Electrically conducting graphene-based polyurethane nanocomposites for microwave shielding applications in the Ku band

• Published in: Journal of materials science 2017-02, Vol.52 (3), p.1546-1560
• Main Authors: Bansala, Taruna, Joshi, Mangala, Mukhopadhyay, Samrat, Doong, Ruey-an, Chaudhary, Manchal
• Format: Article
• Language: English
• Subjects: Annealing; Atomic force microscopy; Characterization and Evaluation of Materials; Chemistry and Materials Science; Classical Mechanics; Crystallography and Scattering Methods; Dielectric properties; Dielectrics; Diffraction; Electric properties; Electrical conductivity; Electrical resistivity; Electromagnetic shielding; Electromagnetism; Graphene; Graphite; Materials Science; Microscopy; Morphology; Nanocomposites; Nanostructure; Original Paper; Polymer Sciences; Polyurethane resins; Polyurethanes; Raman spectroscopy; Scanning electron microscopy; Solid Mechanics; Solution blending; Superhigh frequencies; Urethane thermoplastic elastomers; X-ray diffraction; X-rays
• ISSN: 0022-2461; 1573-4803
• DOI: 10.1007/s10853-016-0449-8

Electrically conducting, thermally reduced graphene nanosheets (TRG) were synthesized through thermal exfoliation and subsequent annealing of graphene oxide at 800 °C. Thermoplastic polyurethane (TPU)-based nanocomposites with different concentrations (ranging between 0 and 5.5 vol%) of TRG nanosheets were prepared by the solution blending method. Morphology, phase purity, and conducting properties of TPU and TPU/TRG nanocomposites were investigated through scanning electron microscopy, X-ray diffraction, conductive atomic force microscopy (C-AFM) and Raman spectroscopy. C-AFM images show the presence of electrically conducting TRG nanosheets embedded in the TPU matrix. Electromagnetic interference (EMI) shielding measurements were also undertaken on 2-mm-thick rectangular pellets. Shielding parameters such as shielding effectiveness, DC electrical conductivity, and dielectric properties, i.e., real and imaginary parts of permittivity were investigated. Our results show that the TPU/TRG nanocomposite at 5.5 vol% loading exhibits an enhanced electrical conductivity of the order of 3.1 × 10 −2  S/m and shows a superior EMI SE of ~−26 to −32 dB in the Ku band frequency region. EMI shielding values were found to be dominated by the material’s absorption behavior. The dielectric properties of TPU/TRG nanocomposites were also analyzed, and they demonstrate a good correlation with EMI shielding.