Development of knitted fabrics with electromagnetic shielding properties


Thesis Type: Doctorate

Institution Of The Thesis: Bursa Uludağ University, Fen Bilimleri Enstitüsü, Turkey

Approval Date: 2013

Thesis Language: Turkish

Student: Serkan Tezel

Supervisor: YASEMİN KAVUŞTURAN

Abstract:

The aim of this Ph.D. thesis is development of knitted fabrics with electromagnetic shielding properties. Within the context of this thesis; conductive composite yarns consisting of cotton yarns with various counts and conductive metal wires are produced. Knitting performances of the conductive composite yarns and electromagnetic shielding effectiveness (EMSE) properties of the fabrics are investigated. Effects of spandex yarn, knitting structure and metal wire amount on EMSE properties of the fabrics are investigated. Double face fabrics with conductive composite yarns in fabric face and cotton yarns in fabric reverse are developed to avoid the touch of metal wires to body of the wearer. In order to adaptation and mass production of electromagnetic shielding knitted fabrics to the industry, a second group of single jersey fabrics are produced with conductive composite yarns consisting of raw and dyed cotton yarns. EMSE properties of the fabrics are investigated following the dyeing, finishing and washing processes. More comfortable and more economical knitted fabrics with sufficient EMSE properties are developed by using the vertically striped (wrapper) knitting technique. Single jersey fabrics consisting of conductive metal yarns and conductive material plated yarns, that have high raw material costs, are produced and the EMSE properties of the fabrics are compared with the fabrics consisting of conductive composite yarns. Unlike the studies in literature, EMSE properties of the fabrics are performed with both coaxial transmission line and free space measurement (by using an anechoic chamber) techniques in the frequency range of 100 MHz 1.5 GHz and 1 GHz 18 GHz respectively and results analysed comparatively. Consequently, it is observed that the type of the EMSE test method, the applied frequency, conductive yarn type, metal wire amount, knitting structure and the course per cm value of the fabric are highly significant on the EMSE of knitted fabrics. In the light of the information obtained from EMSE test results of the knitted fabrics, casually wearable knitted garments with electromagnetic shielding ability have been developed. Four different V-neck sweaters providing electromagnetic shielding in pocket part are produced. While two of the sweaters pocket part have 5 dB (68,38%) or more EMSE, the other two sweaters pocket part have 47 dB (99,998%) or EMSE in the frequency range of 100MHz ?1.5GHz.