Preparation And Properties Study Of Functional Waterborne Polyurethane/CacO₃@TiO₂Composites

Waterborne polyurethane (WPU) is a kind of important polymer materials, which is of nontoxicity and non-pollution for the substitution of traditional organic solvents. For WPU systems, only water was evaporated during the drying process, thus rendering these systems more safety with regard to the environment. The development history of WPU industry is not long, but recently it developed quickly with the increase of environment protection awareness. Waterborne polyurethane (WPU) also shows many excellent features compared to conventional organic solvent-borne polyurethane with the advantages of non-pollution, good mechanical properties, easily processed, non-combustible, non-toxicity and can be used in various fields, such as paints, leather, agriculture, spinning, building, coating, paper, and so forth.However, the thermal stability, insolubility, water resistance, and weatherability of the WPU are still lower than those of the organic solvent borne PU and essential to be improved, so lots of research work has been focused on the modification of WPU. Several attempts have been made to enhance the performance of the WPU including epoxy resion blocking, acrylic grafting, silicone blocking and nanocomposites modification.Inorganic nanomaterials compouding can be used as effective additives to modulate the properties of WPU, such as nano-CaCO3, nano-TiO2, nano-ZnO、 nano-SiO2and carbon nanotubes(CNT), and the results had showed ignificant improvement of the performances of the nanocomposite materials on the mechanical properties, thermal stability,water resistance. The modification results of the fillers is different.In this study, the following aspects are included:(1) CaCO3@TiO2particles were prepared by the method of direct carbonization. The morphology of CaCO3@TiO2composites with various TiO2contents were studied by SEM tests. CaCO3@TiO2were surface-treated by stearic acid(SA), and the contact angel tests suggested that the surface of CaCO3@TiO2have been charged to hydrophobic.(2) WPU/CaCO3composites films and WPU/TiO2composites films were obtained by the method of in-situ polymerization. And the properties of composites were studied by a series of characterization methods, the results indicated that the properties of WPU composites films are different as to the fillers type, for example,the mechanical properties, thermal stability and water resistance of resulting WPU/CaCO3composites were improved by the addition of nano-CaCO3.While, the UV-visible absorption intensity, thermal stability and water resistance of resulting WPU/TiO2composites were improved by the addition of nano-TiO2.(3) CaCO3@TiO2particles were modified by SA, and the composites of WPU/CaCO3@TiO2were obtained by the method of in-situ polymerization. The test results showed that the mechanical properties and UV-visible absorption intensity WPU/CaCO3@TiO2were both improved by the addition of CaCO3@TiO2. Therefore the CaCO3@TiO2particles exbihited more advantages than single nanoparticles in the waterborne polyurethane modification.