Preparation of Lignin/ZnO Composite Nanoparticles and Its Application in Waterborne Polyurethane

A series of lignin/zinc oxide (LQAs/ZnO) composites with different lignin content was prepared through a precipitation method using quaternized alkali lignin (LQAs), zinc acetate and sodium hydroxide as raw materials. The results of X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM) and ultraviolet-visible spectroscopy (UV-Vis) demonstrated that the as-prepared LQAs/ZnO composites exhibited a hybrid structure and the microstructure was significantly influenced by the dosage of NaOH. The UV-absorption performance of LQAs/ZnO composites enhanced remarkably compared with pure ZnO. In addition, the optical and mechanical properties of waterborne polyurethane (WPU) films doped with LQAs/ZnO composites were investigated. The tensile strength and the elongation at break of WPU films blended with LQAs/ZnO composites were 81. 5% and 10. 9%, respectively, higher than those of pure WPU films. The tensile strength and the elongation at break of the WPU composite films were maintained above 25 MPa and 360% by a 192 h of UV-aging test. LQAs/ZnO composites could effectively enhance the UV shielding performance and the anti-ultraviolet aging ability of WPU.