Yarn Twist Research Articles

Biomimicking dual drug eluting twisted electrospun nanofiber yarns for post-operative wound healing

The morbidity rate following a surgical procedure increasing rapidly in the cases associated with surgical site infections. Traditional sutures lack the ability to deliver drugs as the incorporation of the drug in their structure would hamper their mechanical properties. To prevent such infections, we developed an extracellular matrix mimicking electrospun nanofibrous yarns of poly-(D,L)-lactic acid and polyvinyl alcohol loaded with vancomycin and ferulic acid, prepared by uniaxial electrospinning technique. In-vitro characterization such as scanning electron microscopy, Fourier transform infrared spectroscopy, x-ray diffraction, tensile strength testing, degradation studies, and antimicrobial studies along with in-vivo evaluation done with help of incision wound healing rat model and simultaneous testing of microbial load in the incised tissue. The in-vitro studies indicated the nanofiber yarns have size range 200–300 nm with a tensile strength of 7.54 ± 0.58 MPa. The dual drug-loaded yarn showed sustained drug release over a period of 48 h. In-vitro water uptake and biodegradation data indicated optimum results suitable for suturing applications. Antimicrobial study showed excellent antimicrobial activity against both S. aureus and E. coli. Results obtained from in-vivo study suggested excellent wound healing potential of nanofiber yarns as compared with commercial silk sutures. The histopathological studies confirmed restoring ability of nanofiber yarn to the normal skin structure. Enzyme-linked immunosorbent assay (ELISA) study revealed the downregulation of inflammatory markers i.e. TNF-alpha and IL-6, making nanofibers sutures suitable for surgical wound healing applications. Overall, the present study may conclude that the developed dual drug-loaded nanofiber yarns have excellent potential in surgical wound healing applications.

A hierarchical analytical model for twisted yarn reinforced plant fiber composites considering dual-scale filler content, porosity and local aggregation effect

Plant fibers with length limited by natural growing usually require to be twisted into continuous yarns for reinforcing the host matrix. This makes such twisted yarn reinforced plant fiber composites (TYPCs) are hierarchical with two-scale reinforcements: the plant fibers compacted in the yarn and the twisted yarns at the mesoscale. In the present paper, to uncover the internal relationship between such hierarchical structure and the mechanical properties of TYPCs, a bottom-up theoretical model is established. Synergistic effects of the filler content, filler aggregation degree, and porosity at each level are underlined. Accordingly, a three-step homogenization method based on Mori-Tanaka method is applied. To validate the effectiveness and accuracy of this model, comparisons with existing prediction models and available experimental data are made. Furthermore, detailed parameter analysis indicates that the performance of TYPCs depends not only on the filler content, but also on the filler distribution. The enhancement of TYPCs’ properties with increasing filler content may be offset by the weakening effect caused by filler aggregations. Moreover, the helical structure of yarns should not be ignored. The increase of the yarn twisting angle will improve the transverse and shear moduli of TYPCs while sacrificing the modulus in the longitudinal direction to a certain extent.

Spreading of water microdroplets simulating human sweating in polyester yarns and fabrics

Thermo-physiological comfort of human body is highly influenced by the moisture transmission behaviour of the fabric. For active sportswear, intimate apparels and inner layer of extreme cold weather clothing, moisture transport is very crucial. The liquid moisture transport of fabrics is analysed using standardised test methods like vertical wicking, absorbency test and moisture management through moisture management tester. These test methods use large reservoir of liquid in contrast to human sweating behaviour. The human skin generates sweats in the form of microdroplets through sweating glands. Hence, the standard test procedures employed to assess the fabric’s liquid moisture transport fail to capture preciously the sweat transport from human skin to the fabrics. Hence, in this work, the spreading behaviour of water microdroplets simulating human sweat through yarns which are the building block of fabrics and knitted fabrics that are widely used as sportswear or inner layer of extreme cold weather clothing are investigated. The purpose of this study is to understand how the microfluid move along the capillary channels in yarns (in the forms of network of yarns crossing over each other and fabric) by keeping yarn count and twist same for all yarns. A single micro drop representing accumulated sweat droplets and multiple drops showing continuous sweating through sweat glands were allowed to wick through the yarns made up of coarser and finer fibres to understand the role of fibre diameter on wicking kinetics. Results from the conventional wicking test were compared with microfluidic wicking. It is found that the initial wicking speed in coarser-fibres yarn is faster in comparison to finer-fibres yarn, but the final wicking height is longer in finer fibre yarn. Overall liquid spreading length found to be similar for both the yarns. Yarn to yarn liquid transfer at crossover junctions is faster with finer-fibre yarn compared to coarser-fibre yarn. Same trends are found in fabrics constructed with these yarns. The effect of yarn tortuosity on liquid spreading behaviour has also been studied. As the yarn path becomes torturous (straight yarn to fabric form) wicking length also decreases.

Modeling of yarn strength and its influencing factors in the pneumatic splicing process

Yarn splicing strength is one of the most important indexes to evaluate yarn twist quality, and it determines final performance of the yarn. This paper establishes a prediction model of yarn splicing strength. The strength prediction model was used to predict the mechanical properties of yarn composed of different fibers during splicing. The effects of fiber properties, splicing and tensile strain on the splicing strength of yarn were described by using the characteristic parameters of the fiber and yarn. Finally, the interaction between parameters is analyzed by charts, and the optimal solution is obtained. The results show that the yarn splicing strength prediction model established by the mechanical analysis and geometric structure can reflect the mechanical state of the yarn in the pneumatic splicing chamber, and can be used to calculate the yarn splicing strength. Yarns with higher tensile modulus will obtain higher splicing strength under the action of lower twist and higher tensile stress. Therefore, the strength prediction model provides a theoretical basis for the study of the relationship among yarn strength and fiber properties, splicing, tensile strain and other parameters, and also provides guidance for the optimization of the modern spinning process. Furthermore, the influence of air pressure on the splicing strength is also discussed.

Effect of Cotton/Polyester Blend Ratio, Loom Speed, and Air Pressure on Yarn Twist Loss and Yarn Strength Loss: The Case of Air-Jet Loom

ABSTRACT Production of high-quality woven fabric with uniform fabric properties is an essential requirement for manufacturers. But in air-jet weaving, some quality parameters of the fabric are affected by twist loss of weft yarn during weft insertion. The aim of this work is to show the effect of polyester/cotton (PC) blend ratio, loom speed, and air pressure on weft yarn twist loss and tensile properties of the fabrics produced by air-jet weaving machines. Box-Behnken design has been used to design and analyze the experiment. 27 fabric samples were on an air-jet loom with a combination of four factors each at three levels (loom speed (A) 300rpm, 425rpm, and 550rpm), left side relay nozzle pressure (LSRNP) (B) (2.5 bar,3.25 bar, and 4 bar), Right side relay nozzle pressure (RSRNP)(C) (3 bar, 4.75 bar, and 6.5 bar), cotton/polyester blend (D) 100%/0%, 75%/25%, and 50%/50%,). The results of the experiment revealed that PC blend ratio, loom speed, and air pressure affect the twist level and the strength of the yarn significantly. It is found that relay nozzle air pressure is directly proportional to the twist losses and weft yarn strength loss. But the PC blend ratio has a more significant impact on weft yarn twist loss and mechanical properties of the yarn.

SURFACE ROUGHNESS OF POLYAMIDE KNITTED FABRICS

Fabrics are never ideally smooth. Their texture varies between fine and coarse, quantified through the surface’s vertical deviation. Fabric roughness, or its opposite smoothness, is employed as measure of the surface texture of fabrics. In general, texture depends upon fiber properties, yarn count, yarn twist, and fabric structure and fabric design). This research aims to determine the limitations in visual perception of surface roughness in comparison to objective surface roughness measurements of low weight polyamide fabrics. Subjective evaluation is used for the visual assessment, while instrumental measurement of the properties was conducted using a noncontact laser profilometer. Subjective evaluation was conducted by a panel of forty untrained evaluators on a sample of seven polyamide knitted fabrics with different yarn count and composition. The roughness profile parameters were measured using Talysurf CLI 500 according to ISO 4827. Although the surface roughness measured as arithmetic mean deviation (Ra) and roughness through visual inspection of the fabric are correlated, instrumental measurements of roughness are more precise. Differences in the surface roughness arising from significantly different yarn structures will be observed, while those due to the knitted fabric structure are negligible in visual inspection.

Investigation on the effect of cotton-tencel (50:50) siro yarn twist multipliers on fabric stiffness

The properties of fabrics are mainly affected by constituent fiber properties and yarn structures. The yarn structures are primarily dependent on the spinning technique. The twist multiplier is a leading factor influencing yarn structure which directly correlates with fabric stiffness and mechanical properties due to structural behavior. In this study, siro spun yarn has been prepared using different twist multipliers (3.6, 4, 4.4, and 5.0) by blending cotton and tencel fiber at the spinning stage to investigate the effect of twist multipliers on fabric stiffness and the flexural rigidity of woven fabrics. The 1/1 plain, 2/2 twill, and 8-end satin fabrics have been woven using prepared yarns in warp and weft directions. The fabric stiffness has been measured using the ASTM D1388-2018 method. The results reveal that fabric stiffness increased with the increasing twist multiplier. Furthermore, a comparative study on different weave structures shows significant differences in stiffness. Overall, the experimental results present a close relationship between twist multiplier, spinning triangle, float length, fabric stiffness, and rigidity, and also show the optimum twist level for cotton-tencel siro yarn to attain maximum stiffness and strength.

Twisted and coiled yarns for energy harvesting and storage, artificial muscles, refrigeration, and sensing

This overview focuses on our teams work on using twisted yarns and highly elastic coiled yarns for artificial muscles, energy harvesting, energy storage, sensing, and refrigeration. Despite the diversity of these applications for coiled carbon nanotube and polymer yarns, similar fabrication methods are applicable and conversion of coiling twist to yarn twist results in yarn elasticity, actuation, twistocaloric cooling, and the capacitance changes used for energy harvesting and sensing. Likewise, the same biscrolling method yields coiled yarns containing up to 95 weight percent of guest powders that provide various new properties. The obtained performance of the coiled polymer and carbon nanotube yarns are remarkable, such as artificial muscles that generate up to 98 times the output mechanical power than the maximum for the same weight human muscle and mechanical energy harvesters providing a higher peak electrical power per weight than prior art material-based mechanical energy harvesters for stretch frequencies between a few Hz and 600 Hz.

Systematic investigation and evaluation of modified ring yarns by feeding three-roving strands

Spinning is one of the major steps in textiles to convert staple fibers from either natural or synthetic sources into continuous and twisted yarns, and ring spinning has always been the dominant yarn technology since its invention. Recently, many ring-based modifications have been developed to improve yarn productivity and properties. In this work, a modified ring spinning technique has been developed by feeding three-roving strands into a conventional ring frame for producing yarns with better performance. A strand delivery guide with different spacings (1–5 mm) was used for the production of three-strand yarns. The quantitative relationships between the spinning parameters and yarn properties have been systematically investigated. The properties of the modified yarns were evaluated, including yarn tensile properties, evenness, and hairiness, and the statistical relationships were obtained by least squares polynomial fitting. The experimental results indicate that the guide spacing and twist multiplier significantly influence the yarn properties. The spinning triangle of the modified yarns resembles Solospun yarns, suggesting supreme yarn abrasion performance.

Mechanical properties of composites manufactured from low twist hybrid yarns made of discontinuous carbon and polyamide 6 fibres

Composites based on e.g. randomly oriented nonwovens and injection moulded structures from discontinuous carbon fibre (CF), which are processed industrially exhibit low tensile strengths of 200–300 MPa and 400 MPa, respectively. In contrast, composites based on twisted hybrid yarns from discontinuous CF and thermoplastic fibre show higher tensile strengths such as 1150 MPa. Reasons are improved fibre orientation and higher fibre volume content. However, tensile strength is still lower than that of uni-directional carbon fibre reinforced composites (CFRP) based on continuous filament yarn, which is around 1560 MPa. The reason is a low fibre orientation due to yarn twisting and high fibre shortening, which occurs throughout the yarn manufacturing process. As mechanical properties of composites largely depend on fibre orientation and length, there is a high potential to achieve higher mechanical properties in CFRP by ensuring gentle processing of CF and reducing yarn twist. However, due to brittleness and smooth surface of CF, spinning of yarns with low twist (<60 T/m (twist per meter)) is challenging. In order to exhaust the potential of hybrid yarns, a semi-industrial process chain to produce hybrid yarns while ensuring gentle processing of discontinuous CF (fibre length 100 mm) and polyamide 6 fibres (fibre length 80 mm) at significantly low level of twist 20 T/m is reported in this paper. Carbon fibre reinforced composite manufactured from these hybrid yarns show high tensile strength (1453 ± 27 MPa), Young’s modulus (94 ± 6 GPa), flexural strength (1090 ± 41 MPa) and flexural modulus (98 ± 5 GPa).

Effect of Structure on Vertical and Horizontal Wicking Performance Concerning Jute (Chorchorus Olitorius) and Water

ABSTRACT Vertical and horizontal wickings were studied for jute, a lingo-cellulosic natural fiber, as fiber, yarn, woven fabric, and nonwoven. The effect of yarn parameters (linear density, twist density, and tension), fabric type (plain woven, twill woven, and nonwoven) and nonwoven parameters (parallel laid, cross laid, areal density, punch density, and depth of needle penetration) were observed and analyzed using a fabricated setup for wicking testing. Wetting of jute with water was studied by measuring contact angle using Sissili-drop method. The rate of wicking shows two distinct parts: instantaneous and time dependant. The horizontal wicking is always higher than the vertical wicking. The weft shows better wicking than warp yarn followed by two-ply yarn. Yarn twist level and linear density play a significant role. Twill fabric shows better wicking than plain-woven fabric. Wicking effect of needle-punched nonwoven shows lower than woven fabric. It is negatively correlated with areal density and positively correlated with punch density. It will help to design a textile from jute, where wicking plays a significant role.

The effect of loop length, yarn twist and dyeing process on seam strength of knitted fabrics

Seam strength is a key factor both in terms of aesthetics and the life of the apparel. There are many factors affecting seam strength, some of which are relevant to fabric construction and treatment, and the others are about sewing thread and sewing parameters. This research paper focuses on the effects of fabric construction, sewing parameters and the dyeing process on the seam strength of knitted fabrics. For this purpose, seven single jersey knitted fabrics were produced, differing in loop length and yarn twist. The samples were dyed and then sewn with different sewing parameters. The seam strength values were calculated and statistically evaluated. The results showed that fabric construction, sewing thread type and count, stitch density and dyeing process profoundly influence the seam strength of single jersey fabrics. When comparing the effects of dyeing, it was found that dyeing leads to a decrease in seam strength values

Electrospun poly (lactic acid) -cotton core-shell yarns: Processing, morphology, and mechanical properties

In this study, aiming to improve the mechanical performance of the Poly (lactic acid) (PLA)-based nanofibrous structures, the electrospinning method was employed to develop twisted yarns with core-shell structure. Within this process, a conventional ring-spun cotton yarn fed to the electrical field, where nanofibers covered it by a certain orientation owning to the twisting procedure. This approach combines the excellent biological and physical-mechanical properties of cotton with outstanding features of the PLA nanofibers for biomedical applications. The effects of the core and shell structures on the ultimate properties of the electrospun core-shell yarns were investigated. Scanning electron microscopy (SEM) demonstrated that relatively uniform and bead-free fibers with smooth surfaces were formed. SEM images also confirmed that the nanofibers were arranged around the core with a specific angle to the axis (with the angle range of 8–44 based on the twisting rate) to constitute a twisted core-shell yarn. The diameter of the electrospun yarns decreased (∼ 22%) by increasing the twist rate. The influence of the core on the mechanical behavior of core-shell yarn are also discussed. Improvements in mechanical performance of core-shell yarns were generally perceived at low twist levels of the core yarn (αe = 2.8), and electrospun shell (40 rpm).

An efficient virtual modeling regard to the axial tensile and transverse compressive behaviors of the twisted yarns

The mechanical properties of yarns have a decisive effect on the performance of fiber-reinforced composite materials. Predictive simulations of the mechanical response of yarns are, thus, necessary for damage evaluation and geometric reconstruction of textiles. This paper proposed a quasi-fiber scale virtual modeling method regard to the axial tensile and transverse compressive behaviors of the twisted yarns. A stochastic properties model of the yarn was established for characterizing the statistical distribution of tensile strength. The variation of modeling parameters, including coefficient of friction, the amounts of virtual fibers per yarn and element length, versus calculation accuracy has been determined based on axial tensile and transverse compressive behavior of quartz fibers. The relationship between modeling parameters and mechanical behavior of yarn was established within the scope of this study. Axial tensile and transverse compressive behavior of yarns with different twists were predicted. The results show that balance between the modeling precision and computational efficiency can be achieved using the parameters, the COF of 0.35, virtual fiber count of 122 and Le of 0.3. This efficient modeling method is meaningful to be developed in further virtual weaving research.

Free-standing single-helical woolen yarn artificial muscles with robust and trainable humidity-sensing actuation by eco-friendly treatment strategies

Twisted yarn artificial muscles have attracted great interests for diverse applications, such as soft robotics, miniaturization controllers and smart textiles. A challenging issue in fabricating the twisted yarn artificial muscles is to retain the inserted twist. Different from the exiting strategies of forming double-helical structures or harnessing complex chemical technologies, we herein propose a simple combination of plasma and UV-light treatments to train natural wools into twist-stable single-helical yarn artificial muscles without external torsional tethering, which realizes easy fabrication of twisted actuators, and achieves better moisture-actuating performance (nearly five times higher in maximum rotation) compared to equivalent double-helical actuators. The stable morphology of woolen yarn muscles affected by the opening and closing of disulfide bonds is explained from microstructure characterization and theoretical analysis. The charming properties of single-helical yarn muscles will provide new inspiration for the development of fiber-based actuators in industrial routines, which is expected to promote the practical application of yarn muscles in smart textiles and wider fields.

Low Twist Hybrid Yarns from Long Recycled Carbon Fibres for High Performance Thermoplastic Composites

With the increasing demand and use of carbon fibre reinforced composites (CFRP), the disposal of carbon fibres (CF) and end-of-life composite parts is gaining tremendous importance, particularly in terms of sustainability. The current focus of using recycled carbon fibre (rCF) is still on nonwovens or injection-moulded components, characterized by low performance. On the contrary, spinning rCF to yarn constructions offers good potential for improved CFRP material properties due to longer fiber length, high fibre orientation, compaction of rCF and even yarn structure. However, previous experiences reveal that the shortening of fibres increases with longer input rCF during carding. Therefore, the focus of this work is placed on broadening the knowledge concerning gentle processing of rCF, especially for fibres > 60 mm in combination with thermoplastic fibres. In this work, a new yarn construction is developed by significantly reducing the yarn twist to ensure a fibre orientation parallel to the yarn axis in order to increase mechanical properties of composites significantly. With the developed hybrid yarns, tensile strength and E-modulus of 1364 ± 49 MPa and 100 ± 15 GPa, respectively in composites could be achieved.

Antibacterial easy adjustable woven compression bandage for venous leg ulcers

The proposed study aims in first part to discuss the structure and behavior of short-stretch cotton woven compression bandage (WCB), and in second part the production and properties of multifunctional WCB. The bandage includes an integrated tension sensor, which causes a change in the spacing of colored threads during its deformation. The motivation of this research was to investigate the optimum techniques for compression therapy using a modified construction of cotton WCB as a tensiometer. The aim of second part is focused on an industrial product which has the easy adjustable compression and antibacterial properties. Multifunctional WCB can be produced by two methods, the first was using highly twisted warp yarns (ply twist 1800 to 2200 twist/m) and the weft yarns will be treated with silver Nano-particles (NPs). The second method was post-treatment of the WCB with three concentrations of zinc oxide NPs 1–3 % in powder form with 15 g/L acrylic binder. Silver NPs coated yarns showed a comparable antibacterial activity on both tested bacterial strains ( Escherichia coli and Staphylococcus aureus) using quantitative and qualitative test methods. The WCB tested samples achieved 95–99% bacteria reduction, the nanoparticles size and its distribution were confirmed by the Zetasizer Nano, the scanning electron microscopy (SEM), and the energy dispersive X-ray spectroscopy (EDXS). The practical bandage pressure by PicoPress showed significant deviations compared with theoretical pressure calculated by Laplace’s equation ranges ±0.68 to ±15.64% especially at the highest extension levels.

Multiscale analysis on the anisotropic thermal conduction of laminated fabrics by finite element method

In this paper, we present a novel “Two-scale finite element method” (tFEM) based on virtual fiber models to investigate the heat conduction behavior of stacked quartz woven fabrics and predict their anisotropic thermal conductivity. Considering the random fiber distribution and the twisted characteristic of yarns, the yarn-scale model was established. Furthermore, the single-layer fabric was composed of interwoven virtual yarns, which are stacked to be the multi-laminate fabric-scale model. Both the yarn-scale model and the fabric-scale model were combined with air matrix to form the two-phase composite model. Hot-Disk thermal constant analyzer was used to measure the anisotropic thermal conductivity of yarns and woven fabrics. Excellent agreement between simulations and experiments is obtained, which indicates the multiscale finite element models in this paper is accurate. The innovations of the study are that not only the effects of fiber numbers and diameters on the thermal conductivity of twist yarns and quartz ply-fabrics are analyzed, but also the detailed heat flux distribution and temperature distribution between fibers and the air are simulated and analyzed. Moreover, the isotropic thermal conductivity of the yarn radial direction and the anisotropic thermal conductivity of quartz fabrics are illustrated.

Effects of Fe Staple-Fiber Spun-Yarns and Correlation Models on Textile Pressure Sensors.

As an aspect of intelligent clothing, e-textile sensors can flexibly sense and transmit information about human bodies and environments. However, difficulties relating to their technology and the variation in textile materials employed in their manufacture still limit their ability to analyze and be applied. The authors’ previous publication deployed a pressure sensor with warp-knitted spacer fabrics, wet-knitted fabrics, Ag-yarns, and Fe-yarns. An equivalent circuit analyzed the resistance behavior with some effects of the Ag-coated twisted yarns. In the present paper, the authors continue to evaluate the correlation model R-ε and the effects of the Fe staple-fiber spun yarns in detail. Together, the two studies provide an extensive understanding of the textile-related elements that affect pressure sensors. In addition, the process and the analysis (correlation model) could bring the textile sensors here developed close to the manufacturing stage, particularly for high precision/adjustable applications. We also develop a simple touch sensor matrix to demonstrate the potential of the sensor and the analyzing method.

Development of high performance two-way shape memory zinc dimethacrylate/ethylene vinyl acetate composite fibers for building flexible yarn actuators

Soft and flexible mechanical actuators capable of demonstrating large deformations and outputting stress spontaneously in responding to external environmental stimuli have been becoming a research focal point in the field of smart biomimetic systems and devices. Here, a novel twisted yarn actuator consisting of shape memory zinc dimethacrylate/ethylene vinyl acetate (ZDMA/EVA) composite fibers has been created following a four-step fabrication protocol including two-roll milling, melt-spinning, ultraviolet crosslinking, and twisting procedures. The obtained ZDMA/EVA composite fibers demonstrate excellent thermomechanical coupling effect and superior thermal/mechanical stability. In specific, the twisted yarn actuators present strong two-way shape memory capability (up to 8% reversible tensile stroke) and outstanding recovery stress (1.63–1.82 MPa). Notably, this composite yarn actuator (in diameters of 438–719 μm) is able to afford tension loads about 2300 times heavier than its own weight, reaching 7.76% reversible strain and exhibiting an exceptional energy density of 210 J/kg that is 26 times higher than the typical skeletal muscles. In addition, the optimal yarn actuator displays an ultimate rotation speed and rotational energy density of 15456 rpm/m and 5439 J/kg, respectively. This experimental study presents a facile, low-cost, and environmental-friendly manufacturing approach of developing high performance composite fiber-based yarn actuators.