Enhanced Microwave Absorbing Properties of Lightweight Films Based on Polyaniline/Aliphatic Polyurethane Composites in X Band

Polymer blends based on nanostructured polyaniline (PANI) doped with hydrochloric acid (HCl) and para-toluene sulfonic acid (PTSA) introduced into aliphatic polyurethane matrix (PU) are synthesized to produce flexible thin composite films for microwave absorbers. The effects of dopant type, PANI content and film thickness on morphologies, dielectric and microwave absorption properties in the X-band are studied. It reveals that real and imaginary parts of the complex permittivity are proportional to filler concentrations and type of doped PANI. The PANI-PTSA/PU films show higher permittivity and better microwave absorbing properties than PANI-HCl/PU for the same weight fraction of PANI. The minimum reflection loss RL(dB) values for the PANI-PTSA/PU are -37 dB at (20% PANI and 11.6 GHz) and -30 dB at (15% PANI and 11.3 GHz) for thicknesses of 1.2 and 1.6 mm, respectively. These high values of reflection losses make the obtained lightweight and flexible composites promising radar absorbing materials (RAM). (C) 2014 Wiley Periodicals, Inc.