| This experiment used isophorone diisocyanate (IPDI), different molecular weight poly(butylene adipate) (PBA), dimethylol propionic acid (DMPA) as raw material, water as dispersing agent, preparing waterborne polyurethane with different ratio of hard segment and then studying on them. The waterborne polyurethane which is suitable for soft and hard segment is selected as the blank contrast group,on this basis,adding different percentages of nano hydroxyapatite, nano montmorillonite and nano titanium dioxide modified by KH550, in order to prepare the functional WPU composite emulsion with excellent performance and dry them into films. Finally, the testing methods of infrared spectroscopy,XRD, DSC, TGA, AFM, mechanical tensile and particle size analysis were carried out.The ratio of soft and hard segments has a great influence on the performance of waterborne polyurethane. Characteristic absorption peak appeared in 3362cm-1, 1734cm-1 and 1558cm-1, and the absorption peak of 2280cm-1 disappeared, the waterborne polyurethane was successfully synthesized. In the hard segment content is 40%, the surface of the composite films is smooth, no wrinkles, and the tensile strength is 11.51MPa, the elongation at break is 851.26%, and the glass transition temperature is better, at the same time, the contact angle is 81.77 degrees, and the hydrophobicity is better, however, the average particle size of the emulsion is only 235.3nm,therefore this film is better in comprehensive performance.After adding HA into the system, the infrared spectrum appeared the characteristic peak of HA at 1035 cm-1 and 566 cm-1, HA was successfully combined with WPU. HA is an amorphous structure in the waterborne polyurethane matrix. When the addition amount of HA is 1%, the surface of the material is relatively smooth and uniform, the tensile strength is 18.64MPa and the elongation at break is 845.87%. For heat resistance, the initial decomposition temperature is slightly improved,and the final decomposition temperature is also better than that of the non-modified. And the water contact angle is 79.34 degrees, the hydrophobic effect is better. When the addition content of HA is 1%, the system performance is better.After modified by KH550 and KH570, the characteristic absorption peaks of silane coupling agent were found in the infrared spectra. However, after modified by KH550, the heat resistance and the layer spacing are better than that modified by KH570, so the former is used. In the OMMT/WPU composite films, the infrared absorption peak at 1039cm-1 and 466cm-1 is the absorption peak of MMT, successfully combined.The thermal stability increased with the addition of OMMT and the amorphous structure also increased. However,the addition of OMMT leads to the decrease of the mechanical properties and the hydrophobic property in the system. In addition, when the OMMT content is 0.2% and 0.4%, the average particle size is only 91.2nm and 169.8nm, the stability of emulsion is excellent.After TiO2 modified by KH550, the absorption peak of silane coupling agent appeared in the infrared spectrum, successful inserted; at the same time, its thermal stability is better than before. After adding TiO2 into the system,the characteristic absorption peak of TiO2 appeared in the infrared spectrum of 1066cm-1, successful synthesis of composite emulsion.Nano TiO2 can reduce the crystalline properties of the materials. When the content of TiO2 is 0.8%, the thermal decomposition temperature of the material is the highest, and the heat resistance is better; while the hydrophobic performance is good, the contact angle is 78.65 degrees. When the amount of TiO2 was 0.2%, the mechanical properties of the materials were the best. |
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