Synergistically improved thermal stability and electromagnetic interference shielding effectiveness (EMI SE) of in-situ synthesized polyaniline/sulphur doped reduced graphene oxide (PANI/S-RGO) nanocomposites

Polyaniline (PANI) and its composite with sulphur doped reduced graphene oxide (S-RGO) have been succes-sively synthesized via in-situ chemical oxidative polymerization of aniline in presence of 10 wt. % S-RGO nanosheets. Physico-chemical analyses of the synthesized nanomaterial was performed with various character-ization techniques such as X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Spectroscopy (EDS), Atomic Force Microscopy (AFM) and Thermogravimetric analysis/Differential Scanning Calorimetry (TGA/DSC). The results interpreted from the various characterizations confirm the doping of RGO with sulphur as well as strong interaction of PANI nano -fibers and S-RGO nanosheets. TG/DSC curves confirm the enhanced thermal stability of polyaniline/sulphur doped reduced graphene oxide (PANI/S-RGO) nanocomposites with heat resistance index (T-HRI) of 155.2 C in comparision to pure PANI (T-HRI = 145.3 C) at a filler loading of 10 wt. %. TGA validates that thermal stability of PANI/S-RGO nanocomposite improves by 6-7 C than pure PANI in terms of weight loss percentage at a tem-perature of 1117 C. However DSC analysis confirms that PANI/S-RGO retains its structural integrity and con-formity to temperatures as high as 900 C beyond which the polymer composite starts to degrade. The electromagnetic interference shielding effectiveness (EMI SE) of PANI and PANI/S-RGO nanocomposites were measured via open-ended coaxial probe set-up connected to a Vector Network Analyser (VNA) at a broadband frequency range of 1-20 GHz (1000-20000 MHz). For EMI SE measurements the various nanomaterials were incorporated into paraffin wax and made into composite pellets of thickness 5 mm by solution casting technique. The dielectric properties, electrical conductivity and EMI SE were all greatly enhanced for the PANI/S-RGO/ Paraffin composite pellets. The as synthesized PANI/S-RGO/Paraffin composite pellets exhibited highest EMI SE of-22.5 dB (> 99%) as compared to-15.89 dB of PANI/Paraffin composite pellets. The prepared composite pellets revealed an absorption dominant mechanism of shielding with highest SEA of-14.6 dB for PANI/S-RGO/ Paraffin composite pellets.