Synthesis and Electrorheological Property of BaTiO3 Coated Fly Ash Floating Bead/PAn Composites
The fly ash floating beads were covered by polyaniline (FAFB/PAn) by using in situ polymerization method.Sol gel-hydrothermal method was introduced to prepare FAFB/PAn/BaTiO3 composites.FAFB/PAn/BaTiO3 composites had core/shell structure with multilayer,which was composed of the core as hollow FAFB and the first shell as conductive layer PAn and the second one as insulating layer BaTiO3.The structure and performance of the composites were analyzed by FTIR,XRD,SEM,four point probe technique and LCR.The suspension and shear stress of electrorheological fluid were tested.The results of FTIR and XRD showed that PAn and BaTiO3 could successfully be coated on the surface of FAFB by this method.The results of conductivity showed that the value of FAFB/PAn/BaTiO3 was 7.8 × 10-4 S· cm-1,and rose almost by two orders of magnitude in comparison with BaTiO3.It had better dielectric properties in the 1-2000 kHz frequency range.The max value of εr reached 598 if f =1 kHz was provided and with the increase of frequency,the dielectric constant decreased correspondingly.The maximum of tanδ was 1.14 atf =1 kHz and its value decreased to 0.75 until 200 kHz.Comparison with the suspension stability of them,FAFB/PAn showed better suspension ratio as 88％ than BaTiO3 and FAFB/PAn/BaTiO3 after 7 days,while the values of the latter two was similar as only 60％.FAFB/PAn/BaTiO3 based electrorheological fluid showed a significant ER effect and obvious higher capability of breakdown resistance under electric field.When the applied electric field was 4.0 kV/mm,the shear stress arrived at 631 Pa.
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