Exfoliation of graphite via three-roll milling and production of films with high electrical conductivity and electromagnetic interference shielding

Abstract The objective of this study was to develop ecofriendly graphene nanoplatelet (GNP)/polymer films with high electrical conductivity and excellent electromagnetic interference (EMI) shielding performance. We have shown that three-roll milling could produce thin graphite platelet with 6–7 nm in thickness using carboxymethyl cellulose (CMC) as exfoliation agent. A large-area film with oriented exfoliated graphite could be produced by doctor-blade method. In order to maximize the electrical conductivity and EMI properties (0.5–18 GHz) of exfoliated graphite film, the number of passes, graphite particle size, and binder were investigated. It was found that films fabricated with poly(acrylic acid)(PAA) as a binder exhibited high electrical conductivities of up to 773 S/cm owing to doping effects of PAA. In contrast, CMC-based films demonstrated superior EMI shielding, reaching 29.9dB and 1169 dB/mm, which was attributed to the enhanced GNP exfoliation and in-plane orientation. We confirmed that films using graphite exfoliated by a roll mill exhibited superior electrical conductivity and EMI properties to films using commercially available GNPs. Our proposed method is suitable for mass production of high quality GNP, and allows the production of GNP films with low energy and low cost.