Electromagnetic interference shielding of Nitrogen-doped and Undoped carbon nanotube/polyvinylidene fluoride nanocomposites: A comparative study

Nitrogen-doped and Undoped carbon nanotubes (CNTs) were synthesized by selective transmission of source and carrier gases (ethane, ammonia, hydrogen, and argon) over an alumina-supported iron catalyst in a quartz tubular reactor at 650 °C. Conductive nanocomposites were prepared by mixing CNTs and a polyvinylidene fluoride (PVDF) matrix using a small scale melt mixer (APAM mixer) at 240 °C and 235 rpm. Various characterization techniques, such as X-ray photoelectron spectroscopy, transmission electron microscopy, and Raman spectroscopy revealed that nitrogen doping altered the structure of CNTs, reduced the aspect ratio, deteriorated the crystalline structure, and changed the electronic properties of CNTs. It was also observed that the Undoped CNT/PVDF nanocomposites presented better state of dispersion, higher electrical conductivity, lower percolation threshold, and significantly higher electromagnetic interference shielding than their Nitrogen-doped counterparts. For instance, at 3.5wt% the Undoped CNT/PVDF nanocomposites shielded the incident electromagnetic wave 16 times more than the Nitrogen-doped ones. The enhanced electrical properties of the Undoped CNT/PVDF nanocomposites were attributed to enhanced dispersion, superior crystalline structure, and higher aspect ratio of Undoped CNTs.