Enhancing EMI Shielding Efficiency of Polyurethane Foam by Incorporating MWCNT-Decorated Hollow Glass Microspheres

This work explores the enhancement of EMI shielding efficiency of polyurethane (PU) foam by loading multiwall carbon nanotube (MWCNTs)-decorated hollow glass microspheres (HGMs). MWCNT was coated onto the HGM surface by a simple solution casting technique. The coated HGM particles were loaded in PU foams, resulting in an even dispersion of MWCNT in the foam struts, thereby forming an interconnected conductive network in the polymer matrix. The synthesized polymeric foam composites were characterized for bulk density, cellular morphology, Fourier transform infrared spectra, compression strength, electrical conductivity, and EMI shielding efficiency. The highest electrical conductivity, i.e., 15.75 × 10^-3 S/cm, was achieved at 13 wt % loading, which resulted in the EMI shielding efficiency of -25.03 dB. Finally, we proposed a mechanism exploring the enhancement of EMI shielding of PU foam composite showing that the incident EMI radiations are being absorbed into the material due to the presence of interconnected MWCNTs and successive reflection via hollow glass spheres. The synthesized foam can be used as an EMI shielding material in such applications where flexibility and lightweight are the primary requirements.