The influence of graphene nano-platelets (GNP) on the electromagnetic interference shielding effectiveness of biodegradable poly (butylene adipate-co-terephthalate) (PBAT) nanocomposites Sima Kashi, Rahul Gupta, Nhol Kao, Sati Bhattacharya School of Civil, Environmental and Chemical Engineering, RMIT University, Melbourne, Victoria 3000, Australia Electromagnetic radiation from electric and electronic devices can disrupt proper function of other nearby sensitive devices and may also have negative effects on human health. Electromagnetic interference (EMI) shielding can be achieved by minimizing the signal passing through a system by reflection and/or absorption of the radiation by a shielding material. In the current study, PBAT/GNP nanocomposites were prepared via melt blending at six different ratios of GNP (0-15 wt%) and their EMI shielding effectiveness (EMI SE) was determined by measuring the scattering parameters over a frequency range of 8.2-18 Giga Hertz. A vector network analyzer with waveguide setup for X- and Ku-bands (8.2-12.4 and 12.4-18 GHz) was used for the measurements. Results showed that embedding GNPs in PBAT did not alter its magnetic permeability while markedly enhanced its electrical permittivity and consequently improved its EMI SE. Effects of GNP loading and frequency on the EMI SE of the nanocomposites were also determined. It was observed that at low frequencies (X-band), EMI SE of the nanocomposites with a GNP content of up to 6 wt% was almost independent of the frequency while at higher loadings of filler a decreasing trend was seen in EMI SE with increasing frequency. In Ku-band frequency range, frequency dependency of the PBAT/GNP nanocomposites started at 6 wt% of GNP and became very strong for 12 and 15 wt % of GNP loading. Another noteworthy observation was that for PBAT/GNP nanocomposites, reflection was the dominant mechanism in EMI shielding. Keywords: EMI shielding, Nanocomposite, graphene nanoplatelets