Polyaniline Absorbing Materials

The study of microwave absorbing materials applying to military stealth is an important item. People are researching novel microwave absorbing materials presently, but the study on polyaniline(PANI) microwave absorbing material applying to radar stealth still needs going deep into progress. In this paper polyaniline doping proton acids and composite materials of polyaniline/inorigan magnetic material were prepared. The configuration, properties and interrelated influence factors were analysed and discussed systematically. In addition the coating using polyaniline composites as microwave absorbing agent was prepared and its property of microwave absorbing and correlative properties were evaluated.PANI doping HCl(PANI-HCl) has been synthesized by the way of chemical oxidation, and polyaniline doping organic functional sulfonic acids were also prepared by means of doping undoped polyaniline. The materials were analysed and studied referring to FTIR, XRD, TEM, TGA, XPS, Uv-Vis spectrum, four probe conductance law and wave-guide line measurement technique. The results show that : ?The factors, such as oxidant , acidity of system, synthesization temperature, etc. influence the synthesization of polyaniline. With the synthesization temperature increasing the molecular weight of PANI-HC1 reduced and crystallinity accreted. The conductance of polyaniline was in the range of semiconductor material, and it augmented first and reduced later. The conductivity of PANI-HC1 synthesized in medium of HC1/1M on the temperature of 20℃ achieved 0.74S/cm. (2) Dopant influence some properties of polyaniline such as configuration, heat stability, infrared emittance, microwave absorbing. Because the origanic functional sulfonic acids have contra-anion with big size, heat stability of the doped polyaniline is excellent, and turning point of TGA curve is over 250℃. The conductivity value of PANI-DBSA is maximal (0.79S/cm) because of the large size contra-anion of DBSA which making molecule chain stretching and being in favor of electric charge transmit. And its Nir-reflection was higher than polyaniline doping other acids. (3)Doped PANI hold microwave absorbing performance in 9.3GHz. The reflection value of microwave of PANI-HCl and PANI-DBSA was - 4.94dB and - 5.12dB respectively, belonging to electricity losing material.Composites of polyaniline coating magnetic matter were prepared. The configurations and interrelated proteries of PANI-HCl/Fe3O4 and PANI-DBSA/Fe3O4 were studied. The results show that : ① Aniline adhered to particle surface, growing together with Fe3O4, and forming composite with the configuration of doped polyaniline skin combining Fe3O4 particle core. ② Fe3O4 content, characteristic and concentration influence the configuration, heat stability, spectrum characteristic and microwave absorbing performance of composite. Polyaniline coating Fe3O4 possess excellent heat stability, and its heat decompose temperature is above 560℃. Fe3O4 makes conductivity waning, but conductivity is still in rang of semiconductor's. ③ The composite of polyaniline/Fe3O4 possesses microwave absorbing performance. The composite has conductivity and magnetic microwave loss because Fe3O4 endowing the composite with some magnetic loss. Composite material with excellent matching of conductivity and magnetic parameter was abtained by means of adjusting dopant and inorganic magnetic material content. No. 101 composite materials possess good microwave absorbing performance in 9.3GHz, and its reflection of microwave R achieves -11.23dB.The microwave absorbing coating has been prepared combining 101 and polyurethane/acrylic resin, and valuating its general property. The result shows that adhesive force, toughness of the coating are one grade. The properties of physics mechanics are satisfied to the technique request of radar absorbing coating. This coating has weak microwave absorbing performance in 9.3GHz.Above all, the composite of polyaniline/Fe3O4 possess excellent heat stability and microwave absorbing performance, and adjusted infired-emittance.