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Electrical conductivities of the high performance poly(ether ketone)/multi layers graphene or graphite nanoplatelet (2‐10 nm thick) (PEK/GNP) nanocomposites manufactured by three different methods were compared and studied. The percolation threshold of the nanocomposites manufactured by; planetary ball mill followed by hot pressing (method-1) and planetary ball mill followed by cold pressing + sintering (method-2) is lowest, i.e., 0.755 vol% (or 0.0076 volume fraction) GNP, while that of manufactured by a solution method followed by hot pressing (method-3) is about 1.21 vol%.The lower percolation threshold for the method-1 and method-2 was attributed to the better dispersion of GNP in the PEK matrix while the higher percolation threshold for the method-3 was attributed to a non-uniform dispersion of GNP and GNP-aggregates in the matrix. However, above percolation for a given volume fraction (i.e., 1.52 vol%), the electrical conductivities of the nanocomposites manufactured by method-3 showed higher values compared to those of method-1 and method-2. The electrical conductivity of the 3 vol% nanocomposite increased by >12 orders of magnitude as compared to pure matrix. The highest electrical conductivity of the nanocomposites manufactured by method-3 is 1004 S/cm which is interesting. [ABSTRACT FROM AUTHOR]

Abstract: The cost efficient expanded graphite (EG) filled polyetheretherketone (PEEK) nanocomposites were prepared by hot pressing, which exhibited an electrical conductivity percolation threshold of 1.5 wt%. The electrical conductivity of the 1.5 wt% nanocomposite increased approximately eleven orders of magnitude than that of pure PEEK. The conductivities of 5 wt% and 10 wt% nanocomposites were increased to about 3.24 S cm−1 and 12.3 S cm−1, respectively. Scanning electron microscope showed 3-dimensional conductive network of EG across the PEEK matrix. The significant increase in electrical conductivity of the nanocomposites leads to the tremendous increase in electromagnetic interference shielding effectiveness. [Copyright &y& Elsevier]

Polycarbonate (PC)/graphite nanoplatelet (GNP) nanocomposites were prepared using a facile solution-method followed by hot-compaction. The effects of GNP content on electrical properties and electromagnetic interference shielding effectiveness (EMI SE) of the nanocomposites in X-band were studied. A very low percolation threshold of 0.005 vol fraction GNP was achieved. Scanning electron microscopy (SEM) revealed uniform dispersion and three-dimensional network of the GNPs in the matrix. The electrical conductivity of the nanocomposites containing 0.037 vol fraction GNP was about 0.413 S/m. Its EMI SE for 1 mm thick sample was 35 dB, which was further increased to about 47 dB for 2 mm thick sample. An exponential increase in EMI SE was observed with increasing logarithm of electrical conductivity. [ABSTRACT FROM AUTHOR]

• Nanocomposites were fabricated using planetary ball mill followed by hot pressing. • High electrical conductivity of ~0.02 S/cm and EMI-SE of ~33 dB. • Thermal stability and char yield increased to 570 °C and 61.6%, respectively. In this work, the electromagnetic interference shielding effectiveness (EMI-SE) of the poly(ether-ketone) (PEK)-graphene nanoplatelets (GNP) nanocomposites fabricated by planetary ball mill followed by hot pressing were investigated in X-band (8.2–12.4 GHz). A percolation threshold of about 0.4 vol% GNP was obtained. The electrical conductivity was increased to about 0.02 S/cm with an EMI-SE of ~33 dB for 1 mm thick 5 vol% GNP filled PEK nanocomposite. This higher value is corresponding to more than 99.95% blocking of the EMI. The EMI-SE increases with increasing thickness of the nanocomposite. The thermal stability and the char yield of the nanocomposites reinforced with 5 vol% GNP were found to increase to 570 °C and to 61.6%, respectively. The dimensional stability of the nanocomposites was also increased compared to neat PEK. [ABSTRACT FROM AUTHOR]