Synthesis and electrorheological property of fly ash floating bead@BaTiO₃@Pan

Polyaniline (PAn) was applied as one of electrorheological materials with the characters of short reaction time and high yield stress. However, the electric leakage breakdown phenomenon always occurs due to high electric conductivity of PAn. In order to improve suspension stability of PAn, fly ash floating bead (FAFB) was introduced into this system. BaTiO₃ as classic dielectric material was imported into PAn to increase its dielectric property. By using the idea of layer by layer coating, FAFB@BaTiO₃ was prepared by sol-gel method by coating BaTiO₃ on surface of beads. Then, FAFB@BaTiO₃@PAn was formed by in situ polymerization method on the basis of FAFB@BaTiO₃ as core and PAn as shell, respectively. The structure and morphology of materials were characterized by FTIR, XRD and SEM. The electric conductivity and dielectric property of materials were performed by four-probe technique and LCR Data Bridge, respectively. The electrorheological property test was also measured through homemade electrorheological parameter. The suspension stability within 7 d was also inspected. The results show that BaTiO₃ and PAn was coated layer by layer successfully. The electric conductivity, dielectric constant, dielectric loss and shear stress are in line with the composite effect, situated between PAn and FAFB@BaTiO₃, especially, the shear stress could reach to 675 Pa (electric field strength is 3.0 kV/mm). Leakage phenomenon has been alleviated, and the breakdown volt increases by 20%. Comparing the suspension stability, the suspension ratio of FAFB@BaTiO₃@PAn still keeps at 82% after 7 d.