Fibers and Polymers 2013, Vol.14, No.1, 157-163
DOI 10.1007/s12221-013-0157-9
Comparative Study on the Effect of Blend Ratio on Tensile Properties of Ring and Rotor Cotton-Polyester Blended Yarns Using Concept of the Hybrid Effect A. R. Moghassem* and A. Fakhrali Department of Textile Engineering, Islamic Azad University, Qaemshahr Branch, Qaemshahr, Iran (Received January 5, 2012; Revised May 29, 2012; Accepted July 19, 2012) Abstract: Study on the characteristics of blended ring and rotor spun yarns is a topic of major interest to the researchers. The overall properties of these blended yarns are affected by the relative proportion, properties of the components and their interactions. The main focus of this work is on comparing and analyzing effects of blend ratio on tensile properties of the yarns produced in different spinning systems using concept of hybrid effects that has not received enough attention from researchers. Various blends of cotton-polyester ring and rotor spun yarns were prepared. Tensile properties of the samples were examined as well. Interactions between cotton and polyester fibers was evaluated through predicting strength and elongation at break of the yarns using simple rule of mixtures (ROM) and hybrid model. Experimental results showed that, the effect of different blend ratios on tensile properties of the samples is different. In comparison with 100 % cotton yarn, promotion in braking strength of the ring and rotor spun samples occurred after increasing fraction of the polyester fiber to 50 and 66.5 % respectively. The prominent finding of the present work is that the trend of change in tensile properties of different yarns versus blend ratio is predictable via hybrid model and migration behavior of the constituent fibers. Coefficients representing the intensity of the interaction and migration index of the fibers were calculated and all results were discussed based on these calculated factors. Keywords: Blended yarns, Ring spun yarn, Rotor spun yarn, Hybrid effect, Fiber migration, Rule of mixtures, Fibers interaction
regard, structural geometry, inter-fiber friction and fiber migration are three important influencing factors on the load-extension behavior of the yarns [2]. The interesting finding of these investigations is the effect caused by the interactions of the different fibers in the blended yarn [3]. This internal interaction is called hybrid effect. A positive or negative hybrid effect in hybrid composites is defined as a positive or negative deviation of a certain mechanical property from the rule of mixture behavior [7]. In general, if a material is a mixture of more than one constituent component, the overall properties of the blended system are related to the relative proportion and corresponding properties of each component. Also, if the mixture is not uniform, the distribution or local concentration of each component plays an important role in determining some aspects of the system’s behavior. Many properties of a material blended from more than one component can be calculated using the simple rule of mixture (ROM).
Introduction Blending different types of fibers is a widely practiced method to achieve good properties of the components and to increase variety of products that cannot be realized using one fiber type alone [1]. On the other hand, the aim of blending process is to incorporate the more desirable features of the constituent fibers. The gains obtained in certain features are, but, almost accompanied by the loss of or reduction in others [2]. Study on blended structures in textile industry has mostly focused on blended yarns specially cotton-polyester blend [1,3]. This blend couple the good strength properties of polyester with the good feel and absorption properties of cotton to produce fabrics which exhibit wrinkle resistance, while remaining soft and pleasing to the touch [4]. Properties of cotton-polyester blended yarns have been studied for the ring and rotor processes. In comparison with 100 % cotton yarn, CO/PET blends have higher breaking and abrasion strength, crease resistance and are more comfortable to wear, and display better easy-care properties. Also, in comparison with 100 % polyester, CO/PET blends have advantages such as less pilling, less static electrification, easier spinning, better evenness for sliver, roving and yarn [1]. In addition, for an equal linear density and twist, cotton yarns are more hairy than polyester yarns, while blended yarns are situated in an intermediate position [5]. In most of the researches, the emphasis is on practical parameters of yarns such as tensile properties [6]. In this
XS = X1 W1 + X2 W2
(1)
However, some properties such as overall strength and elongation at break which are influenced by the interactions of the different components in the system cannot be accurately predicted by the simple ROM. If there is a mixture of two different constituents, type 1 and type 2 in general, the system property Xs can be calculated by a generalized ROM. XS = X1 W1 + X2 W2 + IW1 W2
(2)
Where Xi and wi are the corresponding property and the fraction of the constituent i = 1 and 2 and I is a coefficient
*Corresponding author:
[email protected] 157
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f
f
representing the intensity of the interactions of two constituents. There are three cases based on the value of I: for I 0, the interactions of constituents will enhance the overall system property, I 0 represents a case where the interactions reduce the system property and I = 0 means that the interactions do not exist. One expression for I can be written as: I = X50% – 2 ( X1 + X2 ) = 4 [ X50% – 0.5 ( X1 + X2 ) ] = 4 [ X50% – ] = 4 ∆X
(3)
Where X50% is the actual system property Xs when W1 = W2 = 0.5 and = 0.5X1 + 0.5X2 is the arithmetic mean of the property for homogeneous constituent composed of X1 and X2 alone [3]. Hybrid effect is an issue that has been used by some researchers to model or to justify properties of the blended structures. For example, in the field of textile science, Marom et al. [7], Duckett et al. [2] and Pan et al. [8] used the concept of the hybrid effect to investigate properties of composite materials, CO/PET blended yarns and twisted blend fibrous structure, respectively. Barella et al. [5] studied diameter and hairiness of ring and rotor CO/PET blended yarns. They observed different trends in the properties of 100 % cotton, 100 % polyester and 50-50 % CO/PET ring and rotor spun yarns based on the blend ratio and spinning system. Baykal et al. [1] investigated tensile properties of CO/PET blended rotor spun yarns. They found that strength and elongation of the samples are related to the blend ratio, properties of each component and the interactions of the components themselves [1]. Pan et al. [3] evaluated mechanical properties of blended fibrous structures including blend of nylon 66 and polypropylene filament and blend of cotton yarn and polyester filament. Also, Aghasian et al. [9] investigated some properties of blended rotor-spun CO/PET yarns via hybrid model. In these studies, they found that, the simple model ROM is not able to follow the trend of the experimental data. On the other hand, there is an internal interaction between constituent components that affects overall properties of the yarns [3,9]. Despite knowing the influence of fibers interactions on yarn characteristics, lack of research works that employ differences in intensity of the interactions of the components to compare properties of the blended yarns produced in different spinning systems is observed. Therefore, this study makes an attempt to compare strength and elongation at break of the ring and rotor spun yarns containing different portion of cotton and polyester fibers with the help of the concept of hybrid effect. At first, it is shown that there are different amounts of internal interactions between constituent fibers in the structure of ring and rotor spun yarns. Then differences between strength and elongation at break of the samples are discussed based on the intensity of the fibers interactions and migration behavior.
Materials and Methods 14 samples were produced from same blended yarns at different blend ratios. These samples included 16.5:83.5, 33.5:66.5, 50.0:50.0, 66.5:33.5, 83.5:16.5 PET/CO as well as 100 % cotton and 100 % polyester in both ring and rotor spinning systems at the same production conditions. Cotton and polyester fibers were used as raw materials for the preparation of the samples. The average fiber length, micronaire of the cotton fiber and maturity index were 28.74 (mm), 4.5 and 0.80, respectively. Also, the average fiber length and fineness of the polyester fibers were 38 (mm) and 1.4 (dtex). For blending of fibers, the carding machine slivers (six slivers) with the same count of 0.11 (Ne) were blended in the draw frame No.1. To produce yarn samples with above-mentioned blend ratios, numbers of polyester slivers (in draw frame No.1) were changed from 0 for pure cotton yarn to 6 for pure polyester yarn with step of one in both ring and rotor spinning systems. Then, six of the prepared slivers with count of 0.16 (Ne) were furnished as second draw frame sliver with linear density of 0.16 (Ne). All the samples from the draw frame were used to produce 20 (Ne) blended yarns. Seven samples were spun on an Elitex rotor spinning machine with 820 (tpm). The opening roller was set to work at the speed of 7500 (rpm). The 35 (mm) diameter rotor worked at the speed of 80000 (rpm). Other samples were produced on a ring spinning machine with 800 (tpm) at a speed of 12.5 (m/min). The spindle speed was 9600 (t·min-1). Load-elongation characteristics of the yarns were examined on the Uster Tesorapid3. A test specimen of 500 mm was elongated at an extension rate of 500 mm·min-1. Table 1 shows the results of the experiment.
Results and Discussion A one-way ANOVA test was conducted to compare average values of ring and rotor spun yarns quality parameters at 5 % significance level separately. Statistical analysis confirmed the effect of blending ratios on yarn properties. Experimental results in Table 1 show that for all rotor spun yarns, elongation at break is more than that of ring spun yarns. Besides, all the ring spun samples were stronger than rotor spun yarns. Elongation at break of both ring and rotor spun samples increases as the percentage of polyester fiber in fiber blend increases. However, the increase in elongation at break when proportion of polyester fiber is low (from 0 % to 33.55) was not considerable. Minimum and maximum values were respectively observed in the samples containing 0 % and 100 % polyester fiber for both spinning systems. Despite the existence of a rather direct relationship between elongation at break and fraction of the polyester fiber, breaking strength did not follow any certain pattern. For the samples produced in ring spinning system, breaking strength of 100 % cotton yarn was more than that of the samples
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Table 1. Strength and elongation at break of the rotor and ring spun yarns in experimental condition Ring spun yarn PET/CO (%) B.S CV% E.B A1 0.0/100 13.20 14.10 16.90 A2 16.5/83.5 11.25 9.42 19.40 A3 33.5/66.5 9.08 13.66 20.30 A4 50.0/50.0 11.66 17.49 30.10 A5 66.5/33.5 15.91 13.23 55.30 A6 83.5/16.5 18.21 9.22 67.40 A7 100/0.0 27.14 17.13 80.30 B.S: breaking strength (cN/tex) E.B: elongation at break (mm). Samples
including 16.5, 33.5 and 50 % of polyester fiber. Increase in proportion of polyester fiber from 33.5 to 50 % led to an increase in breaking strength of the yarn which is, however, not equal or more than the breaking strength of the 100 % cotton yarn. On the other hand, a descending pattern was observed in breaking strength of the yarns when proportion of the polyester fiber in fibers blend was less than 50 %. In addition, for the rotor spun samples, breaking strength of the 100 % cotton yarn was more than that of the samples containing polyester fiber less than 66.5 % of the blend. A slight increase was observed when the fraction of the polyester fiber increased from 50 % to 66.5 %. However, experimental results indicated a descending pattern when the proportion of polyester fiber was less than 66.5 %. Three main findings are derived from the experimental results obtained. Despite employing similar processing conditions and raw materials, the effect of fiber blending on tensile properties, especially on breaking strength, was not the same for the samples produced in different spinning systems. Increase in elongation at break of the rotor spun yarns caused by the increase in the proportion of polyester fiber was obviously more than that of the ring spun samples. Besides, it was understood that employing inappropriate blend of polyester and cotton fibers in spinning mill cannot promote breaking strength of the ring and rotor spun yarns. Obtained results are certainly attributed to the internal interactions of the cotton and polyester fibers in the yarns structure. In the case of cotton-polyester blended yarns, there are three affective frictional forces: cotton-to-cotton, polyesterto-polyester and cotton-to-polyester [2]. In cotton-polyester blended yarn, the low coefficient of friction between the cotton and polyester fibers can reduce the properties such as tenacity and breaking elongation when the cotton content in the blend is low. Also, if the elastic modulus ratio of two fibers in blended yarn increases, the hybrid effect will be more apparent. When this ratio is near to zero, it means that the second fiber is bearing the force alone and the tenacity of yarn will be reduced. When this ratio increases, the share of both fibers in bearing the load will increase [9]. This hypothesis has been assessed via the concept of the
CV% 22.54 7.37 18.72 15.38 16.55 6.45 14.12
Samples A8 A9 A10 A11 A12 A13 A14
B.S 10.11 8.93 8.69 8.26 8.62 12.88 14.53
Rotor spun yarn CV% E.B 11.27 24.50 9.74 26.80 7.48 28.50 11.50 44.10 13.57 60.30 13.35 73.70 14.86 88.30
CV% 14.57 8.58 12.63 14.08 13.17 8.91 3.54
hybrid effect. At first, strength and elongation at break of the ring and rotor blended yarns were predicted using the simple rule of mixtures (ROM) and equation (1). Study showed that, the results of the calculations do not follow the trend of experimental data obtained for blended yarns. This confirms internal interactions between constituent fibers and their influence on tensile properties of the blended yarns. In the next step, experimental results were predicted using generalized form of the ROM (equation (2)). In doing so, coefficients representing intensity of the interaction between constituent fibers (I) and (∆X) were calculated using equation (3). All the results have been shown in Table 2. Also, experimental and predicted values for strength and elongation at break of the samples have been illustrated in Figure 1(a)-(d). The calculated values of the coefficients I and ∆X was found to be negative for both ring and rotor spun yarn samples and different (Table 2) from each other. A negative value means that the interactions of two fibers cause a reduction in the tensile properties of the yarns. The effect of the negative hybrid effect and interaction can be seen in Figure 1. All the experimental data and predicted values by hybrid model are less than values predicted via simple ROM. The effect of fibers interactions on the breaking strength of the blended spun yarns is more sensible in comparison with elongation at break as it is perceptible in Figure 1. The gap between ROM values and experimental data is more when breaking strength is plotted versus PET ratio. The difference between coefficients I and ∆X is a reason for different trends in mechanical properties of the yarns when content of polyester fibers changes. Obtained values for I and ∆X are higher in the case of ring spun yarns. This means more internal interactions between polyester and cotton fibers in the structure of ring blended yarns. Less value of the coefficients I and ∆X in rotor spun yarns mean that fibers cooperation in bearing tensile force is appeared later in the mentioned yarns than in the ring blended yarns. On the other hand, effects of fibers slippage, difference in fibers coefficient of friction and low value of the elastic
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Table 2. Values of coefficients representing intensity of the interactions and predicted properties of the yarns Samples A1 A2 A3 A4 A5 A6 A7
I -34.04 -34.04 -34.04 -34.04 -34.04 -34.04 -34.04
20.3 20.3 20.3 20.3 20.3 20.3 20.3
A1 A2 A3 A4 A5 A6 A7
-74 -74 -74 -74 -74 -74 -74
48.6 48.6 48.6 48.6 48.6 48.6 48.6
A8 A9 A10 A11 A12 A13 A14
-16.24 -16.24 -16.24 -16.24 -16.24 -16.24 -16.24
12.32 12.32 12.32 12.32 12.32 12.32 12.32
A8 -49.20 56.4 A9 -49.20 56.4 A10 -49.20 56.4 A11 -49.20 56.4 A12 -49.20 56.4 A13 -49.20 56.4 A14 -49.20 56.4 E.V: experimental value S.ROM: predicted by value-predicted value by generalized ROM.
Ring spun yarn Breaking strength (cN/tex) ∆X E.V S.ROM G.ROM (E.V-G.ROM) -8.51 13.20 13.20 13.20 -8.51 11.25 15.50 10.81 -0.44 (-3.91%) -8.51 9.08 17.87 10.29 1.21 (13.32%) -8.51 11.66 20.17 11.66 -8.51 15.91 22.47 14.89 -1.02 (-6.41%) -8.51 18.21 24.84 20.15 1.94 (10.65%) -8.51 27.14 27.14 27.14 Elongation at break (mm) -18.50 16.90 16.90 16.90 -18.50 19.40 27.36 17.17 -2.33 (-12.01%) -18.50 20.30 38.14 21.66 1.36 (6.69%) -18.50 30.10 48.60 30.10 -18.50 55.30 59.06 42.58 -12.72 (-23.00%) -18.50 67.40 69.84 59.65 -7.75 (11.49%) -18.50 80.30 80.30 80.30 Rotor spun yarns Breaking strength (cN/tex) -4.06 10.11 10.11 10.11 -4.06 8.93 10.84 8.60 -0.33 (-3.69 %) -4.06 8.69 11.59 7.97 -0.72 (8.28 %) -4.06 8.26 12.32 8.26 -4.06 8.62 13.05 9.43 0.81 (9.39 %) -4.06 12.88 13.80 11.56 -1.32 (-10.24 %) -4.06 14.53 14.53 14.53 Elongation at break (mm) -12.29 24.50 24.50 24.50 -12.29 26.80 35.03 28.25 1.45 (5.41 %) -12.29 28.50 45.87 34.91 6.41 (22.49 %) -12.29 44.10 56.40 44.10 -12.29 60.30 66.93 55.97 -4.33 (-7.18 %) -12.29 73.70 77.77 70.99 -2.71 (-3.67 %) -12.29 88.30 88.30 88.30 simple ROM model G.ROM: predicted by generalized ROM, E.V-G.ROM: experimental
modulus ratio is surmounted faster in the structure of ring spun yarns. This preference is attributed to the yarn structure. In addition to the interaction between the fibers, in nonhomogenous mixture, distribution of each component has an important effect on the system parameters [9]. Number of fibers in the yarn cross section affects the mechanical properties of the yarn. When the blended yarn is subjected to a force, the fiber of both components will be elongated as the force increases, until the weaker fibers break and transfer the entire load to other fibers. If there are enough fibers with
higher elongation in the yarn cross section, the blended yarn will not break [1]. To investigate fibers distribution, several cross sections were taken from each yarn type using Microtome method and the image of the cross section was captured using MOTIC (software to observe the yarn cross section by connecting a microscope to computer). All the yarns were dyed using direct dye (VSF direct black) using the prevalent method. Migration index was calculated based on the method proposed by Hamilton [10]. If FMA is defined as actual
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Figure 1. Ring and rotor blended yarn properties versus blend ratio (PET %); (a) breaking strength of the ring spun yarns, (b) elongation at break of the ring spun yarns and (c) breaking strength of the rotor spun yarns d: elongation at break of the rotor spun yarns.
f
distribution, FMu as uniform distribution, FMi as maximum inward migration and FMo as maximum outward migration, the migration index (M) is given by equation (4). If inward migration occurs, FMa FMu, FMi could be used instead of FMo. FMa – FMu M = ------------------------- × 100 FMu – FMi
(4)
The results of fiber counting and calculated migration index are shown in Table 3-5. A migration index of zero represents an even distribution of the component between core and surface. A migration index of 100 % may represent complete separation of the component from the other fibers. The migration index is positive or negative based on the fact that whether the preferential migration has been outward or inward [9,10]. Non-uniform distribution of the fibers in the yarn cross section is a reason for the occurance of localized placement of the cotton and polyester fibers at the surface and core layers of the yarn. As it can be seen in Table 3 and 4, in the ring blended yarn samples containing lower proportion of the polyester fiber (samples A2, A3), number of polyester fiber concentrated at the center (layers 1, 2) of the yarn is not
comparable with that of the cotton fiber. Negative values of the migration index for the cotton fiber confirm the abovementioned finding. Table 5 shows that the migration indexes of cotton fiber are respectively −12.09 and −4.14 in the ring spun samples containing 16.5 and 33.5 % of polyester fiber. Therefore, the migration of the cotton fiber toward the yarn center decreases the yarn’s breaking strength. For the other ring spun yarn samples in which fraction of the polyester fiber is more than the proportion of cotton fiber (samples A5, A6) number of polyester fibers at the center and even at the surface of the yarn is more than that of cotton fiber. These samples have a migration index of +44.25 and +14.61 for cotton fibers. These values indicate the migration of cotton fiber toward the yarn surface. But, in the case of the ring sample containing equal amount of cotton and polyester fibers (50-50 %), number of polyester fibers at the center of the yarn (layers 1, 2) is more than number of cotton fibers (the difference is considerable) and for the other layers a reverse trend is observed. Thus, breaking strength of the sample is situated in an intermediate position and is more than the braking strength of the samples A2, A3. In the rotor blended yarn, samples with lower content of the polyester fiber (samples A9, A10), the number of cotton
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Table 3. Fiber frequency distribution in blended ring spun yarns Zone no. Fiber type Cotton fiber Polyester fiber Zone totals
1 (core)
2
3
8 1 9
22 1 23
42 7 49
4
5 (surface)
Fiber totals
42 10 52
32 6 38
146 25 171
21 15 36
18 15 33
69 54 123
16 13 29
12 11 23
42 55 97
20 24 44
18 19 37
51 116 167
2 31 33
5 11 16
15 104 119
4
5 (surface)
Fiber totals
26 1 27
24 7 31
100 11 111
19 9 28
10 7 17
66 33 99
15 19 34
18 11 29
65 62 127
23 29 52
16 10 26
77 91 168
4 46 50
5 25 30
15 148 163
Yarn sample A2
Yarn sample A3 Cotton fiber Polyester fiber Zone totals
4 2 6
12 8 20
14 14 28
Cotton fiber Polyester fiber Zone totals
0 6 6
3 17 20
11 8 19
Cotton fiber Polyester fiber Zone totals
1 6 7
3 28 31
9 39 48
Yarn sample A4
Yarn sample A5
Yarn sample A6 Cotton fiber Polyester fiber Zone totals
1 9 10
3 18 21
4 35 39
Table 4. Fiber frequency distribution in blended rotor spun yarns Zone no. Fiber type Cotton fiber Polyester fiber Zone totals
1 (core)
2
3
5 0 5
16 1 17
29 2 31
Cotton fiber Polyester fiber Zone totals
4 1 5
15 9 24
18 7 25
Yarn sample A9
Yarn sample A10
Yarn sample A11 Cotton fiber Polyester fiber Zone totals
4 1 5
14 8 22
14 23 37
Cotton fiber Polyester fiber Zone totals
4 6 10
14 20 34
20 26 46
Cotton fiber Polyester fiber Zone totals
0 10 10
4 28 32
2 39 41
Yarn sample A12
Yarn sample A13
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Table 5. The calculated migration index for each yarn sample Ring spun yarns Yarn code Cotton fiber Polyester fiber
A2 -12.09 +12.09
A3 -4.41 +4.41
A4 +39.54 -39.54 Rotor spun yarn Yarn code A9 A10 A11 Cotton fiber -20.30 -6.45 -2.74 Polyester fiber +20.30 +6.45 +2.74 Sign (-) means inward migration of the fiber sign (+) means outward migration of the fiber.
fibers positioned at the center (layers 1, 2) of the yarn is pretty much more than the number of polyester fibers. Negative values of the migration index for the cotton fiber in samples A9, A10 confirms the above-mentioned finding. Table 5 shows that migration indexes of cotton fiber are respectively 20.30 and −6.45 for the rotor spun samples containing 16.5 and 33.5 % of polyester fiber. Therefore, the migration of the cotton fiber toward the yarn center decreases the yarn breaking strength. In the case of rotor samples containing equal amount of constituents, the number of cotton fibers at the center of the yarn (layers 1, 2) is more than the number of polyester fiber. But total amount of two fibers is equal in the yarn cross section. Cotton fiber has a migration index of −2.74 in this yarn that insinuates an inward migration. Also, yarn sample A12 (PET/CO ratio of 66.5/33.5) has a number of cotton fibers slightly more than polyester in the first layer. However, the number of polyester fiber in layers 2, 3, is more than that of cotton fiber. Therefore, cotton fiber has a positive migration index of +12.03 in this yarn. Since inward migration behavior of polyester fiber cannot dictate tensile properties of the yarn, therefore braking strengths of these two samples are not different from sample A10. For the other yarn in which fraction of the polyester fiber is 83.5 %, the number of polyester fibers at the center and even at the surface of the yarn is more than that of cotton fiber. This sample has a migration index of +12.79 for cotton fibers that ensures increase in breaking strength of the yarn.
Conclusion Five samples of the yarns including different blend ratios as well as 100 % cotton and 100 % polyester yarns were produced separately in ring and rotor spinning systems. Tensile properties of the samples were examined. Experimental results show different values for the samples prepared in different spinning system. Strength and elongation at break of the ring samples were respectively more and less than that of for the rotor spun yarns. Elongation at break of the samples increases by increase in the proportion of polyester
A5 +44.25 -44.25
A6 +14.61 -14.61
A12 +12.03 -12.03
A13 +12.79 -12.79
fiber in blend but promotion was not considerable when the percentage of polyester fiber was less than 33.5 %. In the case of breaking strength, a different trend was observed. In the ring and rotor blended yarns, breaking strength is less than that of the 100 % cotton yarn when the proportion of the polyester fiber is lower than 50 % and 66.5 %, respectively. More increase in polyester content enhances the tenacity of samples. Emphasis of the present work was on the difference in the effect of blend ratio on breaking strength of ring and rotor blended yarns via hybrid effects and migration behavior of the constituent. As the first reason, obtained values for the intensity of the interactions (I) are more in the case of ring spun yarns. This means that in rotor spun yarns, fibers’ cooperation in bearing the tensile force is appeared later than in the ring blended yarns. Secondly, a negative migration index was calculated for cotton fiber in ring blended spun yarns when proportion of polyester fiber was less than 50 %. But, change in the sign of migration index appeared when the content of polyester in the case of rotor spun blended yarns was less than 66.5 %. A negative migration index means that the weaker fiber has been migrated inward.
References 1. P. D. Baykal, O. Babaarslan, and R. Erol, Fiber. Text. East. Eur., 14, 18 (2006). 2. K. E. Duckett, B. C. Goswami, and H. H. Ramey, Text. Res. J., 49, 262 (1979). 3. N. Pan and K. Chen, Text. Res. J., 70, 262 (2000). 4. H. El-Behery and D. H. Batavia, Text. Res. J., 41, 812 (1971). 5. A. Barella and A. Manich, Text. Res. J., 54, 840 (1984). 6. K. P. R. Pillay, N. Viswanathan, and M. S. Parthasarathy, Text. Res. J., 45, 366 (1975). 7. G. Marom, S. Fischer, F. R. Tuler, and H. D. Wagner, J. Mater. Sci., 13, 1419 (1978). 8. N. Pan and R. Postle, J. Tex. Inst., 86, 559 (1995). 9. S. Aghasian, A. A. Gharehaghaji, M. Ghane, and A. Parsian, J. Tex. Inst., 99, 459 (2008). 10. J. B. Hamilton, J. Tex. Inst., 49, 411 (1958).
