Synthesis And Electrorheological Properties Under Low Electric Field Of Graphene/polyaniline Composites

Electrorheological(ER) fluid is usually made of non-conductive or weakly conductive solid particles dispersed in an insulating liquid medium. Under the action of an electric field, the ER fluids can be tuned reversibly from a liquid to solid. ER fluids have such intelligent behavior under electric field, that they have very important potential applications in the smart machine, engineering braking and other materials field. At present, the research on ER effects in the high electric field(kV/mm) has been fruitful. However, it is difficult in designing a steady-high voltage supply device or requiring for higher breakdown strength from ER materials in a high electric field. Therefore, to explore intelligent fluid that can display ER effects in a low electric field is the inevitable trend of ER technology towards practical application.In this paper, we explored the controllable ER performance of the graphene/polyaniline composites under low electric field. The main contents include:1. We have prepared reduced graphite oxide(RGO) and graphene(GE) by the chemical method and physical method, respectively. Then, the polymerization of aniline monomer reacted in the alcohol solution containing RGO to generate the RGO/PANI, and reacted in N-methylpyrrolidone solution dispersed GE particles to form the GE/PANI. Their morphology, structure and thermal stability also were characterized.2. We have mainly done research on ER effects of ER fluid composed of RGO/PANI or GE/PANI composites suspended in silicone oil. Both types of ER fluids showed abrupt shear thickening under the applied electric fields and low shear rates, as well as shear thinning when the shear rate increased. Their shear stress,viscosity, static yield stress, storage modulus and loss modulus were found to increase obviously with an applied electric field from 50 to 350 V/mm, and the static yield stress was proportional to the square of the electric field.3. We have analyzed the flow behavior of electrorheological suspensions containing RGO/PANI and GE/PANI composite particles using CCJ or Bingham model, respectively. The shear stress data obtained experimentally from an electrorheological fluid revealed that the structural reformation of the aligned fibers depended on the shear rate, in good agreement with the CCJ or Bingham model. And their dynamic yield stress was proportional to the square of electric field.4. We have examined the effects about pH, the mass fraction of RGO from the RGO/PANI particles, temperature on ER behavior of RGO/PANI fluid under low electric field. The consequences showed that the ER effect of RGO/PANI(pH=10)became most obvious when the applied electric field was above 100V/mm; The larger mass fraction of RGO the composite particles possessed, the greater shear stress RGO/PANI fluid performed; A higher temperature was beneficial to the shear stress at low shear rates.