Electromagnetic Shielding by Composite Films Prepared with Carbon Fiber, Ni Nanoparticles,and Multi-Walled Carbon Nanotubes in Polyurethane

摘要

Employing polymer blending method, conductive materials are mixed with waterborne polyurethane (WPU) to prepare conductive composite film, and applies it to electromagnetic shielding. Conductive materials, such as carbon fiber, nickel (Ni) nanoparticles and multiwalled carbon nanotubes are added to WPU substrate by a polymer blending method. After that, conductive composite film is prepared by means of coating. Since a conductive network is formed by the conductive material in this film, it has electromagnetic shielding effectiveness. The study applies ASTM 4935-99 standards to measure the far-field plane electromagnetic shielding effectiveness of the prepared conductive composite film within the inspection frequency range 50 MHz-1.5 GHz. According to the experimental results, when the inspection frequency of the conductive composite film prepared by carbon fiber/Ni nanoparticles is 1000 MHz, its shielding effectiveness can reach 28 dB. Furthermore, when the composite film prepared by carbon fiber/carbon nanotube is 0.15 mm thick, its electromagnetic shielding effectiveness reaches 33.7 dB, and its shielding effect is 99.9%.