Effect of the Morphology and Structure on the Microwave Absorbing Properties of Multiwalled Carbon Nanotube Filled Epoxy Resin Nanocomposites

The current research shows the effect of structural and morphological differences of multilayer carbon nanotubes (CNT) on radar absorbing materials (RAM) performance. Two CNT samples, from different manufacturers, had their morphological and structural aspects investigated by XRD, SEM and SEM-FEG analyses. CNT/epoxy resin based nanostructured composites were prepared and characterized by reflectivity measurements in the X-band. SEM results show the formation of agglomerates in the composites and the XRD patterns show structural differences between the two CNT samples. The best RAM performance (-25 dB) was determined for the nanocomposite based on the CNT with the smallest stacking layers (Lc = 26.9 angstrom) associated to the longest length of nanofilament (10-20 mu m). This characteristic can have contributed to the formation of an interconnected network in the composite favoring electrical conductivity and dielectric properties, with the consequent increase of the wave attenuation.