Microwave Absorbing Property of Pre-oxidized PAN Fibers Carbonized in BCl3

Pre-oxidized polyacrylonitrile fibers were carbonized in BCl3. Effect of processing temperature and time on B element content in the PAN-based carbon fibers was studied. A series of techniques including XPS, FTIR and SEM, were employed to characterize the composition and structure of the sample. The microwave absorbing properties of the resultant PAN-based carbon fibers were studied by voten network analyzer. The results indicate that the pre-oxidized polyacrylonitrile fibers are converted to carbon fibers by carbonization in BCl3 and BCN attachments are formed. The resultant fiber forms B–N bonds at the same time. The permittivity of carbon fibers/paraffin is lower in comparison of that of fibers carbonized in N2, especially the imaginary part of the permittivity of carbon fibers paraffin reduces fastly. The carbonization in BCl3 is beneficial to improve the microwave absorbing property.