Synthesis And Characterization Of Cetyl Trimethyl Ammonium Bromide Modified Fly Ash Floating Bead/Polyaniline Composites

Electrorheological materials has wide application prospect in the process of modern industrial technology innovation. Polyaniline as a kind of typical conductive polymer materials, which has high thermal stability, easy synthesis, easy preparation and controllable conductivity, had been commonly used as a dispersed phase of the electrorheological materials. However, if we directly use the polyaniline to be the dispersed phase of the electrorheological materials, there have some problems were always appeared, such as poor dispersion stability, easy sedimentation and the high electrical conductivity which cause the phenomenon of the dielectric breakdown phenomenon, all above of the disadvantage will seriously restricts the application and development of the electrorheological materials.Fly ash floating beads(FAFB) as a kind of hollow microsphere, small density, light weight, good stability, and low conductivity technical characteristics. This study made the fly ash floating beads as nuclear, polyaniline as shell, the preparation of fly ash floating bead/polyaniline composite particles as a dispersed phase of the electrorheological materials, which is important to improve the poor dispersion and the high conductivity of polyaniline in electrorheological fluids.This article mainly studies the phenomenon of different types(cationic, anionic and non-ionic surfactants modified fly ash floating bead, and compare three different chain length cationic surfactant modified drift beads, the five kinds of modified drift beads are has been prepared with polyaniline by emulsion polymerization method, which have got the modified drift beads/polyaniline composite material, the mechanism and structureare described and characterized by FTIR, XRD, SEM, TGA and the conductivity and dielectric properties are measured by LCR and four-probe technique, the main results are as follows:(1)Synthesis and characterization of cetyl trimethyl ammonium bromide modified fly ash floating bead/polyaniline compositesFly ash floating bead(FAFB)was modified with the cationic surfactant cetyl trimethyl ammonium bromide(CTAB)at different conditions. The composite(FAFB-CTAB/PAn)was obtained by emulsion polymerization with aniline(An) as the monomer, dodecyl benzene sulfonic acid(DBSA) as the emulsifier and doping agent,and ammonium persulfate(APS) as oxidant. The structure and performance of the composites were analyzed by FTIR, XRD, SEM, TGA, chemical elemental analysis and four point probe technique. The result indicated that the FAFB was modified by CTAB successfully, the concentration of CTAB was 0.20 mol/l under a normal atmosphere for90 min at 80 ℃, which was the best of given condition in this test, and the FAFB-CTAB/PAn composite was obtained by in situ polymerization method. TGA reveals that the amount of PAn coated on FAFB-CTAB was 9.80%. The thermal stability of FAFB-CTAB/PAn composite was enhanced by 25 ℃ and that could be attributed to the introduction of FAFB, The conductivity of FAFB-PEG increases by104-105 S/cm as the PAn introduced; Fly-ash floating beads were modified by different long chain alkyl quaternary ammonium cationic and preparated with polyaniline that formed FAFB-Cn TAB/PAn composite material, The dielectric property of FAFB-Cn TAB/PAn composites demonstrated that dielectric constant and loss factor decreased with increasing the chain length in the frequency range of 100 KHz–2 MHz.(2)Synthesis and characterization of polyethylene glycol modified fly ash floating bead/polyaniline compositesFly ash floating bead(FAFB) was modified with the nonionic surfactant polyethylene glycol(PEG) with the different concentration. The FAFB-PEG/polyaniline(PAn) composites were synthesized by emulsion polymerization method with different amounts of FAFB-PEG. The chemical structure, crystallinity,microstructure, conductivity and dielectric properties were studied by FT-IR, XRD,SEM, four-probe technique and LCR digital bridge, respectivley. The resultsdemonstrate that FAFB is modified by PEG without destroying the crystalline structure of FAFB, which is also observed that the surface of FAFB-PEG became smoother and the FAFB-PEG incorporated into PAn matix successfully by SEM. The conductivity of FAFB-PEG/PAn decreases by 10-100 S/cm as the FAFB-PEG introduced, but still in the scope of the semiconductor. The dielectric property of FAFB-PEG/PAn composites demonstrated that dielectric constant and loss factor decreased with increasing the amount of FAFB-PEG in the frequency range of 100 KHz–2 MHz.(3)Synthesis and characterization of sodium dodecyl benzene acid modified fly ash floating bead/polyaniline compositesFly ash floating bead(FAFB) was modified with the nonionic surfactant polyethylene glycol(SDBS) with the different concentration. The FAFB-SDBS/polyaniline(PAn) composites were synthesized by emulsion polymerization method with different amounts of FAFB-SDBS. The chemical structure, crystallinity,microstructure, conductivity and dielectric properties were studied by FT-IR, XRD,SEM, four-probe technique and LCR digital bridge, respectivley. The results demonstrate that FAFB is modified by SDBS without destroying the crystalline structure of FAFB, which is also observed that the surface of FAFB-SDBS became smoother and the FAFB-SDBS incorporated into PAn matix successfully by SEM. The conductivity of FAFB-SDBS/PAn decreases by 102-103S/cm as the FAFB-SDBS introduced, but still in the scope of the semiconductor. The dielectric property of FAFB-SDBS/PAn composites demonstrated that dielectric constant and loss factor decreased with increasing the amount of FAFB-SDBS in the frequency range of 100KHz–2 MHz.This study is supported by the national natural science foundation of China(51204131) youth fund.