High-strength conductive yarns and fabrics: mechanical properties, electromagnetic interference shielding effectiveness, and manufacturing techniques

Abstract

The aim of this study is to combine conductive polymer composite with conductive fabrics for the acquisition of electromagnetic interference shielding effectiveness (EMI SE) materials. HS-PET filaments, 316 L stainless steel (SS) wires, and bamboo charcoal (BC) roving are made into woven fabrics and knitted fabrics. Unlike the nonwoven fabrics that consist of entangled staple fibers, the resulting shielding materials have greater air permeability. Accordingly, HS-PET filaments, 316 L SS filaments, and BC roving are made into conductive yarns with different twists per inch (T.P.I.) using a ring spinning manufacture. The conductive yarns are made into woven and knitted fabrics, the electromagnetic interference shielding effectiveness (EMI SE) of which are then evaluated in order to examine the influences of the number of fabric layers, lamination angle, and laminated fabric type. The test results show that with a T.P.I being 8, the conductive yarns have an optimal tensile strength of 43.74 N with the lowest CV% of 4.72%. In the meantime, the conductive yarns have good uniformity but do not demonstrate any significant trend on the linear resistance. In addition, the conductive woven fabrics have better tensile strength along the weft direction (712.49 N). Regardless of whether it is a woven fabric or a knitted fabric, the surface resistivity is 107 Ω/sq. Single-layered knitted fabrics have the optimal air permeability (262.6 cm3/s/cm2), and the three-layered woven fabrics laminated at angle of 0°/90°/45° exhibit the maximum EMI SE (-45.96 dB). Therefore, the three parameters are correlated with the metallic conductive network that directly changes the EMI SE of the resulted fabrics and composites.