Development of “Electromagnetic Shielding Fabrics” Using Carbon-Nanotube-Composite-Fabrics

We propose a unique electromagnetic shielding based on carbon-nanotube(CNT) composite fabrics that a composite material of the CNT and a fabrics.<br/>The electromagnetic wave environment surrounding us diversifies, and various problems are getting obvious currently. As the solution for them, the use of an electromagnetic wave shield (EMS) is attracting much attention. Nowadays, metal is used for the materials of EMS mainly, but the metal has a problem in the cost side or the processing side. For this, we focus on carbon-nanotube (CNT) with the conductivity that is high as substitute materials in this study. Although CNT has difficulty in treating it in a simple substance because CNT usually exists on a nanoscale and powdery state, our approach will solve above problems. Therefore, we may contrive to use it or develop the way for applications such as combining with other materials. In concrete, we compound with CNT and fabrics, fabricate “CNT-composite-fabrics” (CNTCFs) having a superior characteristic of CNT and facilitate the handling of CNT, and propose the “EMS fabrics” based on CNTCFs. To make our CNTCFs, we add 96 mg of multi-walled CNT and 500 mg of dispersant (Sodium Dodecyl Sulfate) in 60 ml of pure water at first. Next, this mixed solution is ultrasonically dispersed for 60 minutes by using an ultrasonic homogenizer to prepare a CNT dispersion. Moreover, we dip a fabric in the dispersion and drying in an oven until water of the dispersion is evaporated, repeat this process several times. As a result, our CNTCFs are obtained. They have unique properties, e.g., flexible and light weight, in addition to showing the shielding effective (SE). In the recent information society, EMS sheets for a high frequency band, the far field(more than a few GHz), are demanded because the information technology develops rapidly and spreads out all over the world.<br/>In this study, we are aiming to develop the feasible level (SE &gt; 30 dB) electromagnetic shielding fabrics. Because it is fabrics, we can apply it to a curtain and a carpet and intercept an electromagnetic wave easily. We perform a performance gain by the introduction of bridge materials and the removal of the dispersant.<br/>As results of measurements, we have found that our CNTCFs has had the SE for the far field (from 0.5GHz to 18 GHz). Moreover, we have also found that the performance of our EMS fabric considerably changes by difference in material and structure of the fabric. In addition, we confirmed that the performance of CNTCFs is improved by increasing the fixation quantity of CNT. We consider that the bridge material is good for CNTCFs because it increases the fixation quantity of CNT by interaction with CNT. Although our CNTCFs does not reach the feasible level yet, obtained results give us hints to improve SE of our EMS fabric.<br/>We believe our CNTCFs will get desired SE and be used as electromagnetic shielding fabrics in near future.