chapter 5 physical characteristics of tencel-polyester and...
TRANSCRIPT
- 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, %
Tencel: Polyester Tencel: Cotton
Ring yarn Rotor yarn MJS yarn Ring yarn Rotor yarn MJS yarn
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
0:100 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
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
Tencel: Polyester Tencel: Cotton
Ring yarn Rotor yarn MJS yarn Ring yarn Rotor yarn MJS yarn
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
0:100 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
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-
cotton ring-, rotor- and MJS yarns
Tencel in
blend, %
Unevenness, U%
Tencel: Polyester Tencel: Cotton
Ring yarn Rotor yarn MJS yarn Ring yarn Rotor yarn MJS yarn
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-,
rotor- and MJS spun yarns
0
4
8
12
16
20
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
Unev
ennes
s, U
%
Yarn type
- 110 -
Fig. 5.8 − Variation in unevenness with blend ratio of tencel blended ring-, rotor- and
MJS spun yarns [(a) Tencel-polyester, and (b) Tencel-cotton]
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-
cotton ring-, rotor- and MJS yarns
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
ring-, rotor- and MJS spun yarns
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
0:100 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
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-
cotton ring-, rotor- and MJS yarns
Tencel in
blend, %
Flexural rigidity x 10-3
, g.cm2
Tencel: Polyester Tencel: Cotton
Ring yarn Rotor yarn MJS yarn Ring yarn Rotor yarn MJS yarn
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
ring-, rotor- and MJS spun yarns
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
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
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-,
rotor- and MJS spun yarns
Fig. 5.14 − Variation in hairiness with blend ratio of tencel blended ring-, rotor- and
MJS spun yarns [(a) Tencel-polyester, and (b) Tencel-cotton]
0
500
1000
1500
2000
2500
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
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.