Electrically conductive and electromagnetic interference shielding of polyethylene composites with devisable carbon nanotube networks

This paper reports a comparative study of the electrical and electromagnetic interference (EMI) shielding performance of three carbon nanotube/polyethylene (CNT/PE) composites with different conductive networks, i.e., segregated structure (s-CNT/PE), partially segregated structure (p-CNT/PE) and randomly distributed structure (r-CNT/PE). The s-CNT/PE composite exhibits superior electrical conductivity up to 2 orders of magnitude over that of p-CNT/PE and r-CNT/PE composites, at the same CNT loading. Only 5 wt% CNT addition in the s-CNT/PE composite realizes an excellent EMI shielding effectiveness (SE) as high as 46.4 dB, which is 20% and 46% higher than that for p-CNT/PE and r-CNT/PE composites, respectively. The selectively distributed CNTs at the interfaces between PE polyhedrons would certainly increase the effective CNT concentrations that form conducting pathways and thus increase the electrical conductivity and EMI SE in the s-CNT/PE composites. Such special structure also provides numerous interfaces that absorb the electromagnetic waves, resulting in an absorption-dominated shielding mechanism. Our work suggests that designing conductive networks in polymer composites is a promising approach to develop high-performance EMI shielding materials.