A study on electromagnetic shielding effectiveness of the conducting nano-composites

• Main Authors: Yun-Min Yeh, 葉雲民
• Other Authors: Ho Chang
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/6fv8kw

碩士 === 國立臺北科技大學 === 製造科技研究所 === 97 === Employing polymer blending method, the paper mixes conductive materials with waterborne polyurethane (WPU) to prepare conductive composite film, and applies it to electromagnetic shielding effectiveness so as to effectively decrease the disturbance of electromagnetic radiation towards electronic instruments and reduce the harm to human body. The study is going to add conductive materials, such as carbon fiber, nickel (Ni) nanoparticles and multiwalled carbon nanotubes, to WPU substrate by polymer blending method. After that, by means of coating, conductive composite film is prepared. Since conductive network is formed for the conductive material existing in this film, it has the function of 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 ~ 3.0 GHz. According to the experimental results, the resistance on the surface of the carbon-fiber-made conductive composite film with thickness 0.25 mm is 118 ohm/square, and the shielding effectiveness is 32.5 dB. When the inspection frequency of the conductive composite film prepared by carbon fiber/Ni nanoparticles is 2450 MHz, its shielding effectiveness can reach 34.8 dB. Furthermore, when the composite film prepared by carbon fiber/carbon nanotube is at the thickness 0.25 mm, its electromagnetic shielding effectiveness is as high as 40.6 dB, and its shielding effect is 99.99 %.