A study of the thermal properties of single jersey fabrics of cotton, bamboo and cotton/bamboo blended-yarn vis-a-vis bamboo fibre presence and yarn count

In this study, the thermal properties of 100% cotton, 50/50 cotton/bamboo and 100% bamboo single jersey fabrics with differing yarn linear density are evaluated and analysed. The linear densities of the yarns composing the fabrics are 20^s, 25^s, 30^s Ne_c and the twist level in the yarns is kept the same. An increasing the presence of bamboo fibre in the fabric causes a reduction in fabric thickness and GSM for all linear densities of yarn. Air permeability and water-vapour permeability also increase with increase in bamboo fibre content while both thermal conductivity and thermal resistance show a decreasing trend. As the constituent yarn gets finer, fabric air and water-vapour permeability both increase in value while the thermal conductivity falls.     

'Fab-chips': a versatile, fabric-based platform for low-cost, rapid and multiplexed diagnostics

Low cost and scalable manufacture of lab-on-chip devices for applications such as point-of-care testing is an urgent need. Weaving is presented as a unified, scalable and low-cost platform for the manufacture of fabric chips that can be used to perform such testing. Silk yarns with different properties are first selected, treated with the appropriate reagent solutions, dried and handloom-woven in one step into an integrated fabric chip. This platform has the unique advantage of scaling up production using existing and low cost physical infrastructure. We have demonstrated the ability to create pre-defined flow paths in fabric by using wetting and non-wetting silk yarns and a Jacquard attachment in the loom. Further, we show that yarn parameters such as the yarn twist frequency and weaving coverage area may be conveniently used to tune both the wicking rate and the absorptive capacity of the fabric. Yarns optimized for their final function were used to create an integrated fabric chip containing reagent-coated yarns. Strips of this fabric were then used to perform a proof-of-concept immunoassay with sample flow taking place by capillary action and detection being performed by a visual readout.     

Modification of Acrylic Fibers: An Overview

Abstract

Among the vinyl monomers, acrylonitrile is the only monomer used for the production of synthetic fibers. Other vinyl monomers lack cohesive forces between the molecular chains of their polymers and, hence, can not compete with acrylonitrile [1]. Acrylic fiber has replaced wool in many major applications, particularly in hand knitting and hosiery garments. The majority of knitting yarns are usually bulky yarns which go into the manufacture of pullovers, sweaters, socks, etc. Acrylic fiber has been able to replace wool considerably in these applications. Blankets and carpets are other applications where acrylic fiber competes with wool [2] because of its high elasticity, color brilliancy, volumenosity, easy shampooing, resistance to pilling, good light and colorfastness values, etc.     

Measurement of fiber blend variability by activation analysis

The modern trend in textiles is to blend various fibers having different fiber properties to produce yarn and fabric with certain desired physical and chemical properties. The quality of blended yarn and the resulting fabric depends upon the uniformity of blending. In spinning yarns from blends of two or more staple fibers there is no convenient method of measuring the variability of each fiber. It was demonstrated that activation analysis could be used to measure the lengthwise variability of polyester fiber in a cotton-polyester blend at each step of the spinning process.     

丙烯腈-衣康酸基纳米纤维纱线的热稳定及碳化研究

碳纳米纤维主要以聚丙烯腈(PAN)作为前驱体,通过纺丝、热稳定、碳化等后处理工艺制备而得。但是,PAN基纳米纤维取向度低、致密性差,热稳定后环化度低,碳化后导电性差等缺点阻碍其在高性能碳纳米纤维领域的发展。因此,在PAN分子链中引入衣康酸(IA),通过溶液聚合法合成了P(AN-co-IA)共聚物并通过静电纺丝法制备了P(AN-co-IA)基纳米纤维纱线。研究了纱线中纳米纤维的取向度、致密性以及在热稳定后的环化反应程度。重点研究了P(AN-co-IA)基碳纳米纤维纱线的线电阻、微观结构与碳化温度的关系。用扫描电子显微镜(SEM)对纱线进行形貌表征。用X-射线衍射仪(XRD)、傅里叶显微红外仪(FT-IR)、拉曼光谱仪(Raman)对纱线进行结构分析。结果表明,P(AN-co-IA)基原丝纱线的结构较致密,取向度较高。热稳定后的P(AN-co-IA)基纳米纤维的环化度高于PAN基纳米纤维。当碳化温度升至1100℃时,P(AN-co-IA)基碳纳米纤维纱线的线电阻明显降低至14Ω/cm。当碳化温度继续升高至1400℃,纱线的线电阻没有明显变化,但通过Raman光谱分析其无序碳结构会大幅增加。本文的研究结果为制备高取向性、高致密性和高电导性的碳纳米纤维纱线提供了一定的理论及实验基础。     

Treatment of bleached wool with trans-glutaminases to enhance tensile strength, whiteness, and alkali resistance

Trans-glutaminases is known as a cross-linking enzyme for proteins. Wool is a proteinous fiber conventionally is treated through several processes to obtain the desirable characteristics. Bleaching is also one of the most important processes usually carried out by using an oxidizing agent in a conventional method. The tensile strength of wool yarns was reduced as a consequence of oxidative bleaching. Here, with the help of microbial trans-glutaminases (m-TGases), a novel bleaching process was disclosed in a way to obtain a bleached wool yarn with no significant reduction in the tensile strength. The results confirmed that the bleached wool yarns with H₂O₂ could be modified by m-TGases post-treatment. The m-TGases treatment on the bleached wool yarns improved the tensile strength and whiteness along with the higher alkali resistance.     

A study of the thermal properties of bamboo knitted fabrics

In this research, the thermal properties of bamboo single jersey knitted fabrics have been studied in relation to stitch length and yarn linear density in tex. The objective was to determine the influence of fabric factors like stitch length and the constituent yarn linear density on fabric properties, such as air permeability, thermal conductivity, thermal resistance and relative water vapour permeability. Yarns with linear densities of 19.6, 23.6, 29.5 tex and with the same twist level were used to construct the fabrics of single jersey structure with stitch lengths of 0.27, 0.29 and 0.31 cm. The anticipated increase in air permeability and relative water vapour permeability with decrease in yarn linear density and increase in stitch length was observed. The thermal conductivity and thermal resistance tended in general to increase with constituent yarn linear density but decreased with increase in stitch length.     

Synthesis of high performance,conductive PEDOT‐coated polyester yarns by OCVD technique

Production of high performance conductive textile yarn fibers for different electronic applications has become a prominent area of many research groups throughout the world. We have used oxidative chemical vapor deposition (OCVD) technique to coat flexible and high strength polyester yarns with conjugated polymer, poly(3,4‐ethylenedioxythiophene) (PEDOT) in presence of ferric (III) chloride (FeCl₃) oxidant. OCVD is an efficient solvent free technique used to get uniform, thin, and highly conductive polymer layers on different substrates. In this paper, PEDOT‐coated polyester (PET) yarns were prepared under specific reaction conditions, and the electrical, mechanical and thermal properties were compared to previously studied PEDOT‐coated viscose yarns. Scanning electron microscopy (SEM) and FT‐IR analysis revealed that polymerization of PEDOT on the surface of the polyester yarns has been taken place successfully and structural analysis showed that PEDOT has strong interactions with viscose yarns as compared to PET yarns. The voltage–current (V–I) characteristics showed that PET yarns are more conductive than PEDOT‐coated viscose yarns. The variation in the conductivity of PEDOT‐coated yarns and the heat generation properties during the flow of current through coated yarns for longer period of time, was studied by time–current (t–I) characteristics. Thermogravimeteric analysis (TGA) was employed to investigate the thermal properties and the amount of PEDOT in PEDOT‐coated PET yarns compared to PEDOT‐coated viscose. The effect of PEDOT coating and ferric (III) chloride concentration on the mechanical properties of coated yarns was evaluated by tensile testing. The obtained PEDOT‐coated conductive polyester yarns could be used in smart clothing for medical and military applications. Copyright © 2011 John Wiley & Sons, Ltd.     

Microfluidics made of yarns and knots: from fundamental properties to simple networks and operations

We present and characterize cotton yarn and knots as building blocks for making microfluidic circuits from the bottom up. The yarn used is made up of 200-300 fibres, each with a lumen. Liquid applied at the extremity of the yarn spontaneously wets the yarn, and the wetted length increases linearly over time in untreated yarn, but progresses according to a square root relationship as described by Washburn's equation upon plasma activation of the yarn. Knots are proposed for combining, mixing and splitting streams of fluids. Interestingly, the topology of the knot controls the mixing ratio of two inlet streams into two outlet yarns, and thus the ratio can be adjusted by choosing a specific knot. The flow resistance of a knot is shown to depend on the force used to tighten it and the flow resistance rapidly increases for single-stranded knots, but remains low for double-stranded knots. Finally, a serial dilutor is made with a web made of yarns and double-stranded overhand knots. These results suggest that yarn and knots may be used to build low cost microfluidic circuits.     

Influence of fabric geometry on yarn pull‐out property and wear performance of hybrid S‐glass/PTFE fabric‐reinforced composites

The friction states between yarns affect the stress transferred in fabric and the fabric structure significantly affects the tribological properties of composites. In this aricle, the effects of fabric structure on yarn pull‐out property and tribological performance of composite were thoroughly studied. Four different fabrics with same tissue cycles number and thread count (2/2 double twills, 1/3 twill, 4‐shaft satin, and 4‐shaft reinforced satin) were used to evaluate the yarn pull‐out property in fabric and the tribological performance of corresponding composites. The results indicate that fabric structure has a significant effect on the yarn pull‐out property in fabric. In particular, the yarn pull‐out property of 4‐shaft reinforced satin was best in the four fabrics structure used in this article owing to the excellent integrity of the 4‐shaft reinforced satin fabric structure and the distribution characteristics of the fabric intersection points. The tribological performance of the 4‐shaft reinforced satin fabric enhanced composites were positively correlated with yarn pull‐out property because the yarn pull‐out property in fabric played an important role in energy dissipation and load carry capacity.     

The Application of High-Modulus Fibers to Ballistic Protection

A new family of experimental organic fibers (X-500) produced by the Monsanto Research Corporation has been evaluated ballistically. The development of this family of fibers made available for the first time a series of organic fibers with moduli and heac resistance more nearly comparable to inorganic fibers such as glass. Tensile analysis of three material types tested in yarn form at conventional loading rates showed physical properties ranging from typically brittle (10.1 g, den tenacity, 2.4% extension, and 550 g, den modulus) to moderately ductile (5.4 g, den tenacity, 15.4% extension, and 135 g/den modulus).

The three samples were evaluated ballistically in fabric, felt, and laminate form. The most ductile sample (Type III) showed considerable promise with a ballistic resistance significantly greater than normal for a material of such modest tensile strength. Tensile recovery tests on this Type-III material showed a large amount of permanent set compared to most commercially available yarns. It appears that this capacity for plastic flow, combined with the inherent high modulus, act in combination to provide good energy absorption.

Scanning electron micrographs of ballistic missile impact areas showed for the more brittle yarns, longitudinal splitting with little evidence of plastic deformation, or fusion of fibers around the hole produced by the missile. The more ductile yarns exhibited a combination of some longitudinal splitting with plastic deformation and fusion around the hole. This latter combination of energy absorbing mechanisms proved to more effective.     

碳纤维三向织物/环氧树脂复合材料的制备与力学性能

选择不同纱线间距[即二经(纬)纱之间的中心距]尺寸的碳纤维三向织物, 采用热压成型技术制备了碳纤维三向织物/环氧树脂复合材料. 研究了纱线间距及样品裁剪角度等对力学性能的影响, 并与碳纤维二向织物/环氧树脂复合材料的力学性能进行对比. 结果表明, 随着纱线间距尺寸从2 mm增加到6 mm, 0°方向断裂强度从221.7 MPa下降到148.1 MPa, 撕裂强力从1000 N下降到600 N; 90°方向断裂强度从50.0 MPa下降到22.1 MPa, 撕裂强力从330 N下降到100 N; 顶破强力从424 N下降到216 N. 这些力学性能的逐渐降低是单位面积的碳纤维增强体含量减少和织物的孔洞增大共同作用的结果. 纱线间距为2 mm的碳纤维三向织物复合材料在0°(以纬纱为基准), 30°, 45°, 60°和90°方向的断裂强度分别为221.7, 48.5, 44.3, 227.7和50.0 MPa, 即断裂强度在0°和60°方向大于在30°, 45°及90°方向. 由三向织物的编织原理可知, 0°与60°方向完全相同, 因此其断裂强度相似, 且样品中有一组纱线与外加载荷平行, 对形变破坏具有一定的约束作用, 而30°, 45°和90°方向样品中三组纱线所在的方向均和外加载荷存在一定的夹角, 有效分散外加载荷的能力减弱. 对比碳纤维三向织物/环氧树脂复合材料与碳纤维二向织物/环氧树脂复合材料的断裂强度、 撕裂强力和顶破强力发现, 前者的综合性能明显优于后者, 碳纤维三向织物/环氧树脂复合材料的断裂强度、 撕裂强力、 顶破强力分别为221.7 MPa, 1000 N和424 N, 三向织物的优势得到凸显, 为后续制备多种类型的碳纤维三向织物复合材料及应用奠定了基础.     

Advanced polymeric composites via commingling for critical engineering applications

The commingled technology is one of the most effective and alternative methodologies for producing more sustainable as well as uniformly distributed natural fiber reinforced composite without inflecting the shearing strength on yarns or reinforcing natural fiber. The term commingled encompasses the materials consisting of both polymer matrix and reinforcing materials over the same fabric cross-section used for the production of highly flexible, continuous fiber-reinforced thermoplastic prepregs. Nonetheless, the increased pathlength and high melt viscosity around 500–5000 Pa s of the molten thermoplastic makes the processing more difficult compared with other thermoset plastic (usually 100 Pa s). Where the commingled hybrid yarns can be considered as one of the promising preforms employed for long fiber reinforced composite because of low cost, ease of storage and manipulation, excellent flexibility, molding capacity, reduced pressure consolidation as well as impregnation time while processing and the ability to form complex-shaped reinforced composite parts. The parameters that affect the process of commingling controls the consolidation of hybrid yarns thermoplastic composite; the degree of commingling depends on the pressure, temperature, and production speed during a fixed period. Recently commingled thermoplastic composite has become one of the possible destines for a wide array of applications in aircrafts, automotive, and sporting goods. This paper reviews types of commingled plastic composite, various processing routes, and the influence of the processing parameters, their properties, and their application. The manufacturing and development of hybrid yarns through air-jet texturing, intermingling process, are also discussed concerning the attributes of advanced composites.     

Laundry process intensification by ultrasound

In domestic textile laundering processes, mass transfer and mass transport are often rate limiting. Therefore, these processes require a long processing time, large amounts of water and chemicals, and they are energy consuming. In most of these processes, diffusion and convection in the inter-yarn and intra-yarn pores of the fabric are limiting mass transport mechanisms. Intensification of mass transport, preferentially in the intra-yarn pores, is the key in the improvement of the efficiency of wet textile processes. Conventional methods of intensification of mass transport (e.g. operation at elevated temperatures) are not always feasible due to the undesired side effects such as fabric damage. Increasing the flow rate does not deliver the desired effect due to the multi-porous complex structure of textile materials. Van der Donck et al. [Tenside Surf. Det. 35 (1998) 119; 36 (1999) 222] reported that the deformation of yarns by placing a fabric in a pulsating flow or repeated mechanical elongation of the yarns improved mass transport. However, the additional mass transport caused by deformation is limited in practice. Power ultrasound is a promising technique to accelerate mass transport in textile materials. Several papers appeared in this field, which report an improvement in energy efficiency and processing time of the wet textile processes in the presence of ultrasound. In this paper, the different time and length scales are discussed in the intensification of the mass transport in laundry processes in the presence of ultrasound and compared with more conventional processes. It has been concluded that the characteristic mass transport rates in textiles can be increased by a factor of 6 applying ultrasound.     

Effect of nano-fillers on conductivity of polyethylene/low melting point metal alloy composites

A novel method for preparing conductive polyethylene(PE) composites has been developed. In the method, the powder of low melting point metal alloy(LMPA) is filled into the PE matrix by using twin screw extruder at a temperature below the melting point of the LMPA, and followed by a die drawing process at a temperature around the melting point of the metal alloy. It has been found that die drawing process, repeating the die drawing process and adding nano-fillers, such as montmorillonite(MMT) and multi-wall carbon nanotubes(MWCNTs), all help reduce the metal particle size in the PE matrix, thus improve the conductivity of the composite. The conductivity improvement is attributed to an increased number of the smaller metal particles. Therefore, conductive composites of polymer/metal alloy/nano-filler with high conductivity are possible to be prepared by using the new method.     

Investigation of the dyeing properties of cotton fabrics and wool yarns using Prunus persica leaf extract

In this study, the dyeing properties of cellulose fabric and wool yarn were investigated using Prunus persica (Peach) leaf extracts. For this concept, the cotton fabrics and wool yarns were subjected to pre–, meta– and post– mordanting processes in the presence of FeSO₄, CuSO₄ and AlK(SO₄)₂ mordants. The studies were carried out using medium pH. Color analyses of the dyed samples were done and the results were evaluated in terms of wash, rubbing and light fastness values. The color codes were determined with Pantone Color Quide, and K/S and L1 a1 b1 values were detected with color measurement spectrophotometer, and also washing–, crocking– fastness levels were evaluated using gray scale. As a result, it was detected that wool yarns exhibited better dyeing potential than cotton fabrics and highest color strength values were obtained using pre–mordanting method. For wool yarns, high color strength were achieved in the presence of AlK(SO₄)₂ mordant.     

Effect of Blending Factors on Eri Silk and Cotton Blended Yarn and Fabric Characteristics

Eri cocoons were prepared into short fibers and subsequently blended with cotton fiber in order to develop the new fiber blended yarn in the short spinning system. The Eri and cotton fibers were blended using the drawframe blending with varying blending factors, viz. blending composition (0–100%) and yarn counts (30 and 50 tex). The results showed that Eri fiber which was longer and stronger than cotton fiber, affected the fiber distribution in the yarn cross-section. The mechanical properties of the blended fibers and yarns increased with increasing silk content. Longer fibers of Eri silk tended to move towards the yarn core, especially at silk content higher than 50%. Moreover, stronger and more extensible Eri silk fiber gave an advantage to the improvement of mechanical properties of those blended yarns with silk content higher than 50%. However, with increasing silk content, the blended yarns were more irregular as shown in %CV. Concerning the yarn count effect, the higher yarn count of 50 tex resulted in a more regular yarn with higher yarn strength than that of 30 tex. The plain-woven fabrics were prepared using the blended yarns as a weft yarn and the cotton yarn or silk yarn as a warp yarn. The mechanical properties of those woven fabrics were characterized in order to study the influence of silk contents. The results showed that tensile strength, %elongation and tear strength of woven fabrics using the blended yarn were increased with an increase in silk content. This is an advantage of Eri silk in the aspect of rendering the strength to the blended yarns and fabrics.     

Fabrication of a Simple and Cheap Screen-printed Silver/Silver Chloride (Ag/AgCl) Quasi-reference Electrode

In this work, a silver/silver chloride ink is fabricated using two steps. First the silver ink is prepare using silver, nail polish and acetone. Then the silver ink is painted in a paper substrate and a silver chloride layer is deposited using a bleach solution. The result is the silver/silver chloride conductive ink. The silver ink is cheap ($2.49/g), well-dispersive and very easy to fabricate. The materials were characterized by SEM and XRD. The Ag ink showed the formation of a continuous network throughout the silver ink film with fewer agglomeration. The effective chlorination process was also observed in the Ag/AgCl characterization. Since the Ag/AgCl substrate will be used as a quasi-reference electrode, it is important to investigate the electrical properties. The Ag ink showed an average ohmic resistance of 2.27 Ω. The addition of the AgCl layer decreases the conductivity, as expected. In summary, the Ag/Ag/Cl ink developed is simple, well-dispersed, cheap and with good conductivity. Therefore, it can be used as a conductive ink in the fabrication of quasi-reference electrodes.     

Compression resilience and impact resistance of fiber‐reinforced sandwich composites

This paper presents an experimental investigation on the compression behavior of fiber‐reinforced sandwich composites. In this study, five different types of sandwich composites were prepared with warp knitted spacer fabric as middle layer. Four different types of woven Kevlar fabric structures were used as outer layers (skin) along with one sample of woven basalt fabric. The middle layer used is 100% polyester spacer fabric. Sandwich composites were fabricated using epoxy resin by wet lay‐up method under vacuum bagging technique. Compression behavior, ball burst, and knife penetration were tested for all samples. The effect of outer layer of these composites on the mechanical performance was studied using the compression stress‐strain curves. It is known that spacers have excellent compression elasticity and cushioning. Maximum knife penetration resistance is obtained with twill weave on surface because of maximum yarn cohesion and resin impregnation. Higher amount of cohesive friction results in higher resistance against penetration of sharp objects like the knife edge. Plain and twill fabrics offer sufficient resistance again ball burst. The yarn deformation allows formation of dome shape after ball impact. Maximum impact resistance in ball burst is obtained for plain weave because of highest level of interyarn binding. The results provide new understanding of knitted spacer fabric‐based sandwich composites under compression and impact loading condition.     

Silicon nanowire fabric as a lithium ion battery electrode material

A nonwoven fabric with paperlike qualities composed of silicon nanowires is reported. The nanowires, made by the supercritical-fluid-liquid-solid process, are crystalline, range in diameter from 10 to 50 nm with an average length of >100 μm, and are coated with a thin chemisorbed polyphenylsilane shell. About 90% of the nanowire fabric volume is void space. Thermal annealing of the nanowire fabric in a reducing environment converts the polyphenylsilane coating to a carbonaceous layer that significantly increases the electrical conductivity of the material. This makes the nanowire fabric useful as a self-supporting, mechanically flexible, high-energy-storage anode material in a lithium ion battery. Anode capacities of more than 800 mA h g(-1) were achieved without the addition of conductive carbon or binder.