Yarn hairiness affecting fluff generation

Fluff (lint, fiber fly) generation, especially related to yarn structure, was investigated. Research centered on the fiber length related to fluff generation during the knitting process. Short fiber length composing yarn structure was a main source of the fluff shedding. High quality spun yarn with longer length of fiber was recommended to the high speed knitting industry in order to reduce process troubles such as yarn breakage, etc. but the cost is doubtable to the manufacturers. A trial to reduce the fluff trouble by using chemicals to hold the short fiber on the surface of the yarn was suggested and the research showed a positive effect to the problem. However, another factors including a by-product of chemical residue and searching more feasible material need to be concerned for the future research.     

Theoretical study on the bending rigidity of filament yarns with an elliptical cross-section using energy method. I. Theoretical modeling

The geometrical model of yarn currently in use is assumed to be a circular cylindrical under the bending deformation, but this assumption is not really true because the cross-section of yarn has to change to an elliptic shape when the compressive force acted on the yarn is considered. Therefore, as the first part of a series of work, the present paper considers the fact that yarn geometry changes from a circular cylindrical to an elliptical cylindrical under an external applied bending moment, and then analyzes the relationship of bending rigidity between constituent filaments and the formed yarn, which is useful in predicting or selecting specified bending property of filaments by the requirements of yarn. In the present paper, the bending and torsional energies stored in filaments are analyzed according to their deformations by the energy method. The explicit formula is then obtained to quantify the bending rigidity relationship between the filament and yarn, in which four characters are featured as the eccentricity of elliptical cross-section of yarn, the ratio of bending to torsional rigidity of filament, the helix angle of the filament on yarn surface and the number of filaments inside the yarn. Moreover, the bending rigidity of filament yarns formulated by an earlier method with a circle shape assumption can also be obtained by the proposed method with the eccentricity being equal to zero. Based on the analytical solution, the earlier method in which the circle shape takes place of the elliptical shape of yarn for simplification can also be evaluated. This will be depicted in the Part II of this series of work, in which the relative error between the ideal and revised model would be analyzed, and the numerical simulations of relationship between filament and yarn would also be made.     

Theoretical study on the bending rigidity of filament yarns with an elliptical cross-section using energy method. II. Numerical evaluation

This is the second part of a series of work investigating on the bending rigidity of filament yarn with an elliptical cross-section. In the present paper, the quantitative error analysis of the earlier simplification of a circular cylindrical of yarn geometry under deformation is evaluated, and the effects of filament properties on yarn bending rigidity are also evaluated. It is highly useful in preciously predicting yarn bending property from filament behaviors for virtual processing of textile materials. So the explicit formula derived in the Part I of this series for the elliptical cylindrical of yarn geometry is used to compute the quantitative error of the earlier model. The four characters, including the eccentricity of elliptical cross-section of yarn, the ratio of bending to torsional rigidity of filament, the helix angle of filament on yarn surface and the number of filaments inside the yarn, are adopted to quantify the bending rigidity relationship between the filaments and yarn. Based on the analytical method, the earlier method in which the circle shape takes place of the elliptical shape of yarn cross-section for simplification is evaluated. The simulation results show that the relative error of the circle assumption is not higher than 10 % when the eccentricity of yarn cross-section is lower than 0.8. However if the eccentricity is higher than 0.8 and the helix angle is larger than 30 degrees, it is suggested to conduct the deformation analysis based on the elliptical cross-section of yarn.     

Comfort and handle related properties of P/V blended air-jet textured yarn fabrics

The effect of blend percentage on comfort and handle related properties of fabrics made from polyester/viscose blended air-jet textured yarn weft were studied and the results were compared with fabrics made from polyester/viscose ring-spun yarn wefts of similar linear densities. It is observed that with increase in polyester content in the blend, the air permeability and water vapour permeability reduces whereas thermal resistance, transverse wicking and shear rigidity increases both in ring-spun yarn and textured yarn fabrics and bending rigidity increases in textured yarn fabrics. Textured yarn fabrics exhibit lower air permeability and extensibility, higher thermal resistance, relative water vapour permeability, transverse wicking values and bending rigidity as compared to the ring-spun yarn fabrics.     

Characterization of conductive polypyrrole coated wool yarns

Wool yarns were coated with conducting polypyrrole by chemical synthesis methods. Polymerization of pyrrole was carried out in the presence of wool yarn at various concentrations of the monomer and dopant anion. The changes in tensile, moisture absorption, and electrical properties of the yarn upon coating with conductive polypyrrole are presented. Coating the wool yarns with conductive polypyrrole resulted in higher tenacity, higher breaking strain, and lower initial modulus. The changes in tensile properties are attributed to the changes in surface morphology due to the coating and reinforcing effect of conductive polypyrrole. The thickness of the coating increased with the concentration of p-toluene sulfonic acid, which in turn caused a reduction in the moisture regain of the wool yarn. Reducing the synthesis temperature and replacing p-toluenesulfonic acid by anthraquinone sulfonic acid resulted in a large reduction in the resistance of the yarn.     

Mechanical modelling of multifilament twisted yarns

A computational approach is proposed for the mechanical analysis of the multifilament twisted yarn based on the Finite Element Method (FEM). The physical and the geometrical properties of the filaments and the ideal yarn geometrical structure are considered for the mechanical modelling. The tensile and bending deformations of yarns are simulated for the prediction of the respective properties and the computation of the deformed shape. Considerable complexity appears in the mechanical analysis of fibre assemblies, including the structural multiformity, the material nonlinearity and the large deformation effects occurring. The FEM applying the beam theory enhanced with advanced solution algorithms approved appropriate for the analysis. Besides the comparison to an existing analytical model, a set of experimental data derived from 2- to 1200-filament twisted yarns is used for the evaluation of the accuracy of the proposed approach. The effect of the major structural parameters as the filament radius and the yarn twist in the elastic properties and the bending rigidity is also examined.     

Correlation of yarn tension with parameters in the knitting process

Tension control is an important factor in producing high quality knitted products and in maintaining good processing condition. Yarn tension during knitting is subject to be affected from many elements of the machine and process parameters. Several factors including yarn feeding speed, feeding angle, and needle gauge that are considered to influence on the tension variation were investigated. Yarn feeding speed did not show high contribution to the tension variation but feeding angle of yarn did show high correlation with the tension. No or negative correlation of the tension with needle gauge was found from the results. In order to keep well-determined process condition in the knitting manufacturing, it is strongly suggested that all knitting elements and parameters should be in the integrated control circumstance.     

Prediction of seamless knitted bra tension

Seamless knitting, as a new technology, has a great potential in the development of lingerie products. Bra knitting using seamless knitting technology is a difficult engineering problem due to the lack of knowledge on how to achieve proper underband tension and cup strain for optimal comfort and shape. In this study, we aim at identifying the key knitting parameters and experimentally investigating their relationships with the knitted bra tension. The knitting parameters under investigation were loop density, elastic yarn tension, cover yarn tension and nylon yarn tension. Factorial experimental design was used to explore the most significant factors affecting the underband tension and cup strain of seamless knitted bra. The results show that the loop density and elastic yarn tension were the two main factors affecting the underband tension. The cup strain was mainly affected by the loop density. Empirical prediction equations have been established to estimate the underband tension and cup strain from knitting parameters.     

Analysis and in-plane shear characterization of polyester plain fabric by yarn pull-out method

The aim of this study was to determine the in-plane shear properties of polyester fabric by the pull-out method and analytical relations were developed to calculate the shearing properties. After the yarn in the fabric was pulled from the top ravel region before the start of the crimp extension stage, it was found that fabric shear strength and rigidity increased when the number of pulled ends increased. In addition, when the fabric width and length increased, fabric shear strength and rigidity increased. On the other hand, the shear strength and rigidity values in untreated fabric were high compared to that of treated fabric due to the fabric treatments by softening agent. It was observed that fabric sample dimensions and the number of pull-out ends as well as the fabric treatments influenced fabric shear strength and rigidity. Also, the shear jamming angles were found to be based on the number of pulled ends. Fabric local shearing properties could be identified by pulling the yarn ends in various regions of the fabric. This could be important for the handling of the fabric during formation. The results generated from this study showed that polyester fabric shear could be measured by the yarn pull-out test.     

Fabrication of continuous nanofiber core-spun yarn by a novel electrospinning method

Continuously twisted polyacrylonitrile/viscose nanofiber core-spun yarns were fabricated through novel self-designed multi-nozzle air jet electrospinning set-up. The effect of voltage, solution flow rate, air flow rate and funnel rotating speed on coating rate of core-spun yarn, nanofiber diameter, twist level and mechanical property were discussed. The results showed that polyacrylonitrile/viscose nanofiber core-spun yarns with perfect nanofiber orientation and uniform twist distribution could be obtained at voltage of 32 KV, solution flow rate of 32 ml/min and air flow rate of 1000 ml/min, and the spinning speed could reach to 235.5 cm/min. The diameters of outer coated nanofiber distributed from 100 nm to 300 nm, and nanofiber coating rate could reach to 70.4 %. In addition, the strength and elongation at break increased from 30.82 MPa to 69.65 MPa and from 28.34 % to 43.29 % at the twist angle of 46.6 °, respectively.     

Study on characteristics of compact yarns under dynamic state

The dynamic testing conditions simulate actual manufacturing conditions more closely than static testing. In most cases, as results from dynamic tests differ significantly from static tests, dynamic tests are more relevant from the point of view of processing of yarn. The yarns are in motion when they are running on different machines during the production process viz. weaving; knitting etc. Compact ring spun yarns have created a fundamental change how the industry views the ring spinning. The new technology compact yarns such as EliTe® yarns need to be compared with the normal doubled yarns in a dynamic way. This study involves dynamic testing of the EliTe® compact yarns and normal ring spun doubled yarns using CTT (Constant Tension Transport) machine, a versatile test instrument to measure the yarn properties such as dynamic breaking strength, elongation, abrasion, lint, yarn faults (thick, thin places, neps), hairiness etc. EliTe® compact yarns showed higher breaking strength, more elongation, with lesser yarn faults and hairiness, less abrasiveness and less lint generating tendencies during the dynamic testing as compared to the normal ring spun doubled yarns.     

Low stress mechanical properties of fabrics woven from bamboo viscose blended yarns

This paper presents the low stress mechanical properties of plain fabrics woven from cotton, bamboo viscose and cotton-bamboo viscose blended yarns. Three blends (100 % cotton, 50:50 cotton-bamboo and 100 % bamboo) were used to produce three yarn counts (20, 25 and 30 Ne). Each of these yarns was used to make fabrics with different pick densities (50, 60 and 70 picks per inch). It was found that bending rigidity, bending hysteresis, shear rigidity, shear hysteresis and compressibility is lower for bamboo fabrics as compared to those of 100 % cotton fabrics. On the other hand, extensibility, tensile energy and compressional resilience are higher for 100 % bamboo fabrics than 100 % cotton fabrics. Higher pick density increases linearity of load-elongation curve, bending rigidity, shear rigidity and compressional resilience. Shear and bending rigidities show very good correlation with the respective hysteresis values.     

Effect of fiber friction, yarn twist, and splicing air pressure on yarn splicing performance

The impact of fiber friction, yarn twist, and splicing air pressure on mechanical and structural properties of spliced portion have been reported in the present paper. The mechanical properties include the tensile and bending related properties and, in the structural properties, the diameter and packing density of the splices are studied. A three variable three level factorial design approach proposed by Box and Behnken has been used to design the experiment. The results indicate that there is a strong correlation between retained spliced strength (RSS) and retained splice elongation (RSE) with all the experimental variables. It has been observed that RSS increases with the increase in splice air pressure and after certain level it drops, whereas it consistently increases with the increase in yarn twist. The RSE increases with the increase in both fiber friction and yarn twist. It has also been observed that the yarn twist and splicing air pressure have significant influence on splice diameter, percent increase in diameter and retained packing coefficient, but the fiber friction has negligible influence on these parameters. Yarn twist and splicing air pressure has a strong correlation with splice flexural rigidity, where as poor correlation with retained flexural rigidity.     

麻棉针织弹力牛仔布的设计与生产

从纱线选择、织物结构、织造染整等方面对麻棉针织弹力牛仔布的设计与生产进行了探讨,提出了进口单面大圆机上氨纶丝的送纱方法,和织造中织针的排列问题。     

Coating Cellulosic Materials with Graphene for Selective Absorption of Oils and Organic Solvents from Water

Development of efficient and eco-friendly sorbents used for selective oil removal after oil spill disasters is one of the main topics in environmental science. By using various cellulosic materials coated with graphene flakes, using simple, one-step dip-coating method, it was possible to manufacture environmentally friendly, selective oil sorbents. The cellulosic materials of different yarn size and distribution such as cotton roving, gauze, fabric, and cellulosic wipe and Whatman filter paper were chosen. The scanning electron microscopy showed that simple dip-coating of any cellulosic materials into graphene dispersion creates a uniformly distributed nanomaterial coating. The wetting tests confirmed that the coating endowed cellulosic materials with hydrophobic properties, regardless of their initial yarn distribution and purity. Moreover, the water repellent samples were simultaneously highly sorptive towards oils and organic solvents. Sorption tests performed for a representative group of organic solvents and oils have shown that depending on cellulosic material the oil sorption capacity varied from 4 g/g to 33 g/g for cotton fabric and roving, respectively. Moreover, the absorption selectivity of chloroform versus water exceeded 90 % for each sample and reached over 99 % for the graphene coated cotton roving and gauze. Finally, the recyclability tests have shown that graphene coated materials are less fragile for reuse than naturally hydrophobic sorbents.     

Sodium carboxylmethylate cellulose from date palm rachis as a sizing agent for cotton yarn

The chemical composition of date palm rachis wastes, which are widely available cellulosic biomass-based agricultural crops in Tunisia, were characterized to determine if they had the potential for use as a starting raw material to prepare cellulose derivatives. To accomplish this, several sodium cellulose carboxylmethylates (NaCMCs) were prepared and tested as sizing agents for coating yarn. The synthesis of NaCMC was conducted in n-butanol containing NaOH (40 %) as a solvent mixture and monochloroacetic acid (MAC) as the etherifying reagent. The NaCMC samples were characterized based on their degrees of substitution (DS) and polymerization (DP). The prepared NaCMC samples were then tested as sizing agents for cotton yarn in textile applications. Specifically, different NaCMC samples were used to prepare a coating bath, which was then applied to size a cotton yarn textile. The quality of the coated yarns was subsequently evaluated by determining three parameters, yarn hairiness, the load at break, and the elongation at break. The sizing performances of the NaCMCs prepared from date palm rachis wastes were then compared with those of commercial NaCMC. The values of hairiness, breaking load, and breaking elongation of some of the NaCMC-treated yarns were as high as those prepared using commercial additives as sizing agents. These findings indicate that the cellulose derivatives prepared in this study are good candidates for alternatives to currently available additives.     

Predicting bending rigidity of woven fabrics using artificial neural networks

This paper reports an investigation on the predictability of bending property of woven fabrics from their constructional parameters using artificial neural network (ANN) approach. Number of cotton grey fabrics made of plain and satin weave designs were desized, scoured, and relaxed. The fabrics were then conditioned and tested for bending properties. Thread density in fabric, yarn linear density, twist in yarn, and weave design were accounted as input parameters for the model whereas bending rigidity in warp and weft directions of fabric formed the outputs. Gradient descent with momentum and an adaptive learning rate back-propagation was employed as learning algorithm to train the network. A sensitivity analysis was carried out to study the robustness of the model.     

Pervaporation separation of dimethyl carbonate/methanol binary mixtures with poly(vinyl alcohol)-perfluorslulfonic acid/poly(acrylonitrile) hollow fiber composite membranes

Using poly(vinyl alcohol) (PVA) and perfluorslulfonic acid (PFSA) as coating materials, poly(acrylonitrile) (PAN) hollow fiber ultrafiltration membrane as substrate, PVA-PFSA/PAN composite membranes were fabricated by dip-coating method. The fabricated composite membranes were used to the separation of dimethyl carbonate (DMC)/methanol (MeOH) binary mixtures by pervaporation process. SEM images verify that the coated layer is well combined with substrate and the thickness nearly linearly increases with the coating solution concentration. The separation factor increases but at cost of the decline of permeation flux when the concentration of the coating solution or its PVA mass fraction increase. The permeation flux increases and separation factor slightly increases with the feed temperature increasing at 30–60 °C. The increase of feed MeOH concentration leads to an improvement of permeation flux and a decline of separation factor.     

The Effects of Fabric and Conductive Wire Properties on Electromagnetic Shielding Effectiveness and Surface Resistivity of Interlock Knitted Fabrics

Our aim in this study was to investigate the effects of course density, yarn linear density and thickness and type of conductive wire on electromagnetic shielding effectiveness. Metal/cotton conductive composite yarns were produced by the core-spun technique on the ring spinning machine, involving stainless steel, copper and silver coated copper wires with 40 μm, 50 μm, 60 μm thicknesses and Ne10/1 and Ne20/1 count yarns. The interlock fabrics were knitted on a 7G flat knitting machine with the three different machine settings. The EMSE and the surface resistivity of knitted fabrics were measured by the co-axial transmission line method according to the ASTM-D4935-10 standard in the frequency range from 15 to 3000 MHz and by the ASTM D257-07 standard, respectively. It was observed that all fabrics shielded around 95 % of electromagnetic waves at low frequencies, 80 % at medium frequencies and 70 % at high frequencies. Increasing the course density and thickness of conductive wire in interlock knitted fabrics increased the EMSE correspondingly. The knitted fabrics that had been produced with high yarn count showed greater EMSE because there was less isolation. The effect of the metal wire type was highly significant between 15 and 600 MHz.     

Properties and performance of polypyrrole (PPy)-coated silk fibers

Different silk substrates in form of spun silk tops, nonwoven web, yarn, and fabric were coated with electrically conducting doped polypyrrole (PPy) by in situ oxidative polymerization from an aqueous solution of pyrrole (Py) at room temperature using FeCl₃ as catalyst. PPy-coated silk materials were characterized by optical (OM) and scanning electron (SEM) microscopy, FT-IR spectroscopy, and thermal analysis (DSC, TG). OM and SEM showed that PPy completely coated the surface of individual silk fibers and that the polymerization process occurred only at the fiber surface and not in the bulk. Dendrite-like aggregates of PPy adhered to the fiber surface, with the exception of the sample first polymerized in the form of tops and then spun into yarn using conventional industrial machines. FT-IR (ATR mode) showed a mixed spectral pattern with bands typical of silk and PPy overlapping over the entire wavenumbers range. DSC and TG showed that PPy-coated silk fibers attained a significantly higher thermal stability owing to the protective effect of the PPy layer against thermal degradation. The mechanical properties of silk fibers remained unchanged upon polymerization of Py. The different PPy-coated silk materials displayed excellent electrical properties. After exposition to atmospheric oxygen for two years a residual conductivity of 10–20 % was recorded. The conductivity decreased sharply under the conditions of domestic washing with water, while it remained essentially unchanged upon dry cleaning. Abrasion tests caused a limited increase of resistance. PPy-coated silk tops were successfully spun into yarn either pure or in blend with untreated silk fibers. The resulting yarns maintained good electrical properties.