Achieving enhanced EMI shielding with novel non-woven fabric using nylon fiber coated with polyaniline via in situ polymerization

Electrically conductive fibers were synthesized by in-situ polymerization of nylon fibers with aniline. A non-woven fabric sheet was successfully fabricated through the compression of fibers. Polyvinyl chloride was used as a binder, which allowed a fabric to form a compact structure during compression. Through characterization, the synthesis of polyaniline (PANI) was confirmed by X-ray diffraction (XRD) analysis. Scanning electron microscopy (SEM) was also used to study the microstructure of nylon fibers after the in-situ polymerization, which confirmed the polyaniline coating on the fibers' surfaces. Using DC conductivity, it was found that there's a massive difference present between the DC conductivity values of pure and coated nylon fibers. After coating of polyaniline nanoparticles, the conductivity exceptionally increases from (8.5 ×10⁻¹³ S/cm) to (3.0 ×10⁻² S/cm). Mechanical testing was also carried out, which confirmed that pure nylon fabric shows a higher ultimate tensile strength (UTS) value than coated nylon fabric because the pure nylon fibers are very strong as compared to the strength provided by polyaniline nanoparticles to the fabric. During infrared (IR) spectroscopy with a 2 mm thick fabric, less than 0.2 % transmission of visible and NIR radiation was observed. PANI coated nylon fabric has a conductive structure, it also has the ability to hide the human hand's temperature and stops IR radiation, and thermal imaging cameras have also confirmed this behavior of coated fabric. Impedance analysis was also carried out to sense the dielectric properties of the conductive fabric and an increase was found in the dielectric constant, dielectric loss, and DC conductivity values in the frequency region of 100 Hz to 5 MHz.