Silk Waste/Cotton Blended Yarns in Cotton Microspinning: Physical ...

RJTA Vol. 9 No. 4 Nov 2005

Silk Waste/Cotton Blended Yarns in Cotton Microspinning: Physical Properties and Fibre Arrangement of Blended Yarn

Chollakup, R.1,2, Sinoimeri, A.1, Osselin, J-F.1, Frydrych, R.3and Drean, J-Y.1

1 Laboratoire de Physique et Mécanique Textiles, Ecole Nationale Supérieure des Industries Textiles de Mulhouse, Université de Haute-Alsace, 11 rue Alfred Werner, 68093 MULHOUSE CEDEX, FRANCE,

2 Kasetsart Agricultural and Agro-Industrial Product Improvement Institute, Kasetsart University, BANGKOK 10900, THAILAND, [email protected]

3CIRAD-CA, Laboratoire de Technologie du Coton, TA70/16 34598 MONTPELLIER CEDEX 5, FRANCE.

ABSTRACT

The microspinning technology has generally been used for cotton in the case of small scale spinning test methods (50 gram fibres). One type of silk fibre waste -pierced cocoon- prepared previously as short silk fibre with cut length of 35 mm is blended with cotton fibre to obtain further data concerning two blending techniques in this microspinning, and to compare pure and blended yarns. The intimate (before carding and drawframe blending as well as the roll settings in the drawing system are being examined. The silk content was changed at 0/100, 25/75 and 50/50 ratio for a yarn count of 30 tex. The physical properties, the irregularity and the fibre arrangement as terms of the Index of Blending Irregularity and the Migration Indices of the blended yarns have been studied. In addition, the effects of the blending techniques as well as those of the silk content have been brought to the fore. Keywords: Microspinning, silk and cotton blended yarn

1. Introduction Blending processes in the last quarter of 20th Century aimed to provide the desired yarn properties to achieve the expected results with few modifications to original spinning machines resulting in wide differences in the characteristics of the constituent fibres and wide variations in nominal blend proportions (Kane et al, 2001). In the most widely used yarn manufacture systems, the cotton system can process cotton, man-made staple fibre and their blends with a mean fibre length of 15-50 mm. To develop the desirable characteristics of products made from different fibre blends, silk fibres, the queen of natural fibres with excellent elegance, lustre, fineness and strength, may be blended with cotton fibres in the cotton system to give comfort, strength and elegance in blended yarn. Silk waste from the reeling silk needs to be prepared into slivers and cut up into short lengths suitable for the cotton spinning system. The feasibility of spinning cotton and silk waste blends on the ring and rotor spinning system has

been already studied (Tsubouchi et al, 1993; Chaichalermvong, 1992; Matsumoto et al, 1991). However, these studies were carried out in the industrial spinning process (in industrial contexts) which needed a great amount of fibres. In the case of small scale spinning test methods, only microspinning can transform quantities as small as 50 gram of fibres. The technology of microspinning has generally been used to develop new cotton varieties on a small scales The yarn counts are of 20, 27 and 37 tex, suitable for weaving fabrics and for various kinds of yarn tests (Frydrych and Drean, 2000). Differently from the previous authors, Chattapadhyay et al (2001) used the improved CIRCOT microspinning techniques to spin wool/cotton blend yarns on a short staple spinning system. The objective of the present study is to obtain further data concerning the blending of Thai silk waste with cotton in the cotton microspinning system. The intimate -before carding- and drawframe blending as well as the roll settings in the drawing system are examined. The physical properties of the blended yarns have been studied, and the effects of the blending techniques as well

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as those of the silk content have been brought to the fore. Furthermore, some preliminary investigations of fibre arrangement in yarn cross section for both blending techniques are carried out. 2. Experimental 2.1 Materials Pierced cocoon fibres are the silk waste selected in this study to be blended with cotton fibre. The silk variety is Chul no. 4 (Bombyx mori), which is a Thai hybrid of Nang noi (native polyvoltine) and Chul no. 1 (foreign bivoltine parents) belonging to Chul Thai Silk Co., Thailand. It was firstly degummed and bleached, and then opened and carded before being cut into 35 mm lengths in an industrial silk spun plant of Shinano Kenshi (Thailand) Co., Ltd. The cotton used in this study is Dora 11, which was bred from Development Oriented Research or Agrasian Systems Project (DORAS), in collaboration with Centre de Coopération International en Recherche Agronomique pour le Développement (CIRAD), France and Kasetsart University, Thailand. 2.2 Fibre Preparation before Blending The silk was first manually opened, then it was processed using an industrial card, DK 760 Trützschler cotton card, in order to remove neps and impurities and to individualize the fibres. If only the minicard of microspinning system was used, the neps and impurity removal would not have been satisfactory. Previous observations and data show that anti-static softener is not necessary to be added before carding silk and cotton blends, due to cotton’s natural lubricating effect. For this reason, the silk fibres designated to be blended with cotton fibre before the minicard of the microspinning system, were carded in the industrial card, DK 760 Trützschler cotton card without any anti-static softener. The physical properties of these silk fibres are as follows: fineness of 156 mtex using Protectina microscope (Switzerland) – the standard method of ASTM-D 2130, mean length (ML) of 18.8 mm, upper half mean length (UHML) of 33.0 mm measured using Peyer’s Almeter AL 100 (Siegfried Peyer AG, Switzerland), bundle tenacity of 23.2 cN/tex, and elongation at peak of 14.1 % evaluated by the dynamometer MTS-20/M (Adamel Lhomargy,

France) - the standard method of ASTM-D 2524 (5 mm clamp length, 2.5 mm/min drawing speed, 2-3 mg sample weight). The silk slivers designated for the drawframe blending, were also prepared by the industrial card but with an anti-static softener which seems to be realistic under industrial considerations. The physical properties of this second set are different from the first one as follows: ML of 21.0 mm, UHML of 36.5 mm, bundle tenacity of 25.7 cN/tex and elongation at peak of 15.0 %, analysed using the same methods above. The cotton used in this study was also prepared in the same way as the silk fibre. It was opened manually and then carded by the industrial card to form slivers. Some of them were used in the drawframe blending. The rest were carded alone or mixed with the silk before the minicard as shown later. The physical properties of the cotton were measured by the High Volume Instruments (HVI 910, Zellweger Uster, Switzerland), and the standard test method of ASTM-D 4604. The IIC Shirley Fineness/Maturity Tester (FMT 3, Shirley Developments Ltd., England) was used for analysis of the fineness. Its physical properties are as follows: the fineness of 175 mtex, ML and UHML of 23.9 and 28.6 mm, bundle tenacity of 27.3 cN/tex, and elongation at peak of 5.4%. 2.3 Microspinning System A new methodology of cotton spinning investigation carried out on variable quantities of cotton ranging from 50 to 500 g has been developed by CIRAD-Programme Cotton (Frydrych, 2000). There are four main processes in the microspinning: the opening, carding, drawing and ring spinning processes. The opening is carried out in the minicard with smooth flats covering the cylinder (Fig. 1a). The fibres should first be manually opened and put on a feed plate of the minicard to form a lap with a surface mass of 850 g/m2. During this operation, the fibres are firstly disentangled and the heaviest impurities removed. The web of 6 g/m2 obtained after the doffer is rolled up on a outgoing cylinder which ensures a first mixture with a regular surface mass (280 g/m2) for an optimised further carding operation. The carding process provides the cleaning and the removal of a part of neps and short fibres, and the ultimate disentangling of

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fibres. This operation is also carried out in the minicard but with wire flats (Fig. 1b). The ingoing lap is divided n two parts in the cross

Fig. 1a. Opening at the minicard with smooth flats

1) Smooth flats 2) Wire flats 3) Cylinder 4) Doffer 5) Cylinder of 0.75 inch diameter. 6) Cylinder of 1.57 inch diameter 7) Calender roller 8) Doffer comb

Fig. 1b. Carding at the minicard with wire flats direction and then a doubling lap of 560 g/m2 is formed by superposing. The outgoing web of 5 g/m2 is also rolled up on the outgoing cylinder. The drawing process consists of drafting the carded lap between four pairs of roll cylinders under pressure (Fig. 2a). It is necessary to perform three drawing operations. The distances of each pair of roll cylinders – called the ratch- (Fig. 2b) depend on the UHML of the fibres in each drawing step as shown in Table 1. The total drafting ranges from 7 to 11.5. The first drawing process transforms the carded lap into a sliver.

Table 1. The distance roll settings in each drawing stage.

Roller The distance roll settings in sequence of drawing (mm) Drawing ratio First DF Second DF Third DF

front to 2nd UHML + 10 UHML + 5 Variable 2nd to 3rd UHML + 10 UHML + 5 Fix, 2.00

3rd to back UHML + 20 UHML + 15 Fix, 1.033 DF : Drawing frame

Fig. 2a Mini drawing frame with 3 drafting zones Fig. 2b Drawing with 3 drafting zones 1) The front roller 3) The 3rd roller 2) The 2nd roller 4) The back roller

F

B

3

2

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The number of drawing processes should be an odd number –3 in the actual microspinning system- as suggested by a number of experimental and theoretical works concerning fibre hooks. The ring spinning process consists of a sliver-to-yarn ring spinning frame, with two drafting zones, each one equipped with an apron, making it possible to achieve a very significant

drafting and therefore eliminating the roving process (Fig. 3). The back drafting ratio (no. 1 in Fig. 3a) is fixed at 6.5, whereas the front drafting one (no. 2 in Fig. 3a) ranges from 11 to 18, so a total drawing of 120 can be obtained. The twist is given to the yarn as in all ring spinning frames by the ratio of the spindle speed (rpm) to the delivery speed (m/min).

2.4 Cotton Yarn Spinning As explained above, the cotton was carded by an industrial card so it does not need any other carding operation in the minicard. The microspinning process of cotton begins at the first drawing frame. In the three drawing frames, the drafting ratio is fixed at 10.9 with a doubling of 10 slivers. The distance roll settings at the first drawing frame are 40, 40, 45 mm from the front to back. In the second and third drawing frames, the roll distances are set to 35, 35, 45 mm. After the third drawing frame the outgoing 3.4 ktex sliver is collected into 4 cans. After that, these slivers are turned into yarns of 30 tex. A spindle speed of 9,600 rpm in conjunction with a ring diameter of 44 mm, twist factor αNm of 110 and a traveller No. 2 (0.076 g) are used. 2.5 Drawframe Blending Technique Due to the differences in the silk and cotton sliver counts, the cotton slivers need to be equalized to the same count as the silk slivers by a pre-drawing process. Silk and cotton blending at a ratio of 50/50 is patterned as C/S/C/S/C/S/C/S/S/C to

ensure that the outer slivers are cotton in the first drawing process (Fig. 4a-b). The cotton sliver will protect silk fibre slippage during drafting. The different roll settings of the three drawing processes are shown in Table 2. In addition, the drafting ratio is maintained unchanged at 10.9, whilst the doubling is 10 for the first and the second drafting and 9 for the last one. In order not to disturb the fibre slippage and mixing, in the first and second drawing processes where the cotton and silk fibres still behave in packages, the roll settings are maintained unchanged - found to be optimum by some preliminary trials - whilst in the third drawing process, three different setting cases are considered. In the first case (Dr-A, i.e. drawframe blending case A), the distances are set to avoid the breaking of silk fibre, whilst in the second and the third cases (Dr-B, Dr-C), these distances are decreased progressively to reduce the floating of the cotton fibres in the fibre flow. Note that after the third drawing frame – case A, B and C- four cans of 2.5 ktex slivers are turned into 30 tex yarn in the sliver-to-yarn spinning frame with the same parameters as the cotton yarn.

Fig. 3a. Ring spinning frame with 4 bobbins 1) The back apron 3) Bobbin

2) The front apron

Fig. 3b. Back view of the ring spinning frame

1

2

3

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Fig. 4a. Input slivers in the first drawing at drawframe blending

Fig. 4b. Sliver output

2.6 Intimate Blending Technique Silk and cotton slivers, after carding in the industrial cotton card without anti-static softener, are first manually opened separately and then opened separately in the minicard with smooth flats. Blending of S/C 50/50 is proceeded by putting one silk lap between two cotton laps (C/S/C) in a sandwich-like fashion. After that, the blended material is reopened twice within the same machine until a uniform distributed fibre web is obtained. Then the blended material is carded in the mini-card machine with wire flats. To obtain appropriate a surface mass of the web

for the drawing machine, the carded web is rolled up into 15 turns of the collecting cylinder (no. 5 of Fig. 1b). This operation is repeated three times. The 3 webs of 20 ktex each (15 g, Fig. 5) are delivered to the first drawing frame separately. The different roll settings of the three drawing processes are shown in Table 3, the drafting ratio is maintained unchanged at 10.9. Two different settings in the first and second drawings are considered. In the second case (Int-B, i.e. intimate blending case B), the distances are lower, as compared to the first case

Table 2. The roll settings in the drawing process of the S/C-50/50 drawframe blending yarn .

Test Sequence of drawing Distance of roll setting (mm)

From front to middle to back

1. Dr-A 1st DF 50-50-50

2nd DF 45-45-50

3rd DF 45-45-45

2. Dr-B 1st DF 50-50-50

2nd DF 45-45-50

3rd DF 42-42-45

3. Dr-C 1st DF 50-50-50

2nd DF 45-45-50

3rd DF 38-38-45

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Cotton sliver


Fig. 5. The three laps of silk and cotton blend after the carding at the intimate blending

Table 3. The roll settings in the drawing process of the S/C-50/50 intimate blending yarn .

Test Sequence of drawing Distance of roller setting (mm) From front to back

1. Int-A 1st DF 50-50-50 2nd DF 45-45-50 3rd DF 38-38-45 2. Int-B 1st DF 40-40-45 2nd DF 38-38-45 3rd DF 38-38-45

(Int-A). However, in the third drawing process, the distances are the same for the two cases considered. It can be noted that the settings of the cases Int-A and Dr-C are the same and so some comparisons can be brought to the fore. The first drawframe passage transforms all carded webs into slivers in three cans. Later the slivers

are doubled ten-fold and then collected into 2 cans in the second drawframe passage. In the third one, 10 slivers are also doubled and collected into 8 cans of 1 ktex slivers. Then the slivers are doubled to spin 4 bobbins of 30 tex yarns (Fig. 6). The parameters of spinning are the same as for 100% cotton yarn spinning.

Fig. 6. Ring spinning frame at the intimate blending: double input slivers Silk and cotton are blended at the S/C ratio of 25/75 following the same procedures as for the S/C 50/50 intimate and drawframe blending. After analysing the results of S/C 50/50, the roll settings for the intimate and drawframe blending of S/C 25/75 are the same as those used for the cases Int-B and Dr-C respectively. Some other

trials concerning S/C 75/25 as well as pure silk have been carried out. The results were not satisfactory enough to be included in this paper. The cotton microspinning system seems not to be well adapted for pure and a majority silk blended fibres.

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2.7 Blended Bundle Fibre and Yarn Physical Properties

The fibre length distribution is also evaluated using Peyer Almeters-Al 100. The sliver cohesion is measured by the method ASTM-D2612 using the dynamometer MTS-20/M (drawing speed of 254 mm/min, clamp length for cotton sliver 128 mm, and for silk/cotton 50/50 blended sliver 138 mm). The yarn unevenness, the frequency of neps, of thin and thick places, as well as the hairiness are measured by the UT3 device, whereas for the tenacity and elongation, the Tensorapid instrument is used. The measures of S/C ratio – i.e. the nominal mass composition - are investigated chemically following the NF G 06-017 method. The data are statistically analysed at a 95% confidence level by One-Way Analysis of Variance - Completely Randomised Design (ANOVA-CRD), and by Multifactorial ANOVA Design and Bonferroni’s multiple comparison procedure. 2.8 Fibre Arrangement of Blended Yarn In order to determine fibre arrangement within the yarn cross section, the yarn is dyed in a small red acid and large blue direct dyes, which are preferentially colouring silk and cotton fibre. The dyed yarn with some 4-5 supporting rayon rovings is pulled through a hole of 1.25 mm in diameter on a stainless steel plate of 0.25 mm thickness . The tuft containing the specimen is pulled through the hole until it seems to be just firmly held and then it is cut flush with the surface of the plate with a razor blade. At least twenty-five good cross sections for each sample are analysed by an optic microscope. The yarn cross section is divided into two concentric zones, the core which is considered to be some 70% of the total surface area, and the external layer. This is carried out by eroding the total area from the periphery to the inner side by the mean of a quasi circular single element of 5 pixels (Osselin, 2001). This method provides more accurate results that what was used previously (Krucińska, 1988). The number of each fibre type is counted and tabulated as real quantitative composition. The Index of Blend Irregularity (IBI) is a normalized standard deviation which measures the degree of the longitudinal blend homogeneity where 0 means perfection blending and 1 means randomness blending. A greater value than 1 suggests a non random inhomogeneity in

blending. The Index of Blend Irregularity is calculated following the equation :

∑−

=pqTWpT

nIBI

i

ii2)(1

where Ti is the total number of fibres in a

given cross-section i, Wi is the total number of fibres of the

component w in that particular section i,

p is the average fraction of the component w for all sections,

q equals 1-p, n is the number of yarn cross sections examined.

Also, the Migration Indices of the two components has been calculated following the method suggested by Townend and Dewhirst (1964) with the difference that in the present paper the core represents 70% of the total area. Following the original definition of Migration Indices (Gupte et al, 1996; Townend and Dewhirst, 1964), M = 0 means equal frequency of component in the core and in the surface layer, implying no preferential radial migration of fibres. Equally, M = +1 indicates maximum migration of one component to the yarn core and M = -1 means the contrary. The Migration Indices of silk (MS) and cotton (MC) components are calculated as :

( )

( )ieei

eiS CSCS

SSM

+−

=

( )( )ieei

eiC CSCS

CCM

+−

=

where Si, Se, Ci, Ce are the proportions of silk (S) and cotton (C) fibres counted in the inner (core) and external zones. 3. Results and Disscussion 3.1 Blended Bundle Fibre and Yarn Physical

Properties In order to evaluate the effect of the different roll settings in the drawing process on the fibre length, the values of ML, UHML, and 5% Length by number (Ln) of fibres and the short fibre count by weight (%SFC-w) after the third drawing frame are compared as a function of the roll

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settings as shown in Fig. 7. The result is that for the drawframe (Fig. 7a) as well as for the intimate blending (Fig. 7b), there is no significant effect (p > 0.05) of different roll settings on fibre length. Following these results, the roll setting in the S/C 25/75 blended yarn production is chosen to be closer in order to prevent the floating fibres. The properties of the 30 tex S/C 50/50 blended yarns for our different roll settings are shown in Table 4. The yarns unevenness (CV%) as well as imperfections (thin places, thick places, and neps) of all drawframe blends do not seem to be significantly different. Nevertheless, the blended case no. Dr-C (with closer settings) seems to give better yarn properties. The same discussions may be applied to the S/C 50/50 intimate blending

results (Table 4). These yarns are not different significantly except for the hairiness. The blended yarn no. Int-B is less hairy than the Int-A. In the sliver-to-yarn ring spinning process, the sliver structure in terms of fibre crimp, hooks and alignment is the main factor affecting the yarn quality. The optimal settings (closer ratch without fibre damage) in the drawing process ensure the sliver structure quality. Following these considerations, it can be explained why the cases Dr-C and Int-B entail better yarns. To study the effect of blend proportions, the S/C 25/75 blended yarn is also spun using both drawframe and intimate blending. The physical properties of all S/C yarns are compared with those of the cotton yarn (Table 5). It can be

Fig. 7. The lengths and short fibre quantities of the blended fibre S/C 50/50 and cotton after the third drawing with different roll settings for a) the drawframe blending and b) the intimate blending

0 5

11223344

ML UHML 5% Ln %SFC -

Cotto Int- Int-

0 5

11223344

ML UHML 5% Ln %SFC -

Cotto Dr- Dr- Dr-

a)

b)

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noticed that for the drawframe blending, the yarn unevenness and imperfections generally increase with the silk content (up to 50%), whereas no effect on these parameters is observed for the case of intimate blending except for the thickness. Obviously, in the drawing frame and during the spinning of the drawframe blending, the different fibres still remain in small packages of pure components. This behaviour may be amplified by the presence of the silk softener. In the case of intimate blending, this phenomenon does not occur because silk and cotton fibres are intimately mixed during the carding process. This explanation seems to be corroborated by the sliver cohesion measurements (ASTM-D2612). For the third drawing frame slivers of pure cotton and intimate blending for the S/C 50/50 blended sliver, the cohesion is estimated to be 82 + 9 and 82 + 6 µN/tex respectively. It can be easily seen that these two values are not significantly different. The third drawing frame blend sliver has a cohesion of 135 + 12 µN/tex, very different of the two previous values. This inter-fibre cohesion may entitle drafting by fibre packages in drawing and spinning processes. Contrary to what was expected, the yarn hairiness for both blending types does not seem to be influenced by the silk contents. Considering the mechanical properties, the values of the yarn tenacity are not

significantly different for either drawframe or intimate blending for the different silk contents. However, the elongation is affected by the silk contents and this influence is not linear in the here-considered domain. For both drawframe and intimate blending, the elongation of S/C 25/75 yarn is lower than that of the pure cotton (at p > 0.05 for drawframe and p > 0.1 for intimate blending) whereas for the S/C 50/50 yarn, the elongation increases at the same level (p > 0.05) as for the cotton yarn. To compare the effect of silk contents and blending techniques as two separate factors on the physical properties of the yarn, a Multifactorial ANOVA Design was carried out as shown in Table 6. It is found that the increase in silk content does not affect the mechanical properties of the yarn, but it reduces the yarn regularity. As far as the blending techniques are concerned, the intimate blending provides a more regular yarn than the drawframe blending does. Furthermore, there is an interaction effect between silk contents and blending techniques on the yarn CV%. As shown in Table 5, the positive effect of the silk content on the yarn CV% (which is a negative one in terms of yarn quality) depends on the blending technique used, which is more accentuated in the drawframe blending.

Table 4. Physical properties of S/C 50/50 blended yarn for different drawframe roll settings and for different blending techniques.

Drawframe blending Intimate blending

Dr-A

32.7 tex

Dr-B

30.2 tex

Dr-C

31.0 tex

Int-A

32.7 tex

Int-B

30.7 tex

CV% of mass

Thin/km (-50%)

Thick/km (+50%)

Neps/km (+200%)

Hairiness

26.29 ns

378 ns

1373 ns

360 ns

7.20 ns

25.75 ns

370 ns

1463 ns

373 ns

7.17 ns

25.40 ns

323 ns

1245 ns

345 ns

7.12 ns

20.90 ns

113 ns

663 ns

153 ns

7.49 ns

20.00 ns

73 ns

783 ns

145 ns

7.15 ns

Tenacity, cN/tex

Elongation, %

12.27 ns

6.68 a

12.89 ns

6.40 b

13.07 ns

6.73 a

13.01 ns

6.61 ns

13.12 ns

6.77 ns

Different letters (a, b, c) in the same row at different drawframe roll settings means the results are significantly different at p < 0.05, ns means no significant difference. One-Way ANOVA is carried out for each blending technique separately.

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Table 5. Physical properties of S/C blended yarns for different silk contents and for different blending techniques.

Drawframe blending

Different percentage of silk Intimate blending

Different percentage of silk

0

32.6 tex

25

30.5 tex

50

28.9 tex

0

32.6 tex

25

30.1 tex

50

30.7 tex

Proportion of silk exact, %

0 27.73 58.98 0 24.03 50.07

CV% of mass

Thin/km (-50%)

Thick/km (+50%)

Neps/km (+200%)

Hairiness

19.26 a

75 a

643 a

145 a

7.22 ns

22.51 b

275 b

878 b

185 a

7.29 ns

25.40 c

323 b

1245 c

345 b

7.12 ns

19.26 ns

75 ns

643 a

145 ns

7.22 ns

18.90 ns

58 ns

545 a

148 ns

6.94 ns

20.00 ns

73 ns

783 b

145 ns

7.15 ns

Tenacity, cN/tex

Elongation, %

13.13 ns

6.52 ab

12.79 ns

6.25 b

13.07 ns

6.73 a

13.13 ns

6.52 ns

12.65 ns

6.29 ns

13.12 ns

6.77 ns

Different letters (a, b, c) in the same row at different silk percentage mean the results are significantly different at p < 0.05, ns means no significant difference. One-Way ANOVA is carried out for each blending technique separately.

Table 6. Two factorial ANOVA analysis on the yarn physical properties. Two factorial ANOVA

Silk content ,% (A) Blending techniques (B)

Physical properties

0 25 50 Dr. Int.

Interaction (A x B)

CV% of mass

Thin/km (-50%)

Thick/km (+50%)

Neps/km (+200%)

Hairiness

A

A

B

NS

A

NS

NS

C

B

B

B

B

NS

NS

A

A

A

NS

NS

S

NS

NS

NS

NS

Tenacity, cN/tex

Elongation, %

NS

NS

NS

NS

NS

NS

NS

NS

Different letters (A, B, C) in the same row at different factor levels mean that the results are significantly different at p < 0.05; NS means no significant difference and S means significant difference.

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Table 7. Index of blending irregularity and Migration Indices of S/C blended yarn at 50/50 for both blending.


Cotton Silk Cotton Silk

Nominal mass composition1, % 41.02 + 1.58 58.98 49.93 + 1.02 50.07

Real quantitative composition, %

- in the whole cross section

- in the yarn core (70%)

- in the external layer (30%)

44.4 + 5.2

42.9 + 6.6

48.0 + 7.3

55.6

57.1

52.0

45.4 + 5.4

44.5 + 6.9

47.5 + 8.9

54.6

55.5

52.6

IBI

- for the whole cross section

- for the yarn core

- for the external layer

1.30

1.41

0.95

1.30

1.41

0.95

1.48

1.62

1.31

1.48

1.62

1.31

M -0.10 0.10 -0.06 0.06

1 The chemical method NF G 06-017.

Drawframe blending

Intimate blending

Silk/Cotton at ratio of 25/75 Silk/Cotton at ratio of 50/50

Fig. 8. SEM of S/C blended yarn at ratio of S/C 25/75 and 50/50 at different blended stages

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Fig. 9. Photos of cross section of S/C blended yarn at ratio of S/C 50/50 at different blended stages

Fig. 8 shows some SEM photographs of 25/75 and 50/50 silk/cotton yarns produced with the drawframe or the intimate blending techniques. In order to evaluate the Index of Blend Irregularity (IBI) and the Migration Indices (M) of these yarns, as mentioned in the Material and Method part, the yarn cross sections have been photographed and studied. This study was carried out only for the 50/50 blending ratio –by weight- because it is easier to bring to the fore the migration tendencies where some quasi equal quantities of blended fibers are concerned. Fig. 9 shows two typical pictures of yarn cross section where the darkened zone is the yarn core with 70% of the total area, whereas Table 7 gives the results of the IBI, real quantitative composition and M Indices. 3.2 Fibre Arrangement of Blended Yarn The analysis of the real quantitative composition and the M indices show that in the drawframe blending, the silk fibres migrate slightly towards the core layer, positive values of M indices (see Table 7). Also, for the real quantitative composition, there is no significant difference between the whole cross section and the inner or external layer. However this significant difference between the yarn core and the external layer exists only for the drawframe blending. The comparison between IBI values does not show any difference between both blending techniques for the whole cross section and for the yarn core. Between the core and the external layer only in

the drawframe blending; there is a significant difference at p=0.10 but at p=0.05 the statistical difference disappears. The IBI values over 1 indicate non random inhomogeneity in blending. Only the external layer of the yarn produced by drawframe blending exhibits random distribution of blending fibres. 4. Conclusion The microspinning technique used generally for cotton provides very interesting data concerning the spinning feasibility of short fibres. In the present study, some silk and cotton blended yarn, at different blending ratio, have been produced and analysed. The results of different roll settings in the drawing system show that there is no significant change on the fibre length of blended slivers during the drafting operation and also on the blended yarn unevenness and the mechanical properties for both blending techniques. The unevenness and imperfections increase with the silk content until 50%, whereas no effect on these properties is observed for the case of intimate blending except for the thickness. Furthermore, both drawframe and intimate blending do not affect the tenacity of the yarn at different silk contents. Only S/C 50/50 yarn for both blending techniques has an elongation as high as the cotton yarn. Concerning the blending techniques, it has been found that intimate blending provides more yarn regularity than drawframe blending does.


○ = silk fibre ■ = cotton fibre

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The analysis of cross section fibre distribution shows that there is a very slight migration tendency of the silk fibres inwards. However the comparison between Index of Blending Irregularity values does not show any difference between both blending techniques for the whole cross section and for the yarn core. The present study illustrates the feasibility to develop silk and cotton blending in the industrial spinning.

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possibilities of spinning blended silk floss with cotton or polyester fibers, Master thesis, Mahidol University, Bangkok, Thailand.

[2] Chattopadhyay, S.K., Bhaskar, P., Chaphekar, A.K., Ahmed, M., Gupta, N.P. and Pokharna, A.K. (2001), ‘Spinning of cotton/wool blends on short staple spinning systems’, J. Tex. Asso., 61, 5, pp. 183-188.

[3] Coplan, M.J. and Klein, W.G. (1955), ‘A study of blended woolen structures, Part I: Statistics of the ideal random blended yarn’, Text. Res. J. 25, 9, pp. 743-755.

[4] Frydrych, R. (2000), Manuel de formation In Fascicule de Formation, CIRAD-CA, Montpellier, France, p. 67.

[5] Frydrych, R., and Drean, J-Y. (2000), ‘A new method usable by researchers and spinners for short staple fibre microspinning’, Proceedings of the

Beltwide Cotton Production Conference, Jan, 4-8, 2, pp. 1555-1556.

[6] Gupte, A.A., Bhattak, B.L., Chattopadhyay, S.K. and Venugopal, V. (1996), ‘Blend irregularity’, Indian. Tex. J., 106, 9, pp. 14-17.

[7] Kane, C.D., Mahajan, S.D. and Kadole, P.V. (2001), ‘Machinery options to spin blended yarns’, Indian Text. J., 111, 21-26.

[8] Krucińska, I. (1988), ‘Fiber blending irregularities in cross sections and on yarn surfaces in relation to yarn properties’, Tex. Res. J., 58, pp. 291-298.

[9] Matsumoto, Y., Tsuchiya, I., Toriumi, K. and Harakawa, K. (1991), ‘Irregularities of blended yarns in waste silk spinning system’, J. Seric. Sci. Jpn., 60, pp. 263-269.

[10] Osselin, J.F. (2001), Génération automatique d’amures de grand rapport algorithme génétique, PhD. thesis, Université de Haute-Alsace, Mulhouse, France.

[11] Townend, P.P. and Dewhirst, J. (1964), ‘Fibre migration of viscose rayon staple-fibre yarns processed on the Bradford worsted system’, J. Text. Inst., 55, 10, pp. 485-502.

[12] Tsubouchi, K., Imai, T., Akahane, T. and Obo, M. (1993), ‘Relationship between the physical properties of silk-cotton blend fabrics and the size of the cocoon filament’, Bull. Natl. Inst., Seric., Entomol. Sci., 9, 89-100 (in Japanese).

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Silk Waste/Cotton Blended Yarns in Cotton Microspinning: Physical ...

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