Single walled carbon nano tube -Polyaniline core-shell/polyurethane polymer composite for electromagnetic interference shielding

Single Walled Carbon Nanotube-Polyaniline core-shell/polyurethane polymer composites (SWCNT-PANI/PU) were prepared by a two-step process. Initially, SWCNT-PANI core-shell was synthesized by in-situ chemical oxidation. Later, polyurethane polymer composites were prepared by dispersing varying percentages of SWCNT-PANI core-shell as a filler into polyurethane. These composites exhibited a percolation threshold at 0.1 wt% filler loading. Percolation theory was applied to estimate the exact percolation threshold of composites. Maximum electrical conductivity 6.28 x 10(-4) S cm(-1) was realized at 3 wt% of filler loading. The enhancement of electrical conductivity was substantiated by FTIR, FESEM, XRD, and TGA. These results confirmed the interaction between SWCNT-PANI core-shell and polyurethane that was responsible for the enhanced electrical conductivity. Further, these polymer composites, as coatings were applied on to the GFRP substrates for evaluating the EMI shielding effectiveness. The coating properties viz. adhesion, scratch resistance and hardness were evaluated according to ASTM procedures and the EMI shielding effectiveness (EMISE) of the polymer composite in X-band (8-12 GHz) and W-band (75-110 GHz) frequencies was assessed by dielectric probe and free space methods respectively. Maximum EMISE of 11 dB in X-band and 10 dB in W-band was realized for 3 wt% SWCNT-PANI core-shell loaded PU polymer composite coating. POLYM. COMPOS., 39:4104-4114, 2018. (c) 2017 Society of Plastics Engineers