Carbon nanotubes and carbon nanofibers based co-continuous thermoplastic elastomeric blend composites for efficient microwave shielding and thermal management

• Novel conductive thermoplastic elastomeric blend composites were prepared by wet mixing method. • Selective distribution of functionalized nanofillers in EMA phase reduces percolation threshold greatly. • Long length FCNF based blend composites exhibit excellent EMI SE and thermal conductivity than short length FCNT. • Electrical percolation threshold is linked with thermal conductivity and storage modulus. Microwave absorbing materials based on polymer blend composites are now receiving great interest to mitigate radiation pollution at ultra-low filler concentrations. Herein, polystyrene (PS)/ethylene- co -methyl acrylate (EMA) thermoplastic elastomeric blend composites were prepared via wet mixing utilizing acid-functionalized multi-walled carbon nanotubes (MWCNTs) and carbon nanofibers (CNFs). The development of a compact spatial conductive network throughout the matrix as a result of selective confinement of these functionalized nanofillers in EMA phase of the PS/EMA co-continuous blend reduces the electrical percolation threshold significantly. Higher aspect ratio of FCNFs helps to construct more interconnected conductive pathway in the composite than FCNTs. The thermal conductivity obtained for PS/EMA/FCNT and PS/EMA/FCNF blend composites with 15 wt% of filler concentration are 0.84, 0.86 W/m.K, respectively. The as-prepared composites have an absorption-dominant EMI shielding performance of −36.7 dB for 15 wt% of nanofiber loading. These highly efficient EMI shields may be applied in the future generation wearable electronics.