粉煤灰漂珠@BaTiO_3@PAn的制备及其电流变性能

聚苯胺(PAn)作为电流变材料具有响应快、屈服应力大的特点,但因其良好的导电性能导致漏电击穿现象发生,为了进一步增加PAn的悬浮稳定性,引入了粉煤灰漂珠(FAFB),BaTiO_3作为经典的电介质材料也引入其中以进一步提高材料的介电性能。采用逐层包覆的思路,利用溶胶-凝胶法在漂珠表面包覆BaTiO_3,获得FAFB@BaTiO_3,再利用原位聚合法制备以FAFB@BaTiO_3为核、PAn为壳的结构复合材料即FAFB@BaTiO_3@PAn。利用FTIR、XRD和SEM对材料的结构与形貌进行分析,借助四探针技术和LCR数字电桥对材料的导电与介电性能进行分析,利用自组装电流变仪进行了电流变特性测试,考察了7d内的悬浮稳定性能。结果表明:BaTiO_3、PAn确实发生了逐层包覆,且电导率、介电常数、介电损耗和剪切应力均符合复合效应规律,介于PAn与FAFB@BaTiO_3之间,其中,剪切应力可达675Pa(电场强度为3.0kV/mm);漏电现象得到缓解,击穿电压提高了20%;比较悬浮稳定性发现,7d后FAFB@BaTiO_3@PAn悬浮率仍为82%。

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 sur-face 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 home-made 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.