Tailored graphene based polyurethane composites for efficient electrostatic dissipation and electromagnetic interference shielding applications

Nanocomposite materials, based on commercial thermoplastic polyurethane filled with graphene, are new alternative candidates for electrostatic charge dissipation and electromagnetic interference shielding applications due to their light weight, ease of processing and tunable electrical conductivities. The solution blending approach was used to fabricate a series of polyurethane/graphene (PUG) nanocomposites with graphene loading ranging from 0-5.5 vol%. For the preparation of polymer nanocomposites, graphene was prepared by the successful oxidation of pristine graphite, followed by thermal exfoliation and reduction. The effect of graphene on the electrical properties of PUG nanocomposites was investigated to evaluate the potential of these nanocomposites as an effective and light weight electrostatic charge dissipative (ESD) and electromagnetic interference (EMI) shielding material in the frequency range of 8.2-12.4 GHz (X band). The suitability of the nanocomposites for ESD was examined by displaying the decay of the voltage as a function of time. The experimental results indicate that a static decay time of 0.49 s at 1.6 vol% graphene and an EMI shielding effectiveness of similar to 21 dB in the X-band for 3 mm thickness was achieved at 5.5 vol% graphene loading. In addition, the electromagnetic attributes, such as the real and imaginary permittivity of the composites as a function of frequency, were also investigated. Therefore, such polyurethane nanocomposites shall not only be useful for antistatic coatings but also have great potential as an effective and light weight shielding material for protection from electromagnetic radiation, in electromagnetic shielding bags for packaging of electronic circuits and in a variety of applications.