Utilization of hazardous red mud in silicone rubber/MWCNT nanocomposites for high performance electromagnetic interference shielding

Abstract

With burgeoning technological advancement in telecommunication and high frequency electronics, its repercussion as electromagnetic pollution is alarmingly high. Hence, much effort has been made to supress this undesired phenomenon using efficient electromagnetic interference (EMI) shielding materials. Red mud, a hazardous by-product of alumina extraction is rich in oxides of iron, aluminium & titanium with ca. 30–60% of hematite, a magnetic lossy material that could be suitable for enhancing microwave absorption and EMI shielding performance of polymer nanocomposites. The impetus for this work was to utilize red mud as magnetically lossy filler in silicone rubber (SR)/multi-wall carbon nanotube (MWCNT) nanocomposites to function as efficient EMI shields with superior microwave absorption. Herein, taking the advantage of conductive percolated network of MWCNT in SR, red mud was incorporated with varying concentration of 5–20 wt% & compression moulded to form flexible sheets. These nanocomposite sheets exhibited a maximum electrical conductivity of 24 S/cm with superior EMI shielding effectiveness value of −83.4 dB in the X band (8.2–12.4 GHz) region making it a suitable candidate for commercial shielding applications. Moreover, sustainable use of a hazardous industrial waste to suppress EMI, which is yet another challenging invisible pollutant, is the key highlight of this work.