Titanium Oxide Based Nanocomposites Er Fluid Preparation And Its Properties

For their controllable properties, Electrorheological fluids (ERFs) are called smart materials. ERFs are suspensions of electrically polarizable particles dispersing in low-dielectric oils. When exposed in an external electric field, the material parameters of ERFs such as viscosity, yield stress, and shear modulus can change obviously and reversibly .These characteristics find practical applications in many fields, e.g. actuators, shock absorbers, active devices, human muscle simulators, ER tactile displays, photonic crystal and various other control systems. Wanted a good effecting in practice using the ERFs should have the following properties: higher yield stress, small leaking current density, broad working temperature range, lower viscosity under zero electric field. The ERFs now always have some shortage, blocking the broad application , so preparing ERFs having better integrative property become desiderate.Physically, ER effect originates from the dielectric polarization of particles. The parameters in connection with particle polarization, such as dielectric constant, dielectric loss, or conductivity have been considered as the basic factors dominating the ER effect. It is well known that the chemical natures, including molecular and crystal structure of materials, are critically important to the dielectric and polarization properties, thus it is possible to modify the dielectric and polarization properties to increase the ER activity by designing the molecular and crystal structure of ER materials. The intercalation method, sol-gel method, modified hydrolysis method and phase transfer method etc. were adopted to prepare series nano titnate composites ERFs materials. The structure modification of materials is aimed at modifying the dielectric and polarization properties of ER materials, so as to improve its ER activity, reduce cost and attain the high cost performance.In this paper, the particles of intercalating nanocomposite series, core/shell coating-structure, titanate organosol series were prepared. The structure of these particles was characterized by XRD, FTIR, TEM, UV-vis spectra and laser particle size analyzer etc., respectively. Then the electrorheological properties of the suspensions of these particles in silicone oil have been investigated under DC electric fields. Theexperimental results are given as follows:1. Acrylamide modified titanium oxide nano particles were prepared by a combination of modified hydrolysis and solution deposition methods, using acrylamide as modification and sodium dodecylbenzene sulphonate (SDBS) as dispersing agent. XRD result shows that the nano particles are amorphous and the size dispersion from 70 to 300 nm characterized by laser particle size analyzer. FTIR patterns show that acrylamide and SDBS modified on the surface of titanium oxide based particles. The improvement of dielectric property caused by the size effect of nano-particles and the wetting resulting from the introduction of SDBS are the intrinsic reasons for the enhancement of electrorheological effect. An excellent electrorheological activity has been found when the nano particles are dispersed into silicone oil. Under electric field of 5kV/mm, the shear stress can be 90 kPa, which the mass ratio of acrylamide and SDBS are 1.875% and 0.75% respectively. The ERF also show very good dispersion stability.2. Modified hydrolysis method was employed to prepare modified TiOx/acrylamide particles doped with chromium ions. XRD, TEM and particle size characterization results indicate that the particles are amorphous, and the average particle size is 140nm. The ERF obtain an optimum property when the Cr/Ti molar rate is 10mol%, under 4kV/mm DC electric field, the static shear stress can reach 152kPa. The mechanic property of ERF was enhanced remarkably due to the good wettability between particle and silicon oil, which result from the decrease of particle size caused by the synergetic effect of employment of Cr ions and SDBS synchronously. The ERF also show very good dispersion stability.3. Intercalated kaolinite/modified titanium oxide nanocomposites were synthesized using intercalation and liquid deposition method. XRD results show that formamide was intercalated into the interlayer of kaolinite and the intercalated ratio can be affected by the reaction time. The SEM images validate that modified titanium oxide was deposited on the surface of kaolinite. The Intercalated kaolinite/modified titanium oxide nanocomposite ERF have excellent electrorheological effect. The dosage of tetrabutyl titanate can influent the dielectrical property of particulate, then the optimal electrorheological property could be obtained.4. Titanate organosol was prepared by phase transfer method. The as preparedorganosol and hydrolsol were charactered by UV-vis spectra, TEM, laser partical size analyzer, photos were also employed to exibit extraction effect. The results show that Organosol and hydrolsolhave obvious quanta size effect;the particles have a narrow size distribution in both organosol and hydrolsol;the class, concentration and HLB value of surfactant all have notable effect on extraction effect. The extraction mechanism of different surfactant was also discussed. The electrorheological effect, temperature effect and dielectric property were studied. Because the good sedimentation property and electrorheological effect, organosol electrorheology was perfect to study.