Correlation between mechanical dissipation and improved X-band electromagnetic shielding capabilities of amine functionalized graphene/thermoplastic polyurethane composites. (October 2017) - Nasr Esfahani, Azam
Graphical abstract: Highlights: Thermally reduced graphene oxide was modified by grafting 2-aminoethyl methacrylate. Polymer nanocomposites of TPU/TRGO and TPU/mTRGO were prepared by solution mixing. The graphene modification enhances interfacial interactions and mechanical damping. The TPU/mTRGO5 with 1mm thickness attenuates 99.7% of emitted electromagnetic waves. The shielding via absorption can be influenced by viscoelastic energy dissipation. Abstract: Graphene-based polymer nanocomposites have demonstrated significant promise to create commercially viable electromagnetic interference (EMI) shielding to protect the next-generation of electronic materials from radiative pollution. In the present study, we carry out a systematic analysis of the dynamic mechanical, dielectric, electrical and X-band shielding properties of thermoplastic polyurethane (TPU) elastomer filled with amine functionalized graphene obtained by the rapid thermal expansion of graphite oxide. By preparation of nanocomposites based on modified and unmodified graphene using solution mixing and hot compression moulding, we demonstrate that the modification with 2-aminoethyl methacrylate enhances the EMI shielding from 14 to 25 dB. We also show by fracture analysis, cross-sectional transmission electron microscopy and dynamic mechanical analysis that the modification significantly strengthens the interfacial interactions between TPU and the functionalized graphene at the same filler loading. We find that the dominant shielding mechanism is through absorption and discuss the correlation between the viscoelastic mechanical loss tangent and the more effective dissipation of absorbed EM radiation which might account for the discrepancy between the theoretically predicted and experimentally observed EMI SE.