The Effect Of Polar Groups On The Surface Of Suspended Particle And The Size Of Particle On The Electrorheologica Leffect

Electrorheological fluid(ERF) is applied in many fields.At present,pepole often get electrorheological materials with high shear stress by introducting polar groups to inorganic materials,but the effect of content of polar groups and the existence of them on the electrorheological effect are still unclear.The differences between traditional electrorheological materials and giant electrorheological materials in the size is so significant that the effect of particle size on the electrorheological effct becomes a new issue in the electrorheological field.In this paper,these two promblem have been studied.H₂SO₄-modified TiO₂ particles were prepared using a sol-gel method followed by impregnating the dry gels with sulphuric acid.The content of polar groups S=O and the combination of them is clear.When titanina combinates sulfate groups in the form of a bridged bidentate coordination,them are stable under the electric field.In this situation,with the content of polar groups increased,increasing the specific surface area of titanina helps to improve ER effect.While titanina combinates sulfate groups in the form of a chelating bidentate coordination,they are instable under electric field.The polar groups dissociat into easy-cartier,the leakage current density increased rapidly.ER effect got worse.To improve ER effect,we should introduce polar groups into inorganic particles in a stable combination.In order to study the effect of size of nano-particles on the ER effect,we have prepared monodisperse spherical particles of titanina.We reduced the size of titania by adding stabilizer of electrolyte.The tetrabutyl titanate modified by glycol hydrolysis in acetone solution with electrolyte aqueous solutions.Monodispersed titania with particle size of 60 nm can be gained.The size of monodispersed titania can be controled from 60 nm to 200 nm.We found that the electrolyte cation valence affected the size of titania greatly.To reduce the size of titania,ation with high valence of the electrolyte is more effective.Smaller monodisperse spherical particles of titania can be gotten at a lower concentration.To study the effect of particle size on ER effect,three size of monodisperse silica spherical particles about 50 nm,70 nm,100 nm were synthesized in the st(?)ber method.The results show that the shear stress increase with the size of silica particle. Aggregation leads to poor repeatability.