Electromagnetic interference shielding behavior of hybrid carbon nanotube/exfoliated graphite nanoplatelet coated glass fiber composites

We investigated the tailored electromagnetic interference shielding effectiveness (EMI SE) of polyester-matrix composites consisting of glass fiber textiles coated with multiwalled carbon nanotubes (MWCNTs) and exfoliated graphite nanoplatelets (xGnPs). The effects of various combinations of material parameters, including MWCNT length, xGnP size, MWCNT:xGnP weight ratio, host-substrate surface configuration of carbon nanomaterials (CNMs), and their amount coated per unit area, on the EMI SE were studied. The shielding mechanisms, namely, absorption, reflection, and multiple reflections, are discussed based on the underlying governing physics. EMI SE measurements showed that coating glass fibers with hybrid MWCNTs/xGnPs at 8/2 ratio yields EMI SEs higher than those of composites containing the same content of a single-type of CNM, ranging from 56.8 dB at 30 MHz to 35.3 dB at 1.5 GHz. Morphological studies showed that, upon placement on glass fiber surfaces, 1D fiber-like MWCNTs serve as interconnects that bridge the randomly oriented 2D platelet-like xGnPs to form an efficient plane shield of electromagnetic waves.