Study On Preparation And Performance Of Pani/Fe₃O₄

The new type absorbing materials were made to become a research hotspot by the requirements of stealth technology in the field of modern military and the applications of Electromagnetic shielding of civilian areas. The new type absorbing materials should achieve the comprehensive performance of "thin, light, wide, strong" in the technology request. The composite of conducting polymer and inorganic magnetic is an important candidate which is widely accept as an effective absorbing composite. In this paper, the composite of Polyaniline (abbr. PANI) and Fe3O4were studied as the object. PANI/Fe3O4composite with core-shell structure was prepared by in situ method. And the influence of the prepared process to micromorphology, conductivity and electromagnetic parameters of PANI/Fe3O4composite were investigated. Then, a series of SSA-PANI/Fe3O4composites were prepared by salicylic acid (abbr. SSA) as doping agent. The effect of mol ratio of the SSA and aniline on the complex permittivity and complex permeability of SSA-PANI/Fe3O4composites was studied in detail.With Ammonium persulfate (abbr. APS) as oxidant, the pure PANI was prepared by the method of chemicals oxidation polymerization. Micro morphologies of the as-prepared PANI were characterized by SEM. And the results showed that, in acidic solution the morphology of PANI tends to granular while the PANI was shown as short fiber in alkaline conditions, the particle of PANI prepared at0℃was larger than that prepared at25℃. PANI/Fe3O4composite was prepared as the following processes: PEG/Fe3O4ferrofluid was prepared through an Oxidation precipitation method in PEG hydrosol in the first. Then, the initiator of APS was absorbed by the prepared PEG/Fe3O4colloidal particles through a static absorption pretreatment. Aniline was initiated to polymerize in situ on the surface of PEG/Fe3O4particles to form the PANI/Fe3O4composite which was with the core-shell structure. The structures, morphologies of the as-prepared PANI/Fe3O4were characterized by FT-IR, XRD and SEM. The results of SEM show that larger particle diameter was obtained in the prepared PANI/FesCU when much longer absorption pretreatment time was designed. The particle diameter was in the range from200nm to500nm. The agglomeration was improved by the increase in particle size. Moreover, conductivities and electromagnetic parameters in the frequency range of2-18GHz were compared and studied, and the results demonstrated that ε′、ε〃、μ′、μ〃 and the conductivity, increased with the increasing of particle size. Then the obtained PANI/Fe3O4product was used to prepare microwave absorbing coatings with the matrix of alkyd resin. The study on the microwave absorption behavior of the obtained coatings in8~18GHz indicated that the reflectivity better than-8dB in a frequency band is about5GHz and the maximum microwave reflection loss reaches-13.7dB with a thickness of2.5mm.The morphologies of SSA-PANI/Fe3O4composites were influenced by the mol ratio of SSA and aniline, aniline and Fe3O4. The testing result of complex permittivity and complex permeability of SSA-PANI/Fe3O4composites showed that the micromorphologies and the doping level could affect the electromagnetic parameters of the products.