ABSTRACT
Nowadays, many electrical and electronic devices emit electromagnetic waves at various frequencies in the environment. There are various studies in the literature about the effects of this electromagnetic waves on human health. In these studies, electromagnetic radiation is associated with some diseases. Electromagnetic shielding is the basic approach to limiting or blocking electromagnetic wave. Textile surfaces including the conductive wires can be used for this purpose with their cost-effectiveness, flexible and lightweight construction. The main problem that occurs during the use of metals is corrosion by oxidation or other chemical effects. Metal surfaces can be coated with various materials against corrosion in order to preserve their properties throughout their lifetime. In this study, the electromagnetic shielding and surface resistivity properties of the fabric samples which are produced by using composite yarns that including the insulated and normal copper wires are investigated. The results of the study showed that the conductivity of the sample containing insulated copper wire was significantly lower than that of normal copper wire, while the both fabrics showed the electromagnetic shielding function.
Key Words: Insulated metal wire, Electromagnetic shielding, Fabric, Surface resistivity
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malzemelerle kaplanabil
numunenin
Anahtar Kelimeler
INTRODUCTION
Nowadays, many electrical and electronic devices emit electromagnetic waves at various frequencies in the environment. There are various studies in the literature about the effects of this electromagnetic waves on human health. In these studies, electromagnetic radiation is associated with some diseases (Zamanian, A. and Hardiman, 2005; Rajendrakumar, K. and Thilagavathi, 2012). Electromagnetic shielding is the basic approach to limiting or blocking electromagnetic wave. Textile surfaces including the conductive wires can be used for this purpose with their cost-effectiveness, flexible and lightweight construction (Perumalraj and Dasardan, 2010). In addition, the electromagnetic shielding (EMSE) properties, the use of conductive metal content can give antistatic feature to the structure. Conductivity of materials can be classified according to their surface resistivity (ohm/sq) as given in Table 1.
together. In these studies, they were noted that the amount/density of conductive content and
increasing electrical conductivity (Kim et al., 2002).
One of the important problem that occurs during the use of metals is corrosion by oxidation or other chemical effects. Metal surfaces can be coated with various materials against corrosion in order to preserve their properties throughout their lifetime. In this study, the electromagnetic shielding and surface resistivity properties of the fabric samples which are produced by using metal composite yarns that including the insulated and normal copper wires are investigated.
MATERIAL AND METHOD In this resear
yarn structures as metal contents. The insulated copper was plied and twisted with 100% cotton spun yarns by two-for-one twisting technique. The yarn including insulated wires were used as warp and weft in produce plain fabrics by a handloom. Standard copper wire was intermingled with textured polyester filament. Single jersey knitted fabric was produced with using the yarn containing standard copper. Since the aim is to examine the condition of the properties, fabric type (weaving or knitting) is not considered.
Surface resistivity of the samples were measured by ELME MULTIMEG megohmmeter at 50.0% relative humidity (RH) and 25.0 0C (Figure 1).
Figure 1. Digital Resistance Meter (megohmmeter)
EMSE properties of sample were measured according to free space technique between 3.0-5.0 GHz frequency ranges. Electromagnetic shielding test diagram is given Figure 2.
Figure 2. Electromagnetic shielding test diagram
EMSE is the logarithmic form of the ratio between the intensity of field in a place with (E0) and without shielding material (Et) in the same measurement. EMSE can be calculated as dB with the Equation 1 (Liang et al., 2018).
Table 2. Means of EMSE values of woven and knitted samples
Frequency Range
Means of EMSE values (dB) Insulated Copper Wire (Woven Fabric)
Standard Copper Wire (Knitted Fabric)
3-4 GHz 20.03 12.84
4-5 GHz 21.74 10.52
In Table 2, it is seen that the woven and knitted fabrics exhibit different EMSE properties as expected. This difference caused from the differences in yarn and fabric production processes. Woven fabrics including insulated copper showed better EMSE values than knitted fabric containing standard copper. Because the copper wires were used in both weft and warp of woven fabric, thus metal amount in woven fabrics was higher than the knitted fabric. This Kumar et al., 2017).
Means of surface resistivity values of woven and knitted fabrics are given in Table 3. Table 3. Means of surface resistivity values of woven and knitted samples
Surface Resistivity (ohm/sq) Insulated Copper Wire (Woven Fabric)
Standard Copper Wire (Knitted Fabric)
According to surface resistivity results, knitted fabric including standard copper wire can be classified as conductive (Table 1). Woven fabric has about 106 times more surface resistivity than knitted sample and it is classified as dissipative. When the results are evaluated together, although the use of insulated metal gives EMSE feature, it does not improved to the conductivity.
CONCLUSION
In this study, the electromagnetic shielding and surface resistivity properties of the fabric samples which are produced by using composite yarns that including the insulated and normal copper wires are investigated.
The results of the research show that textile surfaces produced by using insulated metal wire can be used for electromagnetic shielding. It can be said that such materials will be more resistant to external influences due to the isolation. On the other hand, these type products do not have antistatic properties. If EMSE and antistatic properties are desired together, materials with conductive properties should be preferred.
REFERENCES
1. Rajendrakumar, K., and Thilagavathi, G. (2012). A study on the effect of construction parameters of metallic wire/core spun yarn based knitted fabrics on electromagnetic shielding, Journal of Industrial Textiles, 42(4), 400-416.
2. Zamanian, A., and Hardiman, C. (2005). Electromagnetic radiation and human health: A review of sources and effects, High Frequency Electronics, 4(3), 16-26.
electromagnetic shielding and comfort properties of single jersey fabrics knitted from hybrid yarns containing metal wire, Textile and Apparel, 22(2), 90-101.
6.
properties of woven fabrics made from different hybrid yarns containing stainless steel wires, The Journal of The Textile Institute, , 104(12), 1359-1373.
7. Kumar, B. G., Rosunee, S., & Bradshaw, M., (2017). Measuring electromagnetic International Journal of Clothing Science and Technology, 29(4), 525-538.
8. Kim, M. S., Kim, H. K., Byun, S. W., Jeong, S. H., Hong, Y. K., Joo, J. S., ... & Lee, J. Y. (2002). PET fabric/polypyrrole composite with high electrical conductivity for EMI shielding. Synthetic metals, 126(2-3), 233-239.
9. Liang, R., Cheng, W., Xiao, H., Shi, M., Tang, Z., & Wang, N. (2018). A calculating method for the electromagnetic shielding effectiveness of metal fiber blended fabric, Textile Research Journal, 88(9), 973-986.
