A Comparative Study of Physical Properties of Yarns and Fabrics Produced From Virgin and Recycled Fibers

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1 A Comparative Study of Physical Properties of Yarns and Fabrics Produced From Virgin and Recycled Fibers Mehmet Emin Yuksekkaya, PhD 1, Gizem Celep, PhD 1, Gamze Dogan, PhD 2 Mevlut Tercan, PhD 1, Basak Urhan, MSc 3 1 Usak University, Faculty of Engineering, Department of Textile Engineering, Usak TURKEY 2 Usak University, Faculty of Engineering, Department of Materials Science and Nanotechnology Engineering, Usak TURKEY 3 Usak University, Faculty of Engineering, Department of Chemical Engineering, Usak TURKEY ABSTRACT Products that are produced by various industries such as agriculture, food, mining, chemistry, and textile cannot meet the needs of humankind since the world s population continues to grow exponentially. Furthermore, the reduction in natural resources forced researchers to produce new synthetic products by utilization of technology and led them to study recycling of existing natural resources. This study compares some properties of yarns and fabrics produced by virgin and recycled polyester and cotton fibers. Virgin cotton, recycled cotton, virgin polyester, recycled polyester fibers, and blends of these fibers were used to manufacture open end rotor yarns. Single jersey fabrics were knitted from these yarns. Physical properties of yarns and fabrics such as tensile strength, unevenness, yarn imperfections, burst strength, pilling and coefficient of kinetic friction were measured and statistically compared. Although generally the properties of yarns and fabrics produced from virgin fibers were better than that of produced from recycled fibers, producing textile products with optimum quality is stressed in this study. Correspondence to; Gizem Celep gizem.celep@usak.edu.tr formed for recycling of textile materials. This market is known as the waste exchange system. The main purpose of this waste exchange system is to meet the supply and demand of textile materials as studied by Tereschenko [1].Textile waste can arise at different stages of production (e.g. waste arises from yarn spinning, fabric scraps are generated within the garment industry, etc.). These used fabrics can be opened into fibers that could be used in recycled yarn production. Since recycled cotton fibers are short, it is necessary to blend the recycled cotton fibers with polyester fibers to give strength to the yarn and make facilitate spinning. Blending recycled cotton fibers with polyester fibers also reduces the amount of fiber fly generated during the knitting or weaving. Yuksekkaya studied the effects of fiber length on the fiber fly generation during raising and weaving. He reported that as the length of fiber increases, the amount of fiber fly decreases [2, 3, 4]. It is possible to use many recycled fibers such as cotton, polyester, acrylic, wool, viscose, nylon, polypropylene, and linen to form products such as padding, blanket, tricot and knitwear, woven fabric, or yarn. Keywords: recycling, cotton, polyester, open end rotor yarn, knitted fabrics. INTRODUCTION As natural resources decrease, public awareness of recycling increases rapidly. Emphasis made by various media, advertising campaigns and recycling activities organized by agencies and institutes play an important role in the recent rise of awareness about recycling of materials such as glass, paper, textile, and plastic materials. The textile industry generates large amounts of waste with the potential for recycling. Therefore, a special market has In recycling of synthetic polymers, polyester has a special importance. Bartolome reported that with the help of recycling of polyester fibers it would be possible to reduce the waste problem, reduce the use of petrochemical products, and reduce energy consumption [5]. Harsh mechanical and/ or chemical processes are applied to textile materials during the recycling procedure. In mechanical processing, fabric wastes are torn into individual fibers in tearing machines by harsh mechanical effects. In the case of chemical processing, thermoplastic waste materials are melted at high temperatures. Both chemical and mechanical recycling could cause deterioration in Journal of Engineered Fibers and Fabrics 68

2 physical and chemical properties of recycled materials [5, 6]. Merati and Okamura studied the physical properties of recycled cotton yarns. They stated that the fiber length was a key factor on the strength of the yarn. As the fiber length increases, the strength of yarn also increases [7]. In another study, virgin polyester fibers and recycled cotton fibers were blended at a ratio of 60/40, and the results showed that the strength of open end yarns were depended on the opening roller speed in carded rotor yarn production system [8]. Additionally, Halimi et al. implied that certain process parameters of open end rotor spinning including rotor type, opening roller speed, rotor speed and twist factor were the important factors for spinning of virgin cotton and cotton waste blends. They emphasized that addition of cotton waste at levels up to 25% in the draw frame did not affect the quality of rotor yarn [9]. El-Nouby compared the hairiness of open end rotor yarns produced by blending different ratios of cotton waste (flats, combing nail, spinning, and sliver wastes and long period stored cotton) and recycled waste (fabric waste). According to the results of the study, increases in the applied mechanical processes and the ratio of the recycled waste in yarns led to higher hairiness values for all yarns [10]. Furthermore, Heifetz s patent described a method for producing high quality yarns including at least 10% recycled fibers wherein the yarn count range was Ne 8-18 [11]. In this study, cotton and polyester fibers were chosen as raw materials to produce virgin, blend, and recycled cotton and polyester open end rotor yarns. Single jersey-knitted fabrics were produced using these yarns. The physical properties of these yarns and fabrics were tested and compared. MATERIAL AND METHODS Virgin cotton, recycled cotton, virgin polyester, and recycled polyester fibers were used in this study. Fiber ratios in yarns produced were chosen as extreme values (100% virgin and 100% recycled) and a midpoint value (50/50 virgin/recycled) in order to compare physical properties of the yarns. The properties of virgin and recycled cotton fibers were measured with the Uster HVI Spectrum instrument. The measured properties of cotton fibers are given in Table I. The recycled cotton used in this study was obtained from cotton fabric scraps of garment industry fed to a tearing machine. Figure 1 shows the waste materials in process. Figure 2 shows the photo of the tearing machine used to open fibers. As seen in the photo, machine consists of numerous stages. There are drums clothed with wire that open the fabrics at every stage. The degree of opening increases and finer clothing results at successive stages of the process. Linear densities of virgin and recycled polyester fibers were1.6 and 1.4 dtex, respectively. The lengths of both types of polyester fibers were 38 mm. The virgin polyester fiber bundle tensile strength was 58 cn/tex, whereas recycled polyester fiber bundle was 47 cn/tex. The origin of recycled polyester fibers were waste PET bottles. In recycling process of PET, used PET bottles were purified from contaminants by sorting, washing, and drying, and PET flakes were obtained. Recycled fibers were produced by melt spinning of the PET flakes. FIGURE 1. Waste textile materials in process. One hundred percent virgin and recycled cotton and polyester slivers and 50/50 blended slivers were processed in the draw frame. Linear density of each sliver was 5ktex. Then, the slivers were spun with an Oerlikon BD 320 open end spinning machine. The spinning process parameters are as follows: rotor speed of rpm, rotor diameter of 43 mm, the opening roller OK37 NiDi running at 9500 rpm, and ceramic navels with 8 grooves. FIGURE 2. Photo of tearing machine. Journal of Engineered Fibers and Fabrics 69

3 The linear densities of yarns were measured by Pro- Ser automatic wrap reel. The twists of yarns were measured by Mesdan Lab electronic twist tester using Schutz method (untwisting, retwisting and double counter-check). The linear density, twist, and twist multiplier of all yarns are given in Table II. For the ease of expression yarns types were coded as shown in Table II and similar codings were also given to fabrics. The tensile strengths of yarns were tested with Premier Tensomaxx Unevenness and yarn imperfections were tested with Premier Tester Five samples were tested and the value reported is the mean of those results. Yarn quality index (YQI), comprising tensile strength, elongation, and unevenness of yarns were calculated for each yarn according to the equation given by Yunus and Rahman [12]. The relationship is calculated as follows: (1) Single jersey fabrics were knitted from these yarns on an 8 gauge circular knitting machine. Bursting strength values of the fabrics were measured with Lawson Hemphill Bursting Strength Tester according to EN ISO Pilling tests were made with Nu- Martindale Tester according to the EN ISO A PillGrade instrument was used for the objective evaluation of the fabric pilling. The coefficients of kinetic friction of fabrics were also determined by using FrictorQ Tester. TABLE I. Physical properties of cotton fibers. Fiber Type Virgin Cotton Recycled Cotton Fineness (Mic.) Fiber Bundle Strength (g/tex) Elongation (%) Upper Half Mean Length, UHML (mm) Uniformity (%) Short Fiber Content by Weight (%) Maturity Ratio Trash Area (%) TABLE II. Properties of yarn samples. Groups Yarn Code Yarn Type Linear Density (tex) Twist (T/m) Twist Multiplier (αtex) Cotton V-CO Virgin Cotton R-CO Recycled Cotton V-CO/R-CO Virgin Cotton/Recycled Cotton Polyester V-PES Virgin Polyester R-PES Recycled Polyester V-PES/ R-PES Virgin Polyester /Recycled Polyester Blend V-PES/V-CO Virgin Polyester /Virgin Cotton V-PES/R-CO Virgin Polyester/Recycled Cotton R-PES/V-CO Recycled Polyester/Virgin Cotton R-PES /R-CO Recycled Polyester/Recycled Cotton The statistical analyses of the data were made with IBM SPSS 19. The effects of tested parameters on the properties of yarns and fabrics were analyzed using the One-Way analysis of variances test. Homogeneities of variances were tested with Levene s test. Significant differences were determined using Tukey HSD or Tamhane s T2 post hoc tests according to the homogeneity of variances. The significance level was considered as p=0.05. In order to evaluate the significant differences between yarns and fabrics produced from virgin and recycled fibers, both yarns and fabrics were grouped according to their raw material (cotton group, polyester group, blend group) as seen in Table II. Journal of Engineered Fibers and Fabrics 70

4 RESULTS AND DISCUSSION Results of Yarn Tests Tensile Strength & Elongation As seen in Figure 3, the tensile strength of V-CO yarn was the highest. The fiber tensile strength and UHML are the major parameters that affect tensile strength of open end rotor yarns. Since the V-CO fibers have higher tensile strength, higher UHML value, and also lower short fiber indexes than that of R-CO fibers, this result is expected. When the polyester and blend groups were evaluated, it was observed that yarns that include virgin fibers have a tendency to possess higher tensile strength values. This may be attributed to the higher tensile strength values of virgin polyester fibers when compared to recycled polyester fibers. Since the synthetic fibers are stronger than natural ones, it was observed that the effect of the origin of polyester fiber was much greater than the origin of natural cotton in terms of tensile strength in the blend group. There were no statistically significant differences in the tensile strength values of R-CO and V-CO/R-CO yarns (Table III). Also, there were no differences in between R-PES and V-PES/R-PES yarns. In the blend group, as seen from the Table III, V-PES/V-CO and V-PES/R-CO yarns did not show a significant difference in terms of tensile strength (p value: 0.977). Similarly, R-PES/V-CO and R-PES/R-CO yarns did not show a significant difference too (p value: 0.985). The tensile strength values of the other yarns in blend group were statistically different from each other (Table III). In cotton group, the elongation of V-CO yarn was the highest (Figure 4). In the polyester group, R-PES yarns had the highest value. This may be due to the fineness of the recycled polyester fibers. And all of the yarns in blend group inhibited closer elongation results. According to the statistical analyses, the elongation values of all yarns were significantly different from each other. Unevenness & Yarn Imperfections Unevenness of the V-CO/R-CO yarn was the highest in cotton group (Figure 5). Although the measured virgin cotton fiber properties (except maturity ratio and trash area) are better than recycled cotton fiber, the unevenness of V-CO yarn was higher than R-CO yarns. This can be explained by the high twist value of R-CO yarn. When polyester group is considered, the minimum unevenness value has been observed in R-PES yarns. This result is expected since the fineness of the R-PES fibers is lower than that of V- PES fibers and twist of R-PES yarn is higher than that of V-PES yarn. The maximum unevenness value was recorded in V-PES/R-CO yarns followed by R- PES/V-CO yarn in blended group. The irregularities in the results of the blend group may have arisen from the operating conditions. Generally, the efficiencies of yarn preparation processes (such as opening, cleaning, etc.) have a considerable effect on yarn unevenness and imperfections. The improved unevenness and imperfection properties observed for recycled yarns may be explained by the quality of the fiber and the yarn preparation processes. Also, the operating conditions may vary between textile factories. This situation may affect the unevenness and imperfections values of yarns. FIGURE 3. Tensile strengths of yarns. FIGURE 4. Elongations of yarns. Journal of Engineered Fibers and Fabrics 71

5 higher and the trash area of R-CO fibers is lower than that of the V-CO fibers. This led to lower yarn imperfection values in the R-CO yarn. Additionally, the yarn imperfections are positively affected by yarn twist. Thus, the higher twist values of R-PES and R- CO yarns than virgin ones resulted in lower yarn imperfections in recycled yarns. FIGURE 5. Unevenness values of yarns. According to the statistical analyses there were no significant differences between the yarns in the polyester group and V-PES/V-CO and R-PES/R-CO yarns in the blend group. However, all of the yarns in the cotton group were significantly different from each other in terms of unevenness. The minimum thinness, thickness and neps values were recorded for the R-CO yarn in the cotton group, the R-PES yarn in the polyester group and the R- PES/R-CO yarn in the blend group (Figure 6). For cotton yarns, the maturity ratio of R-CO fibers is All of the yarns in cotton group showed significant differences in terms of yarn imperfections. The V-CO and V-CO/R-CO yarns were statistically indifferent in terms of neps. In the polyester group, there were significant differences between R-PES and V-PES/R- PES yarns in terms of thinness and all of the yarns were significantly different in terms of neps. Thick place values of all yarns in polyester group showed no difference from each other. When blend group is considered, only the difference between V- PES/R-CO and R-PES/R-CO yarns was statistically indifferent in terms of thin places and neps. The only differences in thickness were observed in between the V-PES/V-CO and R-PES/V-CO yarns, and also between the V-PES/V-CO and R-PES/R-CO yarns. TABLE III. Multiple comparison test results of yarns. Group Cotton Polyester Blend Yarn Type Yarn Type Tensile Strength Elongation Unevenness p value Thin Place Thick Place Neps (Tamhane) (Tamhane) (Tamhane) (Tukey) (Tukey) (Tukey) V-CO R-CO * * * * * * V-CO V-CO/R-CO * * * * * R-CO V-CO/R-CO * * * * * (Tamhane) (Tamhane) (Tamhane) (Tukey) (Tukey) (Tamhane) V-PES R-PES * * * V-PES V-PES/R-PES * * * R-PES V-PES/R-PES * * * (Tukey) (Tamhane) (Tukey) (Tukey) (Tamhane) (Tukey) V-PES/V-CO V-PES/R-CO * * * * V-PES/V-CO R-PES/V-CO * * * * * * V-PES/V-CO R-PES/R-CO * * * * * V-PES/R-CO R-PES/V-CO * * * * * V-PES/R-CO R-PES/R-CO * * * R-PES/V-CO R-PES/R-CO * * * * * The difference is significant at 0.05 level. Journal of Engineered Fibers and Fabrics 72

6 TABLE IV. Multiple comparison test results of fabrics. Group Fabric Type Fabric Type Cotton Polyester Blend Burst Strength p value Coefficient of Kinetic Friction (Tukey HSD) (Tukey HSD) (Tukey HSD) V-CO R-CO * * V-CO V-CO/R-CO * 1 R-CO V-CO/R-CO (Tamhane) (Tamhane) (Tamhane) V-PES R-PES * V-PES V-PES/R-PES * R-PES V-PES/R-PES * (Tukey HSD) (Tukey HSD) (Tamhane) V-PES/V-CO V-PES/R-CO V-PES/V-CO R-PES/V-CO * V-PES/V-CO R-PES/R-CO * * V-PES/R-CO R-PES/V-CO * * * V-PES/R-CO R-PES/R-CO * * * R-PES/V-CO R-PES/R-CO * 1 * The difference is significant at 0.05 level. Pilling Grade a b c FIGURE 6. Yarn Imperfections a) Thin place b) Thick place c) Neps values of Yarns. Yarn quality index gives an indication of the satisfaction of customers in three aspects: tensile strength, elongation and unevenness. The yarn quality index was calculated from the mean values of the three properties above mentioned. The V-CO, R-PES, and V-PES/V-CO blend yarns had the maximum yarn quality indices in the cotton, polyester, and blend groups, respectively (Figure 7). The R-CO, V-PES, and R-PES/R-CO yarns followed them in all three groups. Although the tensile strength of R-PES yarn Journal of Engineered Fibers and Fabrics 73

7 is lower than V-PES yarn, the yarn quality index of R-PES yarn was the highest one. This was due to the high elongation and low unevenness value of this yarn. FIGURE 7. Yarn Quality Indexes of Yarns. The fiber parameters showing the strongest effects on open end rotor yarn tensile strength were fiber bundle strength and UHML. The yarn unevenness and yarn imperfections were affected by fineness, trash grade, and maturity ratio. These results agree with studies in the literature [13]. Pilling Grade The pilling grades of all fabrics tested were in the range of 2.2 to 3.2, indicative of medium pilling (Figure 9). The V-CO fabrics, R-PES fabrics, and R- PES/V-CO blend fabrics had the minimum pilling grade values in the cotton, polyester, and blend groups, respectively. The V-CO fabric has a tendency to pill to a much higher degree than the R-CO fabric. This is not surprising, as it is well known fabrics produced by polyester fibers are more prone towards pill formation when compared with cotton fabrics. The difference between the R-CO and V-CO/R-CO fabrics was insignificant in the cotton group. None of the polyester yarns showed a significant difference within the group. The differences between V-PES/V- CO and V-PES/R-CO fabrics and between V-PES/V- CO and R-PES/V-CO fabrics were insignificant. Results of Fabric Tests Burst Strength Results of burst strength of fabrics (Figure 8) were similar to results of tensile strength of yarns. Higher burst strength values were obtained for higher yarn strength values within the cotton and polyester groups, as expected. However, there is little variation in burst strength amongst the samples in the blend group. From the statistical analysis, the V-CO and R-CO fabrics in the cotton group and all fabrics in the polyester group were significantly different. Statistically significant differences were recorded between the V-PES/R-CO and R-PES/V-CO fabrics, and the V-PES/R-CO and R-PES/R-CO fabrics in the blend group. FIGURE 9. Pilling Grades of Fabrics. Coefficient of Kinetic Friction Physical properties of fabrics directly affect the handling properties of the resulting garments. Therefore, fabrics that have lower coefficient of kinetic friction have better handling properties. Twist, linear density and unevenness of yarn as well as fiber length, fiber fineness, and blend ratio of fibers all affect the surface properties of the fabrics. The coefficients of kinetic friction of blend fabrics including recycled polyester fibers were lower than those of fabrics including virgin polyester fibers. This may be attributed to the relative fineness of the recycled polyester fibers. FIGURE 8. Burst Strengths of Fabrics. Journal of Engineered Fibers and Fabrics 74

8 Properties of yarns and fabrics produced from recycled cotton and polyester fibers were related to the opening and cleaning efficiency, quality of the recycling process, and recycled fiber properties. Therefore, the effectiveness of the opening and cleaning process are critical during preparation of the fabrics. FIGURE 10. Coefficients of Kinetic Friction of Fabrics. Coefficients of kinetic friction are statistically indifferent for all fabrics in the cotton and polyester groups. In the blend group, as seen from the Table IV, the V-PES/V-CO and V-PES/R-CO fabrics did not show a significant difference in terms of coefficient of kinetic friction (p value: 0.559). Similarly, the R- PES/V-CO and R-PES/R-CO fabrics did not show a significant difference (p value: 1.000). The coefficients of kinetic friction values of the other fabrics in the blend group were statistically different from each other (Table IV). The results of the study indicate that the fabric properties measured were mainly affected by yarn twist, yarn tensile strength, yarn unevenness and imperfections, and fiber type. CONCLUSION In this study, the mechanical properties of yarns and fabrics produced from virgin and recycled cotton and polyester fibers were investigated and compared. The mechanical properties measured for yarns were tensile strength, elongation, unevenness and yarn imperfections. Fabric properties measured were burst strength, pilling grade and coefficient of kinetic friction. Generally, yarns produced from recycled fibers exhibited better properties in terms of unevenness, yarn imperfections, and yarn quality index value. Yarn tensile strength and fabric burst strength were lower for recycled yarns and fabrics when compared to virgin ones. Coefficients of kinetic friction of the recycled were essentially equivalent. All fabrics showed medium pilling grades. Within cotton group, the fabrics produced from recycled cotton fibers had tended towards lower pill formation. According to the results of this study, yarns and fabrics produced from recycled fibers maybe suitable for applications where the strength of yarns and fabric are less critical, but where unevenness, imperfections and handle properties required. Thus, recycled fibers seem most suitable for use in the manufacture casual clothes such as t-shirts, sweatshirts and sleepwear. ACKNOWLEDGEMENT The authors thank the Uşak University Research Project Coordination Unit for funding this research (Project No: 2010/MF002) and Sesli Textile Company for the support in yarn manufacturing. RFERENCES [1] Tereschenko, K.; Waste Exchanges, 18 th International Scientific Conference Economics for Ecology, 2012, (April), pp , Sumy, Ukraine. [2] Yuksekkaya, M.E.; A Study of Fly Generation during Raising, Journal of the Textile Institute, 99 (2), 2006, pp [3] Yuksekkaya, M.E.; Fiber Fly Generation of 100% Cotton Yarns during Warp Preparation, Journal of the Textile Institute, 101 (3), 2010, pp [4] Yuksekkaya, M. E.; Fiber Fly Generation of 100% Acrylic Yarns during Weaving, Textile Research Journal, 80 (6), 2010, pp [5] Bartolome, L.; Imran, M.; Cho, B.G.; Recent Developments in the Chemical Recycling of PET, Material Recycling Trends and Perspectives, 2012, pp , InTech Publishing. [6] Cornier-Rios, H.; Effect of Recycling on Material Properties of Polyethylene Terephthalate at Various Recycling Ratios and Recycling Generations, Master Thesis University of Puerto Rico, Puerto Rico, Journal of Engineered Fibers and Fabrics 75

9 [7] Merati, A.A.; and Okamura, M.; Producing Medium Count Yarns from Recycled Fibers with Friction Spinning, Textile Research Journal, 74, 2004, pp [8] Duru, P.N.; and Babaarslan, O.; Determining an Optimum Opening Roller Speed for Spinning Polyester/ Waste Blend Rotor Yarns, Textile Research Journal 73, 2003, pp [9] Halimi, M.T.;Hassen, M.B.;Azzouz, B.; Effect of cotton waste and spinning parameters on rotor yarn quality Journal of the Textile Institute, 98 (5), 2007, pp [10] El-Nouby, G.; Hairiness of Yarns Made of Recycled Waste Fabric, Journal of Applied Sciences Research, 3(10), 2007, pp [11] Heifetz, D.S.; Recycled Yams from Textile Waste and The Manufacturing Process, United States Patent No. 5, , [12] Yunus, M.; and Rahman, F.; Micronaire Effects, Textile Asia, 13, 1990,pp [13] Buharalı, G., Ömeroğlu, S., Effects of Factors on Open-End Rotor Yarn Properties, Journal of the Faculty of Engineering and Architecture of Uludağ University, 18(2), 2013, pp AUTHORS ADDRESSES Mehmet Emin Yuksekkaya, PhD Gizem Celep, PhD Gamze Dogan, PhD Mevlut Tercan, PhD Basak Urhan, MSc Usak University Faculty of Engineering 1 Eylul Campus Izmir Road 8th km Usak, TURKEY Journal of Engineered Fibers and Fabrics 76