Analyzing the effect of the elastane-containing dual-core weft yarn density on the denim fabric performance properties

Transcription

1 The Journal of The Textile Institute ISSN: (Print) (Online) Journal homepage: Analyzing the effect of the elastane-containing dual-core weft yarn density on the denim fabric performance properties Osman Gökhan Ertaş, Belkıs Zervent Ünal & Nihat Çelik To cite this article: Osman Gökhan Ertaş, Belkıs Zervent Ünal & Nihat Çelik (2016) Analyzing the effect of the elastane-containing dual-core weft yarn density on the denim fabric performance properties, The Journal of The Textile Institute, 107:1, , DOI: / To link to this article: Published online: 04 Mar Submit your article to this journal Article views: 76 View related articles View Crossmark data Full Terms & Conditions of access and use can be found at Download by: [Cukurova Universitesi] Date: 27 January 2016, At: 04:08

2 The Journal of The Textile Institute, 2016 Vol. 107, No. 1, , Analyzing the effect of the elastane-containing dual-core weft yarn density on the denim fabric performance properties Osman Gökhan Ertaş a, Belkıs Zervent Ünal b * and Nihat Çelik b a Gap Güneydoğu Industry and Trade Inc., Malatya, Turkey; b Textile Engineering Department, Çukurova University, Adana, Turkey (Received 12 September 2014; accepted 16 January 2015) Denim fabrics form today s mostly utilized fabric type. As is the case with the other textile products, there are many factors affecting the properties and the performance of the denim products. Within the scope of this study, we have evaluated the effect of the density changes in the use of the dual-core threads used in an ever-increasing fashion in the textile industry in weft have on the fabric properties. We have analyzed the extent to which the weight, size, elasticity, tensile strength, and cost properties of the denim fabrics woven with the dual-core weft thread in various densities are affected by the changes in the number of dual-core weft threads per unit length. In conclusion, we have come to such striking remarks as that the construction has a much more impact on the fabric width and thus on the unit weight than the elasticity ratio, and that density changes in the elastane-containing threads cause serious differences on the fabric s color values. Keywords: denim fabrics; dual-core weft thread; weft density; performance properties Introduction What differentiates the denim fabric from the other fabrics is that its warp is dyed. Other parameters, except for this one, can coincide with all the other woven fabrics. Especially the gabardine fabric represents exactly the same of the denim fabric but in non-dyed warp version. Today the denim fabrics are categorized under two groups as men s clothing and women s clothing; the fabrics preferred in women s clothing generally have a weft-resembling elasticity (stretch, super stretch), and those utilized in men s clothing are rigid (non-elastic) and comfort (low elasticity). The common construction used in the denim weaves is Twill 3/1Z, 3/1S, 2/1Z, and satin. Fabrics are manufactured mostly within the weights of 4-16 Oz/yd². Warp densities might vary between 10 and 100 thread/ cm (mostly 25 and 35 thread/cm), and the weft densities might vary between 10 and 50 thread/cm (mostly 16 and 24 thread/cm). Warp density and warp thread count are usually higher compared to the weft; cotton being in the first place, such materials as viscose, tensile, etc. could be used in the warp (the reason why there is not a variety of raw materials is that the warp dyeing process can be applied to only cellulosic fibers). Weft compositions are various; cotton being in the first place again, such materials as polyester, elastane, linen, viscose, tensile, etc. and their mixtures could be utilized. In the finishing procedures following the weave, different levels of caustification, softening, desizing, resin, fixing, coating, etc. processes are applied. With the stretch fabrics, the threads used in the weft have the property to give elasticity to the fabric. These threads are manufactured by using elastane (lycra, creora etc.), PBT, and T400. T400 and PBT have low elasticity values, and are used on their own whereas the thread made out of elastane that could elongate up to 4 6 times compared to their own length should have definitely been manufactured with the core-spun technique, or twisted with other threads, or produced with intermingling process. The core-spun thread is generally manufactured by placing elastane to the center while thread is being produced out of cotton (other staple fibers could be used as well). In the case of the Dual-core thread used in this study, two core threads are fed into the center. While the Dual-core thread is manufactured through the ring-spinning machine, previously combined two threads could simultaneously be fed into the center together, or the core threads could separately be fed into the center. Core-spun threads with threads in centers could also be manufactured. As a result of the literature search carried out regarding the impact of the dual-core thread use and the weft density on the fabric performance properties, we have found out several publications about the core-spun threads, and summarized some of the mentioned publications below. However, we have not observed any publications about the fabrics manufactured out of the dual-core threads. Therefore, the findings of our study were compared with the results of the studies about *Corresponding author. belzer@cu.edu.tr 2015 The Textile Institute

3 The Journal of The Textile Institute 117 core-spun yarns. In a study, the effects of elastane dtex, elastan pre-draft, and other fabric construction parameters (weft density, reed number etc.) on elasticity and growth properties of denim fabric have been examined by Çataloğlu. The increase on weft density decreases the elasticity and growth (Çataloğlu, 2007). In the study performed by Özdil, performance characteristics of five different denim fabrics containing various percentages of elastane were compared. After that, mechanical properties such as tensile and tearing strength, bending rigidity, stretching (elongation, maximum elongation, permanent elongation, and elastic recovery) and bagging characteristics of the fabrics were tested. The outcomes reveal that as the elastane content in denim fabrics increase; the stretching, the maximum stretching and the elastic recovery percentages also increase, whereas the permanent stretching percentages decrease. Results of this study indicate that an increase in the elastane ratio of the fabric positively affects the general comfort properties (Özdil, 2008). Meriç and Gürarda studied the mechanical properties of fabrics containing elastane and concluded that high elastane content makes the yarn flexible; however, the yarn that will be used with elastane should allow the fabric to move freely and shouldn t cause any deformation in the fabric. Moreover, it was determined that the elastane drafting ratio plays an important role in the tensile and tearing strengths of fabrics and these properties decrease with increasing rates of the elastane ratio within the fabric (Meriç & Gürarda, 2002). In the other study, physical and stretch properties such as tensile strength, tearing strength, air permeability, fabric growth, permanent stretch, % fabric stretch of woven fabrics containing different amounts of spandex yarns were compared to each other (Mourad, Elshakankery, & Almetwally, 2012). The aim of the study performed by Qadir was to investigate the effect of elastane denier, draft ratio, and elastane percentage on the tensile, tear, stretch, and recovery properties of woven fabrics containing elastane yarn along the weft direction. The elastane percentage in the core-spun yarn has a strong positive correlation with fabric tear strength and recovery after stretch, and a strong negative correlation with fabric tensile strength. The fabric stretchability was found to be dependent not simply on the elastane percentage but on the initial fabric contraction in the weft when the fabric is taken off the loom after weaving (Qadir, Hussain, & Malik, 2014). El-Ghezal et al. have emphasized in their study that the elastane ratio has a substantial impact on the fabric s mechanical properties in the case of using the elastanecored core-spun threads with cotton coated outer layers (El-Ghezal, Babay, Dhouib, & Cheikhrouhou, 2009). Kakvan et. al. have tested and analyzed the chosen properties (resistance, hairiness, unevenness, etc.) of the core-spun threads manufactured with the core filament being fed in different drawing ratios. As a result, the drawing value of 3.49 applied to the elastane represents the best elasticity and resistance values, and the lowest S3 hairiness value (Kakvan, Shaikhzadeh Najar, Ghazi Saidi, & Nami, 2007). In their study, Helali et al. manufactured core-spun thread of different thread numbers and different core drawing values by means of elastane with the commercial name Dorlastan, and emphasized the importance of the elastane ratio and the thread number for its elastic recall property (Helali, Babay Dhouib, Msahli, & Cheikhrouhou, 2012). Imer expresses in his study that there is a linear relationship between the weft density and the weft breaking resistance, and that this relationship is weak with the breaking resistance in the warp direction. Furthermore, it has been determined that tear resistance in the weft direction reduces as the weft density increases (Imer, 1999). Kurtça has identified in his study dated 2001 that there is a linear and positive relationship between the weft density and the breaking resistance, and observed that the tearing resistance shows various behaviors based upon the texture (knit) type and thread properties (Kurtça, 2001). Within the scope of this study, we have endeavored to show the impact that the changes in the weft density and thus in the dual-core thread quantity and elastane ratio per unit area in the denim fabrics manufactured out of dual-core thread with elastane weft has on the fabric s weight and width parameters by using finished product and following the domestic washing processes. Moreover, we have endeavored to determine the impact of the same parameters on fabric s cost per unit, resistance, and color properties. Materials and method Material Preparing the dual-core weft thread We have used the Ne 16/1 ring dual-core 77 dtex PES and 78 dtex Elastane thread as the weft thread in this study. The cotton fiber used in this thread has been tested by means of the USTER HVI spectrum device, and the measured fiber properties have been specified in Table 1. While the thread manufacture is carried out by using the cotton raw material, whose fiber properties are specified above, firstly the manufacturing processes of the combing and drawing sliver of Ne 0.1 count and of the roving sliver of Ne 0.46 count have been performed. After the mentioned processes, these cottony roving slivers, 36 filament polyester thread of 77 dtex thickness, and 78 dtex elastane (lycra ) have been simultaneously

4 118 O.G. Ertaş et al. Table 1. Fiber properties of cotton used in in the study. Parameter Value Parameter Value Parameter Value SCI ( ) (Flexibility index) MIC ( ) (Thinness) MAT ( ) (Maturity) LEN (mm) MOIST 7.40 SFI (%) (short fiber ratio) Rd (%) (Brightness) 66.1 STR (g/tex) (Strength) b (%) (Yellowness) 10.3 ELG (%) (Elongation) C Grade ( ) (Color category) 43 Tr Area (%) (Percentage of contamination 0.58 in the defined area) 38 Tr Grade (%) (Contamination level) 4 (Length) UNF Tr Cnt ( ) (Number of contamination in the defined area) fed into the ring spinning manufacture mechanism with a special apparatus. Thread has been formed by providing 3.6 drawing to the elastane in the thread, which contained cotton fibers on the sides, and both polyester and elastane (lycra ) at the center (the thread has been formed by elongating the elastane by 360%). The composition of the resulting thread is 73% cotton, 21% polyester, and 6% elastane. Preparing the warp thread The conventionally manufactured Ne 10/1 ring slub warp thread has been used as the warp thread, and has been dyed in the rope dyeing machine by being sunk Table 2. Parameter Sample fabric manufacture parameters. Properties into the 6 deep indigo dye. Afterwards, rope opening process and desizing process with modified potato starch have been implemented. The manufactured dual-core weft thread, and the warp thread dyed and shaped into beams by means of the above-mentioned process have been subjected to the weaving process in the manufacture parameters presented in Table 2. In line with the main purpose of the study, the weaving process has been performed with 10 different density values (12, 14, 16, 18, 20, 22, 24, 26, 28, and 30 weft/cm); with all the properties remaining the same, fabric samples of different weft densities have been performed. Maximum and minimum densities have been Weaving machine Dobby weave, rapier Warp thread Ne 10/1 Ring slub, 100% cotton, α e : 4,5 Weft thread Ne 16/1 Ring dual-core (77 dtex PES + 78 dtex elastane (PU) at the center, cotton on sides) PES drawing 1,08 Elastane drawing 3,6 α e : 4,5 Weave type Twill 3/1Z Reed Comber number: 60, 8/4, Comber width: 178 cm, 24 warp thread/cm Composition Elastane Ratio Varies as per the weft density Fabric finishing process Singeing + caustification (NaOH-18 Bè) + finishing (polyacrylate softening) + sanforizing Table 3. The changes in the sample fabric compositions with the weft density. Weft density (thread/cm) Elastane ratio % PES ratio % Cotton ratio %

5 The Journal of The Textile Institute 119 Table 4. Standards predicated in the experimental study. Tests Standards Tests Standards Conditioning ASTM D1776 Tearing strength (weft warp) (grf) Fabric width ASTM D3774 Breaking strength (weft warp) (kgf) Size change (%) AATCC135/ Seam Slippage ISO 6330 Weight ASTM D3776 Spectrophotometer Color Assessment Elasticity/elongation/permanent ASTM D3107 elongation (%) (2.3 kg) ASTM D1424 ASTM D5034 ASTM D434 GretagMacbeth Color-Eye 7000A (10 normal observer, norm light D65) selected as value which can be efficiently woven in the weaving machine and would cause no problems in the final use. The fabrics woven under the above-mentioned conditions have been put into the finishing process. The finishing process comprises of singeing, caustic (NaOH-18 Bè) process (half mercerized), then softening polyacrylic finishing, and finally the sanforizing process. Composition values of the samples following the finishing process have been calculated as given below (Table 3). Method Many performance tests, which are prominent for the denim fabrics have been applied, on the fabrics woven with different densities by using the dual-core elastane-containing thread and the standards predicated in this regard are presented in Table 4. Results of the experimental study Before the application of the tests in the experimental study, the samples have been conditioned under the standard atmospheric conditions. Afterwards, results of the tests applied with the standards in Table 4 predicated, and the graphical assessments as well as the interpretations of these results have been summarized separately for each parameter, and shown below. Fabric width, shrinkage in the weft direction after washing, weight per unit area Width and weight per unit values of the conditioned fabrics have been measured before washing (in the finished product form) and after 3 consecutive domestic washing processes in line with the standards in Table 4, and the results have been cumulatively presented in Table 5. Size and weight changes observed in the elastane-containing denim fabrics after washing is an important parameter that is directly reflected to the final user and could cause problems at the outfitting stage; therefore, size and weight changes in the elastanecontaining denim fabrics has been analyzed within the framework of this study. Furthermore, impact of the density changes on the pre- and post-wash fabric width and weight has been graphically shown in Figure 1. As seen in Table 5, as the weft density of the fabrics woven on the same loom and with a constant warp density increases, fabric width increases as well. When the construction gets denser, movement area of the threads forming the surface is limited, their elasticity levels decrease, and the width values increase. In fact, as can be observed in Table 3, while the elastane ratio is 1.37% with the density level 12, the elastane ratio is 2.53% with the density level 30; hence, the elasticity ratio of the latter is almost 2 times higher than the former. In other words, while the number of elastane is 12 per 1 cm with the density level 12, number of elastane is 30 with the density level 30 and hence, it contains 2.5 times more elastane compared to the sample with the 12 density. In line with these results, it could be stated that the fabric construction (in this study, of the weft density parameter) has a much more impact on the fabric width and post-wash width change than the elastane ratio. As could be observed in Figure 1, similar to previous studies (El-Ghezal et al., 2009), the fabric width increased both before wash and after wash as the density increased, and there were different levels of shrinkage on the fabric after the wash. In the same figure it is seen that shrinkage quantity occurring in the weft direction after the wash changed in an inverse proportion with the density, and that as the density increased, the shrinkage quantity decreased substantially from 21.4 to 4.4%. The reason why these changes take place is thought to be the fact that when the density increases, movement of the threads diminishes due to the elastane. The expected situation about the changes in the fabric weight as per the weft density is that both the finished product and the washed fabric (dried after 3 consecutive washes) should represent an increment in the unit weight in parallel with the weft density (El-Ghezal

6 120 O.G. Ertaş et al. Table 5. Fabric width of the samples, post-wash width change, and weight values. Weft density (thread/cm) Finished fabric width (cm) Washed fabric width (cm) Ratio of post-wash Shrinkage in the weft direction (%) Finished fabric weight (Oz/yd²) Washed fabric weight (Oz/yd²) Figure 1. Density-fabric width, density-shrinkage quantity, density-fabric weight changes. et al., 2009). However, when the test results in Table 5 are analyzed, the finished fabric weight is observed to increase up to the density of 24 thread/cm, and remain constant at higher densities. Impact of the increment in the weft density up to the level of 24 is observed to be higher compared to the increment in the fabric width; after these densities, the fabric width and the weft density balance each other, and weight does not change. If the relationship between the two were a linear relationship, the weight measured to be 9.4 oz/yd² with the density of 12 was supposed to be 13 oz/yd² instead of 10.7 oz/yd² with the weft density of 30. This limit might vary based on the fabric construction; it could be stated that as long as the elastane-containing fabrics are not fixed, increasing the weft density does not hold a strong impact on the weight after a specific level of density. As seen in Figure 1, this case is different with the domestically washed (washed) fabric; the weight reaches at the maximum value when the density is at its lowest, and it remains constant after a small decrease. According to the results obtained from the tests conducted, when the samples in the range of density get to become denim pants, their weight will remain the same as long as they are not subjected to any thermal activities during the confection processes. As the density increases, fabric width of the washed fabrics increase more than the non-washed finished fabric; thus, the grammage increase expected to accompany the density increase is tolerated with the fabric width increase, and the weight per unit area does not change much. Elasticity and permanent elongation Based on the ASTM D3107 standard, we have performed elasticity tests on denim fabrics woven with different densities, and cumulatively presented the test results in Table 6. Relationships between the weft density and elasticity as well as permanent elongation values have been graphically shown in Figure 2. As seen in Figure 2, the elasticity value goes through a dramatic decrease as the weft density increases (similar to the study performed by Çataloğlu). Table 6 shows that the elasticity is 74% with the density of 12 but as the density increases, elasticity decreases down to 20% with the density of 30. When compared with the increment in the elastane ratio, increment in the weft density has a much more impact on the physical properties. In other

7 The Journal of The Textile Institute 121 Table 6. Elasticity and permanent elongation values of the samples. Weft Density (thread/cm) Elasticity (%) Permanent elongation (30 sc) (%) Permanent elongation (2 h) (%) Elasticity/permanent elongation (2 h) Figure 2. Density elasticity, density permanent elongation changes. words, if the elasticity is desired to be increased, reducing the weft density would be a good solution, and it does not cause observable weight changes in the standard weft density ranges. The only disadvantage is the decrease in the fabric width and the increase in the post-wash shrinkage in the direction of the weft. The results relating to the 30-s and 2-h tests, performed within the scope of the permanent elongation test, are coherent with each other (Figure 2). The permanent elongation value at the end of 2 h is the permanent elongation value that is more significant in terms of the final use. Weft density increases cause decreases in the elasticity levels as well as in the permanent elongation values (Çataloğlu, 2007; Özdil, 2008). While elasticity is a definitely desired property, permanent elongation is regarded as a real problem. The reason why the dual-core weft is used is that the permanent elongation value relating to the conventional elastane core wefts is superior at the same elasticity values. The unit we plan to use for measuring this is elasticity/permanent elongation value. As seen in Table 6, this ratio does not change based on the weft density, and attains levels of approximately 8.2 in this construction. As the experimental studies performed with the conventional elastane wefts, this value changes based on the construction and elastane property, and retains a value of 3 7. A decrease in this value means a decrease in elasticity and an increase in the permanent elongation. Strength Values of breaking and tearing strength as well as the seam slippage that are important factors for the denim fabrics due to the usage area, have been tested in line with the standards; the results have been presented in Table 7, and the weft density and strength properties changes have been graphically shown in Figure 3. Strength tests on denim fabrics are performed by measuring the tearing and breaking values in the direction of the warp and weft. Furthermore, although it is not a standard application, abrasion and seam slippage tests as well could be applied. As seen in Table 7, the

8 122 O.G. Ertaş et al. Table 7. Strength values of the samples. Weft Density (thread/cm) Warp tearing strength (gf) Weft tearing strength (gf) Warp breaking strength (kgf) Weft breaking strength (kgf) Seam slippage strength warp (kgf) Seam slippage strength weft (kgf) > > >28 > >29 > >34 > >37 > >34 > >36 > >41 > >37 >36 Figure 3. Weft density tearing strength, weft density breaking strength changes. seam slippage has been occurred in the warp direction with the densities 12 and 14. As the weft density increases, the total friction force between the warps and wefts increase and seam slippage is less apparent. Likewise, the previously performed studies about core-spun yarn (El-Ghezal et al., 2009; Meriç & Gürarda, 2002; Mourad et al., 2012; Özdil, 2008), the weft tearing strength has been observed to go through a definite decrease as the weft density increases (ratio of elastane increases) (Figure 3) (Imer, 1999). Besides, increments in the weft density decrease the warp tearing value in a clearly observable fashion, although not as much as seen in the weft direction. In our study, compared with the densities of 30 and 12, the weft tearing strength has dropped by 42%, and the warp tearing strength has decreased by 20%. The case with the breaking strength, as seen in Figure 3, has been just the opposite of the literature about core-spun yarn (El-Ghezal et al., 2009; Meriç & Gürarda, 2002; Mourad et al., 2012; Özdil, 2008). The weft breaking strength value increases as the weft density increases. This increase is almost linear; and the warp breaking strength value is constant up to a specific density, and shows a slight decrease as of the mentioned specific density level. There are not sufficient results to allow for an assumption about the warp breaking values. Unit cost of fabrics Unit costs of the manufactured fabrics are shown in Table 8 for comparison purposes. When analyzed from a cost point of view, fabrics with dual-core weft are generally manufactured with higher costs when compared to the rigid or elastane fabrics produced with core-spun yarns with the same construction. As clearly seen in Figure 4, since the weft quantity in the unit length increases as the weft density increases, the fabric with the highest weft density has the maximum cost per running meter of the fabric. In the meter square costs, this difference is reduced by the impact of the width change; still, the tight construction in the finished fabric has the highest cost. However, when the meter square cost of the washed fabric is analyzed, the cost remains almost constant after a specific density level (18 density), because of the unit weight change caused by the shrinkage in the weft direction due to the elastane.

9 The Journal of The Textile Institute 123 Table 8. Cost of the samples. Weft density (thread/cm) Cost ($/running m) Finished fabric cost ($/m²) Washed fabric cost ($/m²) Figure 4. Table 9. Weft density-cost changes. Color comparisons for the samples. Figure 5. Images of the samples after washing.

10 124 O.G. Ertaş et al. Table 10. Statistical analysis results. Weft density Finished Fabric Width Washed Fabric Width Post-Wash Shrinkage Finished Fabric Grammage Washed Fabric Grammage Elasticity Color assessment By taking the fabric with a weft density of 30 thread/cm as the reference, we have detected the color differences in the other fabrics by means of the spectrophotometer and in line with the standard; the mentioned differences are presented in Table 9. When evaluated for color, as could be understood from the color assessment index in Table 9 and the results pertaining to the rinse washing (rinsing carried out by giving as little washing effect to the product as possible, and only for providing a non-shrinkage property and hand feeling to the fabric) of the 10 fabrics (Figure 1), there is a big difference in the fabric color although the fabrics with densities of 12 and 30 does not show any differences in the construction except for the density (Figure 5). Depth of the color and the fabric look are quite different from each other especially at edge densities. In this case, it could be stated that warp dyeing in denim does not provide a definite opinion on its own regarding the color and the depth of color. Color differences are not much in the fabrics manufactured with density values close to each other. However, after the difference between the density values is above 4, the color differences show a substantial increase. In this regard, it is understood that while color are assessed, the related comparisons should definitely be performed on close densities. Statistical analysis results We have applied a correlation analysis by using the SPSS 15.0 package program in order to determine the statistical validity of the results obtained and interpreted within the Weft density Correlation Correlation 0.963** a 0.983** Permanent elongation at the end of 30 s Sig. value b Sig. value Correlation 0.986** Permanent elongation at the end of Correlation 0.969** 2h Sig. value Sig. value Correlation 0.973** Warp tearing strength Correlation 0.982** Sig. value Sig. value Correlation 0.976** Weft tearing strength Correlation 0.976** Coefficient Sig. value Sig. value Correlation 0.696* Warp breaking strength Correlation 0.762* Sig. value Sig. value Correlation 0.972** Weft breaking strength Correlation 0.990** Sig. value Sig. value a Strength of the relationship increases as the correlation gets closer to the absolute value 1. b If the significant value is (p) < 0.05, the relationship is understood to have a reliability of 95%; if it is p < 0.01, the relationship has a reliability of 99%. *Correlation is significant at the 0.05 level (2-tailed). **Correlation is significant at the 0.01 level (2-tailed). scope of the experimental study. Using this analysis, we have endeavored to statistically determine the significance, proportion, and strength of the relationships between density and all the other parameters. As a result, the relationship between the weft density and the washed fabric weight and the relationship between the weft density and the warp breaking strength have been found to be statistically significant with 95% reliability, and the relationships between the weft density and the other parameters have been found to be statistically significant with 99% reliability. Results of the statistical correlation applied in between the weft density and all the parameters studied in this study, the correlation, and significance levels (sig. values) have been summarized and separately presented in Table 10. Conclusion In this study, we have manufactured denim fabrics of different weft densities by using elastane-containing dual-core thread with the weft; some selected properties have been tested, and the related results have been evaluated. Hence, the obtained results are summarized below: (1) Impact of the changes in the dual-core weft densities on the fabric properties is parallel to the impact of the core-spun threads with a single core. However, their impacts on the fabric performance have detected to be clearly different from the wefts which do not contain elastane.

11 The Journal of The Textile Institute 125 (2) It has been observed that as the fabric density increases before and after the repetitious domestic washes, the fabric width increases as expected; however, this increase has been found to be higher in the washed fabric. Moreover, as the post-wash shrinkage percentages have been observed to go through a substantial decrease as the density increases. However, it could be stated in the light of the results obtained that the fabric construction (weft density parameter in this study) has a much more impact on the fabric width and post-wash width change compared to the elastane ratio. (3) As the density increases with the washed fabrics, the fabric width increases much more than the non-washed finished fabric; hence, the grammage increase expected to accompany the density increase is tolerated with the fabric width increase, and the weight per unit area does not change much. (4) When the fixing (thermal finishing) process performed on elastane-containing fabrics to retain the constant values of width, shrinkage in the direction of weft, and elasticity is not conducted, the washed weight remains constant in a very broad density range. (5) Although the elastane quantity and ratio in the fabric increase as the density increases, the elasticity value has been found out to decrease substantially when the weft density increases. This is believed to be stemming from the fact that the fabric becomes more rigid as the density increases, and movement of the threads are inhibited due to the elastane. In other words, decreasing the weft density would be a good solution when elasticity is wanted to be increased, and it does not cause any obvious weight changes on the standard weft density ranges. (6) The permanent elongation is observed to decrease as the weft density increases, and this is a definitely desired phenomenon. Additionally, it has been found out that the ratio between the elasticity and the permanent elongation values is not affected from the density changes, and remains at the same value in almost all the fabrics. In fact, the reason why the dual-core weft thread is used is that the permanent elongation value is superior at the same elasticity value compared to the conventional elastane core wefts. (7) Weft density increase has caused a reduction in the strength values in both directions, although this ratio has been higher with the weft-tearing strength. The reason is that the threads slip with difficulty over each other and thus, they tear more easily since the friction force between the threads is higher in the fabrics with high densities. However, the weft-breaking strength has increased as expected when the density has increased. (8) As expected, increments in the density increase the costs of the non-washed fabrics; when the meter square cost of the non-washed fabric is analyzed, shrinkage in the direction of the weft comes into as a result of the elasticity and in parallel with the unit weight change, the cost remains constant after a specific density value. (9) Depth of the color increases as the weft density decreases, and it creates the impression that it has been subjected to a different dyeing process. However, the mentioned color differences stem from the fact that the domination of the non-dyed weft thread increases on the surface and therefore, the fabric seems to have a lighter color. Hence, using fabrics of close densities is definitely of prime importance for comparing and assessing the colors on denim fabrics. Acknowledgements In this study, we were benefited from some trials made as part of the SANTEZ Project (No:0350.FTZ Developing Denim Fabrics with high added value by designing and producing multicomponent core-spun (Dual-core) yarns). References Çataloğlu, A. (2007). Elasticity and permanent deformation properties of the denim fabrics with elastane mixtures (Master s dissertation). Ege University, Institute of Sciences, 79 (in Turkish). El-Ghezal, S., Babay, A., Dhouib, S., & Cheikhrouhou, M. (2009). Study of the impact of elastane s ratio and finishing process on the mechanical properties of stretch denim. The Journal of The Textile Institute, 100, Helali, H., Babay Dhouib, A., Msahli, S., & Cheikhrouhou, M. (2012). Influence of Dorlastan draft and yarn count on the elastic recovery of the Dorlastan core spun yarns following cyclic test. The Journal of The Textile Institute, 103, Imer, Z. (1999). Analyzing the impact of the weft density on some fabric properties by applications carried on cotton fabrics. Tekstil ve Konfeksiyon, 4, (in Turkish). Kakvan, A., Shaikhzadeh Najar, S., Ghazi Saidi, R., & Nami, M. (2007). Effects of draw ratio and elastic core yarn positioning on physical properties of elastic wool/polyester core-spun ring yarns. The Journal of The Textile Institute, 98, Kurtça, E. (2001). Impact of the weft thread properties, density and knit type on the fabric s mechanical properties

12 126 O.G. Ertaş et al. (Master s dissertation). Istanbul Technical University, Institute of Sciences, Istanbul, 64 (in Turkish). Meriç B., Gürarda A. (2002, October). Proceeding of the XIIth Textile and Leather Romanian Conference Mourad, M. M., Elshakankery, M. H., & Almetwally, A. A. (2012). Physical and stretch properties of woven cotton fabrics containing different rates of Spandex. Journal of American Science, 8, Özdil, N. (2008). Stretch and bagging properties of denim fabrics containing different rates of elastane. Fibres & Textiles in Eastern Europe, 16, Qadir, B., Hussain, T., & Malik, M. (2014). Effect of elastane denier and draft ratio of core-spun cotton weft yarns on the mechanical properties of woven fabrics. Journal of Engineered Fibers and Fabrics, 9,