Preparation and investigation of moisture transfer and electromagnetic shielding properties of double-layer electromagnetic shielding fabrics

In this study, a type of double-layer electromagnetic shielding fabric that combined reflection and absorption layers was successfully fabricated. Polypyrrole-coated cotton fabric was prepared by in situ polymerization and used as electromagnetic wave absorbed layer. A type of metal composite yarn containing stainless steel wire was woven into warp-knitted fabric as the reflection layer of double-layer electromagnetic shielding fabric. The electromagnetic shielding and conductive properties of double-layer electromagnetic shielding fabric were investigated in this work. Result showed that the electromagnetic shielding effectiveness could reach up to 15 dB in a large frequency range from 500 MHz to 1.5 GHz. The electrical conductivity of polypyrrole-deposited cotton fabric was 0.15 S/cm. To investigate the physiological wear comfort of prepared sample, the effect of moisture content on drying rate and air permeability was also discussed. Results indicated that the existence of polypyrrole on the cotton fabric displayed negative influence to water absorption. Furthermore, it was also found that the air permeability of electromagnetic shielding fabric decreased linearly with the increased water content in the fabric, and the air almost could not pass over the fabric when the water content reached approximately 80%. The study was designed in order to have a clear understanding of double-layer electromagnetic shielding fabric and provide advice to produce protective clothing to protect humans from electromagnetic radiation.