Polypyrrole functionalized polyester needlepunched nonwoven fabrics for electro-magnetic interference shielding

Development of electro-magnetic shield is an important research area since few decades to protect electronic devices and even human beings from harmful effects of electro-magnetic rays. Textile based flexible shields are also developed as functionalized materials for this purpose. In this work, needlepunched nonwoven textile based electro-conductive fabric is prepared by in-situ chemical polymerization of pyrrole and their effectiveness as electro-magnetic shield is explored. 3(3) Box-Behnken design is used to investigate the influence of manufacturing process parameters of neddlepunched nonwoven fabric such as fabric gsm, punching density and depth of needle penetration on the polypyrrole add-on, surface resistivity and electro-magnetic shielding effectiveness. Surface resistivity as low as 18 (with 16.28% polypyrrole add-on) is obtained for a typical composite fabric. The shielding effectiveness of this fabric is found to be 20.07 dB at 4 GHz frequency. It has been found that the primary mechanism of the shielding is the absorption of electro-magnetic rays into these composite fabrics rather than reflection from their surface. POLYM. COMPOS., 39:3696-3704, 2018. (c) 2017 Society of Plastics Engineers