Properties of Co0.5Ni0.5Fe2O4/carbon nanotubes/polyimide nanocomposites for microwave absorption

High-temperature microwave absorbing materials are of great interest due to their ability to withstand high temperatures. Multi-walled carbon nanotubes (MWNTs) were surface modified by Ar plasma and Co0.5Ni0.5Fe2O4 nanoparticles were doped onto the surface of the MWNTs by a chemical co-precipitation method. Co0.5Ni0.5Fe2O4/MWNTs powders were then added to polyimide to prepare nanocomposites for microwave absorption. After plasma modification, the surface of the MWNTs produced carboxyl groups, which are beneficial for interfacial bonding between the MWNTs and PI. The glass transition temperature of the nanocomposites was 261 °C and their thermostability was preserved up to 500 °C. The maximum reflection loss (RL) value of nanocomposites containing 0.75 wt% modified MWNTs was −24.37 dB and the frequency range where the RL value was less than −10 dB was 5.1 GHz from 7.8 to 12.9 GHz.