Textured Yarns Research Articles

A Comparative Study of Thermomechanical and Chemomechanical Texturing of Nylon 6 Multifilament Yarns

Nylon 6 multifilament yarn is textured by both the conventional false-twist method and a new method of solvent- texturing with aqueous phenol. The physical, mechanical, and structural properties of the textured yarns are compared. It is observed that the solvent-textured yarn has a considerably higher dye uptake than the conventionally-textured yarn. SEM studies reveal interesting differences in the surface characteristics of fibers textured by the two processes.

Identification of Bárré Sources in Circular Knits

Simple but precise test methods for measuring circular knit, course length, and textured yarn bull are presented. Fabric barré is shown in general to be caused by critical, additive, end to end differences in course length, yarn bulk, and relative dye content. The barré response in terms of course length, yarn bulk, and dye content is domonstrated for several common knitting and texturing process conditions.

Sources of skitteriness in the textured yarns of carpet products

Sources of skitteriness in the textured yarns of carpet products

Changes in Fine Structure of Nylon 6 Gut Yarns in Twisting, Annealing and Untwisting Processes

The changes in fine structure of Nylon 6 gut yarns by twisting, annealing and untwisting were studied on the term, simulating the false textured yarn process. Wide and small angle X ray diffraction methods and electron microscopic technique were used to make clear the results of the researches.

Effect of Tension Level on Texturizing of Nylon 6 Multifilament Yarn

Nylon 6 multifilament yarn was textured using various tension levels at the twisting zone. It was found that the breaking-stress and breaking-elongation values of the textured yarns are more dependent on the nature of change in the distribution of the intrinsic viscosities than on average intrinsic viscosity values of the samples. With increase in the tension level, the degradation on the molecular level increases, which in turn leads to an increase in the reformative processes. The final shape of the distribution curve (and as a consequence, the mechanical properties of the yarn) is dependent on the net effect of these two opposing processes.

Evaluation of the Knittability of Synthetic Textured Yarns

Knitting technology has advanced considerably during the past two decades with the introduction of various knitted structures, use of new and modified yarns, and design of versatile knitting equipment. The successful use of the yarns on knitting machines depends on some of the yarn characteristics and the proper selection of knitting process parameters. It appears possible to use some of these yarn properties and the range of working conditions on the knitting machines to assess the knitting performance of the yarns and use this as an index of knittability.

Studies on Texturing of α and γ Forms of Nylon 6

Properties of textured yarns of α and y forms of nylon 6 feeder yarns have been studied. It has been observed that with the y form the crimp-rigidity value is lower than that with the a form. However, at a texturing temperature of 200°C, γ-α transition takes place, and the crimp rigidity of the converted α-form yarns is found to be significantly higher than that of the original α-form yarns. The equilibrium dye uptake and diffusion coefficient for disperse dye are higher with the γ and converted α forms than with the original a form of textured yarn. With acid dye, also, similar trends are observed. The γ form of feeder yarn, when textured at a temperature where conversion to the a form takes place, produces a textured yarn superior in quality to the conventional α form of the feeder yam.

Changes in Molecular Size and Size Distribution and Their Effects on Mechanical Properties of Nylon-6 Yarns During Texturizing

The changes in average intrinsic viscosity and its distribution and their effect on mechanical properties of nylon-6 (poly caprolactam) multifilament yarn during texturizing were studied. It was found that change in average intrinsic viscosity is not the only indicator of the changes taking place in the, mechanical properties of the yarn. The changes in the molecular size distribution, on the other hand, can be regarded as a better indicator in this regard. The reduction in the breaking stress of the textured yarn is dependent on texturizing variables— e.g. : heater temperature, contact time twist, inherent moisture content of the feed yarn, yarn tension in the texturizing zone, etc. The elongation percentage at break, on the other hand, may either decrease or increase. The changes have been found to be dependent on the changes in the low molecular weight, high molecular weight species and broadness of the distribution curve.

Structural and performance changes in polyester yarn brought about by simultaneous draw texturing processes

A partially oriented yarn of polyester has been subjected to the simultaneous draw texturing process and also drawn on the same machine without false twist. The effect of the variation of the applied draw ratio, the temperature of the first heater, the speed of the yarn, and (for textured yarn) the twist on the properties of the processed yarns was investigated. It was shown that the main factor affecting the properties is the applied draw ratio, the other factors having only a secondary influence, which is different from the findings with conventionally textured yarn. A tentative model for the polyesters based on fibrillar units with extended chains is proposed to account for the observed changes.

Interactions of Nonaqueous Solvents with Textile Fibers

An investigation of the effects of prior heat treatments on the stabilization of the polyester structure towards subsequent treatments with dimethylformamide (DMF) has been carried out. The results indicate that a DMF treatment at 140°C can overcome changes in the polyester structure produced by prior heat treatment up to a temperature of about 180°C. Void formation and accompanying high dye uptake under atmospheric dyeing conditions are observed. Heat treatments around 200°C, however, stabilize the fiber structure, and subsequent solvent treatments do not produce irreversible swelling and void formation. A further increase in the heat-treatment temperature again permits void formation and high dye-uptake values to occur. A close correlation between dyeability and void volume calculated from density data is observed. A DMF treatment of a false-twist-set textured yarn leads to void formation and high dyeability, even though the heater temperatures used in the texturing process are near the critical temperature range at which stabilization to sub sequent solvent treatments has been observed. Evidence is presented suggesting that the yarns do not actually experience the temperature of the heaters but rather a significantly lower temperature.

Theoretical Analysis on Tensile Properties of Textured Yarns

In this paper, tensile properties of textured yarns will be analysed. First, the property is calculated on the basis of a “independent fiber model” where each fiber contributes independently to the yarn tensile property, i.e., no mechanical interactions among fibers are considered. One of the purpose of this paper is to examine the accuracy of this no-interaction assumption for making distinct the mechanical interaction among fibers. Second, the tensile property of a crimped single fiber is calculated by applying the so-called “strain additive method”.[1] to a helical coil model of a fiber. Then the tensile property of a textured yarn is introduced by summing up the tensile property of each crimped fiber.A good agreement between the calculated and the observed values is obtained over a wide range of the tensile atrain of the yarn by assuming the independent model. No interaction is observed except the small deformation region.The hysteresis behavior observed at the repeated extension is also examined, and it is confirmed that the independent model is still suitable for this case. The experimental results agree well with the calculated results with good accuracy, too.

The crimp indices of textured yarn

The crimp indices of textured yarn

Thermal Stress Analysis of Textile Yarns

The technique of thermal stress analysis is discussed in terms of basic yarn mechanical properties, particularly stress relaxation, and in terms of fundamental concepts of fiber fine structure. Examples of stress-temperature data obtained by this technique are given for as-spun, drawn, and textured yarns from polyester, polypropylene, and nylon 66. Several process variables are shown to affect significantly the stress-temperature “fingerprint” of a yarn, including, for as-spun yarns: orientation, ageing, and quenching; for drawn yarns: draw ratio and drawing temperature; and for textured yarns: texturing temperature, overfeed, and dyeing conditions.

The Response of Textured Yarn Properties to Process Variables in Relation to Barré

A thermomechanical analysis technique has been used to characterize a set of false-twist pin-textured polyester yarns. These yams were generated under a wide range of texturing conditions from two distinct lots of fully-drawn feed yarn which differed in orientation. The analysis yielded a variety of thermomechanical yarn parameters. One set of parameters had some of the properties of an “effective yarn-texturing temperature.” A different set of parameters correlated with the tensile, shrinkage, or crimp parameters of the yarns and were sensitive to the effects of feed-yarn orientation differences. Other parameters correlated with textured yarn dyeability. Measurements of this type should prove valuable in the quality control of textured yarns and in the diagnosis of yarn faults.

The Response of Textured Yarn Properties to Process Variables in Relation to Barré

Differences in feed-yarn orientation are shown to propagate through texturing and to influence most of the textured yarn properties, but information on feed-yarn orientation differences is lost on high-temperature dyeing. The correlations between the dyeing data and certain combinations of other yarn properties are encouragingly good. Several of the crimp, shrinkage, and tensile properties of the textured yarns are much more sensitive to feed-yarn orientation and to the texturing variables than are the dyeing measurements. The implications for barré problems are discussed.

The Response of Textured Yarn Properties to Process Variables in Relation to Barré

The dyeing behavior of conventional false-twist pin-textured polyester yarns has been studied as a function of the texturing variables. Three different dyes and three different dyeing procedures were employed. The data obtained are discussed in relation to existing quality-control procedures for textured yarns and the role of feed-yarn non-uniformity in barré problems.

The structural causes of the dyeing variations of terylene subjected to the false-twist texturing process

An examination of the effect of the false-twist process on structure and dyeing behavior of Terylene is described. It was found that if dyed without tension, textured yarns had a higher rate of dyeing than when dyed under tension. However, the textured yarns dyed under tension had a lower rate of dyeing than corresponding flat yarns prepared without the application of the false-twist process. An explanation of these results is given in terms of a structure that on heating leads to a higher lateral order of the morphologic units and thence to an increased formation of voids, but superimposed on which is a system of gross elongated cracks brought about by the false-twist process.

Structure of High Stretch Yarns and Their Tensile Properties

To clarify the structure of high stretch yarns in helical coils, various photographs of them and of other textured yarns or models are taken, and the relation between their tensile properties and the structure is studied. Results obtained are:1. Hard-twist two-ply yarns are studied as a model having two first twists per one pitch. They have hollow parts in the center of the yarn, and the radius can be expressed by: a=0.896 2. We have explained the configuration of the crimps or loops of the constituent filaments when hard-twist two-ply yarns are twisted, heat-set and untwisted. 3. We have found that the tensile properties of high stretch yarns are dependent on the configuration of the constituent filaments and on the complexity of assembly of these filaments, and that the fundamental shape of crimps of the yarn consists of a series of rings which develop the high extension property.

Relaxation properties of bicomponent and textured polyester yarns

Relaxation properties of bicomponent and textured polyester yarns

Influence of the parameters of the winding-on process on the properties of the finished textured yarn

Influence of the parameters of the winding-on process on the properties of the finished textured yarn