Design of Lightweight Exfoliated Graphite Based Thin Composites for EMI Shielding

In this work, the design of novel exfoliated graphite (EG) powder based lightweight composites for effective EMI shielding of sensitive electronic instruments, used quite often in various civil and military applications, is proposed. The EG powder in the present situation is synthesized using the microwave assisted chemical intercalation of natural graphite flakes. Further, to study the EMI shielding properties, the EG composites of various concentration (2, 4, 6 and 8 wt.% epoxy) are prepared using the ultrasonication method. The EMI shielding effectiveness is measured with the help of a network analyzer by placing these composite samples in the X-band waveguide. It is observed that 1 mm (~ λ/30) thin EG composite at 6 wt.% epoxy shows EMI shielding effectiveness of more than 22 dB over the complete X band. As the EG powder added into the epoxy is at very low concentration, hence the resultant composite is quite lightweight thus making it suitable for even aerospace applications. The proposed EG composites may thus potentially be used for various EMI shielding applications where the lower filler concentration, lightweight and low thickness is the prime consideration.