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.     

Coating of conductive yarns for electro-textile applications

Conductive yarns are used for integration of sensors and other electronic devices with textile fabrics through weaving, knitting, braiding or embroidery processes. In the lifetime of the textile also several washing cycles might occur. These processes involve rubbing which may lead to displacement of conductive fibres, causing short circuiting between the neighbouring conductive fibres. Also the textile products made with conductive fibres may have to work in the presence of water, where the exposed conductive fibres can get short circuited. In this work, an attempt has been made to protect silver-coated polyamide yarns with polypropylene (PP). This is done through wrapping the PP staple fibres around the silver-coated polyamide yarns through friction spinning and melting the PP sheath fibres in an oven. The influence of twist in the conductive yarns, amount of PP coating and the oven temperature during coating process on the tenacity, electrical insulation in the presence of water and flexibility properties of the coated yarns are studied. The PP coated yarns with plied conductive yarn in the core provide better flexibility but need higher amount of coating to provide complete electrical insulation in the presence of water as compared to those yarns with single conductive yarn in the core.     

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.     

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.     

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.     

玻璃纤维经编成圈编织性能

针对玻璃纤维纱线在经编成圈编织时易受损、不易形成织物的现象,通过对不同生产机型、不同规格纱线的编织试验,探讨了经编成圈机构、送经机构和牵拉机构、纱线捻度、捻向及玻纤浸润剂类型等因素对玻璃纤维编织性能的影响,分析了玻纤纱因捻度和捻向造成的织物单边烂边问题,阐述了玻璃纤维在经编机上生产的关键技术,总结出淀粉型玻璃纤维纱线在复合针特里科经编机上采用积极送经方式可以正常成圈编织成玻纤布。     

玻璃纤维经编针织物的编织工艺分析

针对玻璃纤维纱线在针织加工中不耐扭折、易受损断纱的现象,通过试验,分析了玻璃纤维纱线经编成圈的编织性能,探讨了整经工序中应注意的几个问题。在拉舍尔舌针经编机上编织了几种单梳和双梳织物,研究了玻璃纤维经编针织物的编织工艺。结果表明:玻璃纤维纱线在织针针头和导纱针针孔处的弯曲曲率和包围角越大,纱线越容易断裂;整经时应调整好工艺参数;成圈过程中,断纱最容易发生在套圈阶段,最好采用宽度较小的舌针;在保证顺利成圈的前提下,尽可能减小经纱送经张力;编织高密度织物时,织物表面起毛现象严重。     

不锈钢丝包芯纱针织物电磁屏蔽性能研究

采用涤纶长丝、棉粗纱和超细316L不锈钢丝在HN32-04型棉纺花式捻线机上纺制不锈钢丝包芯纱,并在龙星LXC-252SCV型电脑横机上编织纬平针织物及浮线添纱针织物。介绍纺纱原理及编织工艺,并测试不锈钢丝包芯纱的拉伸性能以及针织物的电磁屏蔽效能。结果表明,不锈钢丝包芯纱的平均拉伸断裂强力为38.96 N,位移为124.30 mm,其拉伸过程分为不锈钢丝断裂、纱线中纤维抽拔、纱线断裂过程。随着电磁波频率的不断增强,纬平针织物和浮线添纱针织物的电磁屏蔽效能下降。针织物结构不同,织物紧密程度和线圈大小不同,对不同频段电磁波的屏蔽能力也不同。     

汽车纺织品用纱线的新功能

描述了表达导电织物EMI屏蔽效果和预测如何达到预定要求的纱线和织物结构的公式.介绍了Trevira Neckelmann公司生产的具有电磁屏蔽效果的纱线和织物的特性和应用.     

The influence of distribution and deposit of conductive coating on shielding effectiveness of textiles

This study presents the investigation of electrically conductive fabrics with low resistivity, coated with formulation containing the conjugated polymer system – poly(3,4-ethylenedioxythiophene)-polystyrene sulphonate (PEDOT-PSS). The samples of fabrics were coated with PEDOT-PSS, using a screen printing method, by different patterns or coating their surface fully with different coating deposit. Methods for measurement of electrostatic properties, reflection and transmission as well as the assessment of electromagnetic radiation (EMR) shielding effectiveness were used for the characterization of electrical properties of developed samples. EMR shielding properties were investigated within 2–12 GHz frequency bands. The highest attenuation of the electromagnetic energy among tested fabrics was obtained on the fabrics fully coated with paste and it depended on deposit considerably. The influence of distribution and deposit of conductive coating on shielding effectiveness of textiles were determined. Correlation between shielding effectiveness and electrostatic properties of developed coated fabrics was also discussed. Electrical properties of samples coated with formulation containing PEDOT-PSS were compared with these of fabrics with metalized yarns, developed by us earlier. The results of EMR shielding measurements showed that fabrics coated with the paste containing conductive polymer system compared to fabrics with in-weaved conductive metalized yarns have certain advantages as EMR shields.     

Investigation on moisture management properties of knitted fabrics produced from vortex-spun yarns

Abstract

The aim of this study was to investigate the liquid moisture management performance of knitted fabrics produced from vortex-spun yarns using different kinds of fibers and ratios. For this purpose, the vortex-spun yarns with 19.7 tex were obtained in different blend ratios in Murata Vortex Spinner by using different fibers. Then, these yarns were knitted in a circular knitting machine at two different stitch lengths and dyed considering fiber types. Moisture management properties of the produced fabrics were tested. The results revealed that moisture management properties of vortex knitted fabrics were much affected by fiber types in comparison with fabric tightness. Modal and nylon fibers have shown very positive results in terms of moisture management performance. The vortex-spun yarns having a low diameter, high shape values that are more rounded, and high density improved moisture management performance of the fabrics whereas the hairy yarns and higher fabric thickness reduced it.     

针织间隔导电织物的压力电阻传感性能

为了研究针织间隔导电织物的压阻传感性能,将镀银锦纶与锦纶/氨纶包覆纱在无缝成型内衣机上进行编织,制备了3种纬编导电织物,将其与经编间隔织物结合,测试并得到了电阻随应变的变化规律,分析了导电区域面积及压缩方式对电阻-应变传感性能的影响。结果显示:压缩面呈平面时,压缩过程分为电阻随应变的增加先缓慢减小、再急速下降两个阶段;曲面压缩时,压缩过程分为电阻微弱减小、缓慢上升、急剧下降三个阶段,其中曲面压缩阶段Ⅲ和平面压缩阶段Ⅱ均具有较好的线性度和灵敏度,且前者灵敏度优于后者;当传感面积为35 mm×35 mm,且从织物横列方向进行曲面压缩电阻的测量时,传感器的综合传感性能最佳。     

采用竹浆纤维开发口罩纹针织面料

阐述了在2+4针道普通双面大圆机上,采用28 tex(21S)竹浆纤维纱开发设计口罩纹针织面料的编织工艺和染整工艺,并给出了面料技术参数指标。重点介绍该口罩纹针织面料上机调试的关键技术,包括用纱要求、三角对位、弯纱深度、张力控制、针盘高度、导纱器的安装位置。该新型面料表面花纹形态类似口罩外观,经过改变上机编织工艺,可以形成直条型、曲折型等各种花纹图案,为在普通双面大圆机上开发设计新颖针织面料提供参考。     

全聚赛络纺双芯纱及其弹性电磁屏蔽针织物的制备

为开发弹性回复性更强的防辐射针织物,在全聚纺细纱机上采用嵌入式纺纱方法纺制3 种不同线密度的棉/ 不锈钢/ 氨纶双芯纱和3 种对应线密度的棉/ 不锈钢包芯纱,设计织制成1+ 1罗纹组织织物,测试分析纱线的包覆效果和主要性能及织物的弹性回复性、电磁屏蔽等性能。结果表明：6 种纱线包覆效果及成纱性能均良好;相比不锈钢包芯纱线织物,双芯纱织物在弹性回复和屏蔽电磁波方面有很大的优势,达到一般性民用电磁屏蔽织物的要求且能保证人体舒适性,这种新结构纱线在全聚纺设备上生产是可行的;开发弹性电磁屏蔽织物时,不仅要合理选择长丝预牵伸倍数等工艺参数,还要考虑到织物的服用性、耐久性及生产成本。     

Assessing colour differences of viscose fabrics knitted from vortex-, ring- and open-end rotor-spun yarns after abrasion

The colour values of fabric samples that are knitted from vortex-spun (VS), open-end rotor-spun and ring-spun yarns were evaluated after abrasion. We measured the changes of colour properties of each sample, considering spinning system, dyeing concentration and abrasion cycle, which have effects on colour values. The colour values of dyed fabrics knitted from ring spun yarns showed less change after abrasion than that of dyed fabrics knitted from open-end rotor-spun and VS yarns, when the spinning systems were compared. The colour values of dyed fabrics knitted from VS yarns showed more changes after abrasion because of the smooth surface of VS yarns.     

芳纶不锈钢复合纱多功能针织面料的设计与研究

传统的电磁屏蔽织物常用机织方法实现,其服用性较差且功能单一,因此,开发出舒适性好且具有阻燃性能的电磁屏蔽织物具有较大的实用价值。文章采用芳纶不锈钢复合纱进行针织面料设计,通过改变织物组织结构、层次配伍的方法,使用电脑横机编织了不同的针织组织,测试并分析织物电磁屏蔽效果及影响因素,同时测试织物的阻燃性和耐水洗性。实验结果表明:芳纶不锈钢复合纱针织物具有优良的阻燃性和耐水洗性,织物的结构是影响电磁屏蔽效果的主要因素,且通过结构优化的织物其电磁屏蔽效能得到了提升。     

亚麻纬编针织物及其拉伸性能

 通过在STOLL电脑横机上开发亚麻针织物的探索,得出了保持一定的湿度,利用双股亚麻纱为原料进行编织前处理,选择合理的编织工艺参数可有效提高亚麻针织物可编织性的结论。对所开发产品的结构、面密度、织物厚度及拉伸变形能力等指标进行测试分析,结果表明:弯纱深度值为10.5时,亚麻四平织物抗拉伸能力和拉伸变形能力较优,其厚度及耗纱量适中,性价比合适,可作为抗拉伸能量吸收性能较好的、环保纺织复合材料的增强体。     

纬编针织增强复合材料的拉伸性能

在电脑横机上用玻璃纤维编织4种不同结构的针织物,作为纬编针织增强复合材料的增强体。采用VARTM工艺复合加工,对这4种纬编针织增强复合材料的纵、横向拉伸性能进行测试,并对拉伸应力与应变特征曲线进行分析;阐述集圈、浮线对纬编针织增强复合材料拉伸性能的影响。结果表明:取向度和拉伸方向上受力纱线根数是影响这4种结构增强复合材料拉伸性能的主要因素;复合材料的破坏形式说明玻璃纤维针织物增强体与树脂结合良好,有潜在的应用价值。     

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.     

Electromagnetic shielding effectiveness and mathematical model of stainless steel composite fabric

In this paper, a kind of novel filaments/short fibers composite yarns containing stainless steel (SS) were produced by an innovative ring-spinning method. On the basis of the shielding mechanism of the electromagnetic (EM) shielding material, a method for fabricating a multifunctional SS composite fabric with EM shielding characteristics was successfully developed. Coaxial transmission line method was used to investigate the influences of different factors, such as radiant frequency, metal content, metal mesh size, and geometry, on electromagnetic shielding effectiveness (EMSE) of the composite fabrics in the frequency range of 15–3000?MHz. The notabilities of these factors were examined using analysis of variance (ANOVA). A regression model equation was setup using the above factors as variables, and verification of accuracy and practicability to this model was also carried out. The experimental results indicate that average EMSE of composite fabrics is 20.76–51.92?dB in the frequency of 15–3000?MHz, which indicates that the influence of the studied factors was considerable.