Effects of hydrogen bonds and volatilization on absorption properties for a microwave absorbing coating

In this work, we demonstrated the effects on reflection loss (RL) for a microwave absorbing coating. The mixture of an absorbing coating before curing process including flake carbonyl iron particles (FCIPs), polymer matrix, and moderate diluting agent butanone were distributed uniformly. Microwave absorption properties RL of the coating were measured during curing process at the frequency range of 2-18 GHz by the arch method, which showed RL changing clearly. Volatilization of diluting agent was investigated, resulting in the increasing of the FCIPs volume fraction, which could elucidate the changing of RL. Polymer matrix for the absorbing coating was generated by reacting polyurethane to epoxy resin, emerging the hydrogen bonds between secondary amides N-H and carbonyl groups C = O. Effect of hydrogen bonds was discussed, revealing it played an significant role in the enhancing of interfacial polarization, resulting in changing of the microwave absorbing coating RL.