Skin collagen fiber-based radar absorbing materials

By using skin collagen fiber (CF) as raw material,Schiff base structure containing CF (Sa-CF) was synthesized through CF-salicylaldehyde reaction.Then a novel radar absorbing material (Fe-Sa-CF) was prepared by chelating reaction between Sa-CF and Fe 3+.The coaxial transmission and reflection method was used to analyze the complex permittivity and complex magnetic permeability of these CF-based materials,and the radar cross section (RCS) method was used to investigate their radar absorbing properties in the frequency range of 1.0-18.0 GHz.Experimental results indicated that the conductivity of CF increased from initial 1.08×10-11 to 2.86×10-6 S/cm after being transferred into Fe-Sa-CF,and its dielectric loss tangent (tanδ) in the frequency range of 1.0-17.0 GHz also increased.These facts suggest that the Fe-Sa-CF is electric-loss type radar absorbing material.In the frequency range of 3.0-18.0 GHz,Sa-CF (1.0 mm in thickness) exhibited somewhat radar absorbing property with maximum radar reflection loss (RL) of-4.73 dB.As for Fe-Sa-CF,the absorbing bandwidth was broadened,and the absorbing intensity significantly increased in the frequency range of 1.0-18.0 GHz where a maximum radar RL of-9.23 dB was observed.In addition,the radar absorbing intensity of Fe-Sa-CF can be further improved by increasing membrane thickness.When the thickness reached to 2.0 mm,the RL values of Fe-Sa-CF were-15.0-18.0 dB in the frequency range of 7.0-18.0 GHz.Consequently,a kind of novel radar absorbing material can be prepared by chemical modification of collagen fiber,which is characterized by thin thickness,low density,broad absorption bandwidth and high absorption intensity.

By using skin collagen fiber （CF） as raw material, Schiff base structure containing CF （Sa-CF） was synthesized through CF-salicylaldehyde reaction. Then a novel radar absorbing material （Fe-Sa-CF） was prepared by chelating reaction between Sa-CF and Fe^3＋. The coaxial transmission and reflection method was used to analyze the complex permittivity and complex magnetic permeability of these CF-based materials, and the radar cross section （RCS） method was used to investigate their radar absorbing properties in the frequency range of 1.0-18.0 GHz. Experimental results indicated that the conductivity of CF increased from initial 1.08×10^-11 to 2.86×10^-6 S/cm after being transferred into Fe-Sa-CF, and its dielectric loss tangent （tan6） in the frequency range of 1.0-17.0 GHz also increased. These facts suggest that the Fe-Sa-CF is electric-loss type radar absorbing material. In the frequency range of 3.0-18.0 GHz, Sa-CF （1.0 mm in thickness） exhibited somewhat radar absorbing property with maxi- mum radar reflection loss （RL） of -4.73 dB. As for Fe-Sa-CF, the absorbing bandwidth was broadened, and the absorbing intensity significantly increased in the frequency range of 1.0-18.0 GHz where a maximum radar RL of -9.23 dB was observed. In addition, the radar absorbing intensity of Fe-Sa-CF can be further improved by increasing membrane thickness. When the thickness reached to 2.0 mm, the RL values of Fe-Sa-CF were -15.0-18.0 dB in the frequency range of 7.0-18.0 GHz. Consequently, a kind of novel radar absorbing material can be prepared by chemical modification of collagen fiber, which is characterized by thin thickness, low density, broad absorption bandwidth and high absorption intensity.