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利用分散聚合法制备单分散的PS及交联PS微球,干燥后经CTAB重新分散制得PS微球分散液;无定型TiO2溶解于H2O2制得钛前驱体过氧钛酸(PTC),并将PTC缓慢滴加入PS微球分散液中,强烈搅拌加热制备得到了TiO2/PS复合微球。经扫描电镜观测,发现微球由于在过氧介质中反应表面发生了破裂;采用化学稳定性更好的交联PS微球,制得表面形貌完整的复合微球。经X射线衍射测定,证明复合微球中TiO2为锐钛矿型。因金红石TiO2介电常数强于锐钛矿型,其电流变性能较强。为了制备金红石TiO2/PS复合微球,向体系加酸以调节体系酸度,发现当加入0.5 ml浓硫酸时,制备得到了表面形貌完整,且表面TiO2晶型为金红石的复合微球,并且再加入少量PVP后,微球表面TiO2的量明显增多,经热重分析测定其含量为8%。将复合微球分散在氨基硅油中,测试其在不同电压下粘度与剪切应力随剪切速率的变化。结果表明使用复合微球作为电流变液固体相时沉降稳定性比纯提TiO2高了25倍;当分散体系两端电压为3000 V时,其屈服压力为525 Pa,最大粘度278.9 Pa.s。
The monodispersed PS and cross-linked PS microspheres were prepared by dispersion polymerization, and then dried and dispersed in CTAB to prepare PS microspheres dispersion. The amorphous TiO2 was dissolved in H2O2 to prepare titanium precursor titanate (PTC) The PTC was slowly dropped into the PS microspheres dispersion, stirring strongly heated prepared TiO2 / PS composite microspheres. Scanning electron microscopy showed that the microspheres ruptured due to the reaction surface in the peroxide medium. The cross-linked PS microspheres with better chemical stability were used to obtain the composite microspheres with the complete surface morphology. The X-ray diffraction measurement showed that the TiO2 in the composite microspheres was anatase. Because rutile TiO2 dielectric constant is stronger than anatase, its electrorheological properties are stronger. In order to prepare the rutile TiO2 / PS composite microspheres, acid was added to the system to adjust the acidity of the system. It was found that when the concentration of sulfuric acid was increased by 0.5 ml, composite microspheres with a perfect surface morphology and rutile TiO2 crystal form were prepared, After adding a small amount of PVP, the amount of TiO2 on the surface of the microspheres increased obviously, and its content was 8% as determined by thermogravimetric analysis. The composite microspheres dispersed in the amino silicone oil, the viscosity under different voltage and shear stress with shear rate changes. The results show that when the composite microspheres are used as electrorheological fluid, the settling stability is 25 times higher than that of the pure TiO2. When the voltage across the system is 3000 V, the yield pressure is 525 Pa and the maximum viscosity is 278.9 Pa.s.