Investigation into dielectric behaviour and electromagnetic interference shielding effectiveness of conducting styrene butadiene rubber composites containing ionic liquid modified MWCNT

Designing new conducting materials with a promise for electromagnetic shielding applications attracted a wide spread interest in recent years. Styrene-butadiene rubber (SBR) is a widely used low cost synthetic rubber for a large number of applications. However, their use in providing an effective barrier for electromagnetic radiations is limited by its poor electrical conductivity. Herein we report a facile synthesis of conducting polymer nanocomposite by incorporating non-covalently functionalized Multi walled Carbon Nanotube (MWCNT) with ionic liquid into SBR matrix and achieve a shielding efficiency of ca.35.06 dB @ 18 GHz (i.e similar to 99.99% shielding attenuation). Importantly, ionic liquid embedded MWCNT makes it dispersible facilitated through cation-pi interaction. A synergy between ionic liquid and MWCNT was well understood by analysing the dielectric behaviour and ac conductivity of composites in the frequency range of 100-20 MHz. A 5 mm thick soft rubber shielding material is fabricated and the shielding performance is analysed by vector network analyser for a frequency range of 2 GHz-18 GHz. A significant enhancement in the shielding effectiveness of the polymer nanocomposite with different amounts of f-MWCNT loading is observed. Electron microscopy analysis (TEM and FESEM) clearly illustrate the excellent dispersion state and microstructural development of MWCNTs within the SBR matrix which in turn accounts for the increase in the shielding performance of the polymer nano composite. This work opens up new paradigm for EMI shielding applications based on soft elastomer with the aid of a sustainable and simplified methodology. (C) 2017 Elsevier Ltd. All rights reserved.