Best practices for correlating electrical conductivity with broadband EMI shielding in binary filler-based conducting polymer composites

Multiple conductive fillers (MWCNT, GNP, Cu@Ag dendrite, EGain) were incorporated in a commercial polypropylene matrix through melt processing. Electrical conductivity, thermal conductivity, and EMI shielding properties of the fabricated composites were examined according to various filler compositions, and it was confirmed that the properties varied according to shape, composition, and mutual compatibility of the particulate fillers. In particular, at broadband frequencies (X-, Ka-, W- band), the EMI shielding properties reached 32.6 dB (at 10 GHz), 39.3 dB (at 28 GHz), 51.1 dB (at 77 GHz) for composites comprising of PC15 (0.3 mm) and the EMI shielding mechanisms according to the material thickness (0.3, 0.5, 1 mm) and the filler content were studied. As the frequency increased from 8.2–110 GHz, the reflection properties decreased from 90.93 % to 80.99 % (at 0.3 mm), and the absorption properties increased 9.01 % to 19.01 % even for PC15 (0.3 mm). In particular, the correlation between the type of electrical conductivity and the EMI shielding properties were investigated using a theoretical (Simon, Drude) model.