Preparation And Properties Of Nano Electrorheological Materials

Electrorheological fluids (ERFs) are typical suspensions composed of micrometer size particles and dielectric liquids. The ER response produces an instantaneous and reversible change in rheological properties of a suspension when exposed to an electric field normal to the flow direction. The material parameters of ERF such as viscosity, yield stress, and shear modulus can change obviously and reversibly upon the application of an external electric field. 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.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 etc. are adopted to prepare three series nanocomposite. 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, nanoparticles series etc. were prepared. The structure of these particles was characterized by XRD, FTIR, TGA, TEM, SEM and EDS etc, respectively. Then the electrorheological properties of the suspensions of these particles in silicone oil have been investigated under DC electric fields. The experimental results are given as follows: 1. A novel type of kaolinite-carboxymethyl starch (CMS) nanocomposite has been...