Investigation of electrical,electromagnetic shielding,and usage properties of woven fabrics made from different hybrid yarns containing stainless steel wires

This paper reports the results of a detailed study about specific properties of hybrid yarns and woven fabrics containing those yarns. For this aim, the fabrication procedures and physical properties of acrylic/stainless steel (SS) and cotton/acrylic/SS ply yarns were presented, and then, relations between those and electrical, electromagnetic shielding effectiveness (EMSE) and some usage properties of woven hybrid fabrics made from those with different constructions were investigated. EMSE of plain and twill fabrics were evaluated against radiating electromagnetic wave spectrum over a frequency 0–3000?MHz. A comparison of physical properties of yarns regarding wire diameter and the use properties of fabrics regarding weave type, wire diameter, and yarn type measured were presented. The functional textile products of complex applications can be achieved with low cost, easily since those yarns and fabrics were produced on conventional textile manufacturing machines with small modifications. The present study indicated that use of SS wire-based yarns in fabrics significantly increased the air permeability, pilling resistance, thermal resistance, and the flexural rigidity of hybrid fabrics. The plain weave fabrics exhibited higher EMSE values over 20?dB in higher frequencies and higher thermal absorbtivity values compared to twill fabrics.     

Investigation of electromagnetic shielding effectiveness of needle punched nonwoven fabric produced from conductive silver coated staple polyamide fibre

In this paper, electromagnetic shielding effectiveness (EMSE) of needle-punched nonwoven fabric produced from silver-coated staple polyamide fibre having a fineness of 1.7 dtex was investigated. This production was carried out at Automatex needle punching line, which consists of carding, cross lapper and needle punching machine. After production, the surface resistivity measurements of needle-punched nonwoven fabric was carried out in accordance with ASTM D 257-07 standard. The EMSE of the as-produced needle-punched nonwoven fabric was determined using a network analyzer as specified in ASTM D4935-10 in the frequency range of 15–3000 MHz. Electromagnetic shielding test shows that needle-punched nonwoven fabric produced from 1.7-dtex silver-coated polyamide fibre has the highest shielding value of 36.53 dB in the frequency range of 15–3000 MHz. The EMSE of needle-punched nonwoven fabric with fibre fineness of 1.7 dtex increased from 11.00 dB maximum to 36.53 dB in the 15–3000 MHz frequency range. It was seen that as the frequency increases, reflection values of the needle-punched nonwoven fabric decrease at floating mode, while absorption values of the nonwoven fabric increase at floating mode in the frequency range of 15–3000 MHz. EMSE results of the needle-punched nonwoven fabric produced from 1.7-dtex silver-coated staple polyamide fibres were compared to carbon fabric and needle-punched nonwoven fabric made from stainless steel fibres.     

Investigation of electromagnetic shielding effectiveness of needle punched nonwoven fabrics with staple polypropylene and carbon fibres

Conductive needle punched nonwoven fabrics are developed from staple polypropylene (PP) and varying weight fractions (10, 20 and 30 wt.%) of staple carbon fibres. A fibrous webs of staple PP and carbon fibres were formed at a wool-type carding machine, and these webs subsequently bonded on needle punching machine with 132 punches/cm² and 13.5 mm needle penetration depth. The electromagnetic shielding effectiveness (EMSE), absorption and reflection characteristics of as-produced needle punched nonwoven fabrics were determined using a network analyser as specified in ASTM D4935-10 in the frequency range 15–3000 MHz. The surface resistivity measurements were carried out in accordance with ASTM D 257-07 standard. These results indicate that the EMSE values increase incrementally with frequency in the 15–3000 MHz range. The nonwoven sample with 30 wt.% carbon fibre showed the lowest surface resistivity of 3.348 kΩ and corresponding highest EMSE of ~42.1 dB in the 3000 MHz frequency range. In comparison, the highest EMSE values from 10 to 20 wt.% staple carbon fibre were found to be 15.6 and 32.2 dB in the 3000 MHz frequency, respectively. It was observed that the absorbance and reflectance curves of each nonwoven fabric move at opposite directions to each other. It was found that as the amount of carbon fibre in the nonwoven fabric increases, absorbance values decrease, but reflectance values increase. The resultant nonwoven fabric samples are expected to be used as garment interlining after thermal bonding and wall interlayer in the future.     

The effect of multiwalled carbon nanotube (MWCNT) ratio on electrical properties and electromagnetic shielding effectiveness of PA 6/MWCNT-coated cotton fabrics

Polyamide 6 (PA 6)/multiwalled carbon nanotube (MWCNT)-coated cotton fabrics having varying amounts of MWCNTs (10, 12, 14 and 16?wt.%) in PA 6 (10, 15 and 20?wt.%) were fabricated with dip coating method to investigate the electromagnetic shielding properties in the frequency range of 15–3000 MHz. The effects of MWCNT loading on electrical resistivity, electromagnetic interference shielding effectiveness and also shielding mechanism have been studied. The highest electromagnetic shielding effectiveness value was obtained at 20?wt.% MWCNT loading in 10?wt.% PA 6 and the PA 6/MWCNT-coated composites showed the absoprtion-dominated shielding mechanism.     

防电磁辐射聚吡咯/ 棉织物的制备及其性能

为获得具备吸波特性的防电磁辐射织物,采用液相化学氧化法制备聚吡咯/棉高分子涂覆类织物,借助法兰同轴法测试织物电磁屏蔽效能,运用KES织物风格仪分析织物物理力学性能,在综合考察制备工艺对织物电磁屏蔽效能的影响以及织物经吡咯处理后的风格变化的基础上,获得最优制备工艺参数。同时,分析了织物电导率、厚度、电磁波频率以及表面孔洞面积对聚吡咯/棉复合织物电磁屏蔽效能的影响。在此基础上,建立了聚吡咯/棉复合织物及表面具有孔洞的复合织物的电磁屏蔽效能预测模型。结果表明：随着织物电导率、厚度的增加,屏蔽效能随之增加;随着电磁波频率的增加,电磁屏蔽效能呈现下降趋势;孔洞大小对电磁屏蔽效能影响显著。     

Investigation of electromagnetic shielding properties of metal composite tufted carpets

Abstract

In this research, it is aimed to develop tufted carpets with electromagnetic shielding (EMSE) effectiveness. For this purpose, stainless steel, copper, silver wires, and metalized silver PA filaments were commingled with textured polyester yarn to produce composite yarn. Composite yarns were used in tufted carpet backing fabric with different densities and directions. The EMSE of carpet samples was measured in the frequency range of 0.8–5.2?GHz by free space technique. The effects of metal type, composite yarn density, and placement direction on the EMSE were statistically analyzed in 0.8–3.0 and 3.0–5.2?GHz frequency ranges separately. Stainless steel and silver wires provided better EMSE in the range of 0.8–3.0?GHz. Stainless steel showed better EMSE in lower frequencies than 3?GHz. The metallized silver was more effective above 3?GHz. The increase in metal density significantly increased EMSE for all metal types. Carpets containing metal in two directions provided multidirectional shielding and maximum EMSE reached up to 44?dB level. As a result of the study, tufted carpets which can provide multi-axial protection were produced successfully.     

Comprehensive performance of compound fabrics in terms of electromagnetic shielding and wearability based on the Euclid approach degree of fuzzy matter elements

In this study, we designed electromagnetic shielding fabrics (EMSFs) that consist of composite yarn containing stainless steel fibers. Ten EMSFs with different metal fiber contents and metal grid sizes were examined as research specimens, and tests were conducted to determine electromagnetic shielding effectiveness (EMSE) and wearability indices. The indices were analyzed and the comprehensive performances of the EMSFs evaluated with the fuzzy matter-element method. Experimental results show that the EMSE improved and fabric wearability worsened when metal fiber content increased and metal grid size decreased. Moreover, fuzzy matter-element evaluation findings suggested that the best comprehensive performance was observed in the composite fabric containing 11.71% metal and whose metal mesh measures 1.41 mm²; these features reflect the maximum Euclid approach degree.     

Electrical,electromagnetic shielding,and some physical properties of hybrid yarn-based knitted fabrics

Recently, increasing number of studies are performed on protective fabrics containing metal wires for electromagnetic shielding purposes. In the present paper, the hybrid fabrics in plain and rib structures were knitted by using single and double ply hybrid yarns obtained by acrylic (PAC) yarns plied with stainless steel wires having two different diameters. The physical properties including conductivity, air permeability, pilling, and abrasion resistance as well as electromagnetic shielding effectiveness (EMSE) were measured. The variations in EMSE as well as reflection, absorption, and transmission and in other physical properties of knitted hybrid fabrics were investigated considering wire content and weave structure. It was seen that an increase in the wire content significantly increased the conductivity. Rib fabrics exhibited better EMSE values as compared with plain fabrics. Fabrics using two-folded yarns exhibited better EMSE values. Fabrics using thinner wire exhibited higher EMSE values. The highest EMSE value was obtained for rib-knitted fabric with 35 micrometer (μm) stainless steel wire.     

Electromagnetic shielding effectiveness of carbon/stainless steel/polypropylene hybrid yarn-based knitted fabrics and their composites

In this study, a range of conductive hybrid knitted fabrics and their composites have been investigated for shielding effectiveness in the frequency ranges of 50 MHz to 1.5 GHz (low frequency) and 4 to 8 GHz (C-Band). Carbon and stainless steel (SS) filaments were combined in Dref-3 spinning machine and different hybrid yarns were prepared. The plain- and rib-knitted fabrics were made in V-bed flat knitting machine from the prepared hybrid yarns. The composite laminate was prepared by sandwiching a ply of fabric between the polypropylene films in compression moulding machine at 180 °C for 5 min under a consolidation pressure of 12 bar. All the fabrics and composites were tested for shielding effectiveness (SE) in coaxial transmission line and C-band waveguide with the help of vector network analyser. It was observed that fabric having both conductive loop and inlaid yarns exhibited higher SE of 20.2 dB than other fabrics in low-frequency range. However, in the composite form, carbon composite with SS inlaid yarn showed better SE of 45 dB than other composites. In C-band frequency range, conductive loop fabric structures yielded high shielding effect in course direction compared to wales direction. Compared to fabric form, the composite showed higher SE for all frequency ranges. This study proposes that knitted fabrics and their composites can be utilized as electromagnetic shields in wide frequency ranges.     

Development and characterisation of polyaniline/polyamide (PANI/PA) fabrics for electromagnetic shielding

In this study, novel conductive fabrics were developed by polymerising of aniline onto the polyamide (PA)-knitted fabrics. The fabric treatment was done by the chemical polymerisation method at 0.5, 0.8 and 1.2?M aniline concentrations. Hydrochloric acid as acidic medium and ammonium per sulphate as oxidant were employed during the polymerisation process. The polyaniline (PANI)-treated PA fabric structures were fully characterised and evaluated in terms of their electromagnetic shielding effectiveness, absorption and reflection characteristics and tensile properties. Additionally, the fabrics were examined by scanning electron microscope (SEM) for the surface morphology and Fourier transform infrared spectroscopy for the chemical functionality. The electromagnetic shielding effectiveness, absorption and reflection characteristics were determined by Network Analyzer with a frequency ranged from 15 to 3000 MHz. The electrical characteristics were measured by the two ends method. It has been concluded that the bursting strength values of the treated fabrics reduced when the amount of monomer in the concentrations decreased as compared to the untreated fabrics. It is interesting to note that 1.2 M treated fabric had the highest bursting strength values as compared to the other treated fabrics. It was also found that 0.5 M concentration of PANI-treated fabric had the lowest surface resistivity due to this it showed the highest conductivity value. Another important finding is that the 0.5 M-aniline treated fabric had the highest shielding effectiveness.     

芳纶/不锈钢纤维混纺机织物电磁屏蔽性能研究

为制备综合性能优异的电磁屏蔽织物,采用芳纶/不锈钢纤维混纺纱,通过改变组织结构、厚度、叠合角度的方法来织造电磁屏蔽织物,并分析其电磁屏蔽性能。结果表明:三原组织中,平纹织物的电磁屏蔽效能最佳,缎纹织物的电磁屏蔽效能最差;织物厚度增加,电磁屏蔽效能随之增强;织物叠合角度为45°时明显优于叠合角度0°和90°时的电磁屏蔽效能;芳纶/不锈钢纤维混纺机织物还具有优异的阻燃性能、机械性能和耐水洗性能。     

The electromagnetic shielding properties of some conductive knitted fabrics produced on single or double needle bed of a flat knitting machine

In recent years, the use of electrical and electronic devices has grown rapidly. These devices cause electromagnetic interferences, which could threaten human life. In order to solve this problem, intensive research to develop textile surfaces having electromagnetic shielding properties continues. In this paper, we study textile surfaces knitted with conductive copper and stainless steel wires wrapped with acrylic yarns and also core yarns produced by using conductive yarns to test the electromagnetic shielding properties of the fabrics. It was concluded that the knitted structure of the fabrics affected the electromagnetic shielding effectiveness (EMSE). Besides, the fabrics knitted on a double needle bed of the knitting machine with higher amounts of conductive yarns and unit weights could not provide the targeted improvement in the EMSE values with respect to the fabrics produced on a single needle bed of the knitting machine.     

Investigating the electromagnetic shielding effectiveness of copper/cotton full Milano and 1 × 1 rib weft-knitted fabrics

In recent decades, the use of conductive textile structures for electromagnetic shielding effectiveness has been increased. In order to reduce, mitigate or completely eliminate destructive and adverse effects of these waves. For this purpose, the Copper/Cotton core spun yarn was manufactured and the copper wires with various diameters (0.06, 0.07, 0.08?mm) as core component were used. Copper/cotton core spun yarns were knitted with two knit structures, Full Milano and 1?×?1 Rib, at machine gauge (8, 10, and 12 per inch). The electromagnetic shielding effectiveness (EMSE) was examined using ASTM D4935-10 standard at frequency range between 0.03 to 1.5?GHz. The results show that heavier and thicker samples with larger stitch density have the higher EMSE values and also Full Milano knit structure with miss stitches provide larger shielding effectiveness values than 1?×?1 Rib knit structures.     

织物屏蔽效能的法兰同轴法和屏蔽室法测试对比研究

为研究不锈钢织物的屏蔽效能,采用法兰同轴法（30 MHz～1.5 GHz）和屏蔽室法（1～18 GHz、18～26.5 GHz）,对样品的屏蔽效能进行了对比测试研究。结果表明,2种不同测试方法和条件下,电磁波的电场分量和磁场分量在样品平面分布显著不同,屏蔽室法可以清晰反映出各向异性织物的电磁屏蔽效能的方向性,而法兰同轴法则不能。法兰同轴测试时,对应的电磁波长较长,导致同样尺寸的金属纱线排列间距和缝隙孔洞对屏蔽效能的影响不如屏蔽室法明显。只有经、纬向具有同样的金属纱线排列间距、电性能宏观各向同性的电磁屏蔽织物,在两种测试方法下才遵循同样的规律性,且也是经济、有效的应对未知方向电磁波的最佳结构形式。     

Electromagnetic shielding effectiveness of copper core-woven fabrics

Copper is selected as a conductive filler to produce copper core yarns to make woven fabric using a network analyser equipment, and the electromagnetic shielding effectiveness of these fabrics is measured in the frequency range of 20–18,000 MHz. With an increase in the number of conductive fabric layers, finer yarn count, warp density, weft density and cover factors, an increase in shielding effectiveness is observed. With an increase in copper wire diameter, a decrease in shielding effectiveness is observed.     

电磁屏蔽织物的导电网格结构及其屏蔽效能的一般影响规律研究

分析了电磁屏蔽织物的纱线和织物的细微结构,提取了由具有加捻结构的金属纤维纱线构成的有效屏蔽网格结构,提出了对应的等效电路及通用影响参数。在1~18 GHz内,采用屏蔽室法,对裸铜丝、金属纤维纱线及织物样品的屏蔽效能进行了研究。结果表明:网格结构很好地反映了该类织物的有效屏蔽结构;金属纱线的周期间距是屏蔽效能的关键影响因素;金属纤维单向排列织物的屏蔽效能具有显著方向性;金属纤维纱线在交叉点处的导通概率对屏蔽效能的影响难以判断,尚需要进一步研究。研究结果对于电磁屏蔽织物具有普适性,为屏蔽效能定量数值计算提取了有效参数。     

电磁纺织品研究进展

从具有电磁学性能的纤维及平面织物、多层复合平面织物、立体结构织物等的制备方法、基本性能、应用等方面,综述了电磁纺织品的相关研究进展。分析了含本征导电高分子的纺织材料、表面镀覆金属的纤维或织物、含金属或金属化纤维的织物、磁性纤维在电磁纺织品领域内的应用及特点;指出平面状电磁屏蔽织物开发中存在的问题,提出电磁纺织品应该向多层复合平面状织物及三维立体结构方向发展,应该注重包含特殊电磁性能的周期金属结构单元或周期性结构的应用。此外,阐述了基于纺织的导电复合材料、电磁屏蔽织物测试方法或理论模型以及该类织物在天线等上的应用。     

几种电磁屏蔽面料屏蔽效能的研究

选择铜镍涂层织物、银纤维交织织物、铜镍金属丝织物、不锈钢交织织物4种电磁屏蔽面料进行研究,利用同轴传输线法测试它们的电磁屏蔽效能。结果表明:材料中的金属丝比例越大,织物的电导率越大,电磁屏蔽效果越好。在金属丝含量相同的情况下,银丝的电磁屏蔽性能优于不锈钢。经洗涤后,银纤维交织织物和不锈钢交织织物的电磁屏蔽效果没有明显变化,而铜镍涂层织物和铜镍金属丝织物的电磁屏蔽性能均有明显衰减。     

Electromagnetic shielding efficiency of nonwoven insulation panels designed with recycled textiles and copper wires

Insulation applications of nonwovens has become increasingly important in the construction and automotive industries since the late 1990s. Besides, recycling and reusing fibrous waste becomes one of the most important raw materials of nonwovens to promote effective use of resources recently. On the other hand, metals are now being increasingly replaced by thermoplastics for housing commercial equipment, due to flexibility, light weight, and low cost for electromagnetic shielding purposes. In this study, we design nonwoven insulation panels containing copper wires with different intensity and length to provide electromagnetic wave protection by using recycled textiles. The method is simple, the material is cheaper, and more importantly, the whole material can be produced by using only waste materials. The electromagnetic shielding characteristics of the panels were measured and discussed. The experimental results indicated that the variation in wire length and amount affects the electromagnetic (EM) shielding property. With this method, the products with electromagnetic shielding effect in certain areas can be developed. In particular, there is a big potential for electromagnetic shielding applications in wide bandwidth, such as 1125–2925 MHz.     

影响金属纤维混纺织物屏蔽效能因素初探

电磁屏蔽织物是一种各向异性的屏蔽材料,其屏蔽效能受到诸多因素的影响,精确计算存在较大困难.文章依照电磁屏蔽的基本理论,介绍了金属纤维屏蔽织物屏蔽的机理与屏蔽效能的测试,着重分析了屏蔽织物相关的结构参数对织物屏蔽效能的影响,如织物组织、厚度、金属纤维混纺纱的结构、金属纤维含量对屏蔽效能的影响等.