Evaluation of the Function and Manufacturing Technique of ... · Evaluation of the Function and Manufacturing Technique of Bamboo Charcoal Complex Yarns and Knitted Fabrics Chin Mei

Journal of Engineered Fibers and Fabrics 106 http://www.jeffjournal.org Volume 7, Issue 1 – 2012

Evaluation of the Function and Manufacturing Technique of Bamboo Charcoal Complex Yarns and

Knitted Fabrics

Chin Mei Lin1, Jia Horng Lin, Ph.D.2,3

1Department of Fashion Design, Asia University, Taichung, Taiwan, R.O.C.

2Department of Fiber and Composite Materials, Feng Chia University, Taichung, Taiwan, R.O.C.

3School of Chinese Medicine, China Medical University, Taichung, Taiwan, R.O.C.

Correspondence to: Chin Mei Lin email: [email protected]

ABSTRACT To satisfy the many requirements of our daily life, complex textiles that are both functional and beneficial have been successfully designed and developed. This research investigates the design of bamboo charcoal/spandex (BC/S) complex yarns, fabricated with a blend of spandex and bamboo charcoal polyester textured yarn, which possess superior elastic recovery. The expansion multiples of the spandex was 1.5 - 3.5, the wrap counts are 2 - 4.5 turns/cm, and the speed of the rotor twister was 4000 - 12000 rpm. When the speed of the rotor twister was between 4000 and 12000 rpm, the expansion multiple was 1.5 and the elastic recovery rate was maintained at 93% or above. Furthermore, the far infrared emissivity of BC/S complex knitted fabric was over 0.9, but descended with the lamination number. The BC/S complex knitted fabric also contained an anion count of 356 anions/cc. Keywords: bamboo charcoal textured yarn; spandex; rotor twister machine; far infrared emissivity; elastic recovery rate INTRODUCTION Flexible knitted fabrics have gained increasing popularity ever since their introduction as materials made from natural rubber (a resource which has been gradually replaced by spandex). Nowdays, people expect higher comfort from their clothing, and this demand has been met by elastic fibers, which can create clothes that are not only comfortable to wear, but also fully express the aesthetic curve of the body without detracting from the article’s functionality or visual appeal.

The one textile fabric currently sold on the market is a blend of fiber and a small amount of spandex (5 to 20%). Owing to its characteristics, spandex transforms thestructure of the textile and can be widely applied to a diverse range of products, such as plain fabrics, warp knit fabrics, underwear, outerwear, lace, socks, domestic textile products, medical textile products and functional textiles, the latter being one of the biggest fields in the textile industry [1-11].

Bamboo charcoal possesses the ability to absorb and emit far infrared rays of 4-14 μm, an amount upon which all living creatures on Earth are dependent. Far infrared rays have even been deemed to be as vital as light and are easily absorbed by the human body, assisting with heat preservation and peripheral blood circulation [12]. Bamboo charcoal is also used in the biomedical field. Hamada et al. studied the effects of far infrared rays on Hela cells and WI-38 cells, and proved that far infrared ray emission at around body temperature effectively inhibited the growth of tumor cells in vivo [13]. Bamboo charcoal also releases anions, which have a stablizing effect on mental health when administered in doses of 700 anions/cc. Anions improve sleep cycles and digestion, as well as preserve a youthful appearance; they even have air purifying properties [13]. Most research these days focuses on functional yarns/fabrics made from cores wrapped with staple fibers. Yarn wrapped with filaments are rarely discussed, however. This paper therefore discusses


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the manufaturing of BC/S complex yarns and knitted fabrics made with spandex cores, which are then wrapped with bamboo charcoal polyester textured yarn. The spandex was expanded with a multi-sectional drawing frame and then wrapped with bamboo charcoal polyester textured yarn on a rotor twister machine [14-16]. The elastic recovery rate of the BC/S complex yarn was tested, after which the yarn is knitted into BC/S complex fabric. The completed BC/S complex knitted fabrics were evaluated by far infrared emissivity, anion count, and heat preservation capacity. EXPERIMENTAL Materials 75d/72f/1 polyester textured yarn and 75d/72f/1 bamboo charcoal polyester textured yarn were both obtained from a commercial fiber corporation in Taiwan, Nan Ta Corporation. 40D Spandex was supplied by DuPont USA. Lycra was obtained from Chyn Hsyong Industry Co., Ltd. Preparation Of The Specimen Figure 1 shows the configuration of the rotor twister. Spandex (A) is expanded on a multi-sectional drawing frame (B), then threaded through the eye (C) and fed into the rotor twister (E); the rotary speed of winding roller (I) determines the feeding speed. The tangent belt (F) connects to the motor (G) and rotates the rotor twister bearing (D). The bamboo charcoal polyester textured yarn (blue) is spun around a plastic hollow cylinder, which is then set onto the rotor twister. When the rotor twister rotates, the bamboo charcoal polyester textured yarn wraps the spandex, forming the BC/S complex yarn (H). Then the winding roller (I) winds the BC/S complex yarn into a spool [17-20]. Figure 2 shows the composition of the BC/S complex yarns, which are knitted into BC/S complex knitted fabrics. Figure 3 illustrates the circular knitting machine with which the knitted fabrics are made.

The expansion multiples of the spandex were 1.5, 2, 2.5, 3, and 3.5, the wrap counts of the BC/S complex yarns were 2.0, 2.5, 3.0, 3.5, 4, and 4.5 turns/ cm, and the speeds of the rotor twister were 4000, 6000, 80000, 10000, and 12000 rpm. Based on the above three parameters, a variety of yarns with different structures was fabricated. The wrap count stood for the number the bamboo charcoal polyester textured yarns wrapping the spandex per centimeter. The elastic recovery rate of these yarns was evaluated using an elastic recovery tester assembled

in our lab and based on the NO 600-05 elastic recovery determinator developed by Haojey Co., Ltd. The yarns were then knitted into BC/S complex knitted fabrics on a circular knitting machine, after which their far infrared emissivity was evaluated by a far infrared emissivity tester. The anion count was also measured by the ITC 201A anion tester, and the fabric’s heat preservation ability was evaluated by a Thermo-Vision 900 Infrared Camera Analysis System.

FIGURE 1. The configuration of a rotor twister

FIGURE 2. BC/S complex yarn with a spandex expansion multiple of 3, a yarn wrap count of 2.5 turns/cm, and a rotor twister speed of 10000 rpm.

FIGURE 3. BC/S complex knitted fabrics. BC/S complex yarn with a 40D spandex expansion multiple of 3.5, a yarn wrap count of 3.5 turns/ cm, and a rotor twister speed of 8000 rpm.

1mm

Spandex

Bamboo charcoal

polyester textured

yarn


RESULTS AND DISCUSSION The Elastic Recovery Rate of the BC/S Complex Yarns Figures 4 to 8 illustrate that when the rotor twister speed is constant, the elastic recovery rate of the BC/S complex yarn decreases with the expansion multiple of the spandex. The spandex (core yarn) was expanded according to the expansion multiple, thus inducing crystallization and orientation. However, as the entropic elasticity of the spandex decreased, recovery of the core yarn became impossible. The elastic recovery rate of yarn with an expansion multiple of 3.5 was 15% lower than that of yarn with an expansion multiple of 1.5. Owing to the high speed of the rotor twister, the wrapping angle was small, resulting in a higher elastic recovery rate. Additionally, when the expansion multiple and speed of the rotor twister were constant, the wrap count of the yarn had little influence on the elastic recovery rate. Therefore, this paper concludes that within the three manufacturing parameters, it is the expansion multiple of the spandex that has the most obvious effect on the elastic recovery of the BC/S complex yarn.

FIGURE 4. The influence of the spandex’s expansion multiple and the yarn’s wrap count on the elastic recovery rate when the rotor twister speed is 4000 rpm.






The Influence of the Spandex’s Expansion Multiple on the Far Infrared Emissivity of Bamboo Charcoal Knitted Fabrics When atoms in a steady state are heated or exposed to electromagnetic wave irradiation, the electrons are excited by the external environment’s energy and thus stabilized. During this process, they release energy which can be absorbed by the knitted fabrics if the electromagnetic waves of the fabric are in the

same frequency range as those which excite the atoms. The knitted fabrics in turn release energy in the form of far infrared waves; hence, their far infrared emission properties.

Figure 9 denotes a total of seven knitted fabrics as follows: PET, BC, BC/S 1.5, BC/S 2, BC/S 2.5, BC/S 3, and BC/S 3.5. PET refers to PET knitted fabrics; BC is the 1.2% bamboo charcoal polyester knitted fabrics; BC/S 1.5 is BC/S complex knitted fabric with a spandex expansion multiple of 1.5; BC/S 2, BC/S 2.5, BC/S 3, and BC/S 3.5 signify BC/S complex knitted fabrics with expansion multiples of 2, 2.5, 3, and 3.5, respectively. In Figure 10, all of the specimens are the same as in Figure 9, except for the addition of a digit ahead each denotation. This digit represents the lamination number— the number of layers that compose the yarn. For example, 1PET designates a single-layer polyester knitted fabric, 2BC is a 2-layer 1.2% bamboo charcoal polyester knitted fabric, 4BC/S 1.5 is a 4-layer BC/S complex knitted fabric with a spandex expansion multiple of 1.5, etc. The lamination numbers are 1, 2, and 4 in order to compare the samples according to their multiple of two. The seven specimens in Figure 9 all have single lamination and the PET fabrics with 0.886 far infrared emission. The far infrared emissivity of the 1.2% bamboo charcoal polyester knitted fabric is 0.911, and the BC/S complex knitted fabrics have emissions of 0.918, 0.922, 0.924, 0.919, and 0.921. Thus, the polyester knitted fabric has the lowest far infrared emissivity, while the emissions from the rest of the specimens are all above 0.9.

According to observations made by a stereomicroscopy, far infrared emissivity increases with the expansion multiple of the spandex; when the multiple is over 3.0, the knitted fabric has a higher density, therefore decreasing the far infrared emissions. This phenomenon can be ascribed to the compaction of the fabric’s pores, which occurs when the expansion multiple exceeds a limited value, affecting the detection and measurement of thermal energy.

Figure 10 illustrates the relationship between the lamination number (1, 2 and 4) of the BC/S complex knitted fabrics and their far infrared emissions. When the expansion multiple of the spandex is 1.5 and above, the fabric's bamboo


charcoal content is higher than that of the polyester knitted fabric, as well as the bamboo charcoal polyester knitted fabric. The far infrared emission levels of the single-layer, double-layer, and four-layer BC/S fabric are 0.918, 0.909, and 0.905, respectively.

Theoretically, the far infrared emissivity is supposed to increase with the volume ratio of the emitting material; however, as our study shows, when the lamination number increased, the fabric’s far infrared emissivity decreased. Because materials emit different levels of far infrared rays at various temperatures, our specimens were heated to 34 °C and kept at this steady temperature throughout the procedures. As the lamination number increased, the thickness of the fabric also grew. The heater generated the same amount of energy during the same period of time, and although the thick BC/S fabric had more bamboo charcoal, it absorbed less of the heat produced by the heater. The far infrared rays were generated by the heat absorption of the fabric as the far infrared powders in the fibers transformed the heat energy into far infrared radiation. Because the BC/S fabric attracted less energy, the amount of far infrared ray emission decreased. Therefore, based on these results, it was concluded that the greater the lamination number of the BC/S fabric, the lower the amount far infrared emissions.

FIGURE 9. The influence of the spandex’s expansion multiples on the far infrared emissivity of BC/S fabric when the rotor twister speed is 8000 rpm and the wrap count of the yarn is 3.5 turns/cm.

FIGURE 10. The influence of the multi-layered fabrics’ expansion multiples on the far infrared emissivity of the BC/S fabric when the rotor twister speed is 8000 rpm and the wrap count of the yarn is 3.5 turns/cm.

The Influence of the Spandex’s Expansion Multiple on the Anion Count Figure 11 reveals that the polyester knitted fabric has the least number of anion-232 anions/cc-which is 36 less than the 268 anions/cc in the bamboo charcoal polyester knitted fabric. The greater the spandex’s expansion multiple is, the higher the anion count in the BC/S complex knitted fabric. When the expansion multiple is over 3.0, the number of anions in the BC/S fabric starts to drop. Excessively large spandex expansion multiples lead to too many compact loops made by the needle, creating a fabric that is woven too tightly to releasing anion; subsequently, the number of anions decreases.

Figure 12 depicts the influence of the lamination number on the anion count in the same seven specimens. Regardless of the polyester fabric samples’ lamination number, they have the least number of anions. The bamboo charcoal polyester fabric has comparatively more anions, illustrating that the addition of bamboo charcoal minimally increases the anion count. When all the samples of fabric have a lamination number of 2, more anions are present. The BC/S fabric with an expansion multiple of 2.5 shows a particular increase in anions; however, when the expansion multiple is 3.0 or 3.5, the fabric’s anion count starts to decline.

When the lamination number is 4, the amount of anions released by the polyester fabric, bamboo charcoal polyester fabric, and the BC/S complex knitted fabric declines. Although the thick knitted


fabric has a larger quantity of bamboo charcoal per unit volume, the multi-layer fabric covers itself and excess fabric lamination prevents the anions from surfacing from within; thus, the anion count decreases.

FIGURE 11. The influence of the fabrics’ expansion multiples on the anion count of the BC/S fabrics when the rotor twister speed is 8000 rpm and the wrap count of the BC/S yarn is 3.5 turns/cm.

FIGURE 12. The figure shows the influence of the multi-layered fabrics’ expansion multiples on the anion count of the BC/S fabrics when the rotor twister speed is 8000 rpm and the wrap count of the BC/S yarn is 3.5 turns/cm.

The Influence of the BC/S Complex Knitted Fabric’s Expansion Multiple on the Heat Preservation Properties of the Far Infrared Rays As a rule, atoms or molecules inside of a material have a certain vibration frequency produced by electromagnetic waves which keeps them constantly moving. When this frequency is in the same as that of molecules in another material, the material will absorb the energy from the electromagnetic waves and further transform it into heat [21]. Therefore, a measurement of the seven fabrics’ heat preservation properties was conducted. The fabrics in Figure 13 are the same as those denoted in Table I; however, in front of each denotation is an A or B. A represents measurement “after” exposure to a halogen lamp, whereas “B” refers to measurement “before” halogen lamp exposure.

As can be seen in Table I and Figure 13, the surface temperatures of the specimens before exposure to the halogen lamp for 10 minutes range from 24.46°C to 24.94 °C. After halogen lamp exposure for 10 minutes, the surface temperature of the polyester knitted fabric is the lowest (29.1 °C), while the surface temperature of the bamboo charcoal polyester knitted fabric is 37.3 °C, and the BC/S fabrics’ (with expansion multiples of 1.5, 2.0, 2.5, 3.0, and 3.5) range from 37.3 °C to 43.15 °C. After the specimens are exposed to halogen light for 10 minutes, the surface temperature of the polyester knitted fabric only increases 4.48 °C, while that of the bamboo charcoal polyester fabric and the BC/S fabric increases 12.54°C to 18.32 °C. These results demonstrate that after the bamboo charcoal absorbs energy, it releases far infrared rays and accordingly generates a thermal effect. Thus, when compared to the polyester knitted fabric, the bamboo charcoal knitted fabric absorbs more heat and generates a stronger thermal effect.

TABLE I. The influence of different spandex expansion multiples of the BC/S complex knitted fabric on the preservation of far infrared ray heat.

Testing Items PET BC BC/S

1.5 BC/S 2 BC/S

2.5 BC/S 3 BC/S

3.5

Surface temperature (°C) B 24.62 24.76 24.7 24.94 24.46 24.49 24.83

A 29.1 37.3 40.34 41.74 42.75 43.0 43.15

Temperature difference (°C)

4.48 12.54 15.64 16.80 18.29 18.51 18.32


CONCLUSIONS In this research functional BC/S complex yarns and knitted fabrics using an originally designed rotor twister were produced. The BC/S yarn yields an elastic recovery rate of over 93% when the speed of the rotor twister is between 4000 and 12000 rpm, the spandex expansion multiple is 1.5, and the wrap count is 2 turns/cm. However, the elastic recovery rate decreases 4.6 % to 14.2% when the expansion multiple increases to 3.5 and the wrap count is raised to 4.5 turns/cm. The far infrared emission of the BC/S fabric increases with the expansion multiple. When the expansion multiple is over 3.0 and the laminated count is one, the fabric has a far infrared emissivity of 0.92. As for the measurment of heat perservation qualities, the BC/S complex knitted fabric has a 12.54°C to 18.32 °C higher surface temperature than the PET knitted fabric after being exposed to a halogen lamp for 10 minutes. This provides the evidence needed to confirm that BC/S fabric first absorbs energy, and then releases far infrared rays, generating a thermal effect which can retain heat. The anion count of the BC/S complex fabric is 356 anions/cc, regardless of the lamination number; in fact, the anions stabilize with an increase in the lamination number. The BC/S complex yarn fabricated in this research can be fabricated with different structural properties by changing the manufacturing parameters, thus providing reference for manufacturers. There is abundant bamboo in Taiwan, enabling future development and promotion of fancy spandex yarns or textiles with composite functions which can enhance BC/S complex fabric. REFERENCES [1] Baley, C., Analysis of the Flax Fibres Tensile

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[22] C. H. Chiou, Master’s thesis, FCU, (2002). AUTHORS’ ADDRESSES Chin Mei Lin Department of Fashion Design Asia University Taichung 41354, Taiwan R.O.C. Jia Horng Lin, Ph. D. Laboratory of Fiber Application and Manufacturing Department of Fiber and Composite Materials Feng Chia University Taichung 40724, Taiwan R.O.C. School of Chinese Medicine China Medical University Taichung 40402, Taiwan R.O.C. Email: [email protected]

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Evaluation of the Function and Manufacturing Technique of ... · Evaluation of the Function and Manufacturing Technique of Bamboo Charcoal Complex Yarns and Knitted Fabrics Chin Mei