Influence of yarn extension on longitudinal structural characteristics of fibres

A detailed study on the effect of progressive yarn extension on longitudinal structural characteristics of fibres has been reported in the present paper. An image processing-based system to characterise and visualise the configuration of fibres in yarn under extended mode has been adopted. A detailed study has been reported on the changes in longitudinal structural characteristics of fibres, such as fibre extent, fibre strain, straightening and slippage of fibres, fibre-pair-overlap length (FPO) and fibre-overlap index (FPI), during axial extension of ring-spun yarn. The actual length of fibre and the fibre extent in the yarn were found to be increased with the increase in yarn extension. With yarn extension from 0 to 4% the fibre strain in the yarn becomes moderate and further increase in yarn extension from 4 to 8% the fibre strain reduces, but with further increase in yarn extension of 8–12% the fibre strain again increases. It has also been observed that the fibre straightening percentage at different intervals of yarn extension is not the same and it decreases with the increase in yarn extension. The fibre slippage percentage is also not the same at different intervals of yarn extension percentage. It is found to be maximum at 4–8% and minimum at 0–4% yarn extension.     

Compression behaviour of woven terry fabrics

Fabric compression is a decrease in intrinsic thickness with an appropriate increase in pressure. The compressibility of the terry fabric depends on fibre properties, yarn parameters, weaving parameters, loop length, loop density, loop geometry and post-weaving treatments. In this research, all the factors responsible for fabric compression have been studied. It is observed that loop density, loop length, loop-shape factor, pile yarn twist, pile yarn count, fibre length and pile yarn structure have a significant effect on the compression behaviour of the terry fabric. With increase in the loop-shape factor, loop length and loop density, the linearity of compression curve, resilience increases and specific compression energy reduces which depict that the fabric is getting better in terms of softness to touch. It is also observed that pile yarns produced from ring spinning, zero twist, MCU-5 cotton, porous yarn and finer yarn produce better terry fabric in terms of compression behaviour and surface properties. The loop geometry modelled in the form of shape factor correlates with the compression of the fabric. The research also helps to design a towel by controlling loop geometry.     

Effect of geometry of end of the fibre transport channel with slotted exit on rotor spun yarn quality

Geometry of end of the fibre transport channel (EFTC) at the entry to the rotor housing of rotor spinning system has an important effect on yarn properties. In this paper, effect of design of fibre exit edge (FEE) of the transport channel on yarn properties in a slotted model similar to R20 of Rieter was studied. Nine designs of FEE were examined for fibre path and the best one was selected for yarn production. Dimension and positioning of FEE were varied and yarn tensile properties, evenness, imperfections and extent were tested. It was concluded from the test results that the new design improves most of the yarn properties and is superior to the original design.     

Dynamic failure behaviour of blended spun yarns during winding

In the present work, the initiative is being taken to study the spun yarn failure behaviour under real dynamic conditions i.e. winding. An attempt is made to study the dynamic failure behaviour of blended ring yarn in relation to yarn structure. Multi-coloured tracer fibre technique is employed to study the broken ends of yarn during the winding process in terms of proportion of fibre break/slip, configuration of yarn broken end and yarn failure length. The ring spun yarn failure during winding is basically dominated by fibre breakage. The length of broken and slipped fibres is found to be different in trailing and leading portion of the broken ends and also depends on viscose content in the blends. The failure zone length and sum of percentage of tapered and slipped broken ends are found to follow the exactly similar trend with fibre failure coefficient with the change in blend ratio. The mathematical model established to explain the spun yarn failure during winding process displays lower error%.     

Studies on cotton–acrylic bulked yarns and fabrics. Part I: Yarn characteristics

The effect of variables, namely yarn fineness, shrinkable acrylic proportion and twist level, on various properties of cotton–acrylic blended bulked yarns has been studied by relaxing shrinkable component of the yarns using boiling water treatment. A three-variable factorial design technique proposed by Box and Behnken was used to investigate the combined interaction effect of the above variables on the properties of these yarns. The design variables were optimized for all the yarn properties by using the response surface equations. The shrinkage percentage of yarn was found to be higher in the case of coarser yarn, yarn with higher proportion of acrylic fibre and higher twist level. During bulking treatment as the yarns shrink, the effective number of twist per unit length also increases significantly. It is observed that the specific volume of the yarn increases with an increase in the acrylic proportion and decreases with an increase in the twist factor. The breaking extension increases significantly after bulking with a slight increase in tenacity. The flexural rigidity and initial modulus of yarn considerably decrease on bulking. The vertical wicking heights for all the bulked yarns were found to be higher than comparable 100% cotton yarn.     

22—FACTORS AFFECTING THE THICKNESS AND COMPRESSIBILITY OF WORSTED-SPUN YARNS

Yarn-thickness measurements have been made on a range of worsted-spun yarns, apparatus being used whereby loads ranging from I to 100 g could be mechanically applied over a length of 0–5 cm of yarn. A linear relation was found when the logarithm of the load was plotted against the logarithm of the yarn thickness, and this has been used to provide a ‘thickness index’ and a ‘compression index’ for each yarn examined.

It has been shown that the two most important factors influencing yarn thickness and compression are the spinning twist and the fibre crimp, these being followed closely by the fibre length. Large differences were observed between the thickness and the compression of yarns spun to the same linear density from a range of different wool qualities, and these were largely due to the combined influence of the fibre crimp, length, and diameter. Considerable increases in yarn thickness and compression were also found between acrylic fibre yarns before and after bulking.

Factors exerting less influence on yarn thickness and compression were the fibre diameter, the fibre cross-sectional shape, the different proportions in wool-Terylene blends, and the use of different processing systems; a large change in relative humidity had no effect on the thickness and compression measurements.     

Towards the Better Understanding of Self-twist Structures

An investigation is described in which several wrapped yarns were spun from 100% polyester staple fibre with different continuous-filament yarns in a wide range of wrapping densities. The tensile properties of the wrapped yarns were studied, and the effects of the linear density of the continuous filament yarn and the wrapping density on the yarn structure and tensile properties were investigated. The morphology of the yarn failure during tensile testing was studied by photographing the yarn during extension.

The yarn structure for the different continuous-filament-yarn wraps was examined by scanning electron microscopy. The study illustrates the effect of the wrapping filaments on yarn structure, yarn tensile properties, and the mechanism of failure during extension. The effect of the wrapping continuous-filament, yarn on yarn characteristics was found to be the predominant factor'.     

光催化竹炭纤维针织物性能研究

采用两种线圈长度分别将光催化竹炭纤维纯纺纱、光催化竹炭纤维/棉（50/50）混纺纱和棉纱编织成不同紧密系数的双罗纹针织物。文章通过分析针织物的基本参数,测试其基本物理机械性能和舒适性,以及针织物性能的对比,研究分析光催化竹炭纤维含量以及紧密系数对针织物物理机械性能和舒适性的影响。     

Effect of yarn extension on migration parameters of fibres in yarns

The present paper deals with a detailed study on the effect of progressive yarn extension on fibre migration. An image processing-based system to characterise and visualise the configuration of fibres in yarn in extended mode has been adopted. A detailed study has been reported on the changes in migration parameters, like mean fibre position (MFP), mean migration intensity (MMI) and root mean square deviation (RMSD), during axial extension of ring-spun yarn. It has been observed that the fibre migration parameters, like MFP, MMI and RSMD, are significantly affected by extension of ring-spun yarn and the trends are different for different levels of extension. It has been observed that the mean fibre position (MFP) increases slightly up to 4% of yarn extension and then decreases up to 8% extension but with a further increase of yarn extension up to 12%, the value of MFP slightly increases again. It has also been reported that with the increase of yarn extension the average RMSD and MMI.     

Effect of structural parameters of injected slub yarn on its tensile properties and abrasion resistance

In injected slub yarn, tensile and abrasion resistance are particularly very important parameters affecting its process performance and end-use. In single base injected slub yarn structure, slubs are developed by injecting fibres from outer side of the yarn with the sequence of untwisting base yarn followed by re-twisting after injecting the fibres. The tensile properties and abrasion resistance of injected slub yarns depend on the slub parameters. The surface of the yarn, especially the slub part is very much susceptible to damage by abrasion during usage, due to lack of fibre migration between base yarn fibres and injected fibres. In this paper, an attempt has been made to see the impact of slub yarn configuration i.e. slub length, slub thickness and slub frequency on tensile and abrasion resistance of injected slub yarn. Empirical models have been developed to find the dependence of these properties on slub yarn configurations. Configuration of slubs in particular slub length and slub frequency were found to be very significant on yarn tenacity, elongation and abrasion damage in terms of tenacity loss, elongation loss and hairiness rise of injected slub yarn. However, the impact of slub thickness is relatively less on the aforesaid parameters.     

The Influence of the Spinning Process,Yarn Linear Density,and Fibre Properties on the Hairiness of Ring-spun and Rotor- spun Cotton Yarns

Cotton–spun yarns from 34 staple stocks were manufactured by means of the ring–spinning process (34 yarns) and a rotor–spinning process (29 yarns) and tested for hairiness with the Shirley Hairiness Meter. For each spinning system, yarns were spun at two values of yarn linear density (15 and 30 tex for ring–spinning and 30 and 50 tex for rotor–spinning), but the twist multiplier was kept constant within the series for each spinning process.

The higher hairiness of ring–spun yarns and an increase ln hairiness with the yarn linear density were confirmed. The effect of the fibre parameters on yarn hairiness explains only about 30% of the total effect for ring–spun yarns and 40% for rotor–spun yarns. Fibre length and its uniformity are the fibre properties having the greatest influence on the hairiness of both ring– and rotor–spun yarns, the Micronaire index having only slight influence on the hairiness of ring–spun yarn.     

A study of peeling-off tension in rotor spinning and its dependence on rotor and fibre variables,Part II: validation

By a series of experiments, the theory of the generation of yarn tension at the peeling-off point (T₀) during rotor spinning as postulated in Part I of the paper has been validated. Under the similar spinning conditions, if the mechanical tension (T_r) is kept constant, then the factors like fibre length, type, linear density, cross-sectional shape and its state of openness can be manipulated so as to increase T₀ and consequently, the yarn compactness. If a fibre has a lower rigidity in torsion, it will require less torque for twisting, leaving more torque available in the PTE, causing it to lengthen and resulting in the manifestation of higher tension at the peeling-off point.     

棉Modal锦纶赛络纺包芯纱的纺制

探讨外包纤维为精梳棉、Modal,芯纱为锦纶长丝的赛络纺包芯纱的生产工艺.介绍了锦纶丝、澳洲棉和Modal纤维的性能特点及纺纱工艺流程,通过纺纱工艺试验,针对原料性能,各工序优化配置了纺纱工艺并采取了相应的技术措施.粗纱工序采用轻定量、低速度、重加压、大隔距、较小后区牵伸和较大粗纱捻系数的工艺,细纱工序减小后区牵伸倍数,放大后区罗拉中心距.实践表明,纺制的精梳棉Modal锦纶丝赛络纺包芯纱为低弹纱,成纱质量良好.在纺制锦纶丝包芯纱时,选用的外包纤维细长、长度整齐度高,可以改善成纱条干和包覆效果,保证成纱质量.     

The Effect of Yarn Twist and Fibre Percentage in Blends on the Dimensional Properties of the Interlock Structure

An account is given of an investigation of the dimensional properties of a series of interlock weft knitted fabrics produced from open-end cotton-polyester blended yarns with different yarn twist, loop length, fibre percentage in blend, and variety of relaxation treatments. A comprehensive experimental analysis shows that the Ks value (stitch density multiplied by the square of loop length) is related to yarn density, fibre percentage in blends, and relaxation treatments. It is also concluded that the correct relaxation state for cotton fabrics to reach the maximum shrinkage is full mechanical relaxation, and for cotton polyester blended and 100% polyester fabrics is chemical relaxation treatment. The empirical results show that the effect of mechanical relaxation decreases as the percentage of polyester in blends increases.     

Influence of spinning parameters on milkweed/cotton DREF-3 yarn properties

In this study, Pergularia milkweed fibre (70%), cotton fibre (30%) core and 100% cotton fibre sheath DREF-3 core yarns of 74?tex were produced using different spinning parameters in order to understand their effect on yarn properties. Box–Behnken design was used for the optimization of core ratio, drum speed and suction pressure, and to evaluate the effects and interactions of the process variables on the yarn properties at a constant opening roller speed of 12,000?rpm and production speed of 100?m/min. The effects of the core/sheath ratio on all the yarn properties are significant. With an increase in the core/sheath ratio, yarn tenacity and elongation decrease due to insufficient wrapper fibres in the yarn and yarn unevenness; imperfection increases due to higher feed rate and draft at higher core ratio. The yarn hairiness increases at higher core ratio due to higher number of short fibres in milkweed and lesser sheath fibres to cover the core fibres effectively. An increase in the spinning drum speed damages fibre in the sheath and increases the number of hooks at the end of fibres, as a result of which the core yarn tenacity decreases at higher drum speed. At a higher air suction pressure, yarn tenacity and the elongation at break increases. The drum speed and suction pressure have no significant effect on yarn unevenness and imperfections. The yarn hairiness decreases slightly with increase in drum speed and suction pressure but is insignificant.     

Simulation on fiber random arrangement in the yarn part II: joint effect of fiber length and fineness distribution

Simulation on fiber random arrangement in the yarn has been studied in our previous research, where only fiber length distribution was considered. In this study, fiber fineness distribution was also taken into account in order to study the joint effect of fiber length and fineness distribution on fiber arrangement in the yarn. Eight-millimeter term limit irregularity of simulated yarn can be re-expressed by calculating the irregularity of the total weight of fibers within each yarn subsection. It can be seen from the results that the calculated irregularities considering fiber fineness distribution are closer to tested values compared with those without considering fiber fineness distribution. Besides, when the variance of fiber fineness gets greater, the difference between the calculated values with and without considering fiber fineness distribution becomes more obvious. For fiber length, the effect of average fiber length on yarn limit irregularity is very little, while its distribution has no significant effect on yarn limit irregularity. The improved simulation on fiber random arrangement in the yarn is more reasonable and can be applied for the prediction of yarn qualities.     

Influence of fibre strength and yarn structural characteristics on tensile failure of blended spun yarns: a prediction model

The study reports on the static failure behaviour of P/V blended ring, rotor and air-jet spun yarns explained on the basis of fibre failure coefficient. Fibre failure coefficient is an index introduced to represent fibre break and slip in combination occurring during tensile failure. Fibre break/slip during tensile failure is found dependent on fibre strength, fibre cohesiveness and internal structural developments in yarns. Tensile failure behaviour of ring, rotor and air-jet yarns found to be different owing to their difference in fibre consolidation mechanism. The contribution of individual components towards fibre failure coefficient varies with the spinning technology. An attempt has been made to develop mathematical models to explain the spun yarn failure behaviour under static condition. The developed mathematical models have incorporated the fibre property (fibre strength) and few structural characteristics of yarns which are strategically selected to justify the essence of models to enhance the prediction capability. Individual models are developed for ring, rotor and air-jet yarns owing to their structural changes caused by their inherent fibre consolidation mechanism. The developed mathematical models are free from assumptions and based on pure applied mathematics and have very high potential for prediction of spun yarn failure behaviour.     

Packing of micro-porous yarns: Part I. Optimization of yarn characteristics

The present paper deals with the factors affecting the packing of a micro-porous yarn, namely proportion of PVA fibre content, yarn twist multiplier (TM) and spindle speed at ring frame, and with their combined effect on various properties of the yarn. The micro-pores within the structure of the yarn have been created by dissolving the PVA fibres using washing treatment in hot water. A three-variable factorial design technique proposed by Box and Behnken is used to investigate the combined interaction effect of the above variables on the properties of the yarn. The present experiment variables, namely proportion of PVA fibre, yarn twist multiplier (TM) and spindle speed, were found to have significant impact on various properties of yarns before and after wash. For yarns before wash, the specific volume reduces with the increase in the PVA content, yarn twist and spindle speed. In the case of yarns after wash, there is reduction in the yarn specific volume with the increase in TM and spindle speed, but with the increase in the PVA percentage the yarn specific volume increases. The tenacity of yarns before wash increases with the increase in the PVA content, but for yarns after wash, the proportion of PVA content has comparatively less influence. The compressibility of yarns before wash reduces with the increase in the PVA content, but a reverse trend is observed in the case of yarns after wash. The design variables were optimized for all the yarn properties by using the response surface equations.     

Studies of the hybrid effect in mechanical properties of tencel blended ring-, rotor- and air-jet spun yarns

This paper presents a study of hybrid effect on mechanical properties of tencel blended ring-, rotor- and Murata jet spinning yarns. The tensile strength, breaking elongation, flexural rigidity and abrasion resistance of tencel-polyester and tencel-cotton blended yarns are examined and compared with the value predicted using linear and quadratic rule of mixture (ROM). It is observed that there is no significant hybrid effect on abrasion resistance of tencel-polyester mix yarns and tenacity and breaking extension of tencel-cotton mix yarns; hence, a linear ROM is found better in predicting the yarn properties. Further, for all yarn types, there is a significant hybrid effect on tenacity, breaking extension and flexural rigidity of tencel-polyester mixes and flexural rigidity and abrasion resistance of tencel-cotton mixes. A quadratic ROM model suits well for these yarns. Overall, it is found that there is a negative hybrid effect on tenacity and breaking extension whereas there is a positive hybrid effect on flexural rigidity for all the yarn samples irrespective of fibre and yarn type. The abrasion resistance has a mixed trend. Further, tencel-polyester yarns yield more satisfactory results than the tencel-cotton yarns in terms of strength and breaking extension but behave poorly during abrasion test for 200 cycles. Increasing tencel content both in tencel-polyester and tencel-cotton fibre-mix produces a rigid yarn with reduced abrasion resistance.