Microwave absorption of single-walled carbon nanotubes/soluble cross-linked polyurethane composites

Processable composites of single-walled carbon nanotubes (SWNTs) with soluble cross-linked polyurethane (SCPU) were prepared at various loadings of SWNTs (0-25 wt%), and they exhibited strong microwave absorption in the microwave range of 2-18 GHz. For example, 5 wt% loading SWNTs/SCPU composite has a strong absorbing peak at 8.8 GHz and achieves a maximum absorbing value of 22 dB. The absorbing peak position moves to lower frequencies with increasing SWNT loading. Theoretical simulation for the microwave absorption using the transmission line theory agrees well with the experimental results. The microwave absorption of these composites can be mainly attributed to the dielectric loss rather than magnetic loss.