Indian Joual of Fibre & Textil e Research Vol. 3 1 , June 2006, pp. 298-301 An investigat ion on the physical propert ies of core yarns V Viswarajasekaran" & K Raghunathan Departmcnt of Textile Technology, Alagappa Coll ege of Teehnology, Anna University, Chennai 600 025, India Received 7 March 2005;revised received alld accepted 19 May 2005 The effect of different process parameters on core-spun yas made from a modi fied r ing frame has been studied. It is observed that the properties of core-spun yas vary with respect to the process parameters like type of fibres in core and sheath, different twist leve ls and different core: sheath ratio. Reduced sheath content in all types of core yas inc reases the tensile strength and ya regularity but decreases the breaking extension and yarn regularity. The opt imum twist level for filament and spun core yas has also been observed. The core-spun yas have the better physical character ist ics than cotton yas. Keywords: Core-spun ya, Cotlon. Elongati on, Polyester, Tensi le strength IPC Code: Int. CI 8 D02G3/00, GOIN33/36 1 Introduction Core-spun yarns belong to mul ti component yas. In general practice, core-spun yas are produced from continuous filament material with a s taple covering, having a variety of applications. The functional features can be obtained by va rying the core: sheath ratio, mater ials or by the appl ication of spun yarn in the core. Sawhney and Ruppenicker i have produced core- spun yarns on the patented ARS core spinning systems using 100% cotton, fibreglass core and dyneema core covered with cotton. The yarns were used to develop special purpose fabrics, like flame retardant fabrics for US Army tents, fabrics for fire barrier, fabrics for indust rial abrasives and sand papers. Core-spun yas can be produced using modified ring frame 2." , ring doubler, open-end spinning and air vortex systems. The present work aims at manufacturing the core- spun yarns from 35den medium tenacity polyester filament core, 62s polyester/cotton (P/C) blend (65:35) yarn core, 60s polyester spun ya rn core and 60s polyester/ viscose (PlY) blend (65:35) yarn core and studying their properties. The charac teris tic behaviour of components has been analysed by the assessments of the contribu tions of different core and "To whom all the correspondence should be addressed. E-mail: [email protected]cotton sheath to the yarn properties. The geometrical disposition of the filament in the yarn is set cons tant at the pretension and the feeding arrangements selected. The introduction of spun ya as core in this context is to study the blend behaviour of the core yarns with the regular blended yarns. 2 Materials and Methods 2.1 Yarn Preparation As shown in Fig. 1 , core-spun yarn is produced by feeding a continuous filament yarn or spun yarn to the front drafting roller, whereas the fibres proceeding from the feed roving of the drafting uni t cover i t. The aim is to cover the inner filament uniformly and completely. The greatest risk involved in this process is the breaking of this filament. It is difficul t to detect this on both the spinning frame itself and during the subsequent processes (winding, weaving, etc.); the feeding of the filament must be centred and monitored carefully to achieve a flawless effect. Special additional equipment for manufacturing core-spun ya rns is attached to the Lakshmi ring frame, thus enabling core-spun yarns to be of superior quality. The method involves essentially the introduction of core filament o r spun yarns during the spinning of staple fibre. The core yarn is taken from a supply package with sui table guides and passed through a tensioning device along with the drafted strand at the fron t roller nip.
Transcript
I ndian Journal of Fibre & Texti le Research Vol. 3 1 , June 2006, pp. 298-301
An investigation on the physical properties of core yarns
V Viswarajasekaran" & K Raghunathan Departmcnt of Texti le Technology, Alagappa College of Teehnology, Anna University, Chennai 600 025, I ndia
Received 7 March 2005;revised received alld accepted 19 May 2005
The effect of d ifferent process parameters on core-spun yarns made from a modified ring frame has been studied. It is observed that the properties of core-spun yarns vary with respect to the process parameters l ike type of fibres in core and sheath, di fferent twist levels and different core: sheath ratio. Reduced sheath content i n al l types of core yarns increases the tensile strength and yarn regularity but decreases the breaking extension and yarn regularity. The optimum twist level for filament and spun core yarns has also been observed. The core-spun yarns have the better physical characteristics than cotton yarns.
Keywords: Core-spun yarn, Cotlon. Elongation, Polyester, Tensi le strength
IPC Code: Int. CI 8 D02G3/00, GOI N33/36
1 Introduction
Core-spun yarns belong to multi component yarns . In general practice, core-spun yarns are produced from continuous fi lament material with a staple covering, having a variety of applications. The functional features can be obtained by varying the core: sheath ratio, materials or by the application of spun yarn in the core.
Sawhney and Ruppenickeri have produced corespun yarns on the patented ARS core spinning systems using 1 00% cotton, fibreglass core and dyneema core covered with cotton. The yarns were used to develop special purpose fabrics, l ike flame retardant fabrics for US Army tents, fabrics for fire barrier, fabrics for industrial abrasives and sand papers. Core-spun yarns can be produced using modified ring frame2.", ring doubler, open-end spinning and air vortex systems.
The present work aims at manufacturing the corespun yarns from 35den medium tenacity polyester filament core, 62s polyester/cotton (P/C) blend (65 :35) yarn core, 60s polyester spun yarn core and 60s polyester/ viscose (PlY) blend (65 :35) yarn core and studying their properties. The characteristic behaviour of components has been analysed by the assessments of the contributions of different core and
"To whom all the correspondence should be addressed. E-mai l : [email protected]
cotton sheath to the yarn properties. The geometrical disposition of the filament in the yarn is set constant at the pretension and the feeding arrangements selected. The i ntroduction of spun yarn as core in this context is to study the blend behaviour of the core yarns with the regular blended yarns.
2 Materials and Methods
2. 1 Yarn Preparation
As shown in Fig. 1 , core-spun yarn is produced by feeding a continuous filament yarn or spun yarn to the front drafting roller, whereas the fibres proceeding from the feed roving of the drafting unit cover it. The aim is to cover the inner filament uniformly and completely. The greatest risk involved in this process is the breaking of this fi lament. It is difficult to detect this on both the spinning frame itself and during the subsequent processes (winding, weaving, etc . ) ; the feeding of the filament must be centred and monitored carefully to achieve a flawless effect.
Special additional equipment for manufacturing core-spun yarns is attached to the Lakshmi ring frame, thus enabling core-spun yarns to be of superior quality. The method involves essential ly the introduction of core filament or spun yarns during the spinning of staple fibre. The core yarn is taken from a supply package with suitable guides and passed through a tensioning device along with the drafted strand at the front rol ler nip.
VISWARAJASEKARAN & RAGHUNATHAN: PHYSICAL PROPERTIES OF CORE YARNS 299
By varying the twist, three polyester filaments (35 den multifilament) core-spun yarns (PET) of 38s resultant count were produced. Three core-spun yarn samples of resultant count 20s with core: sheath ratio of 2: 1 , polyester spun yarn, PIC blend yarn and PlY blend yarn as core were produced. By varying the core: sheath ratio, four samples (PSF) of resultant counts 30s, 1 3s, 20s and 1 5s with polyester spun yarn (core) and cotton (sheath) were prepared.
2.2 Test Methods
All the yarns were tested for single yarn strength and breaking extension on an Instron tensile tester
Filament/yarn
"-'--._-- Tension d iscs
Drafting rollers
Core guide
Core-spun yarn
Spinning ring
Fig. I - Method of yarn manufacture
with 50 cm long test specimens being elongated at the rate of 200 mmlmin . Yarn evenness and imperfections were recorded by an Uster evenness tester.
3 Results and Discussion Table 1 shows that the polyester filament (35
denier) core with cotton sheath (S8) gives even yarn at a twist level of 25 TPI. A further increase in twist (S9) i ncreases the unevenness. Nylon filament core yarns also show the same results as reported in an earlier research work.
3
The polyester spun core with cotton wrap yarn (S3) is more even as compared to the polyester filament core yarns. This is because of the fibre friction between the core and the sheath fibres. Decreasing the sheath content in the yarn (S3) increases the tenacity and improves the evenness in the given resultant count. Hence, the evenness and tenacity improve by i ncreasing the ratio of core to sheath. The imperfections of yarn also decrease significantly with the i ncrease in core:sheath ratio. The polyester spun core with cotton wrap (S3) yarn is more even as compared to PIe: cotton (S5) and PlY: cotton (S6) core-spun yarns, but gives s lightly higher number of thin places and a nominal U%.
3.1 Effect of Twist on Unevenness, Strength and Breaking Extension of Cotton with Polyester Filament Core Yarns
The influence of pretension has already been studied.4.5 In the present experiment, the optimum pretension of l OOg is kept constant for all the samples. Mi ller6 used doubler winder to produce corespun yarn products. He observed that below certain level of twist the core covering would not be fully
Table I - Quali ty characteristics of core-spun yarns
Yarn Filament Core: sheath TPI ImQerfections 120 km U% Count ref . no. den ratio Thick Thin Neps s
places places
S I 60s PSF I : I 20 7 2 3 1 0.2 30
S2 60s PSF 2 : I 20 8 0 4 9.4 1 3
S3 60s PSF 2 : 1 20 5 1 6 1 5 9.44 20
S4 60s PSF 3: 1 20 22 1 3 9. 1 8 1 5
S5 60s PIC 2: 1 20 22 I 1 3 1 1 .2 20
S6 60s PlY 2 : 1 20 20 4 1 3 1 1 .6 20
S7 35 den PET 3 : 1 20 1 6 148 1 l .2 38
S8 35 den PET 3: 1 25 2 1 1 29 1 0.9 38
S9 35 den PET 3 : 1 30 22 2 1 32 1 l .3 38
PSF - Polyester staple fibre, PIC - Polyesterlcollon, PlY - Polyesterlviscose and PET - Polyester fi lament.
300 INDIAN J. FIBRE TEXT. RES., JUNE 2006
accomplished. The maximum covering of the core is achieved with optimum level of twist that also influences the tensile properties of yarn. Tables I and 2 show that the properties of core-spun yarns are influenced by twist considerably.
The increase i n twist makes the yarn more even 7 up to certain extent in polyester filament core-spun yarns, l ike the yarns made from conventional ring frame. However, further increase in twist makes the yarn uneven and higher twist makes the yarn snarl and unbalanced.
Tensile properties of core-spun yarns vary directly with respect to TPI in the core yarn. S ingle thread strength increases with the increase in twist from 20 TPI to 25 TPI and then reduces with the further increase in twist to 30 TPI. But the breaking extension · reduces with the increase in twist, which is in agreement with the reported work.H Further increase in twist makes the yarn unbalanced.
3.2 Effect of Blend Material Composition on Strength in PSF, PIC, PN Core Yarns
Table 2 shows that the properties of core-spun yarns are influenced by blend material composition of the core. Tensile properties of core-spun yarns vary directly with the type of fibre used in the core. The core-spun yarn made from polyester spun core shows
increased tensile strength than the core-spun yarn made from PIC blend and PlY blend core. But the breaking extension is lower for the core-spun yarn made from PIC blend core than the core-spun yarn made from PlY blend core for 20 TPI . The polyester spun core yarn shows increased breaking extension.
3.3 Effect of Core : sheath Ratio on Tensile Properties and Unevenness
Balasubramanium and Bhatnagar9 made an extensive study on core-spun yarns produced in a modified ri ng frame. It has been reported that the relative disposition of the filament and sheath material contributes to the tensile properties of the core-spun yarns. Table 2 shows the properties of core-spun yarn samples obtained from same count of polyester spun yarn core with cotton sheath of different core: sheath ratios. The polyester staple core yarn samples of 30s, 20s and I Ss are made with core: sheath ratios of I : 1 , 2 : 1 and 3 : 1 respectively.
By reducing sheath content, the tenacity increases. Also, it increases the breaking extension percentage. In general, core-spun yarns have very good tenacity lO
(Table 3) as compared to 1 00% cotton ring yarns. Table 1 shows the unevenness percentage of core
spun yarns . Yarn samples of 30s, 20s and I Ss are made with core: sheath ratios of 1 : 1 , 2: 1 and 3 : 1
respectively. By reducing cotton content in the sheath, the unevenness percentage decreases. This effect is due to less binding fibres in the sheath of the yarn . Overall, the core-spun yarns are more even (Table 3) as compared to the yarns made from conventional ring frame.
4 Conclusions 4.1 The tensile properties of the core-spun yarns
depend on the core: sheath material, twist and core : sheath ratio.
4.2 Polyester spun core and cotton sheath core-spun yarns have the advantage of good strength, tenacity, breaking extension and evenness as compared to cotton and polyester spun yarns produced from conventional ring frame.
4.3 Polyester staple core and cotton sheath corespun yarns with reduced cotton content i n sheath exhibit higher strength, yarn regularity and higher breaking extension. In general, all these properties of staple core yarns are superior to that of the conventional ring-spun yarns.
4.4 The optimum twist for all the core-spun yarns is found to be 20 TPI. Further increase in twist makes these yarns snarl and unbalanced. Yarn tenacity
increases with the increase in twist up to certain level. But the breaking extension decreases in increasing the twist.
4.5 Core-spun yarns are more even having a very good tenacity and breaking extension as compared to ordinary yarns produced from conventional ring frame.
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