Indi an Journal of Fibre & Textile Research Vol. 26. December 200 I, pp. 392-397

Influence of spin finish and opening roller speed on the mechanical properties of polyester OE rotor yarns produced with different draw-off nozzles

G K Tyagi" & Rakesh Jindal The Techno logical Institute of Textile & Sciences, Bh iwani 127021 , India

and

K R Salhotra Department o f Textile Technology, Indian Institute of Technology, New De lhi I 100 I 2, India

Received 3 April 2000; revised received and accepted 22 Jun e 2000

The effec t of spin fini sh level, opening roller speed and types of draw-off nozzle on the mechanical properties of the polyester OE rotor yarns has been studied. It is observed that the higher level of spin fini sh and notched nozzle offer considerable advantage in rotor spinning in respect of yarn tensi le properties. The opening roller speed has the greatest innuence on yarn breaking strength , breaking extension, work of rupture and abras ion resistance. All these properties deteriorate to diffe re nt degree. depend ing upon the level of spin fini sh. Twi st e fficiency is higher with a higher level of spin fini sh, higher opening roller speed and a notched nozzle.

Keywords: Draw-off nozzle, Fibre friction. Opening roller speed , Polyes ter yarn , Spin fini sh, Twi st effic iency

1 Introduction Over the last 30 years, the opening roller system of

fibre separation in rotor spinning has been the subject of much intensive research. As a fibre-separating device, the opening roller system gives a high degree of fibre separation but at the expense of fibre breakage. Some of the process variables which determine fibre breakage include the configuration of the fibres in the feed sliver, the physical and mechanical characteristics of the fibres, the feed rate and the speed of the opening roller. Another important influencing factor in fibre breakage is the spin finish . Its level determines the frictional properties of fibres and hence the yarn qualityl. In general, a higher coefficient of friction interferes with the degree of fibre separation by the opening roller and thus produces a more irregular yarn. The lower coefficient of friction, on the other hand, leads to the poor inter­fibre cohesion and poor yarn strength. Although the influence of opening of fibres by the opening roller on the yarn properties has already been investigated extensivel/-6, most workers have studied it from the point of view of fibre types such as cotton, viscose and acrylic fibres. A relatively few have experimented

'1'0 whom all the correspondence should be addressed. Phone: 42561; Fax : 009 I -0 I 664-43728; E-mail : titsintr @nde.vsnl.net.in

on the effect of spin finish on fibres . Sprenkmann 7

studied the role of spin fini sh and oiling agents as aids in rotor spinning. Keller 8 studied the effect of dyes and spin finish on rotor deposit and periodic yarn defects. Sengupta et al. 9 observed an increase in tenacity and specific work of rupture of polyester OE rotor-spun yarns with the increase in level of spin finish. ]n a recent study , Roosli 10 showed that the mass irregularity and imperfections, particularly thick places and neps, of the Iyocell OE rotor-spun yarn increase as a consequence of added spin fini sh. However, the report does not mention about mechanical properties. In view of the importance of the subject, it was thought necessary to investigate the influence of spin finish and opening roller speed on the evenness and tensile properties of polyester OE rotor yarns spun with different draw-off nozzles. Such a study would be useful for establishing the optimum spin fini sh for polyester fibres spinning on a rotor frame. Besides, ' the study would also be useful for interpreting the performance of fibre and spin finish deposit.

2 Materials and Methods 2.1 Preparation of Yarn Samples

Polyester staple fibre of 38mm, 1.33 dtex and 3.01 cN/tex (stelometer gauge, 1/8") specifications was hand opened and separated into four lots of Skg each.

TY AGI et al.: MECHANICAL PROPERTIES OF POLYESTER OE ROTOR YARNS 393

Spin finish L Y 40 was dissol ved in water and sprayed as uniformly as possible on three lots of polyester. Three different add-on finish levels viz. O.OS%, 0.10% and O.IS% (owf) were used. The conversion to drawn sliver was carried out by using a MMC carding machine and a Lakxmj Reiter' draw frame Do/6. Two drawing passages were given to carded slivers. The drawn slivers of 3.7 ktex were spun into yams on Inglostadt rotor spinner RUll1RU80 (4620). The process parameters used are given in Table 1. The machine parameters used were: 48 mm rotor, tooth opening OS121 (24 teeth/cm2 and 100° face angle) and two draw-off nozzles (notched and plain) having external and internal diameters of IS .S mm and 3 mm respectively .

2.2 Test Methods 2.2.1 Yarn Twist

The yam twist was determined by Eureka twist tester using detwist-retwist method. Forty test specimens were tested for each yam sample.

2.2.2 Tensile Properties Yam tensile properties were tested on Instron

tensile tester (model 4411) using SOcm test specimen and 20 crn/min extension rate. Fifty measurements were taken on each yam sample. Work of rupture was calculated from the following expression:

Work of rupture = O.S [Yam tenacity (g/d) x Breaking extension (expressed as fraction)]

2.2.3 Abrasion Resistance CSI abrasion tester was used to measure flat

abrasion resistance of yam samples. Thirty observations were made and the average number of cycles required to break the specimen was taken as a measure of abrasion resistance.

2.2.4 Yarn Diameter Yam diameter was determined by the optical

microscopic projection method. Fifty readings were taken for each yam sample.

2.2.5 Yarn Unevenness and Imperfections Yam unevenness and imperfections were measured

on an Uster evenness tester using a test length of 12Sm. The sensitivity levels used were: thin places, -SO%; thick places, +SO%; and neps, +200%.

2.2.6 Fibre Friction Coefficients The coefficients of fiber-to-fibre and fibre -to-metal

friction were measured on an Instron tensile tester using the attachment developed by Sengupta et alII.

Two fibre tufts of uniform density were pl aced one above the other. A known weight of 40 g was placed on the tufts. One tuft was attached by an inextensible cord to the load cell of the Instron . The crosshead was made to move up and the maximum frictional force developed between the fibre tufts was recorded. In the case of fibre-to-metal friction , a single tuft was laid on a bare metal plate and the same procedure was repeated. From the recorded values, the values of coefficients of fibre-to-fibre and fibre-to- metal friction were determined using Amonton's law.

3 Results and Discussion The Influence of three experimental variables, viz.

type of draw-off nozzle, level of spin finish and opening roller speed, on yarn properties was assessed using analysis of variance (ANOY A) at I % level of significance (Table 2). Only first order interactions were considered.

3.1 Twist Efficiency Table 3 shows the influence of spin finish and

opening roller speed with plain and notched nozzles

Table I-Spinning parameters for rotor-spun yams"

Yam Level of Rotor Draw-off Tex twi st Opening roller ref. spin fini sh speed x 10.3 nozzle profile fac tor speed, rps no. % rpm

S, Nil 50 Plain 38.28 116.661133.331150

S2 0.05 50 Plain 38.28 116.66/133.331150

S3 0.10 50 Pl ain 38.28 116.6611 33.331150

S4 0.15 50 Plain 38.28 116.661133.33/150

S5 Nil 50 Notched 38.28 116.66/133.33/150

S6 0.05 50 Notched 38.28 116.661133.33/150

S7 0.10 50 Notched 38.28 116.66/133.33/150

S8 0.15 50 Notched 38.28 116.66/133.3311 50

" Yam linear density, 29.5 tex

394 INDIAN J. FIBRE TEXT. RES ., DECEMBER 2001

on some yarn properties. It is observed that the yarns spun with plain nozzle have considerably lower twist efficiency. As the ex ternal and internal diameters of both plain and notched nozzles are the same, the higher values of twist efficiency with notched nozzle can be attributed to the increased false twist. The false twist increases the torsional moment in the twist-in zone so that the twist propagation and, therefore, the twist-in zone are extended ' 2.

The higher opening roller speed shows the higher twist efficiency (Fig. 1). An obvious reason for the hi gher twist effic iency is the decrease in the percentage of sheath fibres. The greater fibre separation at the higher opening roller speed reduces the possibility of some fibres becoming wrapper, just because they happen to be entangle with the fibres undergoing belts formation 13. It has been shown that there is a strong corre lati on between per cent sheath fibres and twi st efficiency. So, any reduction in sheath fi bres leads to the greater yarn twist. Twist efficiency also increases considerably as the level of spin fini sh increases. This is due to the higher fibre-to-metal friction (Table 4) with higher level of the spin finish. The hi gher finish, in turn, generates greater frictional

contact between the yarn and the nozzle, resulting in higher twist efficiency . However, the poor fibre individualization , resulting from the increased fibre­to-fibre friction, would bring down this increase in twist efficiency.

3.2 Tenacity

The effect of spin finish, type of draw-off nozzle and opening roller speed on the yarn tenacity is shown

100 ~ 0"lt.5pn Inlsh. PlaIn fKl'ZZM ~ 0%SF*1 finish, notched nozzle

-.- O.05~ sf*' ........ PlaIn nozz1a -M- 0.057. Spin ft04ll , nc:Ghod nozzle

___ 0.1% Spin flll.h, Pttlkl noaSo -.- 0.1"" 3~llnnlah.llUtci'" TIOl2b

9() '-+- 0.15% Splnlnlol!. PIoInI1Ql21. - 0 .15% Spin "nloh._n<>IZIe

80

70

60

116.66 133.33 150

Opening roller speed, rps

Fig. I-Twist effi ciency at various opcning roller speeds

Table 2-ANOV A tes t resu lts

Process Y arn ~ro~erties variables Twist Tenaci ty Breaking Work of Abrasion

efficiency extension rupture resistance A s s

B s s s

C s s s

A*B ns ns ns ns ns

B*C ns s s ns

A*C ns ns ns ns ns

A*B*C ns ns ns ns ns

s-Significant at 99% confidence level; and ns-Non-sign ificant at 99% confiden.::e level. A-Draw-off nozzle profile; B-Level of spin finish ; and C-Opening ro ller speed.

Diameter Irregul arity

s

ns ns

ns

ns ns

ns ns

Table 3-Effect of type of nozzle, level of spin finish and openi ng roller speed on twi st efficiency, tenacity, breaki ng eXlension and work of rupture of polyester OE rotor-spun yarns

Yarn Twist efficiency, % Tenac ity, cN/tex Breaking extension, % Work ofruplUrexl0-3, g/den re f. no. 116.66" 133.33" ISO" 116.66" 133.33" ISO" 11 6.66" 133.33" i50" 116.66" 133 .33" ISO"

S, 65.7 71.8 74.5 15.98 15.04 13.67 18.08 16.85 16.14 163 152 125

S2 67 .8 75. 1 78.6 17.01 15.50 13.8 1 18.27 17.67 17.35 176 ISS 135

SJ 70.2 77.4 81.8 17.25 17 .06 16.80 19.49 19.34 19. 18 190 186 182

S4 75 .7 80.3 83.6 17.33 17.69 17.55 20.50 20.73 19.34 20 1 207 192

Ss 68.5 74.6 76.3 16.07 15.74 14.04 17.52 16.31 15 .41 159 145 122

S6 71.0 76.8 80.8 17.38 15.80 14.62 17 .80 17.00 16.13 175 152 133

S7 72.3 79. 1 82 .7 17.69 17.40 17.33 18.81 18.67 18.44 188 183 180

SH 76.7 8 1.9 85.6 17.80 17.94 17.75 19.75 20. 16 19.10 199 204 191

"Opening speed in rps.

TY AGI el al. : MECHANICAL PROPERTIES OF POLYESTER OE ROTOR YARNS 395

Table 4-Effect of spin finish and opening roller speed on tenacity. breaking extension and frictional coefficients of polyester fibre

Level of Tenacity. cN/tex spin finish Parent After oQening Parent

% fibre I 16.66a 133.33a 150a fibre

Nil 26.57 23.44 23.39 22.955 32. 14

0.05 26.57 21.84 22.69 21.92 32.14

0.10 26.57 19.28 21.83 19.25 32. 14

0.15 26.57 22.80 22.22 22.07 32.14

"Opening roller speed in rps.

in Fig. 2. It is observed that the yarn tenacity increases as the level of add-on spin finish is increased from 0% to 0.15%. The increase in tenacity is due to the increase in fibre-to-fibre and fibre-to­metal friction obtained as a result of added spin finish. This is due to the gre~ter yarn twist with higher fibre­to-metal friction and higher inter-fibre friction because of the higher fibre-to-fibre friction.

The increase in opening roller speed affects the tenacity of four sets of yarn in different ways. The tenacity of yarns spun with 0, 0.05and 0.10% add-on spin finish decreases with the increase in opening roller speed as expected. However, for 0.15% spin finish level, the yarn tenacity does not change much as the opening roller speed is increased (Table 3). The decrease in yarn tenacity at higher opening roller speed arises due to the greater fibre damage. This is born out by the fact that both the fibre tenacity and the breaking extension drop considerably after opening (Table 4). Apart from this, the higher opening roller speed also leads to deterioration in fibre straightness and degree of alignment along the yarn 14. It may be observed that the order of drop in tenacity at high opening roller speed is lower in yarns spun with higher level of spin finish than the equivalent yarns spun with lower level of spin finish. This is expected as the fibre-to-fibre friction also increases with the increase in the level of spin finish, which, in turn, restricts the slippage of fibres in the yarn during tensile loading.

The use of notched nozzle results in considerably higher yarn tenaci ty, i rrespecti ve of the level of spi n finish and opening roller speed.

3.3 Breaking Extension Table 3 illustrates the effects of different

processing factors on the breaking extension of polyester OE rotor-spun yarns. It is apparent from the table that the yarns spun with higher level of spin finish have substantially higher breaking extension. This behaviour is similar to that observed for yarn

Breaking extension. % Coefficient of fibre fricti on After oQening Fibre-fibre Fibre-metal

116.66a 133 .33a 150a (~ff) (~ji,,)

29.31 29.10 28.80 0.387 0199

28.60 28.22 27.21 0.397 0.209

27.81 26.63 26.34 0.409 0.225

29.01 28.41 27.42 0.423 0.231

20 __ ~pIn finloh. PIoln nozzle __ O~Spln Onl.n. notched nozzle

-.- O.06'11.Spln rmh. Plain nozzle ____ O.06'11.SpIn finloh. notched nozzle

__ O.I'II.Spinflnloh. Pia., nozzle __ O.I'II.Spinflnlsh . notchadOOlZle

)( 18 -+- O.15'11.Spln finish . Plain nozzl. - O.IS%Spin finish. noIchGd nozzl.

~ u

f:. 16 U I'll C G> I- 14

12 116.66 133.33 150

Opening roller speed, rps

Fig. 2- Tenacity at various opening ro ller speeds

tenacity. In regard to the opening roller speed, the breaking extension follows the same trend as yarn tenacity (Fig. 3). The use of notched nozzle significantly lowers the breaking extension of polyester yarns, a trend just opposite to that for yarn tenacity.

3.4 Work of Rupture Table 3 shows that the yarns produced with plain

nozzle possess considerably higher work of rupture. The work of rupture increases with the increase in the level of spin finish. The increase in opening roller speed significantly reduces the work of rupture. All these trends are in line with the fact that the work of rupture is the combined effect of yarn tenacity and breaking extension.

3.5 Abrasion Resistance The values of abrasion resistance of the yarns are

shown in Fig. 4 and Table 5. In general , the yarns spun with higher level of spin finish have a higher abrasion resistance. This is possibly due to the higher fibre-to-fibre friction with the higher fibre fini sh which reduces the slippage of core fibres . For all the yarns, the increase in opening roller speed generall y

396 INDIAN J. FIBRE TEXT. RES., DECEMBER 2001

reduces the abrasion resistance. This may be attributed to the expected reduction in mean fibre length with the increase in opening roller speed. The yarns produced with a notched nozzle withstand fewer abras ion cycles than the yarns produced with a plain nozzle.

3.6 Diameter Table 5 and Fig. 5 show that the diameter of all the

yarns tends to increase with the increase in opening roller speed owing to the increased proportion of curved fibre ends and decreased coefficient of fibre parallelization I 5

.16

, resu lting in low packing which ultimately causes an increase in yarn diameter. Type of draw-off nozzle is an another important factor which affects the yarn di ameter. Fig. 5 shows that the notched nozzle produces a considerably less bulky yarn . This is attributed to the higher fal se twist in serted by it which leads to more compact yarn 17

. On the other hand, an increase in the level of spin fini sh further reduces the yarn diameter. The reduction may be ascribed to more compact packing of fibres owing to an increase in the twi st efficiency, which, in turn , depends upon the fibre-to-metal friction.

24 __ O'llSpin finlsll . PIaIIl nozzle __ ~pln finis/!, ~ched rlOZ2Ie

"if!. __ O.OS%Spin a_, Plain oozzIo __ O.ll5'!lS(>in InidI, ndched nazzIo

e- 22 __ O.I'ltoSpin ronlsh, P1a<l nozzle __ O.I%Sp1nr .. isll, nolched nozzle

-+- O.IS'ltoSpinfillis/\, PIoIn nazzIo -9.1S'ltoSp1otlrioh, no4cI>o4nazz1t

;; :~

~

0 'iii c: 20 Q) -)( CD

CI 18 c: :2 rei

16 l!! m

14 '16.66 133.33 150

Opening roller speed, rps

Fig. 3-Breaking extension at various opening roller speeds

3.7 Yarn Irregularity and Imperfections Tables 5 and 6 show that the yarn unevenness,

thick pl aces, thin places and neps of the four yarns produced with the notched and pl ai n nozzles are not very different. With respect to the application of spin finish , the yarn irregularities do not show any particular trend, There are some evidences to show that the higher openi ng roller speed tends to give slightly lower yarn unevenness and imperfections of added spin finish.

II) Q)

u >­c.J

ai c.J r:: l'G -III "iii l!! r:: o "iii E ..c «

1000

800

600

400

200

--+- O%Spin finash , Plain nozzle

.-tr- O.05%Spin finish , Plain nozzle

____ O.1%Spln finish, Plein nozzle

--+- O.15%Spin finish, Plain nome

li -• • :I

:: ; II III

___ O%Spin finish, notched nozzle

-*""- O.05%Spin rlnish. nofched nozzle

~ O.1%Spin finish, notchod noule

- O.1S%Spin finish, notched nozzle

~

• -- --. ::

116.66 133.33 150

Opening roller speed, rps

Fig. 4-Abrasion resistance at various opening ro ll er speeds

E E ..: Q)

0.3

~ 0.25 l'G

i5

0.2

--e-- O%Spin finish, Plain nozzkt ~ O%Spin finish, notched no.zz~

--Ir- O.05%Spin finish . Plain nozzle .-*- O.05%Spin finish, notched nozzle

____ O.l%Spin finish , Plain nozzle .-.- O.l%Spin finish, notched nozzle

-t-- O.15%Spin finish, Plain nozzle ·-O.lS%Spin finish, notched nozzle

f23A==1 ~-

116.66 133,.33 150

Opening roller speed, rps

Fig, 5-Diameter at various opening rolle r speeds

Table 5- Effect of type of nozzle, level of spi n finish and opening roller speed on abrasion resistance, irregu larity and diameter of polyester OE rotor-spun yarns

Yarn Abrasion resistance, c~c les Irregularit~ , U% Diameter, mm ref. no. 116.66" 133 .33" ISO" 11 6.66" 133.33" ISO" 116.66" 133.33" ISO"

SI 456 445 4 15 12A 12.6 13. 1 0.252 0.256 0.261

S2 574 528 503 12.6 lOA 11.7 0.243 0.250 0.254

S) 656 622 608 13.1 10,8 II. I 0.236 0.244 0.248

S4 668 676 630 13.3 11.2 10.5 0.229 0.232 0.241

S5 345 3 18 278 11.8 12A 12.9 0.248 0.250 0.252

S~ 380 366 347 12.0 10.2 11.6 0.239 0.248 0.250

S7 472 458 420 12.7 10.6 10.8 0,226 0.239 0.241

S8 483 502 446 13.0 10.9 lOA 0.224 0.230 0.237 "Opening roller speed in rps.

TY AGI et 01 .: MECHANICAL PROPERTIES OF POLYESTER OE ROTOR YARNS 397

Table 6-Effecl of lype of nozzle, level of spin fini sh and opening roller speed on imperfeclions o f polyesler OE rolor-spun yarns

Yarn I mperfeclions/ 125 m ref. no. 116.66 " 133.33 " ISO "

Thick Thin Neps TOlal Thick Thin Neps TOlal Thick Thin Neps TOlal places places +200% places places +200% places places +200% +50% -50% +50%

SI 2 I 4 7 I

S2 12 2 6 20 II

S3 4 2 12 18 2

S4 4 2 22 28 3

S5 4 9 3 16 5

S6 5 10 5 20 3

S7 4 4 II 19 4

S8 8 II 20 39 5

'Opening roller speed in rps.

4 Conclusions 4.1 The notched nozzle at higher level of fibre finish

and higher opening roller speed gives higher twist efficiency.

4.2 Yarn tenacity increases as the level of fibre finish increases. However, it generally decreases with the increase in opening roller speed. The yarn produced with a notched nozzle is considerably stronger.

4.3 Breaking extension of the yam increases with the increase in level of fibre finish. However, it decreases with the increase in opening roller speed. The yarn spun with notched nozzle has lower breaking extension.

4.4 Yams spun with higher level of spin fini sh, lower opening roller speed and notched draw-off nozzle have higher abrasion resistance.

4.5 Yams spun with higher opening roller speed, pl ain draw-off nozzle and lower level of fibre finish are more bulky.

4.6 Yarn unevenness and imperfections appear to improve as the opening roller speed is increased.

-50% +50% -50% I

5

I

10

2

9

7

10 12 2 I 17 20

4 20 6 7 14

8 II 3 7 9 19

8 12 2 0 6 8

6 21 4 13 13 30

4 9 6 19 7 32

7 20 2 7 10

7 19 3 4 8

References I Salholra K R, Spinning of Man-modes and Blends on COllon

System (The Texlile Associalion, India) , 1989, 12. 2 Simpson J & Murray M F, Text Res J , 40 ( 1970) 506. 3 Salholra K R & Challopadhaya R, Text Res J , 54 ( 1984) 194 . 4 Ozipek B, Text Res J , 56 (1986) 354. 5 Kong L & Plalfool R A, Text Res J , 66 ( 1996) 30. 6 Tyagi G K, Salholra K R & Dhamij a S, Indian J Fibre Texi

Res,24 (1999) 2 1. 7 Sprenkmann W, Melliand Textilber, 56 ( 1975) 751. 8 Ke ller H A. Text Month , OClober ( 1969) 84. 9 Sengupta A K, Challopadhaya R & Majumdar P K.

Proceedings, 33rd Joint Technological Conference of A TI RA . BITRA, SITRA & NITRA (BTRA, Bombay), 1992.53.

10 Roosli H, Melliand 1111, (I) (1998) 23. 11 Sengupta A K, Challopadhaya R, Venkatachelapathi G S &

Padmanabhan A R, Melliand Textilber. 73 (1992) E83. 12 Gay ler J & Schuren A, Text Ind, 79 (1977) 591. 13 Salhotra K R, Text Res J. 51 (1 98 1) 710. 14 U1ku S, Ozipek B & Acar M, Text Res J , 65 (1995) 557. 15 Ishtiaque S M & Kumar P, Indian J Fibre Text Res. 19

(1994) 6. 16 Ishtiaque S M & Sharma N, Indian J Fibre Texi Res, 20

( 1995)6. 17 Tyagi G K. Chand Beer & Mehta A, Indian Text J , 103

( 1992) 86.