Development of conductive knitted-fabric-reinforced thermoplastic composites for electromagnetic shielding applications

This paper presents a feasibility study to develop conductive knitted-fabri c-reinforced thermoplastic composites for electromagnetic shielding applica tions. Polypropylene is the matrix phase, and glass fibers are the reinforc ement phase of the composite material. Stainless steel wires and staple yar ns are incorporated as conductive fillers to facilitate the electromagnetic shielding properties of the composite material. Owing to their high stiffn ess, knitting of glass fibers and stainless steel wires is very difficult. To facilitate the knitting, uncommingled yarns comprising stainless steel w ires, glass, and polypropylene fibers are produced using a hollow spindle s pinning method. Different kinds of weft knitted fabrics are produced, which are subsequently consolidated into composite materials using a compression molding method. The electromagnetic shielding effectiveness (EMSE) of vari ous knitted composites is measured in the frequency range of 300 kHz to 3 G Hz. The variations or EMSE of knitted composites with the fabric structure, stitch density, number of plies, and amount of stainless steel are describ ed. The suitability of the knitted composites developed in this study for e lectromagnetic shielding applications is also discussed.