Open-cell phenolic carbon foam and electromagnetic interference shielding properties

In this study, phenolic foam composites (PFC2Fs) with closed-cell structure consisting of multi-walled carbon nanotubes (MWCNTs) and nano-Fe3O4 were prepared via in-situ polymerization. The introduction of MWCNTs and nano-Fe3O4 can endow the PF with electromagnetic interference (EMI) shielding property. The sample with 2 wt% MWCNTs and 7 wt% Fe3O4 (PFC2F7) with thickness of 2 mm exhibited the EMI shielding effectiveness (SE) with ∼34 dB at 8-12 GHz. Furthermore, novel high-performance carbonized PF/2 wt% MWCNTs/Fe3O4 composite foams (C-PFC2Fs, carbon foam) with open-cell structure were fabricated by using high-temperature heat treating method. The obtained C-PFC2F7 exhibited the highest EMI SE of ∼62 dB at 8-12 GHz. The shielding mechanism of MWCNTs and nano-Fe3O4 was investigated. The method is fast and simple, which may promote the commercialization of composite foams in the potential applications as EMI shielding materials in the fields of spacecraft and aircraft.