X-band dielectric and microwave-absorbing properties of the incompletely carbonized polyacrylonitrile cloth

Incompletely carbonized polyacrylonitrile (PAN) cloths were prepared by heating stabilized PAN cloth at 600-800°C in different atmosphere. Their X-band dielectric and microwave-absorbing properties were investigated. Results showed that the complex permittivity constantly increased with the increasing heating temperature due to the growth of carbon sheets. Conversely, the cloths carbonized in air exhibit lower complex permittivity than those carbonized in nitrogen because the reaction with oxygen restricts the progress of carbonization. The reflection loss below -10 dB can be obtained in X band for the sample carbonized at 650°C for 2 h in air.