Indian Journal of Fibre & Textile Research Vol. 30, June 2005, pp. 148-152 Effect of inter-fibre friction on yam quality Ajay Kumar' & Anita Nishkam Govt. Central Textile Inst itute, Kanpur 208 1, India and S M lshtiaqueb Northern India Textile Research Association, Ghaziabad 201 002, India Received J 3 November 2003; revised received alld accepted 19 August 2004 The effect of inter-fibre friction and tuft behaviour during yarn preparation on yarn quality has been studied. The higher level of inter-fibre friction is observed on application of spin finish (polyethylene glycol) which improves the inter-fibre cohesion and positively influences the yarn evenness, breaking strength, elongation-at-break and hairiness. The tuft behaviour at different friction levels improves but mixed trend is observed for the yarn quali ty parameters, perhaps due to the uneven fibre sl ippage. Keywords: Acrylic fibre, Fibre surface geometry, Inter-fibre cohesion, Inter-fibre friction, Protruding hairs, Tuft behaviour IPC Code: Int. C1. 7 D02J l/ꝃ 1 Introduction Friction is the important physical property which affects the quality of yarn as the fibres are held in yarn by inter-fibre frictional contact. It is the resisting force on the fibre body sliding over another under a normal load which is due to the force needed to lift one surface over the irregularities of the other. The predominant effect is due to the union or welding of two surfaces at the point of real contact and breaking of these junctions when sliding starts. Morrow I defined th is force as nearly constant and independent of pressure, area of contact and rate of relative motion of the surface. Actually it is not so, the quant ity of force will depend on both pressure and area of contact and may vary in qu ite complicated way with any change in surface condit ions. Bowden and Tabor 2 also observed a linear relation between load and contact area. The area of real contact will be independent of no. of points of contact. However, this behaviour is found correct for metals only and different for non-metals (elast ic materials). The relat ion between load and area of "To whom all the correspondence should be addressed. Present address: Central Sheep and Wool Research Insti tute, Arid Region Campus, Bikaner 334 006, India Phone: 2250936; Fax: +91-151 -2250322; E-mail : [email protected]b present address: Department of Textile Technology, Indian Institute of Technology, New Delhi 1 10 016, India contact depends on the geometry of the contact area. The fibre surface geometry of synthetic and natural fibres is sub-divided into surface roughness, cross- sectional shape and crimp/convolution. Scardino and Lyons 3 deduced that the roughness has adverse effect while the crimp and cross-sect ional . shape (toward circular) have pos itive effect on inter-fibre friction. During the processes involved in spinning of yarn, the friction determines the deformation behaviour of fibre and control of fibre flow. Fibres are withheld in different strands, i.e. sliver, roving and yarn, due to some cohesive force which contributes to the quality of final yarn produced. Deluca and Thibodeaux 4 observed that the inter-fibre frictional forces play secondary role initially at preparatory processing level (sliver and roving formation) while they play important role at final stage of yarn spinning and contribute to yarn strength. As reported by Hearle and Hussain 5 , the fibre treatment by . PEG increases the coefficient of dynamic friction and decreases coefficient of static frict ion. The PEG-treated samples also have softer handle properties due to the least difference between these two coefficients of friction. Balls 6 found that the fibre length, l inear density and frict ion at low normal load, influence the yarn strength and the yarn irregularit ies are qu ite sensitive to the coef ficient of frict ion. There are some other factors 7.8 which influence the frictional properties of fibres.
Transcript
Indian Journal of Fibre & Textile Research Vol. 30, June 2005, pp. 148- 1 52
Effect of inter-fibre friction on yam quality
Ajay Kumar' & Anita Nishkam
Govt. Central Textile Institute, Kanpur 208 00 1 , India
and
S M lshtiaqueb
Northern India Textile Research Association, Ghaziabad 201 002, India
Received J 3 November 2003; revised received alld accepted 19 August 2004
The effect of inter-fibre friction and tuft behaviour during yarn preparation on yarn quality has been studied. The higher level of inter-fibre friction is observed on application of spin finish (polyethylene glycol) which improves the inter-fibre cohesion and positively influences the yarn evenness, breaking strength, elongation-at-break and hairiness. The tuft behaviour at different friction levels improves but mixed trend is observed for the yarn quality parameters, perhaps due to the uneven fibre slippage.
1 Introduction Friction is the important physical property which
affects the quality of yarn as the fibres are held in yarn by inter-fibre frictional contact. I t is the resisting force on the fibre body sliding over another under a normal load which is due to the force needed to l ift one surface over the irregularities of the other. The predominant effect is due to the union or welding of two surfaces at the point of real contact and breaking of these j unctions when sl iding starts. Morrow I defined this force as nearly constant and independent of pressure, area of contact and rate of relative motion of the surface. Actually it is not so, the quantity of force will depend on both pressure and area of contact and may vary in quite complicated way with any change in surface conditions.
Bowden and Tabor2 also observed a l inear relation between load and contact area. The area of real contact will be independent of no. of points of contact. However, this behaviour i s found correct for metals only and different for non-metals (elastic materials). The relation between load and area of
"To whom all the correspondence should be addressed. Present address: Central Sheep and Wool Research Institute, Arid Region Campus, Bikaner 334 006, India Phone: 2250936; Fax: +91 - 1 5 1 -2250322; E-mail : [email protected] bpresent address: Department of Textile Technology, Indian Institute of Technology, New Delhi 1 10 0 1 6, India
contact depends on the geometry of the contact area. The fibre surface geometry of synthetic and natural fibres is sub-divided into surface roughness, crosssectional shape and crimp/convolution. Scardino and Lyons3 deduced that the roughness has adverse effect while the crimp and cross-sectional . shape (toward circular) have positive effect on inter-fibre friction.
During the processes involved in spinning of yarn, the friction determines the deformation behaviour of fibre and control of fibre flow. Fibres are withheld in different strands, i .e. sliver, roving and yarn, due to some cohesive force which contributes to the quality of final yarn produced. Deluca and Thibodeaux4
observed that the inter-fibre frictional forces play secondary role i nitially at preparatory processing level (sliver and roving formation) while they play important role at final stage of yarn spinning and contribute to yarn strength.
As reported by Hearle and Hussain5, the fibre treatment by . PEG increases the coefficient of dynamic friction and decreases coefficient of static friction. The PEG-treated samples also have softer handle properties due to the least difference between these two coefficients of friction.
Balls6 found that the fibre length, linear density and friction at low normal load, influence the yarn strength and the yarn irregularities are quite sensitive to the coefficient of friction. There are some other factors 7.8 which i nfluence the frictional properties of fibres.
AJA Y KUMAR et at.: EFFECT OF INTER-FIBRE FRICTION ON YARN QUALITY 1 49
The role of friction in textile processing although not quantified is well recognized. Broughton et al. 9 reported that the inter-fibre friction contributes a lot i n yarn strength and can be the dominant factor in determining the tensile properties of a yarn. In the present work, an effort has been made to optimize the level of inter-fibre friction and tuft behaviour during processing by mixing acrylic fibres at different friction levels and their influence on yarn qual i ty studied.
2 Materials and Methods
2.1 Materials
Acrylic fibre of 5 1 mm staple length and 1 .5 denier fineness was used in preparing samples by applying spin finish with adhesive property (polyethylene glycol or PEG). Three lots of samples were prepared for the study. The sample preparation and testing were done at the Indian Institute of Technology, New Delhi, and the Northern India Textile Research Association, Ghaziabad.
2.1.1 Primary Mixture
Lot I - Acrylic fibres w ithout polyethylene glycol (0% PEG sample).
Lot II-Admixture of acrylic fibres and 0.2% PEG by weight of acrylic fibre (0.2% PEG sample).
Lot Ill-Admixture of acrylic fibres and 0.3% PEG by weight of acrylic fibre (0.3% PEG sample).
The acrylic fibres ( 1 4 kg for each lot) were laid i n layers and the 5% solution of PEG in water sprayed over every layer of the laid fibres. The sandwich of the laid fibres was then vertically cut and thoroughly hand mixed to homogenize the mixture.
2.1.2 Binary Mixture
Three binary mix samples were prepared by mixing (in equal amount) any two of the above three lots (0% PEG+ 0.2% PEG, 0% PEG+ 0.3% PEG and 0.2% PEG+ 0.3% PEG). The fibres of the different lots were laid i n layers one over the other, cut vertically and hand mixed to homogenize.
2.1.3 Tertiary Mixture
The tertiary mixture was prepared by mixing all the three lots in equal amount by laying the fibres of each lot in a sequence one above the other and getting the sample homogenized in a similar manner as done for binary mixture.
In yarn preparation, the samples pass through following preparatory and spinning operations :
The conversion to drawn sliver was carried out using Lakshmi Rieter C 112 carding mlc and Lakshmi Rieter Draw Frame D02/S. Two drawing passages were given to carded sliver. The drawn 0 . 1 s sliver was converted i nto roving of 1 .0s on Lakshmi Rieter Speed Frame 5S and the prepared roving was spun into 20s yarn on a Spinner M ark-2 Ring Frame.
2.2 Test Methods
2.2.1 Measurement of Inter-fibre Friction Coefficient
The coefficient of fibre-to-fibre friction was measured on an Instron tensile tester (Model 4301 )using the attachment similar to that used by Sengupta et aZIO• The two fibre fringes with a uniform density of 5 mg/cm2 were placed one over the other and a known weight of 40 g was placed on them as suggested by Lord I I . The upper fringe was attached to the load cell of Instron by an inextensible cord through a frictionless pulley and the lower fringe was clamped on the attachment itself. The crosshead speed was kept at 1 0 mmlmin and the maximum draw force developed between the fibre fringes at the point of slippage was recorded by the Instron under the applied known weight. From the recorded draw force values, the coefficient of fibre-to-fibre friction was determined using Amonton' s law. A sketch diagram to show the assembly to test i nter-fibre friction is shown in Fig. 1 .
2.2.2 Measurement of Yarn Unevenness and Imperfections
The yarn unevenness and imperfections were measured on an Uster evenness tester (UT-3) which monitored the variation in weight per unit length of �he resultant yam. The 1 600 m yarn length was tested for each sample at 37.5% pre-tension and 400 mlmin testing speed. The sensitivity levels used were thin places (-30%, -50%), thick places (+50%, +100%) and neps (+200%).
2.2.3 Measurement of Tensile Propertus
The yam tenacity and elongation-at-break were measured on commonly used i nstrument i n industries. For tensile properties of yam, the Uster Tensorapid was used in which force calibrating transducer at the upper jaw measures the i ncreasing (stretch) load and the breaking extension is monitored by a rotational movement transducer. Fifty tests per sample were carried out using yarn length of 50 em /test, testing speed of 5 m /min and pre-tension of 0.5 cN/tex.
1 50 INDIAN J. FIBRE TEXT. RES., JUNE 2005
2.2.4 Measurement of Yarn Hairilless
The yarn hairiness was measured using Electronic Inspection Board-Multi Threshold/Hairiness System (EIB-MTH). Only the hairiness module of this instrument is used which works on photoelectric principle.The yarn is passed through an optical scanner and the images of protruding hairs are scanned by photosensitive transducer which calibrates the length of protruding hairs and classifies the hairs in fol lowing six groups (TI - T6) according to their length distribution.
Group
Threshold I +Yarn 2+Yarn in ITIm diam. diam.
Steel Plate
Over Over
Weight(40g)
[:J
Fibre Fringes
TJ T4
3+Yarn 4+Yarn diam. diam.
Over Over
Instron upper jaw
IRON BASE
e
e Fibre fringes IRON BASE
ASSEMBLY TOP VIEW
T5 Tr,
5+Yarn 6+Yarn diam. diam.
Over Over
Thread
Pulley
Fig. I -Assembly to test inter-fibre friction
The protruding hairs of T I group have length over I mm but less then 2mm on yarn diameter, similarly for T2-T6 groups . The yarn was tested at a speed of 50 m /min and 500 m length of yarn was used for each sample. The image scanning rate was 3875 ± 5 images/ min.
2.2.5 Measuremellt of Seldom Occurring Faults
The Uster Tester (Model Classimate -III) was used to know the seldom occurring faul ts/ l Oa km of yarn length for each sample. The faults were classified in the following three groups according to their sizes and lengths:
Fault Short thick (S) Long thick (L) Th in (T)
Size + 200 % or above + C - 1 00 %
-30 % to -75 %
3 Results and Discussion
3.1 Inter-fibre Friction
Length 0-8 mm 8-32 mm or above
8-32 mm or above
Table 1 shows that the samples treated by polyethylene glycol at different levels show remarkable increase in coefficient of friction ().l) than the untreated sample. Similar trend is observed for both mixed and unmixed samples. This increase in coefficient of friction is attributed to the increase in inter-fibre cohesion and ultimately reduction in fibre slippage within the fibre strands.
3.2 Mass Irregularity and Imperfections
There is a remarkable improvement in yarn unevenness (U%), CVO/O of unevenness and imperfections level (Table 1 ) for the samples in which the spin finish is applied. This is due to the better fibre control during attenuation of fibre strand at various drafting operations. The unevenness and imperfections for mixed samples show improvement
Table I -Coefficients of friction and yam unevenness
Sample Coefficient of CV% Uster CV % friction (ft) U %
Unmixed
O % PEG 0.486 8.94 1 1 .20 1 4.28
0.2%PEG 0.5 1 5 1 0.6 1 0.29 1 3. 1 1
0.3%PEG 0.539 6.87 1 0. 1 4 1 2.90
Binary mix
0% +0.2%PEG 0.527 8.3 1 1 .80 1 5 .26
0%+0.3%PEG 0.529 9.39 9.93 1 2.50
0.2%+0.3% PEG 0.530 9.69 9.80 1 2.37
Tertiary mix
0%+0.2%+0.3%PEG 0.535 4.88 1 1 .64 1 4.63
Thi n places (-30%) (-50%)
1 375 1 5
78.8 3
62 1 4
1 069 34
547
502
699
Thick place Neps (+200%) (+50%) (+100%)
54
2 1
2 1
85
7
6
I I
3 28
29
6
1 5 34
I 9
2 8
2 6
AJA Y KUMAR et ai.: EFFECT OF INTER-FIBRE FRICTION ON YARN QUALITY 1 5 1
but the trend is not proper as the fibre control during yarn preparation depends upon the no. of fibres of different friction levels in the cross-section of resultant yarn. The grey fibre (without spin finish) proportion in mixed samples highly influences the evenness and imperfections as evident from the results observed with tertiary mix sample.
The statistical analysis ( 'T' test) shows that the observed t value (0. 1 7707) for calculated correlation coefficient (r =0.0308 1 ) between inter-fibre friction and yarn evenness (U%) is very low as compared to the desired t value (2.402) at 5% level of significance. Though there has been the positive correlation, it is so insignificant that with the increase in inter-fibre friction the evenness of resultant yarn does not increase in the same magnitude or may even decrease as surmised.
3.3 Tenacity and Elongation-at-Break
The tenacity and elongation-at-break for different samples (Table 2) improve as the proportion of higher friction coefficient fibres increases. This may be
attributed to the higher inter-fibre cohesion and thus better fibre control during spinning of yarn. On the other hand, CV% for tenacity and elongation-at-break increases due to the non-uniform slippage of adhered and un-adhered fibre tufts in yarn cross-section. Here, again the gray fibre proportion influences the tensile properties of the resultant yarn.
The statistical studies for correlation between interfibre friction and single yarn strength of the resultant yarn show that the observed t value for correlation coefficient (r =0.3496) is positive and highly significant at 5% level of significance. This proves that the single yarn strength corresponds to the interfibre friction. This means that if the inter-fibre friction is increased, the strength of the resultant yarn also increases.
3.4 Seldom Occurring Faults
Table 2 shows the reverse trend for long thick (L) and thin (T) faults, while mixed results for short thick (S) and objectionable faults. This may be attributed to the intermittently uneven accumulation of one friction
Table 2-Yarn tenacity, elongation-at-break and seldom occurring faults
Sample UTR results Classimate-III results Tenacity CV % Elongation-at- CV % S L T Objectionable
level fibre in fibre strand (yarn). The count strength product (CSP) which is a useful measure to judge the yarn strength,spinning quality and efficiency of material shows no significant change at 5% level of significance.
3.5 Hairiness
It is observed that in all the samples, the length of the majority of protruding fibres i s 1 -2 mm. There i s definite decrease i n number of protruding hairs, though not uniform trend, with the i ncrease in inter-fibre friction for unmixed and mixed samples (Table 3).
This improvement in yarn hairiness with the increase in friction level for both unmixed and mix samples applied with spin finish is attributed to the better helical binding of fibre in yarn structure due to the improved inter-fibre cohesion.
4 Conclusions 4.1 There is remarkable improvement in yarn
quality parameters with the increase i n i nter-fibre friction by applying spin finish (polyethylene glycol) for unmixed samples. Thi s signifies the role of fibrefrictional properties i n determining the yarn quality. The application of polyethylene glycol in optimum quantity prior to blowroom operation i n spinning of acrylic yarn is recommended to obtain yarn of better quality.
4.2 Yarn quality parameters for mixed samples show improvement when compared to those of untreated sample but no proper trend is observed. This may be attributed to uneven slip behaviour of different friction level fibres in different proportions within the fibre strand.
References 1 Morrow I A, J Text Inst, (9)( 1 93 1 ) T 425.
2 Bowden F P & Tabor D, The Friction alld Lubrication of Solids (Oxford University Press, London), 1950.
3 Francis L Scardino & Lyons W I, Surface Characteristics (�f Synthetic fibres, edited by M J Schick (Marcel Dekker Inc, New York, USA), 1977, 1 65- 1 9 1 .
4 Deluca L B & Thibodeaux D P, Text Res J, 62 ( 1992) 192.
5 Hearle I W S & Hussain A K M, J Text Inst, 62(2) ( 1 97 1 ) 83- 1 07.
6 Balls W L, Studies of Quality in Cotton (Macmillan, London), 1 928, 248.
7 Gupta B S, Frictional Properties of Textile Materials in Surface Characterstics of Fibres and Textiles, edited by C N Pastore and P Kiekins (Marcel Dekker Inc, New York and Basel), 200 1 .
8 Hersh S P, Surface Characteristics of Synthetic fibres edited by M I Schick (Marcel Dekker, Inc, New York, USA), 1977, 225-294.
9 Broughton R M (Ie), Mogahzy Yehia EL & Hall D M, Text Res J, 62(3) ( 1 993) 1 3 1 .
1 0 Sengupta A K, Chattopadhyay R, Venkatachelapahti G S & Padmanabhan A R, Milliimd Textilber, 73( 1992) E83.
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