New computer geometric modeling approach with filament assembly model for two-ply yarns structures

This article presents a new computer geometric modelling approach for three-dimensional of two-ply yarn structures with filament assembly model. The geometric of individual filaments in two-ply yarn structures with uncompressed and compressed states were studied. In the uncompressed state the filaments in ply yarns have the form of coaxial double wound helices; we simulate the paths of these filaments in the ply yarns. In the compressed state the transformation of the initial filament distribution from the uncompressed state into the distribution after compression by a transverse force. The ply yarns cross-section uses the concept of virtual locations to simulate the filament distributions. Each cross-section is rotated along the single yarn and the ply yarn length. The curve of each filament in each two successive cross-sections is approximated by NURBS and then each curve is created by sweeping a closed curve along the centerline of the single yarn and ply yarn path. The method described is demonstrated in the uncompressed and compressed state of two-ply yarns by the CAD model using geometric parameters of the double-rove acrylic-fiber yarns. The simulation using this approach can demonstrate more realistic and improved visual simulations of real two-ply yarns.     

复合纱体中长丝分布形态对纱线性能的影响

为研究长丝复合纺纱过程中由长丝与短纤维须条复合产生的不同纱线内部结构对纱线性能的影响,设计并建立了6种长丝复合纺纱线结构模型,分析和预测了模型对应的成纱性能,并进行实验验证,对比分析了各复合纺纱形式所得纱线的毛羽、条干、强伸性能。结果表明：相比单独的包芯结构和长丝单侧包缠结构,长丝由两侧对须条进行包缠优化了纱线结构,表现出更佳的复合纱拉伸和成纱条干性能;同时拥有长丝双侧包缠和包芯结构的复合纱,表现出最优的成纱强力和条干;较大的长丝与须条隔距与张力更有利于长丝束缚和控制纤维外露,有效降低成纱毛羽。     

Microscopic deformation mechanisms of unidirectional fiber bundles under transverse compressive stresses

The high-performance filament yarns, such as carbon fiber yarn, glass fiber yarn, and Kevlar fiber yarn, have characterized as unidirectional,high parallel filament in fiber bundle. However, due to the difficulties in statistically analyzing the micro-structural characteristics of high-performance fiber bundles comprising of thousands of filaments, Nylon (PA6) filament yarns were chosen as the substitute of high-performance fiber bundles to study the deformation micro-mechanisms of fiber bundles under transverse compressive stresses. In order to evaluate the effects of different compressive stresses on the deformation properties, the synchrotron radiation X-ray micro-computed tomography (micro-CT) was used to obtain cross-section images of the fiber bundle during the compression testing. In particular, the influences of compressive stress on the fiber volume fraction, fiber distribution, fiber contact, and fiber orientation were studied. Results indicate a strong dependence of the microstructure of fiber bundles on the compressive stress.     

A comparative study on performance characteristics of multicomponent core-spun yarns containing cotton/PET/elastane

Abstract

This paper experimentally investigated the characteristics of different (filament and multicomponent) core-spun yarn type. Filament core-spun yarns comprised cotton covered drawn textured (DTY) polyester (PET) filaments with four different filament finenesses. Regarding the production of multicomponent (dual) core-spun yarns, both PET with four different filament finenesses and elastane with four levels of draft variable were fed simultaneously. Yarn samples were produced with modified ring spinning system at the same spinning conditions. As a control group, 100% cotton ring-spun yarn was also manufactured. Tensile properties, unevenness, imperfections and hairiness of yarn samples were determined. Also, fatigue characteristics of yarn samples were examined at two different loading of cycles. The results showed that filament fineness had a significant effect on all yarn properties being determined. Dynamic modulus and dynamic strain properties of yarns, filament fineness, elastane draft and number of cycle were found to be statistically significant at 0.05 level.     

长丝喂入位置对赛络纺包芯纱结构与性能影响

针对赛络纺包芯纱纺制过程中,长丝不同喂入位置对纱线结构和性能的影响,分别纺制了涤纶长丝在左侧粗纱须条中心、两粗纱须条中间、右侧粗纱须条中心3种结构的短纤/长丝赛络纺包芯纱。对比分析了纱线截面、成纱质量、耐磨性能、拉伸断裂过程和纱线退捻特征。结果表明:3种包芯纱中涤纶长丝均在纱线中心附近,无明显漏丝,条干均匀,毛羽较少;左侧粗纱须条中心喂入纱线拉伸断裂曲线有多峰特征,两粗纱中间喂入纱线拉伸断裂曲线有密集波动特征;右侧粗纱须条中心喂入纱线初始弹性模量最高,拉伸断裂特征为阶梯性断裂,退捻最困难,且在退捻过程中部分纱段被反向加捻,纱线结构最稳定,耐磨性好,纱线强力最高。     

加捻对转杯纺复合纱结构性能的影响

在2种长丝超喂率下,通过调整复合纱的捻系数使棉纤维和涤纶长丝复合以纺制不同类型的转杯纺复合纱。测量了纱线张力并研究了加捻对转杯纺复合纱结构和性能的影响。结果表明,复合纱捻系数在2种长丝超喂率下对复合纱的结构和性能都有显著的影响;涤纶长丝在复合纱中是以螺旋线形式与棉纤维纱条加捻复合,当长丝张力随着复合纱捻系数的增加和长丝超喂率的减小而增加时,长丝趋向于复合纱内层,复合纱的主要性能也会随之发生变化;与常规转杯纺纱线相比,复合纱表面较光洁,结构较紧密,主要性能得到了改善。     

36—THE BREAKING MECHANISM OF TWO-PLY NYLON 6 CONTINUOUS-FILAMENT YARNS

The breaking mechanism of two-ply nylon 6 continuous-filament yarn is investigated, and the breakage of the yarn under simple tensile-loading conditions is compared with that of a filament subjected to the same loading. The simplest types of model yarn were prepared for this purpose. These yarns were ruptured at a low rate of extension, and the fracture morphologies of the filaments in the yarns were inspected by scanning electron microscopy. Two typical kinds of morphological feature are obtained in these yarns. In order to understand the breaking mechanism of the yarn, the cause of these features is discussed on the basis of the breaking mechanism of a single filament.     

Towards the Better Understanding of Self-twist Structures

An investigation is described in which several wrapped yarns were spun from 100% polyester staple fibre with different continuous-filament yarns in a wide range of wrapping densities. The tensile properties of the wrapped yarns were studied, and the effects of the linear density of the continuous filament yarn and the wrapping density on the yarn structure and tensile properties were investigated. The morphology of the yarn failure during tensile testing was studied by photographing the yarn during extension.

The yarn structure for the different continuous-filament-yarn wraps was examined by scanning electron microscopy. The study illustrates the effect of the wrapping filaments on yarn structure, yarn tensile properties, and the mechanism of failure during extension. The effect of the wrapping continuous-filament, yarn on yarn characteristics was found to be the predominant factor'.     

An approach to predict the tensile strength of a two-ply yarn from single filament yarn

It is considered that the strength of the ply yarn consisting of continuous filaments mainly depends on the properties of the single yarn and the cohesion forces among the single yarns, thus a mathematical model with relatively few parameters under given assumptions is established to predict the tensile strength of a two-ply yarn from single filament yarn. Relative relationships of the tensile force part and the interaction part are developed, respectively. The single yarn is tested to obtain fundamental data e.g. yarn strength and breaking elongation. After two strands of filament yarns are twisted into the ply yarns under different twist levels, the tensile strength, breaking elongation and structure parameters are measured or calculated for verifying the model later. Finally, the results show good agreement with the experimental values, and this model can be used to predict the performance of the finished strand yarns in actual productions.     

Effect of polyester and elastane linear density on the physical and mechanical properties of dual-core-spun cotton yarns

ABSTRACT

The use of single-core elastic spun cotton yarns is well established in textiles and denim industry but interest in the use of dual-core-spun yarns has started to grow only recently. The aim of this study was to investigate the effect of polyester and elastane linear density on the physical and mechanical properties of dual-core-spun cotton yarns. Yarn samples were prepared on industrial-scale spinning machines using cotton as the sheath fibers and two different linear densities of polyester and three different linear densities of elastane filaments in the core. Statistical analysis of the results revealed that yarn tenacity, elongation, uniformity, and hairiness are significantly affected by the linear densities of both the polyester and elastane filaments in the core, with statistically significant interaction between them. Yarn imperfections (IPI), however, are affected mainly by the polyester denier, while the elastane linear density did not show statistically significant effect on the IPI. Regression equations for different yarn properties were also developed which showed fairly high values of coefficient of determination (R-sq).     

Study of yarn twist angle using numerical simulation

The twist angle is an important parameter of the yarn which determines the degree and shape of the filament’s deformation produced along their length. So, in this paper, a 3D numerical modelling of filaments assemblies has been developed. The twist behaviour of the multifilament was simulated using ABAQUS finite element package by modelling the yarns as 3D continuum elements. The distribution of filament helix angle according to the radial position of the yarn is evaluated. Results show that the helix angle draws near zero in the yarn axis but does not fall to zero in presence of migration, and becomes bigger as the filaments are positioned on the surface. Moreover, the twist angle is calculated for different twist level which proves that twist angle is highly affected by torsion level. The target of the research was to establish a relationship between twist angle, twist value and yarn linear density for a series of models varying in the filament radius, twist value and filament number.     

Effect of blending two fiber-grade polypropylenes with different molecular weight distributions on the physical and structural properties of melt-spun filament yarns

In this study, the structural and physical properties of polypropylene fibers produced from the blending of two types of polymers having similar melt flow index but different molecular weight distributions (MWD) were investigated. Polypropylene with broad MWD (V30S grade) was blended with polypropylene with narrow MWD (511P grade) in various fractions (from 0% to 100%) to produce melt-spun filaments. Although the fraction of 511P in blends is higher than 25%, the blending is effective. Increasing the fraction of 511P in the blend increases tenacity and decreases breaking elongation. Mechanical properties of drawn yarns show the same trend as those of as-spun yarns with the blend composition. For as-spun yarns, addition of 10% of 511P polymer increases birefringence in comparison with the V30S yarn. There is little or no effect of blend composition on the development of crystallinity. Drawing increased the birefringence and crystallinity of as-spun filament yarns, but the values of increase are different for the samples.     

Characterization of fabric properties knitted from multifilament polyester textured yarns with various number of filaments

The purpose of this study is to investigate the physical and mechanical properties of fabrics knitted from textured polyester multifilament yarns with various numbers of filaments in the yarn cross-section. In this regard, some of the characteristics of yarns and fabrics, knitted from the mentioned yarns, were measured and analysed. Analysis of results showed that increasing the number of filaments in the yarn cross-section leads to a decrease in yarn’s diameter and abrasion resistance. Moreover, examining the properties of the weft-knitted fabrics revealed that increasing the number of filaments causes a rising trend in the compressibility and bursting strength of fabric. On the contrary, the thickness, air permeability and abrasion resistance decreases due to a growth in the number of filaments. A decline in the strength and elongation of yarns and fabrics produced from them is also another result of increasing the number of filaments in the yarn cross section.     

A Study on Wicking in Natural Staple Yarns

In this study, natural staple yarns of cotton and wool were investigated for wicking properties. Fibre packing density reflected by yarn wicking rates was measured in ply cotton yarns. It was seen that with the samples measured in this work, both twist level and number of ply in a yarn can affect yarn wicking behavior. When twist and yarn count remained unchanged, wool yarns with different fibre diameters were measured for wicking rates and the best wicking was found on the yarn with the coarsest fibre diameter. Comparison was made in this work on the treatment methods, and on both synthetic continuous filament yarns and the natural staple yarns. While prewash treatment could improve yarn wicking by changing fibre surface condition, plasma treatment was a more effective way in increasing yarn wicking rate for both filament yarns and staple yarns.     

摩擦空心纱的结构特点和拉伸性能

对以PVA短纤维纱为芯纱,棉纤维为外包纤维的摩擦包芯纱,通过水煮处理去除可水溶的PVA芯纱后,制得摩擦空心纱。对摩擦空心纱以及具有加强芯纱的摩擦空心纱的结构特点和拉伸性能进行了试验研究。摩擦空心纱的结构特点是空心部分位于纱线的中心,溶芯后纱线结构膨松,直径增大。试验结果表明溶芯后摩擦空心纱的强力很低,其原因为去除了高强力的芯纱,溶芯后纱线膨胀引起纤维间抱合力减小;用涤纶长丝作为加强芯纱可以显著提高摩擦空心纱的强力。     

Sodium Benzoyl Thiosulphate: A Water-soluble Benzoylating Agent for Wool

The tensile behaviour of wrap-spun yarns is influenced by their structure and by the properties of both the parallel-fibre core and the filament binder yarn. A general model of wrap-spun yarns is proposed, which, with appropriate assumptions, can be used to predict the relationship between yarn strength and structural parameters.     

Fabrication of core-sheath nanoyarn via touchspinning and its application in wearable piezoelectric nanogenerator

Abstract

A simple and versatile touchspinning method is demonstrated for the fabrication of core-sheath nanofibrous piezoelectric yarns with a single filament electroconductive core. The polyvinylidene fluoride (PVDF) piezoelectric nanofibers are fabricated in a continuous spinning process with relatively controlled structure, orientation, and dimensions to form a sheath layer. The PVDF core-sheath nanoyarn is assembled into a piezoelectric nanogenerator (PNG) capable to convert mechanical energy of body motion into electricity. It was demonstrated that an electrical potential difference of 0.72?V can be generated under compression of 0.33?MPa for a single 3-cm long yarn. The touchspun nanoyarn fabrication method has great potential for the fabrication of functional smart textile products.     

不锈钢纤维/棉复合纱的开发及其性能

为更好地开发和利用功能性纱线和面料,以不锈钢短纤维、不锈钢长丝以及棉纤维为原料,采用一种长丝/短纤维复合结构纱线的纺纱工艺开发出不同金属纤维含量的新型复合结构纱线。对复合结构纱线的结构,毛羽,拉伸性能以及导电性能进行测试分析。同时测试了利用该种复合结构纱线开发出的电磁屏蔽面料的屏蔽性能。实验结果表明：利用此种复合结构纱线制作方法所开发出的纱线具有较优异的毛羽性能、力学性能和导电性能,并且不锈钢纤维含量对纱线性能有着较大的影响。利用该种复合结构纱线开发出的面料屏蔽率达到90%-99.9%,可用于日常生活用电磁防护装材料。     

A study on siro-, solo-, compact-, and conventional ring-spun yarns. Part I: structural and migratory properties of the yarns

Properties of spun yarns are mainly affected by fiber properties and yarn structure. Yarn structure is principally influenced by the spinning system. In fact, each spinning system tends to produce a distinctive yarn structure. Recent refinements in spinning technologies have yielded significant improvement in yarn structure. Siro, solo and compact spinning are the new spinning systems to have made a breakthrough until recently. Of the various structural parameters for staple yarns, fiber migration has a crucial influence on the yarn mechanical properties. Thus, the need for precise and concise information about fiber migration becomes important for better understanding of yarn structure and hence yarn mechanical behavior. The work presented here aims to analyze fiber migration in siro-, solo-, compact-, and conventional ring-spun yarns by varying the twist factor. The results demonstrate that the siro-spun yarns exhibit the highest fiber migration parameters, followed by compact-spun yarns, solo-spun yarns, and conventional ring-spun yarns.     

Structure–property relationship of different types of polyester industrial yarns

Four major types of polyester industrial yarns (1000 Denier) which are used commercially were studied for their key structural parameters. An attempt has been made to establish a relationship between morphology and properties of these yarns. High tenacity (HT) polyester yarn has the highest birefringence, amorphous orientation, and long period but is relatively less crystalline. High shrinkage characteristic of HT polyester yarn can be accounted for its higher amorphous orientation. High modulus low shrinkage (HMLS) polyester yarn has higher crystallinity and crystal size compared to HT yarn. Fraction of tie molecules of these yarns has been calculated and found that low shrinkage (LS) and super low shrinkage (SLS) yarns have lesser tie molecules. These LS and SLS yarns are tailor-made to achieve lower shrinkage and at the same time maintaining a good level of tenacity. This is achieved with lower amorphous orientation in the final drawn yarn structure. Amorphous orientation was found to have stronger influence than any other structural parameter on the key yarn properties like modulus, tenacity, elongation, and shrinkage.