Cost efficient PMMA/NG nanocomposites for electromagnetic interference shielding applications

Cost-efficient polymethylmethacrylate/exfoliated nanographite (PMMA/NG) nanocomposites were prepared through the melt blending technique. The crystalline size of NG in nanocomposites was estimated using Scherrer's formula and was found to be in the range of 42.4-50.6 nm. Scanning electron micrographs showed the homogeneous dispersion of NG in the PMMA matrix. The thermal degradation temperature (T-d) of nanocomposites was found to rise monotonically with increase in the loading of NG. Differential scanning calorimetry measurement showed a significant improvement in glass transition temperature (T-g) from 97.2 degrees C for neat PMMA to 106.4 degrees C for 4.0 wt% PMMA/NG nanocomposites. DC electrical conductivity measurement revealed that the prepared nanocomposites exhibited a low percolation threshold of 0.45 vol%. The s-parameters (S-11 and S-21) were measured through vector network analyser and were explored in the estimation of electromagnetic interference (EMI) shielding effectiveness (SE). The EMI SE of 19.2 dB (similar to 99% attenuation of incoming microwave (MW) power) was attained in the 4.0 wt% PMMA/NG nanocomposite at 12.7 GHz MW frequency. Moreover, the observed broadband EMI SE spectra indicate that the prepared nanocomposites can be employed in lightweight and low-cost commercial EMI shielding applications.