chapter 5 physical characteristics of tencel-polyester and...

- 97 -

Chapter 5

Physical characteristics of tencel-polyester and tencel-cotton yarns

produced on ring, rotor and air-jet spinning machines

5.1 Introduction

All important properties of staple fibre yarns are decisively influenced by the

constituent fibre properties and their distribution in yarn cross-section. Further, the

complex interrelationship of fibre and yarn structure is decided by the process of yarn

formation i.e. the interaction of material with the spinning system. Each spinning

system produces yarns with different structures. The ring spinning system produces a

yarn where the fibres are effectively interlocked, the unconventional spinning systems

deliver yarn structure with inadequate fibre entanglement. Because of the geometrical

variations in the structure of ring-, rotor- and air-jet spun yarns, the substrate

characteristics are different for each spinning technology. Various studies have been

made for the comparison of yarns spun on these systems. Kumar et al. [114-115]

investigated the effect of spinning process variables on tensile and physical properties

of ring-, rotor- and air-jet spun yarns and found that ring yarn has the highest tenacity

and breaking extension, whereas the air-jet yarn the lowest. Further, they concluded

that ring yarn is highly even and has least number of thin places and neps, whereas the

air-jet yarn is least even and has highest number of thin places, thick places and neps.

Also, the total hairiness is minimum in rotor yarn and S3 hairs are least in ring yarn,

whereas the total and S3 hairiness is highest in air-jet yarn. Soe et al. [116] compared

the structure and properties of cotton yarns spun on ring, open-end rotor and vortex

spinning systems and concluded that vortex yarns are stiffer and least hairy than ring

and open-end rotor spun yarns while ring yarns have the highest tenacity values.

Jackowska- Strumillo et al. [117] also examined the quality of cotton yarns spun on

ring, compact and rotor spinning machines. Erdumulu et al. [118] compared the

properties of yarn spun in different counts from cotton, viscose rayon and 50/50

cotton-modal blended fibres on vortex, ring and open-end rotor spinning systems.

Tyagi et al. [97] also studied the properties of OE rotor and air-jet spun bamboo-

cotton yarns and reported that bamboo-cotton air-jet yarns are weaker, less extensible,

more even, have fewer imperfection, more hairy and rigid and have better abrasion

resistance than OE rotor-spun yarns.

- 98 -

The structural development during yarn forming process is further

complicated by an additional factor that is the blending of two or more fibres with

dissimilar properties and type. Generally, the purpose of blending of different fibres is

to produce a yarn that has the desirable attributes of the constituent fibres and to lower

the cost. The advent of new cellulosic fibres like tencel and the availability of fibres

with different types and properties have opened up a rich diversity of materials to be

blended. Tencel fibre offers luxury and practicality while working in tandem with

nature. Fabrics made of 100% tencel or blends have a luxurious, sensual and silky

hand and vibrant colours. Unlike the previous generation of cellulosic fibres, the new

generation of tencel has a tenacity that withstands rigorous processing. Across the

fashion spectrum, it has been embraced by well known designers and retailers. The

compatible stress-strain characteristic of tencel with respect to polyester and cotton

fibres also makes it suitable for blending with these fibres. There are various studies

dealing with the effect of blend ratio on yarn properties [46, 50, 51, 119].However,

there is no extensive survey comparing the characteristics of tencel blended yarns

spun on ring, rotor and MJS spinning systems. This study aims at investigating the

quality aspects of tencel-cotton and tencel-polyester ring-, rotor- and MJS yarns.

5.2 Experimental

Ring, rotor and air-jet yarns of 29.5 tex were spun from tencel and its blend

with polyester and cotton fibres using different blend ratios as discussed in Section

3.2 in Chapter 3. The fibre specifications of tencel, polyester and cotton fibres are also

mentioned in Table 3.1 in Chapter 3.

All the yarns were tested for single strand strength, breaking extension, yarn

irregularity, hairiness and flexural rigidity. The test procedures for all yarn properties

are given in Section 3.2.2 in Chapter 3.

5.3 Results and Discussion

The influence of three experimental factors, viz. fibre type, blend ratio and

yarn type, on the yarn characteristics was assessed for significance using ANOVA at

99% level of significance and results are shown in Table 5.1. ANOVA shows that

there is a statistically significant difference between the three factors, but it does not

specify which means are different. This problem can be solved by conducting post

hoc test. This test is used when we find statistically significant difference between

- 99 -

treatment conditions. Tukey post hoc test was selected with a view to make a pair

wise comparison of yarn type, viz. ring, rotor and MJS yarns. The results of Tukey

post hoc test are shown in Table 5.2. Since no significant variation was noticed in thin

places, neps and total imperfection in the different yarn types, Tukey post hoc test was

not applied.

5.3.1 Tenacity

Table 5.3 shows the results of tensile test. The results show that yarn strength

is sensitive to the fibre type and yarn structure, and is considerably higher for ring-

spun yarns. However, the pair wise comparison of the yarn type reveals no significant

difference between the strength of rotor and MJS yarns, though MJS yarns, except

cotton-mix ones, are slightly stronger than the rotor-spun yarns. This difference is

caused by the presence of few shorter cotton fibres, which gives insufficient wrapped-

in length [97] and hence a lower yarn strength. The highest strength of ring- spun

yarns, on the other hand, is due to superior alignment and extent of constituent fibres,

and uniform twisting which create a stronger bond between the fibres as compared to

the parallel core fibres wrapped by a few wrapper fibres in MJS yarns, which fails to

provide sufficient cohesion. The rotor yarns are weakest due to disorientation and

presence of wrapper fibres (Fig. 5.1). Increasing proportion of tencel fibre in the fibre-

mix improves the strength of tencel-cotton yarns but has an adverse effect on the

strength of yarns made with tencel-polyester mix (Fig. 5.2). As stronger polyester

component is replaced by weaker tencel, yarn strength declines. However, in tencel

cotton yarn, replacement of weaker cotton by stronger tencel enhances yarn strength.

Significantly, however, the influence of blend composition is not well marked in

yarns spun on ring-, rotor- and MJS spinning systems as indicated by F- ratios (Table

5.1). Moreover, the tencel-polyester blended yarns are noticeably stronger than the

tencel-cotton yarns regardless of blend composition and yarn structure.

-100-

Table 5.1 − ANOVA test results

Process

variables

F–ratio

Tenacity Breaking

extension Work

of

rupture

Unevenness Imperfection Flexural

rigidity Hairiness

Thin

places Thick

places Neps Total 1mm 2mm S3

A 167.82

(11.26)

412.25

(11.26)

153.77

(11.26)

264.539

(11.26)

15.293

(11.26)

58.864

(11.26)

117.05

(11.26)

105.207

(11.26)

2.96

(11.26)

8.07

(11.26)

0.22

(11.26)

3.12

(11.26)

B 3.53

(7.01)

42.70

(7.01)

15.01

(7.01)

6.282

(7.01)

3.397

(7.01)

4.736

(7.01)

7.149

(7.01)

7.331

(7.01)

68.61

(7.01)

34.64

(7.01)

34.91

(7.01)

24.904

(7.01)

C 91.07

(8.65)

128.11

(8.65)

47.63

(8.65)

10.569

(8.65)

5.055

(8.65)

9.274

(8.65)

5.971

(8.65)

7.390

(8.65)

700.43

(8.65)

582.28

(8.65)

142.27

(8.65)

65.199

(8.65)

A*B 23.61

(7.01)

66.16

(7.01)

26.56

(7.01)

25.483

(7.01)

3.397

(7.01)

7.946

(7.01)

16.354

(7.01)

14.655

(7.01)

1.54

(7.01)

0.46

(7.01)

0.36

(7.01)

0.633

(7.01)

A*C 8.66

(8.65)

12.17

(8.65)

8.76

(8.65)

9.256

(8.65)

5.055

(8.65)

8.506

(8.65)

4.036

(8.65)

6.144

(8.65)

4.57

(8.65)

3.27

(8.65)

3.30

(8.65)

7.961

(8.65)

B*C 0.46

(6.03)

6.17

(6.03)

0.88

(6.03)

0.860

(6.03)

1.00

(6.03)

1.070

(6.03)

0.765

(6.03)

0.866

(6.03)

3.26

(6.03)

8.68

(6.03)

7.86

(6.03)

4.159

(6.03)

R2 .984 .993 .982 .982 .898 .951 .967 .966 .995 .994 .984 .973

Figures in parentheses indicate critical value

A—Fibre type; B—Blend ratio; and C—Yarn type

-101-

Table 5.2 − Tukey test result for yarn characteristics of ring, rotor and MJS yarns

Yarn type Yarn characteristics

Tenacity Breaking

extension

Work

of

rupture

Unevenness Imperfections Flexural

rigidity

Hairiness

Thick

places

Thin places/

Neps/ Total

1mm 2mm S3

Ring

Rotor s ns s ns ns

Not performed

because yarn

type does not

affect these

properties

significantly

s s s ns

MJS s s s ns ns s s s s

Rotor

Ring s ns s ns ns s s s ns

MJS ns s ns s s s s s s

MJS

Ring s s s ns ns s s s s

Rotor ns s ns s s s s s s

s—Significant at 99% confidence level; and ns—Non-significant at 99% confidence level.

- 102 -

Table 5.3 − Influence of blend ratio on tenacity of tencel-polyester and tencel-cotton

ring-, rotor- and MJS yarns

Tencel in

blend, %

Tenacity, cN/tex

Tencel: Polyester Tencel: Cotton

Ring yarn Rotor yarn MJS yarn Ring yarn Rotor yarn MJS yarn

0 35.4 23.0 27.3 18.9 14.7 10.1

25 29.9 20.0 23.4 20.5 15.0 12.1

50 26.7 18.2 21.5 20.7 15.7 13.5

75 25.4 17.6 18.8 21.0 15.9 15.6

100 23.4 16.3 17.5 23.4 16.3 17.5

Fig. 5.1 − Variation in tenacity of tencel-polyester and tencel-cotton blended ring-,

rotor- and MJS spun yarns

0

10

20

30

40

50

Ring Rotor MJS

0:100 TEN/PET 25:75 TEN/PET 50:50 TEN/PET 75:25 TEN/PET

100:0 TEN/PET 0:100 TEN/COT 25:75 TEN/COT 50:50 TEN/COT

75:25 TEN/COT 100:0 TEN/COT

Ten

acit

y,

cN/t

ex

Yarn type

- 103 -

Fig. 5.2 − Variation in tenacity with blend ratio of tencel blended ring-, rotor- and

MJS spun yarns [(a) Tencel-polyester, and (b) Tencel-cotton]

5.3.2 Breaking Extension

Table 5.4 presents the breaking extension data of tencel-polyester and tencel-

cotton ring, rotor and MJS spun yarns. From the ANOVA analysis (Table 3), it is

observed that all process variables and their interaction influence the breaking

extension significantly. However, the ring- and rotor-spun yarns behave differently

for tencel-polyester and tencel-cotton blends, though the difference is not statistically

significant. The rotor yarns are more extensible than the ring-spun yarns for cotton

and its blend with tencel. But for tencel-polyester mix, rotor yarns have lower

breaking extension than the equivalent ring-spun yarns because of more number of

wrapper fibres and belts formed with longer length manmade fibres, which, in turn,

reduce load sharing core fibres which break early during tensile test. This agree well

with the earlier finding of previous researchers [120-121] that advantage of rotor

spinning over ring spinning in term of breaking extension cannot be realized in

manmade fibres. Amongst all yarns, the MJS yarns have least breaking extension as

the wrapping characteristic of MJS yarn is most irregular which encourages early

failure (Fig. 5.3). With regard to blend ratio, the breaking extension shows distinct

trends for ring-, rotor- and MJS yarns. For tencel-polyester fibre-mix, the breaking

5

10

15

20

25

30

35

40

0 25 50 75 100

RING

ROTOR

MJS

0 25 50 75 100

RING

ROTOR

MJS

Ten

acit

y,

cN/t

ex

Tencel in blend, %

- 104 -

extension of all three yarn types decreases with increase in proportion of tencel fibre

in the mix (Fig. 5.4). In the case of tencel-cotton blends, an increase in tencel content

in the mix increases the breaking extension of ring and MJS yarns but lowers the

breaking extension of rotor-spun yarns. The breaking extension is mainly governed by

breaking extension values of blend constituents. Addition of more extendable fibre

increases breaking extension of the yarn. The lowering of breaking extension with

addition of tencel component in the case of tencel-cotton blended rotor yarn can be

ascribed to the incidence of lot of wrapper fibres as tencel being longer than cotton

and free from short fibres. The tencel-polyester yarns are more extensible than tencel-

cotton yarns for all experimental combinations.

Table 5.4 − Influence of blend ratio on breaking extension of tencel-polyester and

tencel-cotton ring-, rotor- and MJS yarns

Tencel in

blend, %

Breaking extension, %



0 13.08 12.58 9.46 6.05 7.80 2.75

25 11.08 10.16 8.07 6.35 7.51 4.39

50 9.64 8.45 6.98 6.25 6.85 4.76

75 8.30 6.92 6.29 6.34 6.76 5.09

100 7.22 6.31 5.25 7.22 6.31 5.25

- 105 -

Fig. 5.3 − Variation in breaking extension of tencel-polyester and tencel-cotton

blended ring-, rotor- and MJS spun yarns

Fig. 5.4 − Variation in breaking extension with blend ratio of tencel blended ring-,

rotor- and MJS spun yarns [(a) Tencel-polyester, and (b) Tencel-cotton]

0

4

8

12

16

20

Ring Rotor MJS




0

3

6

9

12

15

0 25 50 75 100

RING

ROTOR

MJS

0 25 50 75 100

RING

ROTOR

MJS

Bre

akin

g e

xte

nsi

on

, %

Yarn type

Bre

akin

g e

xte

nsi

on

, %

Tencel in blend, %

- 106 -

5.3.3 Work of Rupture

The relationship between work of rupture and processing factors for ring, rotor

and MJS yarns is shown in Table 5.5. In general, ring- spun yarns exhibit

considerably higher work of rupture than both rotor and MJS yarns (Fig. 5.5) and the

difference is statistically significant (Table 4). Amongst rotor- and MJS yarns, the

former have marginally higher work of rupture than the later. With regard to fibre

type, the work of rupture shows a similar trend as yarn tenacity, and tencel-polyester

yarns possess higher work of rupture than tencel-cotton yarns. The effect of blend

ratio on work of rupture is similar to that on yarn strength and breaking extension but

the effect is less marked in tencel-polyester yarns than in tencel-cotton yarns (Fig.

5.6).

Table 5.5 − Influence of blend ratio on work of rupture of tencel-polyester and tencel-

cotton ring-, rotor- and MJS yarns

Tencel in

blend, %

Work of rupture x 10-3

, g/den



0 262.6 164.2 146.1 64.8 65.0 15.7

25 187.8 115.1 107.2 73.7 63.8 30.0

50 145.8 87.3 84.9 73.2 60.9 36.5

75 119.3 68.8 67.1 75.4 60.8 45.0

100 95.8 58.4 51.9 95.8 58.4 51.9

- 107 -

Fig. 5.5 − Variation in work of rupture of tencel-polyester and tencel-cotton blended

ring-, rotor- and MJS spun yarns

Fig. 5.6 − Variation in work of rupture with blend ratio of tencel blended ring-, rotor-

and MJS spun yarns [(a) Tencel-polyester, and (b) Tencel-cotton]

0

70

140

210

280

350

Ring Rotor MJS




0

70

140

210

280

0 25 50 75 100

RING

ROTOR

MJS

0 25 50 75 100

RING

ROTOR

MJS

Work

of

ruptu

re x

10

-3, g/d

en

Yarn type

Work

of

ruptu

re x

10

-3, g/d

en

Tencel in blend, %

- 108 -

5.3.4 Mass Irregularity

The values of yarn irregularity (U%) for ring-, rotor- and MJS yarns spun from

tencel-polyester and tencel-cotton blends of varying blend compositions and twist

factors are given in Table 5.6. In single fibre yarns, cotton yarn is most uneven

followed by tencel and polyester yarn. The uster values (U%) of blended yarns lies

within the boundary set by its blend partners. For tencel polyester blended yarns, the

evenness values are practically same for all blend ratios irrespective of technology

used to produce them. There is a discerning trend of evenness to increase with

increased tencel content. Rotor-spun yarns are slightly more even than the equivalent

MJS yarns spun under identical processing conditions (Fig. 5.7). The higher evenness

of rotor-spun yarns is believed to results from back doubling of fibres and absence of

drafting irregularities associated with the ring- and MJS yarns. In the case of tencel-

cotton blended yarn, inclusion of cotton fibre in the fibre-mix makes the MJS yarn

more uneven than both ring- and rotor- spun yarns. Cotton, being much more variable

in length, leads to more irregular wrappings and hence irregular mass distribution.

The magnitude of the effect, however, depends on the cotton content in the fibre-mix.

Variation in blend composition has little effect on mass irregularity, which, however,

improves with the addition of tencel in tencel-cotton mix (Fig. 5.8). The impact of

polyester is along the expected lines, a higher polyester content result in better

evenness. Furthermore, the tencel-polyester yarns have better evenness than the

tencel-cotton yarns of all types regardless of the processing parameters used.

- 109 -

Table 5.6 − Influence of blend ratio on unevenness of tencel-polyester and tencel-


Tencel in

blend, %

Unevenness, U%



0 9.04 8.91 9.02 14.12 12.96 15.32

25 9.16 9.14 9.10 11.81 11.47 14.06

50 9.45 9.21 9.32 11.70 11.28 13.87

75 9.58 9.36 9.40 11.42 11.14 12.07

100 10.51 10.14 10.43 10.51 10.14 10.43

Fig. 5.7 − Variation in unevenness of tencel-polyester and tencel-cotton blended ring-,


0

4

8

12

16

20

Ring Rotor MJS




Unev

ennes

s, U

%

Yarn type

- 110 -

Fig. 5.8 − Variation in unevenness with blend ratio of tencel blended ring-, rotor- and


5.3.5 Imperfections

Table 5.7 shows the influence of process parameters on imperfection indices

.It is observed from the test results that imperfections follow a similar trend as that of

mass irregularity. In general, rotor-spun yarns exhibit lower frequency of

imperfections than the ring-and MJS yarns. Thin places are absent in all type of yarns

spun from tencel-polyester blends and rotor- spun tencel-cotton yarns. There are,

however, no distinct differences in imperfection level for three yarn types except the

thick places, where rotor yarns have considerably lower thick places as compare to

MJS yarns. Further, tencel-cotton yarns have noticeably more imperfections than the

tencel-polyester yarns due to high length variability of cotton fibre which generates

more drafting irregularity both in ring-and air-jet spinning (Fig. 5.9). Increasing tencel

content affects the imperfections of two sets of yarns to different degrees. While the

imperfection figures of tencel-polyester yarns invariably increase with increasing

tencel content, the trend is different for tencel-cotton yarns (Fig. 5.10). In this case,

yarn imperfections considerably reduce with increase in tencel content in the mix on

account of increased fibre length [51], and better control exercised on fibre movement

during drafting [78].

8

10

12

14

16

18

0 25 50 75 100

RING

ROTOR

MJS

0 25 50 75 100

RING

ROTOR

MJS

Unev

ennes

s, U

%

Tencel in blend, %

- 111 -

Table 5.7 − Influence of blend ratio on imperfection of tencel-polyester and tencel-


Fibre

type

Blend

ratio

Imperfections/km

Thin places/ km Thick places/ km Neps/ km Total/ km

Ring

yarn

Rotor

yarn

MJS

yarn

Ring

yarn

Rotor

yarn

MJS

yarn

Ring

yarn

Rotor

yarn

MJS

yarn

Ring

yarn

Rotor

yarn

MJS

yarn

Tencel:

Polyester

0:100 0 0 0 0 0 2 4 0 0 4 0 2

25:75 0 0 0 4 0 2 12 10 12 16 10 14

50:50 0 0 0 6 2 4 40 16 16 46 18 20

75:25 0 0 0 10 4 8 64 35 40 74 39 48

100:0 0 0 0 28 10 18 52 40 44 80 50 62

Tencel:

Cotton

0:100 24 0 40 100 80 240 356 154 360 480 234 640

25:75 10 0 20 56 42 140 252 134 240 318 176 400

50:50 4 0 13 48 30 100 184 120 190 236 150 303

75:25 2 0 6 40 20 84 108 84 114 150 104 204

100:0 0 0 0 28 10 18 52 40 56 80 50 74

- 112 -

Fig. 5.9 − Variation in imperfection of tencel-polyester and tencel-cotton blended


Fig. 5.10 − Variation in imperfection with blend ratio of tencel blended ring-, rotor-

and MJS spun yarns [(a) Tencel-polyester, and (b) Tencel-cotton]

0

300

600

900

1200

1500

Ring Rotor MJS




0

200

400

600

800

1000

1200

0 25 50 75 100

RING

ROTOR

MJS

0 25 50 75 100

RING

ROTOR

MJS

Imper

fect

ions/

km

Yarn type

Imper

fect

ions/

km

Tencel in blend, %

- 113 -

5.3.6 Flexural Rigidity

A comparison of the values of flexural rigidity in Table 5.8 and Fig. 5.11

reveals that MJS yarns possess significantly higher flexural rigidity than the ring- and

rotor- spun yarns. This seems to be caused by the clustering effect of core fibres due

to their parallel arrangement and winding by surface wrappers fibres, which, in turn,

restricts the freedom of movement of fibres during bending. Inclusion of tencel fibre

in the mix also results an increase in flexural rigidity of the three types of yarns (Fig.

5.12). The high modulus and lower bulk of tencel fibre resulting in the close packing

of fibres, which, in turn, impedes the freedom of fibre movement during bending and

hence higher rigidity. Further, no significant difference in rigidity is observed for

tencel-polyester and tencel-cotton yarns.

Table 5.8 − Influence of blend ratio on flexural rigidity of tencel-polyester and tencel-


Tencel in

blend, %

Flexural rigidity x 10-3

, g.cm2



0 2.87 3.56 6.38 2.69 3.10 6.51

25 3.23 4.43 7.51 3.60 3.98 9.02

50 3.36 4.88 8.56 4.42 4.57 9.52

75 4.55 5.18 9.59 4.73 5.08 9.82

100 5.04 5.29 10.25 5.04 5.29 10.25

- 114 -

Fig. 5.11 − Variation in flexural rigidity of tencel-polyester and tencel-cotton blended


Fig. 5.12 − Variation in flexural rigidity with blend ratio of tencel blended ring-,

rotor- and MJS spun yarns [(a) Tencel-polyester, and (b) Tencel-cotton]

0

3

6

9

12

15

Ring Rotor MJS




2

4

6

8

10

12

0 25 50 75 100

RING

ROTOR

MJS

0 25 50 75 100

RING

ROTOR

MJS

Yarn type

Fle

xura

l ri

gid

ity x

10

-3, g. cm

2

Fle

xu

ral

rigid

ity x

10

-3, g. cm

2

Tencel in blend, %

- 115 -

5.3.7 Hairiness

A cursory look at the hairiness results in Table 5.9 reveals that spinning

technology affects both short and long hairs irrespective of the fibre composition

used. The hairiness results are consistent with previous finding [122] that hairs (1-3

mm) are lowest for rotor yarn and highest for MJS yarns. Amongst ring-and rotor-

spun yarns, the former display more long hairs (Fig. 5.13) whereas according to

ANOVA analysis, the differences between long hairs of ring-and rotor-spun yarns are

non significant. As far as short hairs (1-2 mm) are concerned, the rotor-spun yarn has

the least hairiness followed by ring-and MJS yarns [123]. The absence of roller

drafting in rotor spinning might contributes to the lowest value of hairiness.

Furthermore, the spreading of fibres leading to incomplete binding of fibres within the

yarn body at yarn formation point is thought to generation of more hairs. The fibre

composition has no significant influence on yarn hairiness, though more short and

long hairs are observed for tencel-majority mix (Fig. 5.14) on account of high

modulus and higher rigidity of tencel fibre. Moreover, the hairiness values of tencel-

polyester yarns are not much different from the tencel-cotton yarns.

- 116 -

Table 5.9 − Influence of blend ratio on hairiness of tencel-polyester and tencel-cotton

ring-, rotor- and MJS yarns

Fibre

type

Blend

ratio

Hairs/10m

≥ 1mm ≥ 2mm ≥ S3

Ring

yarn

Rotor

yarn

MJS

yarn

Ring

yarn

Rotor

yarn

MJS

yarn

Ring

yarn

Rotor

yarn

MJS

yarn

Tencel:

Polyester

0:100 688 151 1242 45 38 164 11 10 40

25:75 787 161 1370 55 47 278 12 12 116

50:50 974 169 1481 80 66 302 17 15 120

75:25 1152 178 1781 129 72 332 31 29 140

100:0 1670 243 2033 278 76 431 96 43 152

Tencel:

Cotton

0:100 1076 252 1050 86 36 65 20 15 14

25:75 1152 279 1374 99 59 161 23 19 27

50:50 1059 272 1591 103 66 285 25 23 88

75:25 1281 252 1853 144 75 353 37 31 90

100:0 1670 243 2033 278 76 431 96 43 152

- 117 -

Fig. 5.13 − Variation in hairiness of tencel-polyester and tencel-cotton blended ring-,


Fig. 5.14 − Variation in hairiness with blend ratio of tencel blended ring-, rotor- and


0

500

1000

1500

2000

2500

Ring Rotor MJS




0

40

80

120

160

0 25 50 75 100

RING

ROTOR

MJS

0 25 50 75 100

RING

ROTOR

MJS

Hai

rs/1

0m

, S

3

Yarn type

Hai

rs/1

0m

, S

3

Tencel in blend, %

(a)

- 118 -

5.4 Conclusions

5.4.1 In general, the ring yarns made from tencel and its blend with polyester fibre

are stronger, more extensible and possess higher work of rupture than rotor- and MJS

yarns irrespective of fibre composition. However, for 100% cotton and tencel-cotton

mix, ring-spun yarns exhibit lower extensibility than rotor- spun yarns. In comparison

with rotor-spun yarns, MJS yarns display higher strength, less extensibility and lower

work of rupture, except for 100% cotton and tencel-cotton mix, where former

superseded the latter in respect of yarn tenacity. Moreover, tencel-polyester yarns are

noticeably stronger, more extensible and have higher work of rupture than tencel-

cotton yarns regardless of yarn type. Increasing polyester content improves all tensile

characteristics of tencel-polyester mix yarns. Addition of cotton in the tencel-cotton

mix, on the other hand, leads to a deterioration in tensile characteristics but improves

the breaking extension and work of rupture of rotor-spun yarns.

5.4.2 Both blend composition and spinning system have marked influence on

regularity characteristics such as evenness and thick places. Amongst ring-, rotor- and

MJS yarns, the rotor yarn is most regular, and there are marked differences between

the thick places in three types of yarns. However, an increase in proportion of tencel

fibre in the fibre-mix increases neps in tencel-polyester yarns but reduces in case of

tencel-cotton yarns. Invariably, all tencel-polyester yarns are better in terms of

regularity characteristics than the tencel-cotton mix yarns.

5.4.3 Under all experimental conditions, MJS yarn has the highest rigidity whereas

ring yarn the least. Blending of tencel fibre with polyester or cotton fibres

substantially increases the yarn rigidity, but the differences between rigidities of

tencel-polyester and tencel-cotton yarns are not significant.

5.4.4 Rotor and ring yarns have the lowest hairiness and MJS the highest. Rotor-

spun yarns apparently contain fewer short and long hairs than ring-spun yarns, which

further increases with addition of tencel fibre both with polyester and cotton fibres

significantly. However, the differences in both short and long hairs between tencel-

polyester and tencel-cotton yarns are insignificant.

chapter 5 physical characteristics of tencel-polyester and...

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