Preparation And Electrorheological Properties Of ZnO/polyaniline Composites

Electrorheological fluid (ER fluid) is a kind of smart fluid whose rheologicalbehaviors can be controlled by the applied electric field. ER fluids have receivedmuch attention in the intelligent materials and engineering application due to thecharacteristics of rapid response, controllable and reversible, and continuouslyadjustable. This paper outlined the history and the compositions of ER fluids, themechanism and the influencing factors of the ER effect. Zinc oxide/polyaniline(ZnO/PANI) composites with different doping acids through a double surfactant layerassisted polymerization method were synthesized and their ER performances werestudied. The main contents are as follows:Hydrochloric acid doped (H-ZP)，citric acid doped (C-ZP) and p-toluene sulfonicacid doped (T-ZP) ZnO/PANI composites were synthesized in aqueous solution withnano-ZnO treated by PVP-SDS bilayer surfactants. The morphology, composition andthermal stability of the resulting composites were characterized. And the ER effects ofthe suspensions of the composite particles in silicone oil were investigated. Theresults are summarized as:(1) The mass ratio of ZnO and aniline monomer has great influences on the ERperformance of the composite suspensions. The suspension based on the compositeswith the mass ratio of1:2of ZnO to aniline shows the best ER performance.(2) The level of anti-doping has significant impacts on the ER effect of the threecomposite particles. H-ZP, C-ZP and T-ZP composite materials was synthesized bythe mass ratio of1:2of ZnO to polyaniline have the best performance in ER effect atthe anti-doping level of pH value of9,11and8, respectively.(3) Different doping acids has influences on the ER effect of ZnO/PANIcomposite materials, and the C-Z1P2composite materials showed high ER efficiencyunder applied electric fields.(4) The effect of temperature on the ER effect of three composite materials wasstudied. The results showed that the static yield stresses are increasing with theincreasement of temperature. The rheological analyses of ER fluid indicated that theER fluids show Newtonian behavior without applied electric field but in goodagreement with Cho-Choi-Jhon (CCJ) model and Bingham model under appliedelectric filed with the CCJ model presents better fitting results for the rheological curve. The relationship of dynamic yield stresses and static yield stresses (τ) for allsuspensions with the electric field strength (E) was found to be in good match of theformula: τ∝Eα,1≤α≤2.5.