The Effect of Yarn Twist and Fibre Percentage in Blends on the Dimensional Properties of the Interlock Structure

An account is given of an investigation of the dimensional properties of a series of interlock weft knitted fabrics produced from open-end cotton-polyester blended yarns with different yarn twist, loop length, fibre percentage in blend, and variety of relaxation treatments. A comprehensive experimental analysis shows that the Ks value (stitch density multiplied by the square of loop length) is related to yarn density, fibre percentage in blends, and relaxation treatments. It is also concluded that the correct relaxation state for cotton fabrics to reach the maximum shrinkage is full mechanical relaxation, and for cotton polyester blended and 100% polyester fabrics is chemical relaxation treatment. The empirical results show that the effect of mechanical relaxation decreases as the percentage of polyester in blends increases.     

The Air-permeability Measurement of Open Fabrics by Using Superimposed Fabric Layers

An account is given of an investigation of the dimensional properties of a series of plain weft-knitted fabrics produced from open-end-spun yarns. The results are compared with those for similar fabrics knitted from ring-spun yarns.

It is shown that fabrics knitted from the two types of yarn possess different properties and particularly that the amount of relaxation shrinkage observed in fabrics knitted from open-end-spun yarns is greater than that which occurs in fabrics knitted from ring-spun yarns. The aesthetic properties of fabrics made from open-end-spun yarns are inferior to those of fabrics made from ring-spun yarns, particularly with regard to a lack of stitch clarity and a somewhat harsher handle, although the latter effect is shown to be apparently unrelated to differences in the frictional properties of the two types of yarn.     

46—THE GEOMETRY,DIMENSIONAL PROPERTIES,AND STABILIZATION OF THE COTTON PLAIN-JERSEY STRUCTURE

Dimensional stability in cotton plain-jersey fabrics can be attained by either mechanical-relaxation techniques (consecutive laundering and tumble-drying cycles) or chemical treatments (fabric mercerization without tension). Both treatments cause large linear-dimensional changes (shrinkage) leading to the same final stable condition, that is, to a fixed loop configuration, categorized by unique values of k _c and k _w. Although, for all practical purposes, the ultimate k-values are close enough to constants, they are not entirely independent of fabric tightness (K) and some yarn variables. They are substantially the same as the values found for completely relaxed wool fabrics that have been treated to prevent felting. Geometrical fabric thickness and bulk density are significantly dependent on fabric tightness. Photographic evidence reveals that cotton yarns, like those of wool, bulk in the fabric during relaxation (both mechanical and chemical) to cause changes in ‘cover’. It seems that the fixed loop configuration occurs when bulking leads to a completely ‘jammed’ structure.     

15—EXPERIMENTAL STUDIES OF THE DIMENSIONAL PROPERTIES OF EYELET FABRICS. PART I: THE DIMENSIONAL PROPERTIES OF CLOSE-EYELET COTTON FABRICS

The geometrical parameters of the eyelet structure are related to its loop length in both the dry- and the wet-relaxed states. The effects of the structural characteristics of the stitch on its dimensional properties are discussed. Formulae relating the weight per square yard and weight per running yard to the loop length are given and confirmed experimentally.     

The dimensional and mechanical properties of wool/polyester fabrics made from vortex and ring-spun yarns

Fabric woven from wool/polyester (PES) Murata vortex spun (MVS) blend yarn is a commercially viable proposition particularly on the basis of advantageous wear-resistant properties, compared with fabric made from traditional worsted ring-spun yarn. However, in some early industrial trials with fabric made from 45/55-blend wool/PES MVS yarn, significantly greater relaxation shrinkage was found relative to comparable worsted ring-spun fabric. It was noted at the time that the amount of relaxation shrinkage in MVS fabric could be reduced to a large extent by using steamed MVS yarn.

In this study, the extent of variations in the dimensional and mechanical properties of fabric samples woven from a combination of steamed and unsteamed MVS yarn and equivalent worsted ring-spun yarn is examined. In general, greater hygral expansion and relaxation shrinkage were found in loom-state fabrics made from unsteamed MVS yarns, whereas the fabric made from steamed MVS and ring-spun yarns gave relatively low levels of relaxation shrinkage and hygral expansion. Permanent setting of fabrics, by pressure steaming, was found to be more effective than yarn pre-steaming in reducing relaxation shrinkage levels of fabrics made from unsteamed MVS yarn. After pressure steaming, all fabrics showed similar levels of relaxation shrinkage and hygral expansion.

Permanent setting of the fabrics, by pressure steaming, resulted in similar levels of relaxation shrinkage and hygral expansion, irrespective of the yarn production method; relaxation shrinkage fell to around 1% and hygral expansion increased by about 1%, relative to the loom-state samples. MVS fabrics were relatively heavier and fuller and had a firmer handle than the worsted ring-spun fabrics, reflecting the greater fabric weight, thickness and shear rigidity measured on these fabrics. These attributes are associated with different structures of the worsted ring-spun and MVS yarns used to make the fabrics.     

羊毛畦编针织物尺寸特性分析

通过实验的方法,研究了横机编织的罗纹、半畦编和畦编羊毛针织物的尺寸特性,对3种织物的线圈长度、纵横向水洗收缩率、纵密及横密等各尺寸特性进行了分析与比较,实验得出,由于集圈线圈的存在,半畦编和畦编针织物的尺寸特性显著不同于罗纹针织物.通过建立尺寸变化率公式,计算出畦编织物与罗纹织物尺寸参数间的关系,可用于工厂实际生产设计时参考.     

6—DIMENSIONAL STABILITY OF PLAIN-KNITTED FABRICS

An account is given of a study of the dimensional changes of plain-knitted fabrics brought about by various relaxation treatments. A wide range of natural and synthetic-polymer fibres was encompassed.

It was found that, for synthetic-fibre fabrics, dry tumbling at elevated temperatures causes higher levels of relaxation shrinkage and larger changes in shape than static wet-relaxation treatments, whereas the opposite is true of fabrics produced from hydrophilic fibres. A wet treatment at an elevated temperature is proposed that brings about complete relaxation of all the fabrics investigated. It is only in this completely relaxed state that the loop shape is similar for all the fabrics investigated.     

32—FACTORS AFFECTING THE STABLE DIMENSIONS OF DOUBLE-JERSEY STRUCTURES

An account is given of a study in which the dimensional properties of five popular double-jersey structures, made from shrink-resist-treated worsted yarns and knitted under very different machine conditions at the optimum tightness factor (K = approximately 15), were investigated in various relaxed states, including the fully laundered condition, or the ‘completely relaxed’ stable state. In the initial experiment, the machine variables chosen—take-down tension, stretcher-board width, and dial height—were altered selectively to give the maximum distortion to the structural knitted cell (SKC) at the knitting stage. This experimental procedure was repeated in the second experiment at a variety of run-in ratios (but at the same average K value) for three structures: Punto-di-Roma and Swiss and French double piqué.

Whereas the machine variables markedly influence the linear (i.e., length and width) dimensions of all structures off the machine, and noticeably after steam relaxation, linear dimensions after further relaxation and laundering, although affected by the processing history of the fabric, are close to being equal within a structure. Thus, machine variables only temporarily distort the SKC: after correct relaxation, this distortion is, for all practical purposes, lost. However, the variable run-in ratio does affect the stable linear dimensions, even at a constant fabric tightness, although the magnitude of the effect of the run-in ratio on linear dimensions depends entirely on the structure. Consequently, the stable linear dimensions of double-jersey structures appear to be determined by two parameters: the structural-cell stitch length (l _u) and the run-in ratio. Speculations as to why the run-in ratio affects the stable linear dimensions are presented.     

机织针织复合织物与多层双轴向纬编织物拉伸性能对比

选用玻璃纤维作经纱、纬纱和高强涤纶作针织纱分别编织机织针织复合(CWK)织物和多层双轴向纬编(MBWK)织物,测试两种织物的横向、纵向的拉伸性能,分析比较拉伸负荷和位移特征曲线。研究表明：在拉伸过程中,CWK织物MBWK织物均先由其中的经纱或纬纱,在较低的伸长下,承担较高的负荷,直至经纱或纬纱断裂,然后由针织结构,在较高的伸长下,承担较低的负荷,直至针织结构破坏;经纱和纬纱以交织形式衬入针织结构中,使得CWK织物的轴向的拉伸强度稍低于MBWK织物,但起到一定的“预牵伸”作用,可使针织纱对经纱和纬纱捆绑效果更好。     

Measuring loop lengths of elasticised knitted fabrics

The methods for loop length measurement have mostly been developed for knitted fabrics made from conventional yarns. When measuring the loop lengths of knitted structures made from highly extensible staple yarns, problems arise because of an uncontrolled yarn extension at the low stresses. The present study proposes a test method for knitted loop length determination in which variable preloads are applied. In the study, the loop lengths measured on an INSTRON dynamometer using variable preloads and a HATRA Course Length Tester using a fixed preload were compared. The results demonstrated that knitted structures made from elasticised yarns exhibit only small changes in loop length after relaxation. The addition of elastane does not significantly influence loop lengths for fabrics knitted using the same machine, the same cam setting and relaxed by the same process. The loop lengths measured on an INSTRON dynamometer exceed the loop lengths measured on a HATRA Course Length Tester.     

Modelling loop length in weft-knitted fabrics with an interlock structure after the dyeing process with a stitch density,Wales and courses per centimetre analysis

Abstract

One of the variables that we need to know in knitted fabrics in order to explain variations in dimensions in their different relaxation states, which might occur during the production process, is the yarn length that a loop forms, known as loop length. To experimentally calculate it, quite a lengthy process is required and the following need to be identified: direction of wales, direction that samples unreave in, counting the number of loops in the fabric length, separating and measuring yarn with specific measuring equipment, and repeating these 10 times, according to regulation UNE-EN 14970. Thus, depending on the structure type to be analysed, the whole process can take a relatively long time to do this calculation. This study proposes a calculation system that simplifies the process, for which the yarn length absorbed by an estimated interlock structure was modelled, as was loop length, without having to follow such a time-consuming process.     

黄麻混织针织物的设计与开发

本研究针对黄麻纱线粗硬、毛羽较多,弹性低等特点,对纱线毛羽、细度及强度进行测试并选择适合的棉及涤纶纱线进行混合。将黄麻与棉及涤纶纱线经过合股上蜡处理后,在针织横机上设计并编织罗纹、移圈、圆筒等不同组织和结构的黄麻混织织物及产品。通过对黄麻混织织物的耐磨性、透气性、抗起毛起球等性能进行测试与分析,结果表明麻涤1罗纹织物耐磨性、耐起毛起球性最好,而麻棉4为单面圆筒织物线圈密度最小,透气性能最优;麻棉2由于具有移圈及凹凸效果,透气性能次之,耐磨性稍差。所织织物适合制作具有田园风格的家居类装饰物,从而开发黄麻纤维更广泛的应用领域。     

Air permeability and bursting strength of weft-knitted fabrics from glass yarn. Part II: knit architecture effect

In this study; the effects of loop, skip, and tuck stitch types, and weft-inlay yarn, on air permeability and bursting strength of weft-knitted fabrics from glass yarn were revealed. Due to clockwise rotation of wales and their arrangement being one on top of the other, besides the dramatic shortening of fabrics after their removal from the machine; fabrics with tuck stitches exhibited the highest stitch density, fiber content, and the shortest loop length. This caused the lowest air permeability and the highest bursting strength. Contrary to expectations, weft-inlay yarn did not contribute to bursting strength as much as tuck stitch did. An overall negative correlation between air permeability and bursting strength was disrupted by structures with tuck stitches. While tuck stitches from cotton yarn increased air permeability and decreased bursting strength in previous studies; this study indicated that tuck stitches from glass yarn decreased air permeability and increased bursting strength.     

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.     

Ideal stitch model for interlock-knitted fabric

This analysis is presented as two- and three-dimensional ideal models for an interlock structure. These are developed from the ideal model loop for plain structure that was suggested in our pervious research works (Jeddi et al., Int. J. Eng., 12, 39–40, 1999; Semnani et al., J. Text. Inst., 94(1), 204–213, 2003). These models are based on the classic curve of the strophoid equation as the loop shape of face and back loops and improved by adopting an elastica configuration. Then, a quadratic equation is taken as the linking portion between face and back loops. Thereafter, the nondimensional constant of stitch density values (U _s ) obtained from the theoretical models was compared with the experimental values, which were obtained from measurements of cotton interlock fabrics. It is observed that there is a good agreement between the theoretical predicted and experimental U _s values.     

Study on strength property of fabric under low-stress condition

A testing method for tensile under low-stress condition based on the characterization system of the handle properties of fabrics and yarns (CHS-FY) was introduced. The CHS-FY system measured weight, bending, as well as frictional and tensile behaviour by one pulling-out test. In addition, it characterized the tactile handle of fabrics and yarns. This article analyses tensile measurement of fabrics based on CHS-FY. The theoretical analysis and modeling to tensile were performed by structural analysis, and the corresponding formulae of tensile elastic constants (E ₁ and E ₂) before and after friction force involved were obtained. In addition, the tensile indexes were obtained through pulling-out force and distance curve in the CHS-FY tensile step, which include slope, work, linearity, and extension of tensile between sample and the surface of three-point beam structure. Comparisons and correlations of tensile indexes for theoretical and experimental results were conducted. Correlation coefficients between tensile elastic constants (E ₁ and E ₂) and (E ₃) measured by CHS-FY and KES-FB1 were found to be 0.857 and 0.870, respectively. The comparison of theoretical and experimental results indicate that the theoretical modeling of tensile is effective and accurate in measuring tensile indexes and the CHS-FY system can be utilized for characterizing the tensile properties of fabrics.     

The Dimensional Properties of Single-Jersey Loop-Pile Fabrics. Part II: Studies of Fabrics With Textured Continuous-filament Yarns in the Ground Structure

Studies of the dimensional properties of single-jersey loop-pile fabrics produced from cotton pile and textured polyamide- and polyester-fibre ground yarns are reported. The model proposed for flat continuous-filament ground-yarn fabrics also applies to these structures. It is shown that the fully relaxed dimensions of fabrics produced with textured ground yarn are controlled by the stitch length as well as the bulking potential of the ground yarn.     

Comfort properties of bamboo/cotton blended knitted fabrics produced from rotor spun yarns

The comfort characteristics of bamboo/cotton-blended knitted fabrics made from rotor-spun yarns were studied in this research work. Five different blend proportions namely 100% bamboo, 100% cotton, 50:50 cotton:bamboo, 70:30 cotton:bamboo and 30:70 cotton:bamboo were used to produce rotor-spun yarns of 30^sNe_c. The yarn samples developed out of these different blend proportions were evaluated for yarn strength and elongation, yarn unevenness, yarn imperfections and used to produce single-jersey-knitted fabrics. All the fabric samples were dyed and finished. Fabric samples were evaluated for geometrical properties such as course/inch, wales/inch, stitch density and thickness apart from measuring comfort properties such as airpermeability, thermal conductivity, thermal resistance and water vapour permeability. The results indicated that 50/50 bamboo/cotton-blended knits have comparable fabric quality in terms of comfort properties with respect to 100% bamboo fabrics.     

14—THE GEOMETRY,DIMENSIONAL PROPERTIES,AND STABILIZATION OF THE COTTON PUNTO-DI-ROMA STRUCTURE

Dimensional stability of cotton Punto-di-Roma double-jersey fabrics can be attained by either mechanical-relaxation techniques (consecutive laundering and tumble-drying cycles) or chemical treatments (fabric mercerization without tension). Both treatments cause large linear-dimensional changes (shrinkages) leading to the same final stable condition, that is, to a fixed structural-knitted-cell configuration, categorized by unique values of u _c and u _w. Although, for all practical purposes, the ultimate u-parameters are close to constants, u _w is not entirely independent of fabric tightness (K)nor u _c of fibre type. They are very similar to those parameters found for wool fabrics prevented from felting. Geometrical fabric thickness is significantly dependent on both the fabric tightness and fibre type. Fabric stabilization is also induced by dry-cleaning (consecutive cycles in perchloroethylene), but the final u _c(DC)-parameter is not the same as that found after mechanical or chemical relaxation. The mean u _w(DC)-parameter is similar only at the mean of the practical K-range. Like the plain-jersey structure, it seems that the stable double-jersey fabric made from hydrophilic yarns occurs when yarn-bulking leads to a completely ‘jammed’ structure.     

On the contribution of yarn–yarn slippage to woven fabric failure

Failure of woven fabrics involves an interaction between yarns, which can be predicted by yarn slippage. To investigate the contribution of yarn slippage to the failure, we analyzed the relation between various failure properties and critical slippage force (F_S) using plain and twill weaves of fabrics with different characteristics. Results show that F_S increases with yarn density and yarn linear density. The properties in tension for fabrics with different weaves, yarn density, and yarn linear density superimpose on master curves described by a linear relationship when expressed as a function of F_S. The same linear behavior is observed when the critical jamming force of yarns expressed as a function of F_S. For the tearing energy, a master curve is also obtained when expressed as a function of F_S; however, the curve has a polynomial shape. F_S thus appears as a valuable tool to predict the onset of damage in fabrics.