Preparation Of Polyaniline And Composite Wave Absorbing Material

Polyaniline with high conductivity was prepared on the basis of the impacts of the process parameters, the effect of process on dispersion of inorganic particles in DBSA-An emulsion formation were analysed, and a stable emulsion was obtained through process optimization. Then, the composites with polyaniline and inorganic absorbed particles were prepared.With the polyaniline gained in different emulsion conditions, the effects of methods on the emulsification were researched, and the synthesis process was optimized. The results showed that: the existence of the ultrasonic field favored aniline polymerization, which stabilized emulsifying system and reduced the amount of emulsifier. The particle size of polyaniline powder gained under ultrasonic was less than 150 nm, and the conductivity of product had been improved, the conductivity of PVA film changed from 10-4S/cm to 10-2S/cm. The best process of aniline polymerization under ultrasonic field was as mixed An aqueous solution and DBSA (nAn: nDBSA = 2:1), stirred slowly for 1 h with ultrasonic at 200mA in ice water bath, dropped oxidant APS (nAn : nAPS = 1:1) solution in 30 minuets, reacted for 1 h, and then stop ultrasonic, reacted for 5 h continue with the same temperature.The effects of emulsification dispersion process parameters such as shearing time, work current and time of ultrasonic to the dispersion of inorganic particles in the DBSA-An emulsion formation were analysed. The results showed that: the shearing had a decisive effect on the stability of emulsion system and dispersion of particles in the DBSA-An emulsion, while ultrasonic only played a supporting role. To get stable emulsion system suspending inorganic particles, inorganic particles should be mixed first with aniline monomer, and then added DBSA solution, at last dispersed by high-speed shearing and ultrasonic vibration compound. Emulsificated the DBSA-An system while dispersing particles by mechanical method. For SiCN nano-powder suspension system, the following method could make dispersion system stable in 6h.: 10000r/min high-speed shearing for 2 minutes, and then 200mA ultrasonic for 30 minutes, 10000r/min high-speed shearing for 5 minutes. And 200mA ultrasonic for 60 minutes, 10000r/min high-speed shearing for 12 minutes, 250mA ultrasonic for 30minutes could make SiCN nano-powder suspending system adding ferromagnetic material stable.On the basis of above work, absorbing coatings were prepared with different inorganic particles and the absorption properties were characterized. The results showed that: the absorbing coating containing 3.98 wt% CIP, 3.56wt% NiLa0.15Fe1.45O4, and 3.93wt% Ni0.2Zn0.8Fe2O4 could broaden absorption band to 9.5-18 GHz.