Preparation And Properties Of The Current Surface Modification PS Composite Microspheres Changed

ER fluid is a kind of important intelligent materials, but it is not yet industrialized. This is mainly due to the mechanics performance of developed ER fluid has not yet reached the requirements of industrial use and the chemistry and physical performance of it has not been good enough. Wenwei Jia prepared an ER fluid which property of shear stress was increased to more than120kPa in2003. In this way, the industrial applications of the ER fluid may be realized. And then they proposed the giant electrorheologicl theory. At the same time the particles were burned to remove the polar groups on the surface, and they found that the performance of shear stress is similar to traditional electrorheological fluids. Thus it proves that the properties of surface have great influence on electrorheological performance. In this paper, the surface modifications of PS micrcospheres were used as solid phase in ER fluids. There were two advantages in this way:one. the suspension of ER fluids was more stable; the other one. the PS microspheres were easily modified on suface. and the composit microspheres which were used PS micropheres as template have been widely reported. Firstly, through chemical copolymerizable acrylic acid, chemical etched by sulfuric acid and the low-temperature plasma method, the surface of the PS microspheres were modified and grafted some polar group such as carboxyl group, sulfonic acid group, amino group, hydroxyl group and so on. In this way, the effect of polar groups on ER performance was studied. Secondly, TiO2/PS composite microspheres were prepared. By this means, the PS microspheres can be covered by TiO2which is high dielectric constant. Furthermore we can study the surface which transformed by inorganic particles effects on the ER performance. In the same time TiO2/PS composite microspheres can also reduce the density of the solid particles by compositing TiO2and PS. So the sedimentation stability of ER fluid is enhanced. Then in the intermediate layer of TiO2/PS composite microspheres reabsorbed a layer of conductive material-MCNTs. The role of MCNTs is to make the composite particles have more polarized electric charge, which increased the force between particles with the polarization charge. This is considered important force to generate ER effect, which make the ER performance increase.1. Modification of PS microspheres surface and properties of ER fluidThis chapter mainly used three kinds of method to modify the surface of PS microsphere: firstly, the styrene and acrylic acid were copolymerized makes the surface of PS microspheres contain a small amount of-COOH. And then it was tested through the FT-IR. Secondly PS microspheres were dispersed into sulfuric acid with a certain concentration, ultrasoniced, heated for24h to make it sulfonation. Graft group and morphology surface of PS microspheres were analyzed by FT-IR and TEM. Thirdly, PS microsphere was modified by low temperature plasma, which makes it graft polar group such as-NH3,-OH and so on. In order to investigate the surface polarity of PS microspheres when modified by low-temperature, we used the plates of PS firstly and tested the static contact angle. The amount of polar group was changed by controlling RF power, the reaction time and the gas flow rate. The particles and the amino silicone oil were mixed; the rotational rheometer was used to test the change of the viscosity and shear stress of the dispersion with shear rate under the electric field, and then compared their performance.2. Preparation of TiO2/PS composite microspheres in suit method and properties of TiO2/PS composite microspheres/Amino silicone ER fluidThe monodisperse PS microspheres were got by the dispersion polymerization, dried and dispersed in water with CTAB. Then peroxotitanic acid(PTC) were added into PS disperse system and heated80℃for24h. By this means, the TiO2/PS composite microspheres were got. The relationship of the surface of the microspheres with the concentration of titanium precursor and hydrogen peroxide were disscussed. The relevant properties of the composite microspheres were characterized by transmission electron microscopy(TEM), scanning electron microscopy (SEM), X-ray powder diffraction instrument(XRD), thermal gravimetric analyzer (TG). Composite microspheres particles prepared were dispersed into amino silicone oil by ultrasonic. Then how the viscosity and shear stress of the dispersion changed with shear rate under the electric field was got. Finally we compared the performance of composite microspheres which is sedimentation stability and mechanical properties with pure PS microspheres and pure TiO2.3. Preparation of TiO2/MCNTs/PS composite microspheres and properties of TiO2/MCNts/PS composite microspheres/Amino silicone ER fluidMCNTs were dispersedin water uniformly with the anionic surfactant NaSDBS by ultrasonic. Because of electrostatic interaction MCNTs were absorbed onto surface of PS microspheres which was modified with CTAB. The microspheres particle size was discussed on the influence of MCNTs adsorption. Then in the same way, we added peroxotitanic acid into MCNTs/PS dispersion, and then the TiO2/MCNTs/PS composite microspheres were got by heterogeneous nucleation. The stirring rate on the influence of surface morphology of microspheres was studied. The relevant properties of the composite microspheres were characterized by Fourier transform infrared spectroscopy(FT-IR), scanning electron microscopy(SEM), transmission electron microscopy(TEM), X-ray diffraction(XRD), thermal gravimetric analyzer(TG). Composite microspheres particles prepared were dispersedinto amino silicone oil by ultrasonic. Then we got how the viscosity and shear stress of the dispersion changed with shear rate under the electric field. Finally the performance of composite microspheres with TiO2/PS composite microspheres was compared.