The effect of the acid/dithionite/peroxide treatments on reactively dyed cotton and indigo dyed denim and the implications for waste cellulosic recycling

Abstract

Previous studies have established that the application of crosslinking dyes and easy care finishes to cotton can significantly reduce the dissolution of waste cotton in swelling solvents and limit potential recycling of cellulosic materials through Lyocell fibre regeneration process. In this study, a sequential hydrolysis/reduction/oxidative treatment was investigated as a potential method to completely strip all types of reactive dye chromophores from cotton. It was established that the treatment could completely strip off colours from the reactively dyed fabrics and post-consumer denim jeans fabric resulting in a white, NMMO-dissolvable cellulosic material, which could be used as a feedstock for Lyocell fibre regeneration. The white cellulose had an acceptable degree of polymerisation and the regenerated fibres had structural and mechanical properties similar to those of fibres regenerated from conventional wood pulp. Blending conventional wood pulp and recycled cotton pulp allowed manufacturing of regenerated Lyocell-type fibres with acceptable properties.     

Cotton in the new millennium: advances,economics, perceptions and problems

Cotton is the most significant natural fibre and has been a preferred choice of the textile industry and consumers since the industrial revolution began. The share of man-made fibres, both regenerated and synthetic fibres, has grown considerably in recent times but cotton production has also been on the rise and accounts for about half of the fibres used for apparel and textile goods. To cotton’s advantage, the premium attached to the presence of cotton fibre and the general positive consumer perception is well established, however, compared to commodity man-made fibres and high performance fibres, cotton has limitations in terms of its mechanical properties but can help to overcome moisture management issues that arise with performance apparel during active wear.

This issue of Textile Progress aims to:

1. Report on advances in cotton cultivation and processing as well as improvements to conventional cotton cultivation and ginning. The processing of cotton in the textile industry from fibre to finished fabric, cotton and its blends, and their applications in technical textiles are also covered.

2. Explore the economic impact of cotton in different parts of the world including an overview of global cotton trade.

3. Examine the environmental perception of cotton fibre and efforts in organic and genetically-modified (GM) cotton production. The topic of naturally-coloured cotton, post-consumer waste is covered and the environmental impacts of cotton cultivation and processing are discussed. Hazardous effects of cultivation, such as the extensive use of pesticides, insecticides and irrigation with fresh water, and consequences of the use of GM cotton and cotton fibres in general on the climate are summarised and the effects of cotton processing on workers are addressed. The potential hazards during cotton cultivation, processing and use are also included.

4. Examine how the properties of cotton textiles can be enhanced, for example, by improving wrinkle recovery and reducing the flammability of cotton fibre.

     

THE FASHION CONSUMER IN THE GLOBAL MARKETPLACE

Abstract

This monograph traces the various means by which flax fibre is transformed into linen yarns and fabrics. The principal innovations and developments of the past fifty years are identified. An extensive range of relevant literature is reviewed. Details are given of how the fibre is extracted from the stem of the flax plant and of the stages of yarn and fabric production. An explanation is given of how yarns are produced from short fibres (known as tow) using carding, drafting and dry spinning, and from long fibres (known as line) using hackling, drafting, doubling, roving and wet spinning in warm water. Further areas covered include yarn winding, linen weaving, dyeing and finishing. New applications for flax fibre, beyond traditional uses in apparel or furnishing fabrics, are also identified.     

Effect of Weave Parameters on the Tear Strength of Woven Fabrics

ABSTRACT

The fabric tear strength is an important parameter in textile material, ever since it is close to relate to the service of the fabric. Tear strength of the fabrics depends on the flexibility of the yarn in fabric structure. In this research, the tear strength of 11 cotton woven fabrics is analyzed based on the weave parameters such as crossing over firmness factor (CFF), Floating Yarn Factor (FYF), Fabric Firmness Factor (FFF) and weave factor (P1).     

32—THE SURFACE ABRASION OF COTTON FABRICS AS SEEN IN THE SCANNING ELECTRON MICROSCOPE

Experiments are described in which cotton fabrics at different stages of chemical processing were abraded to different extents on a Wira Abrasion Tester with three different abradants, namely, a smooth paper, a similar paper with a rough unfinished surface, and a standard worsted fabric. The three different plain-weave cotton fabrics selected were (a) desized and scoured, (b) bleached and mercerized, and (c) dyed and resin-treated. Scanning electron microscopy revealed that progressive chemical finishing, especially resin-finishing, reduced the abrasion-resistance of these fabrics. The rate of attrition of the cellulosic material at the surface of the fabric was much faster for rough paper than for a smoother type of paper abradant. The crossbred-worsted abradant was less severe than paper in its abrasive action. It also produced, in general, a more fuzzy fabric surface, with several loose fibre ends on the surface. Resin-treated fabrics had fewer of these loose surface fibres than the other two samples, particularly the scoured fabric, which had the most. In the resin-treated fabric, the abraded single fibre ends did not exhibit any twisting, whereas this characteristic feature was rather extensive in the non-resin-finished samples. The lack of twisting and rolling of the fibres probably arose from the constraints imposed by the resin crosslinks, which made the fibres more rigid and caused them to tend to fracture or rupture sharply rather than fibrillate over a somewhat extended length.     

Permeability properties of single jersey fabrics made of hollow yarns

In this work effect of using hollow yarns on the permeability properties of the single jersey knitted fabrics were studied. Firstly yarns were produced by ring spinning machine using cotton, viscose and acrylic fibres in the mantle and water soluble polyvinyl alcohol (PVA) fibre in the core. Single jersey fabrics were knitted and PVA core was removed subsequently by washing process to create hollow yarn. Weight, air permeability and water transmission rate properties of fabrics were measured before and after washing and compared with reference fabrics. Due to the removal of PVA fibres from the yarn core after washing treatment, air permeability and water vapour transmission rate of the all kind of single jersey fabrics which were produced with hollow yarns increased as well as weight of the fabrics decreased which will cause more comfort during any exercise. It was also found that mantle fibre type and PVA ratio have significant effect on the fabric properties.     

Ag nanoparticles-coated cotton fabric for durable antibacterial activity: derived from phytic acid–Ag complex

Abstract

This study focuses on the preparation of functional cotton with high and durable antibacterial activity by in situ formation of Ag nanoparticles (NPs) onto cotton fabric derived from phytic acid-Ag complex. The route can be divided into two simple steps, adsorption of silver ions onto cellulose matrix with phytic acid as a capture agent and subsequent reduction of Ag⁺ to Ag NPs by sodium borohydride. The successful deposition of Ag NPs on cotton fabric was verified by SEM, EDS and XPS. The bacterial reduction rate against E. coli and S. aureus for the as-treated fabrics was above 99%, even after 10 laundry cycles. The phytic acid was found of benefit to distribution and bonding of silver on the cotton fabric, which might lead to the enhancement of antibacterial property and durability against wash. This study may provide a green, novel and simple strategy to manufacture Ag-based antibacterial cotton for potential applications in textile industry.     

Study on effect of blend ratio on thermal comfort properties of cotton/nylon-blended fabrics with high-performance Kermel fibre

This study presents the thermal comfort properties of woven fabrics made of Kermel, cotton/nylon and cotton/nylon /Kermel-blended yarns. Our aim in this study is to combine the high comfort properties of cotton/nylon fibres with high thermal protective properties of Kermel fibre in different woven fabrics. Thus, Kermel (100%), cotton/nylon (50:50) and four blends of the 50% cotton fibres with nylon and Kermel (40:10, 30:20, 20:30 and 10:40) were spun on a ring-spinning frame and twisted into two-folded yarns with the same yarn count of 30/2(Ne) and twist level of 560 TPM. Using the produced yarns, woven fabrics with identical characteristic and structure were also produced. Then, the thermal comfort and physical properties of fabrics were studied in terms of fabric porosity, thermal resistance, thermal conductivity, water vapour resistance and air permeability. The results show that the porosity, air permeability and thermal resistance increase with Kermel fibre blend ratio. Conversely, the water vapour resistance decreases with increase of Kermel fibre blend ratio up to 40%, while 100% Kermel-woven fabric exhibits a higher water vapour resistance value. Nevertheless, the thermal conductivity of cotton/nylon-blended Kermel woven fabric is unchanged with increase of Kermel fibre blend ratio up to 40%, whereas at 100% Kermel fibre blend ratio, the lowest thermal conductivity is obtained. The obtained results implied that woven fabric produced from cotton/nylon (50/10) blended with 40% Kermel fibre resulted in proper thermal comfort properties.     

Structure of Naturally Coloured Cottons

Previous work on the morphology of naturally coloured green cottons has suggested that the secondary wall of the fibres consists of alternate layers of cellulose and a waxy organic substance called suberin. The work described in this paper has shown that modem varieties of green cotton do contain a large proportion of suberin. Data from fibre swelling is consistent with alternate layers of suberin and cellulose in the secondary wall. The naturally coloured fibres have a lower tenacity and work of rupture than conventional white fibres although they have an acceptable level of textile properties. The crystallinity of the coloured fibres is lower than of white cotton, but the cellulose has the Cellulose I structure normally found in cotton.     

Improved Methods of Determining Fibre Density

An account is given of an investigation of the effects of fibre type (rayon, acrylic fibre, wool, and cotton) and dimensions on the properties of needled fabrics, the test methods used being those described in a previous paper. Some fabrics show a stick-slip behaviour in extension; others deform smoothly. Rayon webs consolidate more easily on needling than Courtelle or wool webs. Longer fibres give higher fabric strengths. Finer fibres also give higher strength, unless fibre damage occurs. The influence of fibre friction is discussed.     

废旧聚酯纤维制品近红外定量分析模型的建立及验证

为解决废旧纺织品回收利用中纯聚酯的分拣问题,以聚酯、棉、锦纶、羊毛、聚酯/ 棉混纺、聚酯/ 锦纶混纺、聚酯/ 羊毛混纺织物共计276 个样品为研究对象,利用近红外光谱仪获取样本的原始近红外光谱图,通过化学计量学软件CM-2000 对样本原始近红外光谱图进行预处理,并用偏最小二乘法作为校正方法建立废旧聚酯纤维制品近红外定量分析模型。所建模型的校正集相关系数为0.994,验证集相关系数为0.989,校正标准偏差为1.832,验证标准偏差为2.065,内部预测正确率为90.58%。用未参与建模的173 个样本（7 种织物）对模型进行外部验证,验证正确率为88.44%,而对纯聚酯样本的外部预测正确率可达96%。结果表明,该模型可以较准确地将纯聚酯织物从废旧纺织品中鉴别出来。     

Studies on cotton-acrylic bulked yarns produced from different spinning technologies. Part II: fabric characteristics

The present work is concerned with the study of the characteristics of plain woven fabric produced with cotton-acrylic high-bulk yarns from different spinning technologies. The effects of different factors, namely spinning technologies (ring, rotor and DREF-II, i.e. Group A fabrics), position of shrinkable acrylic feed sliver in DREF-II friction spinning system (Group B fabrics) and proportion of shrinkable acrylic core fibre in core-sheath type DREF-III friction spun yarns (Group C fabrics) on various properties of cotton-acrylic blended bulked yarn fabrics have been reported. The influence of these three variables on the mechanical, handle and comfort properties of fabrics have been studied. The properties of fabrics made of bulked yarns from different spinning technologies are found to be different from the normal 100% cotton yarn fabrics in all respect. Even though the bulked yarns were used only in weft direction, the fabrics with modified yarn structures show appreciable improvement in thermal resistance, moisture vapour transmission, wicking and air permeability. The bending rigidity of the fabrics in weft direction also reduced with improvement in crease recovery in weft direction.     

Plasma technology in wool

The textile industry processes a large quantity of fibres obtained from various animals of which wool is commercially the most important. However, it has some technical problems which affect the quality and performance of the finished products such as felting shrinkage, handle, lustre, pilling and dyeability. These problems may be attributed mainly to the presence of wool scales on the fibre surface. The scales are relatively hard and have sharp edges which are responsible for causing fibre directional movement and shrinkage during felting. Furthermore, the scales also serve as a barrier for diffusion processes which will adversely affect the sorption behaviour. In recent years, there has been an increase in the modification of wool surface scales by physical means such as mechanical, thermal and ultrasonic treatments, and chemical methods such as oxidation, reduction, enzyme and ozone treatments which can solve the felting and sorption problems to a certain extent. Hitherto, chemical treatments are still the most commonly used descaling methods in the industry.

Owing to the effect of pollution caused by various chemical treatments, physical treatments such as plasma treatment have been introduced recently as they are capable of achieving a similar descaling effect. Since the 1960s, scientists have successfully exploited plasma techniques in materials science. The plasma technologies have been fully utilised to improve the surface properties of fibres in many applications. The fibres that can be modified by plasmas include almost all kinds of fibre such as textile fibres, metallic fibres, glass fibres, carbon fibres, fabrics and other organic fibres.

Plasma-treated wool has different physical and chemical properties when compared with the untreated one. The changes in fibre properties alter the performance of the existing textile processes such as spinning, dyeing and finishing to produce a series of versatile wool products with superior quality. Therefore, the aim of this monograph is to give a critical appreciation of the latest developments of plasma treatment of wool. In this monograph, different surface treatments of wool including plasma treatment will be precisely described. Since plasma treatment can be used to alter material surfaces by removing outer layers, thus the method of generation of plasma and the reaction mechanisms between material surface and plasma species will be highlighted in this monograph. Similar to other chemical reactions, the factors such as (i) the nature of gas used, (ii) gas flow rate, (iii) system pressure and (iv) discharge power affecting the final results of plasma treatments will be described.

The main content of this monograph includes the application of plasma treatment on wool under different industrial conditions such as dyeing and shrinkproofing processing which will be reported and discussed respectively. In addition, the common analytical methods such as Scanning Electron Microscopy, X-ray Photoelectron Spectroscopy and Fourier Transform Infrared Spectroscopy with Attenuated Total Internal Reflectance mode analysis employed for characterising the surface properties of plasma-treated wool will be discussed. Based on the surface characterisation results, more details about the mechanism of plasma treatment that affects the wool processing such as dyeing and shrinkproofing can be explored.

In the latter part of the monograph, the serviceability of plasma-treated wool fabrics is discussed and the possibility of applying the plasma-treated wool fabric to industrial use is evaluated based on standard performance specification, e.g. ASTM. The fabric performance in terms of tailorability and sewability are also discussed with reference to the Kawabata Evaluation System for Fabric (KES-F) results. As the plasma process is a “dry” process, i.e. the water used in the plasma system can be recycled, thus it can solve the industrial effluent problem resulting in providing an effective means for the modification of wool fabrics.     

Polylactic acid/lyocell fibre as an eco-friendly alternative to polyethylene terephthalate/cotton fibre blended yarns and knitted fabrics

Abstract

Polylactic acid (PLA) and lyocell fibres blend can offer an eco-friendly alternative to commonly employed blend of polyethylene terephthalate (PET) and cotton fibres in textiles. PET fibre is non-biodegradable and depletes fossils fuels and adds to landfill sites whereas conventional cotton, dominant part of global cotton production, requires large quantity of water and pesticides during its production. In this study, 100% PLA, 100% lyocell and PLA-lyocell (PL) blended yarns, in varying ratios, were ring spun and subsequently weft knitted and compared with the PET/cotton blend (50/50). The yarns were evaluated for tensile properties while the fabrics were investigated for bursting strength, bending length, pilling propensity, water vapour resistance, thermal resistance and air permeability. The economic comparisons of the two blends were also included. The results indicated that comparatively PL blends (in particular lyocell fibre rich blends) can offer environmental and performance advantages compared to PC blended knitted fabrics for casual summer clothing and active wear.     

Polypyrrole-Coated Conductive Cotton Prepared by Laccase

Conductive cotton fabric was prepared using laccase as catalytic agent, pyrrole as electric monomer and paratoluene sulfonic acid sodium salt as dopant. The electric resistance of the prepared conductive cotton fabric was 1.22 × 10⁷ Ω compared to 3.11 × 10¹¹ Ω of the original cotton fabric. The abrasion test indicated that polypyrrole was well integrated with the cotton fibers. The conductive cotton fabric also had good antistatic performance and good UV shield capability at 280–400 nm compared to the original cotton fabric. Moreover, the coating of polypyrrole improved the thermo-decomposition behavior of cotton fabrics. Nevertheless, the prepared conductive cotton fabric preserved the same breaking strength as the original cotton fabrics. Compared with original cotton, conductive cotton showed lower gas permeability.     

Effect of blend proportion on thermal behaviour of bamboo knitted fabrics

This study presents the thermal comfort properties of single jersey knitted fabric structures made from cotton, regenerated bamboo and cotton–bamboo blended yarns. Cotton, bamboo fibre and blends of the two fibres (100% cotton, 100% bamboo, 50:50 cotton:bamboo, 67:33 cotton:bamboo, 33:67 cotton:bamboo) were spun into yarns of identical linear density (20?tex). Each of the yarns so produced was converted to single jersey knitted fabrics with loose, medium and tight structures. The thermal conductivity of the fabrics was generally found to decrease with increase in the proportion of bamboo fibre. The relative water vapour permeability and air permeability of the fabrics were observed to increase with increase in bamboo fibre content. Statistical analysis also indicates that the results are significant for air permeability, thermal resistance, thermal conductivity and relative water vapour permeability of the fabrics.     

Sustainability and Profitability Through Intelligent Value Chain Management in Bast Fibre Processing

Abstract

The excellent properties of natural fibres like flax and hemp have not yet been fully exploited for high added value applications such as use in bio-based natural textiles and high performance fibres. There are few practical applications, although today's know-how in fibre purification, modification and application allow for a large array of viable bio-based products. Currently the development of these natural fibres is strongly determined by the EU subsidy regulations, which drive the motivation of farmers and processors. Due to the expansion of the European Union, agricultural subsidies will decrease in the next decade. Natural fibres will compete only successfully against these reductions by fulfilling three key factors:

? Product quality: The continuing lack of pure, fine and homogenous fibres has to be overcome.

? Market demand: Market demand is driven by product quality. There is a big and increasing demand for high quality upgraded natural fibres in textile and non-textile industry.

? Price: Farmers and fibre producers must have a reasonable economic basis.

Today the economic situation in the agricultural sector is extremely poor without subsidies. However, with each subsequent processing step in the fibre production value chain (mechanical refining, fibre upgrading by wet refining) the profitability increases significantly. To gain economic sustainability in the whole value chain (including spinning and weaving) the more profitable, high added value processing steps at the end of the chain should be employed to offset the less profitable steps. To realise this, we recommend a contract-network between agriculture, mechanical refining, upgrading and manufacturing of half-finished products. The business, which upgrades fibres, owns the innovative key-processing step (quality drives demand). It will lead the network and market fabrics with higher value and better profit by itself. All partners in the network participate by receiving fair prices. This will also guarantee continuous production of high quality raw material by farmers. A detailed operational calculation of the network shows promising results with a good internal rate of return.     

Reactive Pad-Batch Dyeing in CORONA Discharged Fabrics

Abstract

The present work aims to the study of the increase of pick-up, together with uniformity degree, concerning the application of reactive dyeing baths by padding in a dry cotton fabric previously treated with CORONA discharge.

Dyeing recipes, with and without wetting agent, are compared and advantages of CORONA discharge are analysed. Reactive dyes are used, expecting also to increase washing fastness of the difficult dark colours due to higher penetration of the dye into the core of the fibres when submitted to plasmatic treatment.

The use of CORONA discharge intends to modify hydrophility of cotton fabrics even when they are presented to padding in hydrophobic state. A good alternative to wetting agent presence in recipes is found and more uniform and intense dyeings are performed in all cases.     

废旧棉与涤纶纺织品化学法循环再生利用的研究进展

针对我国废旧纺织品中棉和涤纶制品产量高、循环利用率低、高品质产品少等问题,介绍了化学法循环再生利用废旧棉、涤纶纺织品的方法,分析了废旧棉再生浆粕及其纤维制备技术和废旧涤纶纺织品解聚单体及其再聚合技术的现状。相关研究表明:目前已能采用低比例废旧棉再生浆粕与原生木浆混合的方式实现废旧棉再生Lyocell纤维的小规模生产;采用乙二醇醇解-甲醇酯交换技术可实现废旧涤纶纺织品化学法再生聚酯的万吨级规模生产,但仍存在技术难度大、生产成本高、回收利用率低、产品品质差,且面临“治废产废”程度有待进一步降低等难题;开发废旧棉、涤纶纺织品清洁再生与高值化利用技术是废旧纺织品循环利用的发展趋势。