Enhancements of foamability, electromagnetic interference shielding and mechanical property of epoxy microcellular composite foam with well-dispersed f-MWCNTs

In this work, the well-dispersed functionalized MWCNTs (f-MWCNTs), which was fabricated by simply decorating the polyether amine (M2070) and organosilanes (KH560) chains, has been applied as filler in preparation of the epoxy/f-MWCNTs microcellular foam through batch foaming process with supercritical carbon dioxide (scCO₂). Compared with acidified MWCNT (acid-MWCNTs) without decorating the organic groups, the f-MWCNTs achieved more uniform dispersion in epoxy matrix, acted as plasticizing agent to reduce the glass transition temperature (T_g) of epoxy/f-MWCNTs composites, as well as increasing the composite CO₂ adsorption ability, hence greatly enhanced the foamability of epoxy/f-MWCNTs composite. By adding 20 wt% f-MWCNTs, the average cell size reduced from 46.32 μm to 0.21 μm and cell density increased from 2.70 × 10⁷ cell/cm³ to 2.74 × 10¹³ cell/cm³, respectively. In addition, the epoxy/f-MWCNTs microcellular foams presented enhanced electrical conductivity to 5.2 × 10⁻⁴ S/m, electromagnetic interference shielding effectiveness (EMI SE) to 22.73 dB and compressive strength to 26.46 MPa.