Investigation of inter fiber cohesion in yarns. I. Influence of certain spinning parameters on the cohesion in cotton yarns

This paper investigates the influence of raw material and process parameters in spinning that affect the inter fiber cohesion in yarns. An instrument has been developed for measuring the minimum twist of cohesion. With regard to the raw material parameters, the influence of different cotton fiber mixings for a given count of yarn is investigated. Also the effect of spinning to varying counts for a given cotton variety is studied. With regard to the process parameters, studies have been carried out to investigate the influence of noil extraction in comber, number of draw frame passages, draft pressure in ring frame and direction of twist. Cohesion improved with increase in the noil extraction percentage in the comber. Increase in the number of draw frame passages also improved the cohesion. Draft pressure in ring frame improved the fiber cohesion in yarn up to a pressure of 2.1 kg/cm². Direction of twist had no effect on the cohesion.     

Prediction of strength and weavability of blended spun yarns

In this paper, we report on predicting the strength of polyester/viscose spun yarns made on ring, rotor and air-jet spinning systems. A system has been developed to measure the weavability of yarns. Hamburger’s fibre bundle theory is modified to predict the strength of blended yarns from the strengths of single-fibre component yarns. The modified model predicts blended yarn strength more accurately than the original Hamburger’s model emphasizing the importance of yarn structure on blended yarn strength. The weavability of blended yarns is measured on a CTT instrument incorporating a shedding device which addresses the stresses viz., cycle extension, flex abrasion and beat up occur during weaving. The measured weavability compared well with that obtained on a commercial Sulzer Ruti Reutlingen Webtester. Yarn structure and strength and cohesion of fibres affect the strength and weavability of yarns.     

A comparative study on performance properties of yarns and knitted fabrics made of biodegradable and conventional fibers

Biodegradable products are parts of a natural cycle. The biopolymers and the fibers that can be produced from them are very attractive on the market because of the positive human perception. Therefore, PLA being a well known biodegradable fiber and some conventional fibers were selected for the current study to examine the differences between them and to emphasize the importance of biodegradability beside fabric performance. 14.8 tex (Ne 40/1) combed ring spun yarns produced from biodegradable fiber PLA, new generation regenerated fibers Modal and Tencel, synthetic and blends 50/ 50 % cotton/polyester and 50/50 % viscose/polyester, polyester were selected as yarn types and by using these yarns, six knitted fabrics were produced and some important yarn and fabric properties were compared. In this context, moisture and the tensile behavior of yarns and pilling, bursting strength, air permeability and moisture management properties of the test fabrics are discussed.     

Predicting the unevenness of polyester/viscose blended open-end rotor spun yarns using artificial neural network and statistical models

In this study, an artificial neural network (ANN) and a statistical model are developed to predict the unevenness of polyester/viscose blended open-end rotor spun yarns. Seven different blend ratios of polyester/viscose slivers are produced and these slivers are manufactured with four different rotor speed and four different yarn counts in rotor spinning machine. A back propagation multi layer perceptron (MLP) network and a mixture process crossed regression model (simplex lattice design) with two mixture components (polyester and viscose blend ratios) and two process variables (yarn count and rotor speed) are developed to predict the unevenness of polyester/viscose blended open-end rotor spun yarns. Both ANN and simplex lattice design have given satisfactory predictions, however, the predictions of statistical models gave more reliable results than ANN.     

The mechanism and/or prediction of the breaking elongation of polyester/viscose blended open-end rotor spun yarns

In this study, an analysis on the breaking elongation mechanism of the polyester/viscose blended open-end rotor spun yarns has been carried out. In addition, a back propagation multi layer perceptron (MLP) network and a mixture process crossed regression model with two mixture components (polyester and viscose blend ratios) and two process variables (yarn count and rotor speed) are developed to predict the breaking elongation of polyester/viscose blended open-end rotor spun yarns. Seven different blend ratios of polyester/viscose slivers are produced and these slivers are manufactured with four different rotor speed and four different yarn counts in rotor spinning machine. In conclusion, ANN and statistical model both have given satisfactory predictions; however, the predictions of ANN gave relatively more reliable results than those of statistical models. Since the prediction capacity of statistical models is also obtained as satisfactory, it can also be used for breaking elongation (%) prediction of yarns because of its simplicity and non-complex structure. In addition, it is also found in this study that yarn count, rotor speed and breaking elongation of polyester-viscose fibers and the blend ratios of these fibers in the yarn have major effects on yarn breaking elongation.     

Effect of blends proportion on the characteristics of dry and Pre-wet nylon/viscose blended air-jet textured yarns

Blending of nylon filament with viscose can overcome the drawbacks of these yarns. Thermoplastic and thermoset filament yarns can be blended in air-jet texturising method. The characteristics of nylon/viscose blended filament yarns are required to be understood in order to convert them in to useful products. Therefore, nylon/viscose blended yarns in different proportions were produced using nylon 6 and viscose filament yarns in air jet texturising machine. The textured yarns were also produced in dry and pre-wet conditions to understand the effect of water on textured yarn characteristics. It was found that the loops frequency, bulkiness of nylon/viscose blended textured yarns increase with increase in viscose proportion. The Loops stability, tenacity and breaking elongation decrease with increase in viscose proportion. Pre-wet textured yarn show higher loops, bulkiness, and good loop stability than their corresponding dry textured yarns.     

Dimensional and physical properties of plain knitted fabrics made from 50/50 bamboo/cotton blended yarns

In this study, the dimensional and some physical properties of plain knitted fabrics made from 50/50 bamboo/cotton blended yarns are investigated. In order to see the differences and similarities, the results are then compared with those for similar fabrics knitted from 50/50 conventional viscose/cotton and 50/50 modal/cotton blended yarns. Each fabric type was produced with three different stitch lengths. After all fabrics were dyed under identical dyeing conditions, they were subjected to dry and full relaxation treatments. For dimensional properties of fabrics, course, wale and stitch densities were measured. Then, by calculating statistically best-fit lines passing both through the experimental points and the origin, dimensional constants i.e. k values were predicted in terms of the fiber types. The result show that each fabric type knitted from bamboo/cotton, viscose/cotton and modal/cotton blended yarns behaves in a similar manner. However, in both dry and fully relaxed states, the modal/cotton knitted fabrics tend to have slightly higher k values than the bamboo/cotton and viscose/cotton knitted fabrics. For physical properties, fabric weight per unit area, thickness, bursting strength, air permeability and pilling were evaluated. The results show that the weight, thickness and air permeability values are independent of the fiber type. Plain knitted fabrics from modal/cotton blended yarns have the highest bursting strength values. Plain knitted fabrics from bamboo/cotton blended yarns tend to pill less.     

Study on thermal treatment of hybrid technical yarns

The present paper reports the impact of thermal treatment on the characteristics of core-sheath type hybrid technical yarns. The core-sheath type hybrid yarns are prepared using DREF-III technology. Polyester and glass multifilaments are used as core components whereas the cotton and polyester staple fibers are the sheath components wrapped around the core filament with different proportions to form a hybrid structure. The thermal treatment is carried out both in dry and in wet state under relaxed condition and the thermal shrinkage, sheath-slipping resistance and tensile and bending properties of hybrid yarns have been studied. Thermal treatment markedly increases the thermal shrinkage and sheath-slipping resistance of hybrid yarns with polyester multifilament in core, but insignificant effect for yarns with glass multifilament in core. Breaking elongation of hybrid yarns with polyester multifilament in core increases with treatment temperature. The hybrid yarns with glass multifilament in core are least affected by thermal treatment.     

Developing an intelligent fiber migration simulator in spun yarns using a genetic fuzzy system

The mechanical and physical properties of spun yarns and fabrics depend not only on mechanical properties of the fibers making up the yarn, but also geometrical arrangement of fibers, known as fiber migration. The main aim of this research is to introduce a new approach to predict migratory behavior of spun yarns. Achieving the objectives of this research, general physical, mechanical and structural properties of spun yarns together with existing standards were thoroughly studied. A hybrid intelligent model was developed based on a Genetic Fuzzy System (GFS) to model the relationships between migration of fibers in spun yarns and some physical and mechanical properties of spun yarns. Results indicated that the developed fuzzy expert system can be used as an intelligent simulator to predict yarn migratory parameters.     

Comparative study on the effect of blend ratio on tensile properties of ring and rotor cotton-polyester blended yarns using concept of the hybrid effect

Study on the characteristics of blended ring and rotor spun yarns is a topic of major interest to the researchers. The overall properties of these blended yarns are affected by the relative proportion, properties of the components and their interactions. The main focus of this work is on comparing and analyzing effects of blend ratio on tensile properties of the yarns produced in different spinning systems using concept of hybrid effects that has not received enough attention from researchers. Various blends of cotton-polyester ring and rotor spun yarns were prepared. Tensile properties of the samples were examined as well. Interactions between cotton and polyester fibers was evaluated through predicting strength and elongation at break of the yarns using simple rule of mixtures (ROM) and hybrid model. Experimental results showed that, the effect of different blend ratios on tensile properties of the samples is different. In comparison with 100 % cotton yarn, promotion in braking strength of the ring and rotor spun samples occurred after increasing fraction of the polyester fiber to 50 and 66.5 % respectively. The prominent finding of the present work is that the trend of change in tensile properties of different yarns versus blend ratio is predictable via hybrid model and migration behavior of the constituent fibers. Coefficients representing the intensity of the interaction and migration index of the fibers were calculated and all results were discussed based on these calculated factors.     

Effect of opening roller speed, drums speed difference and suction air pressure on properties of open-end friction spun polyester and acrylic yarns

The present paper is concerned with the influence of opening roller speed, drum speed difference and suction air pressure on properties of polyester and acrylic open-end friction spun yarns. The results shows that the opening roller speed and the suction air pressure have considerable influence on the characteristics of polyester and acrylic open-end friction spun yarns. In case of polyester yarns the unevenness, imperfection and hairiness decreases and the yarn tenacity increases with the increase in opening roller speed and suction air pressure. However for acrylic yarns the unevenness and imperfections decreases and tenacity increases with the increase in opening roller speed and suction air pressure.     

Study on splicing performance of different types of staple yarns

The present paper reports the detailed study on the splicing behavior of viscose staple fiber yarns made from ring, rotor, friction and air-jet spinning technologies. The linear density of all the yearns was kept constant at 29.5 tex. The splicing parameters like splicing pressure and duration of the splicing were taken as variables. Three levels of splicing pressure at constant splicing duration and three levels of splicing durations at constant splicing pressure were considered. Splices were introduced at all these levels for the four different technologies. These splices were tested for their tensile properties and the properties of splices were evaluated in terms of retained splice strength (RSS) and splice break ratio (SBR). The splice photographs were taken and splices were analyzed for their structure and for diameter profile along the length of the splice.     

Study on the static and dynamic strengths and weavability of spun yarns

This study reports on the analysis of tenacity and breaking elongation of ring-, rotor- and air-jet-polyester/viscose spun yarns measured using static- and dynamic tensile testers. The weavability, a measure of performance of these yarns in post spinning operations is quantified. The yarn diameters and helix angles of fibres in these yarns are measured in order to analyze the effect of types of spun yarn and blend proportion on yarn elongations. The dynamic tenacity is highly correlated with the weavability than the average static tenacity measured at 500 mm gauge length. The minimum static tenacity obtained from 100 tests has high correlation with the dynamic tenacity. The present study indicates that it is appropriate to evaluate the performance of spun yarns in winding, warping and weaving based on the dynamic yarn tenacity measured while running a 200 m length of yarn in a constant tension transport tester or the minimum static yarn tenacity obtained using any conventional constant rate extension (CRE) tensile testers corresponding to a total test length of 50 m.     

Exponentially autocorrelated mass distribution along staple fiber yarns

In this work, a series of cotton carded ring-spun yarns of different counts and different twist multipliers is prepared and the mass distribution along the yarns is studied as a random process. The mass autocorrelation coefficients of the coarser yarns are found to be higher as compared to those of the finer yarns and this difference is found to be low at lower twist multiplier of the yarns. The decay of mass autocorrelation at higher distances along the yarns is explained by a double exponential autocorrelation function which raises the probable existence of two highly different random effects that are acting additively on the yarns to decrease the mass autocorrelation at higher distances along the yarns. The finer yarn exhibits faster decay of mass autocorrelation than the coarser yarn, but this difference is low at lower twist multiplier of the yarns.     

Prediction of the water absorption capacity of VIS/PES needle-punched webs using genetic algorithms

Needle-punched webs for wet cleaning wipes were produced using a dry-laid method of web- forming. Fibrous webs with a different content of hydrophilic viscose and hydrophobic polyester fibers, as well as webs made from 100 % polyester fibers, were utilized during this study. The webs were compared in terms of their water absorption capacity on the basis of their basic construction parameters, such as fiber fineness, raw material (e.g. fiber density), and web density. The higher water absorption capacity of the viscose/polyester-blended needle-punched webs was achieved at higher content of viscose fibers which coincide with the higher fiber density, finer fibers, and lower web density. A prediction model regarding water absorption capacity of viscose/polyester needle-punched webs was developed on the basis of the mentioned construction parameters and a non-deterministic modelling method, e.g. genetic algorithms, and could provide a guideline for the engineering of nonwoven webs in order to fit the desired water absorption capacity.     

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.     

Effects of recycling processes on physical, mechanical and degradation properties of PET yarns

Mechanical properties and the long-term degradation properties of the recycled PET yarns are typically lower than the virgin PET yarns due to the contaminants coming from non-PET bottles, labels and caps etc. For environmental reasons, recycling of post-consumer polyester bottles into textile fibers has become commercially attractive. We studied mechanical and chemical recycling processes and examined their effects on yarn properties such as tensile properties, thermal characteristics, hydrolysis and photo-degradation. It was found that the virgin and the chemical recycled yarns with sufficient purification show similar processability, physical and mechanical properties, and long-term degradation behavior. The results provide useful information on recycled PET yarns for processability and serviceability for the high-end use.     

Study on the wicking property of polyester filament yarns

In this paper, the capillary rise method was applied to evaluate the wicking property of polyester filament yarns. Effects of twist, monofil cross sectional shape and texturing on the wicking height were discussed in details. The results indicated that with the increase of twist level, the wicking height ascends until reaching the maximum height, and then descends. It is also observed that under the same twist level, the wicking height of the five-leaf low-stretch yarn is the largest among all those three kinds of yarns, and then is that of the conventional low-stretch yarn. The wicking height of the parallel-drawn yarn is the smallest.     

Effect of strand spacing and twist multiplier on structural and mechanical properties of Siro-spun yarns

The effect of strand spacing and twist multiplier on strength of Siro-spun yarns with reference to the yarn structural parameters was investigated. Of the various structural parameters for staple yarns, fiber migration has a crucial influence on the yarn strength, which in turn to a considerable extent is influenced by the strand spacing and twist multiplier. Achieving the objectives of this research, the yarns were produced from lyocell fibers at five strand spacings and four different twist multipliers. Tracer fiber technique combined with image analysis were utilized to study the yarn migration parameters. Afterwards, the yarns were subjected to uniaxial loading by a CRE tensile tester. The measured results are presented in forms of diagrams and tables. The findings reveal that, as strand spacing is increased, yarn tenacity increases up to strand spacing of 8 mm beyond which it reduces. Analysis of the results indicates that the higher tenacity values at the strand spacing of 8 mm can be attributed to the higher mean fiber position, higher migration factor, higher proportion of broken fibers and lower hairiness.     

Structural analysis of finer cotton yarns produced by conventional and modified ring spinning system

Yarn structure plays an important role in determining the properties of spun yarns. Recently, a modified spinning technique has been developed for producing a low torque and soft handle singles yarn by modifying the fiber arrangement in a yarn. Comparative studies revealed that the finer modified yarns possess significantly higher strength and lower hairiness over the conventional yarns of the same twist level, implying a different structure of finer modified yarn. Thus this paper aims to quantitatively study the structures of the finer conventional and modified cotton yarn (80 Ne) produced at the same twist level. Various measuring techniques, namely the Scanning Electron Microscope (SEM), cross section technique and tracer fiber technique, are adopted to analyze their structural characteristics, including fiber configuration, fiber spatial orientation angle, fiber packing density, yarn surface appearance, and fiber migration behavior. Results showed that finer modified yarns exhibit a smoother surface and much more compact structure with less hairiness. The fibers in the finer modified yarn have a complicated fiber path with relatively lower fiber radial position, larger migration frequency and magnitudes. In addition, it was noted that 73% of fibers in the finer conventional yarn follow concentric conical helix, which is contrary to those in the coarser conventional yarn. The analyses conducted in this paper provide deep insights into the mechanism of modified spinning technique and evidential explanations on the difference of properties between the finer conventional and modified yarns.