraviolet radiation, antibiosis