S. M. Ishtiaque

Comfort Properties of Fabrics Woven from Ring-, Rotor-, and Friction-spun Yarns

Fabrics woven from ring-, rotor-, and friction-spun yarns, have been compared from the standpoint of comfort. Emphasis has been placed on the tactile and thermal aspects of comfort by the use of the Kawabata Fabric Evaluation System. The effect of the weave on the comfort aspects of the fabric has also been studied. Although ring-spun yarn has been found to be the best yarn from the tactile comfort point of view and friction-spun yarn has been found most suitable from the standpoint of thermal comfort, fabrics woven from friction-spun yarns do tend to bag during usage. Ring- and rotor-spun yarns are comparable from the thermal comfort aspect, the rotor-spun yarn being slightly better. A twill-woven fabric has been found preferable to a plain-woven fabric in all aspects of comfort.

Packing of micro-porous yarns. Part II: optimization of fabric characteristics

Abstract 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.

Rotor Yarn Structure by Cross-Sectional Microtomy

A mathematical model is suggested for studying the radial packing density of yarn, and the proposed model is used for a comparative study of ring and rotor spun yarns. The results show that rotor spun yarn consists of a smaller number of fibers in the cross section compared to ring spun yarn, which explains the lower strength of rotor yarn. Although the radial packing density of both yarns is non-uniform, that of rotor yarn is nearer the yarn axis and less towards the yarn surface compared to ring spun yarn.

Impact of structural variations in hollow yarn on heat and moisture transport properties of fabrics

The use of hollow/microporous yarns plays an important role in enhancing the thermo‐physiological comfort properties of fabrics. Depending on structural variations in hollow yarn, heat and moisture regulation behaviours of fabrics can be affected significantly. In this study, three types of hollow cotton yarn fabrics, produced by introducing polyvinyl alcohol (PVA) filament in the core, PVA staple fibres in the blend and PVA filament in doubling with cotton spun yarn, are studied. All three types of pre‐hollow yarns and reference yarns are made with a variation in spinning technique (single roving/double roving) to prepare eight single jersey knitted fabrics. The hollow/microporous structure of the yarn is created by dissolving the PVA fibres using hot washing of the fabrics. On overall evaluation of the fabric’s thermo‐physiological comfort properties, the doubled hollow yarn fabrics are found to be better than other fabrics. In general, thermal resistance, thermal absorptivity, wicking and drying properties of all types of hollow yarn fabrics increase after repeated laundering, while air permeability, water vapour permeability and water absorbency of hollow yarn fabrics mostly decrease. In contrast with fabrics made from yarn produced through single roving technique, use of double roving technique only improves fabric water vapour permeability.

Stress–strain characteristics of different spun yarns as a function of strain rate and gauge length

Abstract The influence of strain rates and gauge lengths on the characteristics of the stress–strain curves of ring, rotor, air-jet, and open-end friction spun yarns is investigated. A modified form of Vangheluwes model is used in describing the stress–strain characteristics of spun yarns. The proposed model can fairly well replicate these characteristics.

Contribution of Core and Sheath Components to the Tensile Properties of DREF-III Yarn

The contribution of individual core and sheath components to the tensile properties of DREF-III yarn is reported here. Three different yarn types are made by the DREF-III system: staple viscose fibers in both core and sheath, staple viscose fibers in the core and staple PVA fibers in the sheath, and staple PVA fibers in the core and staple viscose fibers in the sheath. Because PVA fibers are soluble in water, they are removed afterwards with boiling water to produce individual core and sheath components. In all samples, the core-sheath ratio is kept at 50:50. The parameters discussed here are the core contribution factor, the sheath contribution factor, the core-sheath interaction factor, and various other structure- related parameters such as yarn diameter, helix angle, helix diameter, and mean fiber extent. Process variables are the spinning drum speed and the yarn delivery rate. The paper reports the effects of these process variables on tensile properties of the parent DREF-III yarn as well as individual core and sheath components. Structural changes due to removal of either core or sheath are also reported.

The Internal Structure of Sheath Fibre in DREF-3 Yarn

This paper is concerned with a study of the structure and twisting mechanism of sheath fibres in DREF-3 yarn, in which a tracer-fibre technique was used. The yarn was made from a polypropylene-fibre multifilament core and cotton staple-fibre sheath. An analysis of the twist and migration behaviour of the sheath is made to quantify the sheath structure. Process variables investigated are the spinning-drum speed, the yarn-delivery rate, and the surface structure of the core component. Other process variables, e.g. the suction pressure, yarn count, core-sheath ratio, and number of wrapper slivers, are kept constant. The effects on the sheath structure (quantified as the total twist, twist distribution, and migration behaviour) of certain process variables are discussed and possible causative factors identified. Conclusions arising from these in addition to visual observation of the sheath structure are used to explain the twisting mechanism of sheath fibres in DREF-3 yarn. An attempt is also made to explain the yarn properties for various process parameters on the basis of the sheath structure.

Analysis of spinning process using the Taguchi method. Part V: Effect of spinning processvariables on physical properties of ring, rotor and air-jet yarns

Abstract Effect of lap hank and drafts, of various spinning sequence of machines, was studied on physical properties of different yarns using Taguchi method and analysis of variance. The ring yarn is highly even and has the least number of thin places and neps but thick places are the least in rotor yarn. The air-jet yarn is the least even and has the highest number of thin places, thick places and neps. The total hairiness is the least on rotor yarn and number of hairs =3 mm (S3) the least in ring yarn. In air-jet yarn the total hairiness and S3 are the highest. The finer lap hank and higher card draft in preparatory process produces even ring and rotor yarns with lower hairiness. However, the higher speed frame draft improves the evenness of yarn produced from coarser lap hank and lower card draft. Lower ring frame, rotor and high air-jet draft improves the properties of the respective yarns. Increase in ring/air-jet draft increases S3.

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.

Analysis of spinning process using the Taguchi method. Part II: Effect of spinning process variables on fibre extent and fibre overlap in ring, rotor and air-jet yarns

Abstract The fibre orientation in 24s Ne ring, rotor and air-jet yarns has been studied using tracer fibre technique. The effect of drafts at different stages of spinning process on fibre orientation in different yarns has been analyzed using Taguchi Method and analysis of variance. The fibre orientation was studied in terms of fibre extent (FE) and two newly defined indices (FOIs), fibre-overlap index (FOI) and fibre-pair-overlap length (FPO). Ring yarn is seen to have the highest FE and FOIs and rotor yarn the least. A medium card draft (101 or 114) and a corresponding ring or speed frame draft give the highest FE. The effect of fibre parallelization in finisher sliver is retained in respect of FE and FOIs in rotor and air-jet yarns. The effect of fibre parallelization in rovings is manifested on FOI of ring yarns. A higher card draft and correspondingly lower air-jet draft give higher FE and FOIs.