Tailoring electromagnetic interference shielding effectiveness of SiO₂-decorated MWCNT/polymer nanocomposites

While the decorated process has been demonstrated to be a highly efficient method to tailor the electrical conductivity of multi-walled carbon nanotube (MWCNT)-based nanocomposites, the corresponding influences on the agglomeration and electromagnetic interference (EMI) shielding behaviors still remain unknown. In this paper, the decoration-dependent EMI shielding behavior of progressively agglomerated SiO₂@MWCNT/polymer nanocomposites is investigated through a hierarchical homogenization scheme of electromagnetic properties in the X-band. Various microstructural features including the MWCNT waviness, progressive agglomeration, hollow structure of MWCNT and decoration-dependent functional interfacial effects have been fully considered. The multiscale theoretical prediction of decorated EMI shielding effectiveness (SE) of progressively agglomerated SiO₂@MWCNT/polymer nanocomposites agrees with the experiments along a wide range of decoration thickness. The SiO₂ decorated interphase is demonstrated to tune both the nonuniform distribution of MWCNTs and the functional interface effects in the nanocomposites, and therefore tailor the decoration-dependent EMI shielding performance. The effective EMI SE is revealed to first enhance with the decoration thickness, but then decreases with it. The optimal decoration thickness for high EMI SE is obtained numerically. This research provides a guidance to tailor the X-band EMI shielding performance of progressively agglomerated SiO₂@MWCNT/polymer nanocomposites by the decoration process.