Preparation And Characterization Of Nano-Titania/Waterborne Polyurethane Composite Materials

Waterborne polyurethane has become one of the major research and development fields because of its environmental friendliness,the water is used as dispersant instead of organic solvent in waterborne polyurethane. But compare to organic polyurethane, waterborne polyurethane usually suffers from some bad properties, including inferiors heat resistance, mechanical property, and water resistance, Titania is one of the most important inorganic materials in modified WPU due to Titania is one of the most important inorganic materials which have beneficial properties such as high thermal stability, strength, chemical stability, UV absorbance and high refractive index. But due to their extremely large surface-area/particle-size ratio, Titania particles tend to strongly agglomerate to form twice particles, hence reducing the mechanical properties of the nanocomposite materials. Many efforts have been taken to overcome this problem and enhance the dispersity of Titania in organic polymer. To obtained TiO₂ better dispersed in waterborne polyurethane,One mean is the surface of nanoparticles was modified with organic matter,but due to the reaction group of TiO₂ is few, the function of modified TiO₂ is restricted, another mean is breaking down the agglomerated nanoparticles applying mechanical shear forces such as ultrasonic. However, this approach is restricted due to the limited interaction between the inorganic materials and the polymeric matrix, compared with the very strong interaction between individual nanoparticles.Taking these problems, in the paper, we report two experimental programs to conquer the problems. One approach is breaking down the agglomerated nanoparticles applying mechanical shear forces such as ultrasonic while modified the nano-Titania with KH550 to get better interaction between Titania and WPU. In the process of emulsification, Sodium polyacrylate as polymer dispersing agent was addict in the Titania/WPU composites emulusion to get better disperse of Titania in WPU. For illustrate the advantages of KH550 on the Titania,we prepared Titania/WPU without modified with KH550, compare these two composites, and study the effect of KH550 on the disperse on the Titania in WPU. In this paper, we also investigate Titania sols from the hydrolysis and condensation of titanium n-butoxide under acidic condition. And the Titania sols were then addict in the preparing triethoxysilylpropylamine-capped polyurethane to obtain waterborne polyurethane/Titania hybrid emulsion (triethoxysilylpropylamine as the coupling agent to improve their compatibility) after emulsification process, Thus the–OH and–OR at triethoxysilylpropylamine can easily react with–OH and–OR at Titania during preparing hybrid films. The Titania phase and polyurethane phase should have very different interactions from these systems reported previously. And those interactions can influence the combination property of waterborne polyurethane/Titania hybrid films. The FTIR results indicate successful bonding between the organic polyurethane and inorganic Titania. The more Titania, the higher the tensile strength, refractive index, heat resistance, water resistance and UV absorbance of the hybrid films were. The morphological analysis suggested the Titania segment in the prepared hybrid thin films had a nanosized less than 10nm. The compatibility of Titania and WPU is perfect, hence reducing the performance variation caused due to aggregation of nanoparticles.