Yarn Strength Research Articles

Characterization of carbon nanotube yarn after exposure to hyperthermal atomic oxygen and thermal fatigue

Carbon nanotube (CNT)-yarn was evaluated for the survivability under hazardous space environmental conditions which were thermal fatigue, atomic oxygen and additive effect of these two exposures. Its tensile strength, tenacity, stiffness, strain to failure and electrical conductivity were characterized at the two extreme space temperatures of −150 and 120°C before and after exposure to these environmental conditions. Tensile strength, stiffness and electrical conductivity of unexposed CNT yarn increased at the cryogenic temperature relative to at the elevated temperature. There was no change in the tensile properties after exposure to the space environmental conditions when measured at the elevated and cryogenic temperatures. Electrical conductivity decreased after exposure to three hazardous environments involving thermal fatigue, but it had no or small decrease when exposed to atomic oxygen only. No additive effect of thermal fatigue followed by atomic oxygen or by atomic oxygen followed by thermal fatigue environments on the CNTs’ tensile properties and electrical conductivity was observed. Considering the low density 0.59g/cc and good resistant to the extreme hazardous space environment, CNT-yarns have potential for applications in spacecraft and satellites.

Simulating three-dimensional dynamics of flexible fibers in a ring spinning triangle: chitosan and cotton fibers

A three-dimensional particle-level simulation method is developed to simulate fiber dynamics in the ring spinning triangle. The fiber is modeled as a chain of beads connected through massless rods, and its flexibility is defined by the stretching, bending and twisting displacements. As the application of the proposed approach, the effects of the chitosan (CS)/cotton (CT) fiber initial position and length on fiber motion and yarn properties are discussed. The deflections of CS fibers along the roller axis are larger compared with those of CT fibers, which will lead to CS migrating outwards in CS/CT blended yarn. The short CS fibers (22 mm) will move toward the top roller surface and shift quickly out of the roller nip, and thus yarn strength is lower. The tailing end of the longest CS fiber (46 mm) will drift off the roller nip, which makes little or no contribution to the yarn strength. For 38 mm length CS fiber, it moves toward the bottom roller surface and is bound into the roller nip, and thus can produce the highest tenacity CS/CT blended yarns. The simulation results agree with the spinning experimental data reported by other researchers.

Melt-spun talc-filled polypropylene fibers and yarns with higher thermal shock resistance

An increase in the application areas of textiles has resulted in the need for improved and additional properties and functions, which should be provided by polymers with different functionalities or the addition of particles to the fibers. In the framework of this study, microsized talc particle-filled polypropylene (PP) fibers and yarns were produced and the mechanical, physical and thermal properties of the fibers and yarns were analyzed with respect to production parameters. The main motivation of the selection of talc as the filler material is to improve the thermal shock resistance and decrease the shrinkage of PP fibers and yarns. As a result of experimentation, it was observed that an increase of talc ratio decreases the tensile strength of fibers and yarns. However, this reduction does not seem to be an obstacle to produce fabrics. Furthermore, the addition of microsized talc particles in PP yarns dramatically improved thermal shock resistance and helped to decrease the shrinkage of these yarns.

Microstructural foundations of the strength and resilience of LLDPE artificial turf yarn

ABSTRACTThe production of linear low‐density polyethylene (LLDPE) yarns for artificial turf is an advanced extrusion process, which relies heavily on the polymer's semicrystalline structure and inherent strengthening mechanisms to obtain the tailored mechanical properties so typical for turf yarns: a combination of strength and resilience. This review aims to bring together all relevant aspects in the structure–materials–processing interaction triangle which is so strongly in evidence in this application, by first summarizing the specific structural origins of the properties of the semicrystalline LLDPE and then discussing how structure evolves during the different steps of the production process, to eventually come to the final product properties of the yarn. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44080.

Design methodology of the strength properties of medical knitted meshes

One of the most important utility properties of medical knitted meshes intended for hernia and urological treatment is their bidirectional strength along the courses and wales. The value of this parameter, expected by the manufacturers and surgeons, is estimated at 100 N per 5 cm of the sample width. The most frequently, these meshes are produced on the basis of single- or double-guide stitches. They are made of polypropylene and polyester monofilament yarns with the diameter in the range from 0.6 to 1.2 mm, characterized by a high medical purity. The aim of the study was to develop the design methodology of meshes strength based on the geometrical construction of the stitch and strength of yarn. In the environment of the ProCAD warpknit 5 software the simulated stretching process of meshes together with an analysis of their geometry changes was carried out. Simulations were made for four selected representative stitches. Both on a built, unique measuring position and on the tensile testing machine the real parameters of the loops geometry of meshes were measured. Model of mechanical stretching of warp-knitted meshes along the courses and wales was developed. The thesis argument was made, that the force that breaks the loop of warp-knitted fabric is the lowest value of breaking forces of loop link yarns or yarns that create straight sections of loop. This thesis was associate with the theory of strength that uses the “the weakest link concept”. Experimental verification of model was carried out for the basic structure of the single-guide mesh. It has been shown that the real, relative strength of the mesh related to one course is equal to the strength of the yarn breakage in a loop, while the strength along the wales is close to breaking strength of a single yarn. In relation to the specific construction of the medical mesh, based on the knowledge of the density of the loops structure, the a-jour mesh geometry and the yarns strength, it is possible, with high accuracy reaching up to 95 - 87%, to determine the actual bidirectional strength of medical meshes.

Effect of Lowering Twist Levels on Quality Parameters of Rotor Spun Cotton Yarn

Investigations were made to explore the influence of lowering twist level on quality characteristics of rotor spun yarn. Three levels of yarn linear density (i.e. 40, 35 and 30 tex) and five levels of twist (i.e. 700, 600, 550, 500, and 450) were employed during yarn spinning trials. Each twist multiple was investigated at all linear densities for tensile strength, elongation, total CVm (Coefficient of Mass Variation) imperfection index and hairiness. 100% cotton yarn samples were prepared on Reiter R-40 at rotor speed of 90,000 rpm. Determination of elongation, yarn strength, hairiness, mass variation, and total imperfections index was carried out on Uster Tensorapid-4 and Uster Tester-4 as per set standards of ISO standard test methods. Based on investigations it is established that yarn strength and elongation declined minutely (Insignificant) with lowering twist levels but still can be confidently used for knitting yarns. However, significant improvement in total imperfection index and marginal enhancement in CVm were experienced.

Continuous High-Aligned Polyacrylonitrile Electrospun Nanofibers Yarns via Circular Deposition on Water Bath.

A novel strategy for preparing high-aligned continuous Polyacrylonitrile (PAN) electrospun nanofibers yarns is introduced. The yarn is rolled up from circular deposition, which can be changed by controlling the humidity of spinning environment. High-aligned yarn is obtained with the rolling speed of 57 m/min. Very few defects are found in the received yarn. Also the as-spun yarn is drawn in hot water bath to improve its mechanical properties further. The mechanical properties and X-Ray Diffraction (XRD) tests are systematically investigated. The tensile strength of the as-spun yarn rolled with 57 m/min can reach 240 MPa, close to that of as-spun fibers from wet spinning. Furthermore, after drawn of 5 ratios, tensile strength of yarn comes to 580 MPa, which broaden the applied fields of electrospun nanofibers. In addition, the forming mechanism of yarn in the water bath is analyzed and compared with the previous work. Actually, it can be testified experimentally that PAN nanofibers yarn has the same mechanical properties as that prepared with the other approaches with the same testing conditions in this work. The continuous high-aligned electrospun nanofibers PAN yarn via circular deposition in this paper is capable of meeting the requirement of the more applications needing of high mechanical properties and alignment degree.

Biodegradation in Landfilled of Biodegradable Micro-braided Yarn

Biodegradable polymer yarns of polymer blends of poly(lactic acid) (PLA) and poly(butylene succinate-co-adipate) (PBSA) reinforced with natural fiber were prepared by a micro braiding technique. The biodegradation of the micro-braid yarn was studied by field tests. The yarn are prepared from polymer blends of PLA:PBSA with ratios of 100:0, 90:10, and 85:15 (wt%) by a single screw extruder. Braided samples were prepared using jute as a braided core fiber. The mechanical property analysis showed tensile strength of polymer yarn with jute fiber higher than polymer yarn without jute. Biodegradation of micro-braiding yarn with and without jute fiber was studied by buried under controlled conditions compared with cellulose. The field biodegradation test was carried out for 28 days with period of 7 days sampling. It was found that humidity and soil temperature affected the biodegradability of polymers. Analysis of samples confirmed that buried at low temperature position showed higher degradation than at high temperature. High humidity enhanced the degradability due to hydrolysis reaction. Micro-braided polymer yarns of PLA:PBSA (85:15) and PLA:PBSA (85:15)/jute showed similar biodegradability confirmed that the mechanism of biodegradation from surface of the yarn was priority.

Strong, Twist-Stable Carbon Nanotube Yarns and Muscles by Tension Annealing at Extreme Temperatures.

A high-speed incandescent tension annealing process (ITAP) is used to increase the modulus and strength of twist-spun carbon nanotube yarns by up to 12-fold and 2.6-fold, respectively, provide remarkable resistance to oxidation and powerful protonating acids, and freeze yarn untwist. This twist stability enables torsional artificial-muscle motors having improved performance and minimizes problematic untwist during weaving nanotube yarns.

Morphology-dependent load transfer governs the strength and failure mechanism of carbon nanotube yarns

The outstanding properties of individual carbon nanotubes (CNTs) have motivated interest in CNT fibers and yarns for composite materials, high-strength conductors and multifunctional textiles. However, despite advances in manufacturing, the strength of CNT yarns remains 10–100 fold less than individual CNTs. In light of the complex, multi-scale load transfer in CNT yarns, a hierarchical model taking into consideration the morphology-dependent mechanics is necessary to understand this limitation. We present a coupled analytical and finite element model of three-dimensional morphology and the full tensile behavior of CNT yarns. By incorporating load-induced changes in morphology, simulations of yarns in tension show different load paths such as fracture-type or stick–slip failure depending on the waviness and number density of CNTs. The strength of untwisted pristine CNT yarns is shown to be limited to <10% of the intrinsic CNT strength, even at practical limits to CNT packing density and alignment. Load-induced changes in CNT morphology are verified by tensile testing of CNT yarns along with in-situ X-ray scattering. In addition, the nominal structure of the yarn is shown to strongly influence the improvement in strength achieved by densified and/or cross-linking, and a sublinear relationship between CNT contact enhancement and yarn strength is predicted. Thus, this work provides a means to investigate the complex load transfer mechanisms in CNT yarns and other assemblies, to further study their process–structure–property relationships, and to understand potential property limits.

An investigation on the distribution of massive fiber granules in rotor spinning units

Rotor spinning is an open-end spinning method that uses air as the medium to transform the fibers into yarn. Nowadays, the properties of its final product—yarn—such as yarn strength and yarn twist, are not satisfied due to the fiber morphology, which greatly depends on the distribution of the massive fibers in the rotor spinning unit (RSU). In this paper, theoretical analysis is given to describe the trajectory of fiber on the slide wall. A numerical study is performed with the massive fibers being simplified into granules to study their distribution characteristics in the RSU. According to our numerical results, the forming process of the fibrous ring is discussed and the effects of two variables, the rotor speed and the angle of the slide wall, on the distribution of fiber granules were also studied. The simulation results indicate that the fiber granules are not evenly distributed during their transport in the fiber transport channel (FTC) and they tend to accumulate on the upper and lower edge of the FTC. The distribution of fiber granules in the groove (fibrous rings) is closely related to the rotor speed. The higher the rotor speed, the longer and thinner the fibrous ring. The distribution of fiber granules on the slide wall is related to the angle of the slide wall such that a smaller angle leads to a scattered distribution on the slide wall, while a larger angle tends to bring a concentrated one. The simulation results show good agreements with our experimental results.

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.

Strength prediction for bi-axial braided composites by a multi-scale modelling approach

Braided textile-reinforced composites have become increasingly attractive as protection materials thanks to their unique inter-weaving structures and excellent energy-absorption capacity. However, development of adequate models for simulation of failure processes in them remains a challenge. In this study, tensile strength and progressive damage behaviour of braided textile composites are predicted by a multi-scale modelling approach. First, a micro-scale model with hexagonal arrays of fibres was built to compute effective elastic constants and yarn strength under different loading conditions. Instead of using cited values, the input data for this micro-scale model were obtained experimentally. Subsequently, the results generated by this model were used as input for a meso-scale model. At meso-scale, Hashin’s 3D with Stassi’s failure criteria and a modified Murakami-type stiffness-degradation scheme was employed in a user-defined subroutine developed in the general-purpose finite-element software Abaqus/Standard. An overall stress–strain curve of a meso-scale representative unit cell was verified with the experimental data. Numerical studies show that bias yarns suffer continuous damage during an axial tension test. The magnitudes of ultimate strengths and Young’s moduli of the studied braided composites decreased with an increase in the braiding angle.

Analytical Design of the Strength for Worsted Yarn with Linear Density 19-42 Tex

We present theoretical calculations of the strength of single-ply worsted yarn in the major classification groups used by the TsNIISherst’ scientific industrial company (central wool research institute and pilot plant). We have established and calculated the basic characteristics of worsted yarn in the major classification groups. Results are presented for analytical calculation of the strength of single-ply worsted yarn.

Effects of Kevlar® 29 yarn twist on tensile and tribological properties of self-lubricating fabric liner

Yarn twist in textile technology is an important characteristic since it considerably affects the properties of knitted or woven fabrics. Many researchers have investigated the effect of staple-spun yarn twist on the properties of the yarns and fabrics. However, the effects of twist level of Kevlar® 29 filament yarn on the properties of yarn and its resin-impregnated self-lubricating fabric liner are not fully known yet. In this study, we have investigated the effects of Kevlar® 29 twist level on the tensile and tribological properties of the fabric liner (Kevlar® 29/polytetrafluoroethylene fabric-resin composite). Two unexpected findings about the effect of yarn twist have been observed, namely (1) asynchronous twist effect on the yarn’s and the liner’s tensile strength and (2) dissimilar yarn twist effect on the liner’s performance. These findings are mainly attributed to the synergic contributions of the yarn twist and strength and the interaction of the resin with the yarn orientation in the woven fabric structure of the liner.

Manufacturing techniques and property evaluations of conductive composite yarns coated with polypropylene and multi-walled carbon nanotubes

This study uses a melt extrusion method, a method for producing wires, to coat polyester (PET) yarns with polypropylene (PP) and multi-walled carbon nanotubes (MWCNTs). The resulting PP/MWCNTs-coated PET conductive yarns are tested for their tensile properties, processability, morphology, melting and crystallization behaviors, electrical conductivity, and applications. The test results indicate that tensile strength of the conductive yarns increases with an increase in the coiling speed that contributes to a more single-direction-orientated MWCNTs arrangement as well as a greater adhesion between PP/MWCNTs and PET yarns. 8wt% MWCNTs results in an 18°C higher crystallization temperature (Tc) of PP and an electrical conductivity of 0.8862S/cm. The test results of this study have proven that this form of processing technology can prepare PP/MWCNTs-coated PET conductive yarns that have satisfactory tensile properties and electrical conductivity, and can be used in functional woven fabrics and knitted fabrics.

Research on the Performance of a Drafting Device for the Four-Line Compact Spinning System

2Key Laboratory of Eco-Textile, Ministry of Education, Jiangnan University, Wuxi 214122, P. R. China **E-mail:gaowd3@163.com Abstract Compact spinning is one of the most important improvements of traditional ring spinning, which is implemented by adding a fibre condensing device to condense the fibre bundle and decrease the spinning triangle, thereby improving the qualities of yarn. Pneumatic compact spinning is the most widely used compact spinning method at present. Four-line compact spinning is one of the most important kinds of pneumatic compact spinning, which is implemented by using a Lattice apron to achieve fibre condensing, decrease the spinning triangle and improve the yarn qualities, especially reducing yarn hairiness. In this paper, the performances of drafting devices for Four-line compact spinning were studied. First the structure and performance of an SDDA2122PH pneumatic cradle equipped with a new kind of block top roller retaining bar were discussed and the pressure distribution of the cradle presented firstly. Then 7.3 tex T65/JC35 was spun on an EJM128K spinning frame equipped with an SDDA2122PH pneumatic cradle, the pressure distributions measured, and the spun yarn qualities were measured and analysed accordingly. Then the acting mechanism of three kinds of top pin: a common top pin without a press bar, a top pin with a front pressure bar, a top pin with a back pressure bar, with respect to yarn qualities was analysed firstly, and then JC 18.2 tex, JC60/T40 18.4 tex and T 18.4 tex yarns were spun on an EJM128K spinning frame equipped with different top pins. Then the qualities of the spun yarns were analysed according to the acting mechanism of the top pin. The results show that by using the new block top roller retaining bar, the pressure of the pneumatic cradle is larger and more stable, thereby improving the spun yarn’s comprehensive qualities. For cotton yarn, we can reduce yarn hairiness by using a top pin with a pressure bar; for chemical fibre and cotton blended yarn, yarn strength can be improved by using a top pin with a pressure bar, and for chemical fibre pure yarn, the usage of a top pin with a pressure bar is beneficial for improving yarn strength and evenness, but not for yarn hairiness and yarn thin and thick places.

Bond investigation of hybrid textile with self-compacting fine-grain concrete

This paper presents an experimental investigation into the influence of bond characteristics between textile and matrix on the mechanical behavior of textile-reinforced concrete (TRC). Two types of tests were performed, i.e. pullout test and uniaxial tensile test. Self-compacting fine-grain concrete was adopted. Two kinds of hybrid textile, consisting of both carbon and E-glass yarns, were specially prepared for this study. The experimental results show that sticking sands on the textile after epoxy resin impregnation can improve the interfacial property between textile and matrix. The specimens with textile of 10 mm × 10 mm mesh have stronger bond strength than those with textile of 25 mm × 25 mm mesh, and can reach the maximum tensile strength of yarns when the initial bond length is between 30 mm and 35 mm. Moreover, sticking sands on the textile can improve the multiple cracks form and the ultimate bearing capacity of TRC under uniaxial tensile load. Specimens with textile of 10 mm × 10 mm mesh have higher first-crack loads than those with textile of 25 mm × 25 mm mesh whether or not the textile surface treatment was conducted, and also have better crack distribution. Finally, based on the experimental results from TRC under uniaxial tensile load, a double linear constitutive equation of stress–strain relationship of carbon fiber yarn is provided in this paper.

Application of Terminalia chebula natural dye on wool fiber\u2014evaluation of color and fastness properties

In the present study, Terminalia chebula (Myrobalan/Harda) natural dye extract was used for the development of eco-friendly shades on woolen yarn with different hues and tones. The effect of dye concentration on color strength (K/S) of woolen yarn dyed with T. chebula was assessed. Increasing the concentration of dye decreased lightness (L*) values of woolen yarn samples, indicating darker shades. Different metal salts such as alum, ferrous sulfate, and stannous chloride were used to enhance the fastness properties (light, wash, dry and wet rubs) of dyed woolen yarn. Pre-treatment of woolen yarn samples with metal salts has shown encouraging results with better fastness properties and enhanced color strength values. Five percent ferrous sulfate mordanted samples show greater saturation with increasing dye concentration from 0.5 to 15 % (o.w.f.). Fourier-transform infrared (FT-IR) analysis of T. chebula dye extract shows presence of carbonyl and hydroxyl functionalities.

Characterization of the Twist Distribution Function and Twist Unevenness of Self-twist Yarns

In in-phase self-twist yarn there exists an obviously weak twist area between the twisted and no twisted zones. Therefore, during the self-twist spinning process, different distances from the two strands to the convergence point is adopted to produce a certain phase difference to improve the yarn strength. There are two methods used for calculating the twist distribution function of self-twist yarn: 1. using the difference in distance c, and 2. using the twist distribution function of strands A and B, respectively. Then the average twist over a half cycle length is calculated by the twist distribution functions from the two methods mentioned above. Comparing the calculation value from the two methods with actual test twists for the half cycle length, the result shows that the calculation value from method 2 is closer to the values measured, namely the twist distribution function derived from that of strands A and B, respectively. The twist unevenness of self-twist yarn is calculated by the twist distribution function from method 2. The twist unevenness of yarn 1 is the highest. That of yarns 2 and 3 decreases in turn. From the test data of 49×2 tex and 113×2 tex selftwist yarns, in-phase self-twist yarn 1, with maximum twist unevenness, has the minimum tenacity and maximum unevenness of tenacity, and in the same way phased self-twist yarn 3, with the minimum twist unevenness, has the maximum tenacity and minimum unevenness of tenacity.