(Xi¡¯an Polytechnic University) 

 

To understand the knitting performance of bamboo carbon fiber and cotton blended yarn knitted fabric, the article tested the performance of bamboo carbon fiber and cotton fiber blended yarn. Taking the bamboo carbon fiber/cotton 40/60 14.5 tex ¡Á 2 as an example to weave four kinds of basic structures in the flat knitting machine. Bamboo carbon and cotton blended yarn has much hairiness; we can improve its cluster performance through wax treatment. As the bamboo fibers belong to the low-strength high-elongation-type of fiber, we need to adjust the feeding tension and drawing-off tension when weaving; when the yarn tension is controlled 2 cN-3 cN, the basic performance is in line with quality standards of knitted fabric.

 

Knitted products are the textile products that developed rapidly over the past 20 years, the annual growth rate of international knitted goods consumption and trade volume have reached 5%. The annual growth proportion of knitted products consumption in China is above 10%, of which, the consumption growth rates of T-shirt, underwear and other knitted products are higher than the average consumption level of various types of clothing. The knitted products that are weaved by flat knitting machine have a wide selection of colors and designs, which are popular with consumers. These products not only have wide markets in China, but also are important component of exporting for earning foreign exchange of China¡¯s textile industry. At present, China¡¯s flat knitting machine products focus on color and style, these products have been significantly increased in aspect of the product series and fashion-oriented, but compared with other textiles, and its function has a significant gap. Therefore, accelerating the development of new knitted products, enhancing value-added of knitting has become a future trend. The development of bamboo carbon fiber offers more choices for design and developing of knitting products. Bamboo carbon fiber is a new type of function fiber, which has the launch of anion, far infrared and anti-bacteria functions.

 

1 The Performance Index of Bamboo Carbon Fiber Blended Yarn

Using the bamboo carbon fiber of Shanghai Nande and cotton blended yarn, the blending ratio is 40/60 (bamboo carbon fiber/cotton), yarn fineness is 14.7 tex.

 

The testing results of strength and elongation performance of bamboo carbon fiber/cotton 40/60 14.7 tex are showed as follows.

        Project                                Parameter

Breaking strength/cN                           162.9

Breaking strength CV/%                  5.85

Breaking tenacity/cN?tex-1                     11.0

Breaking tenacity CV/%                  5.86

Elongation at break /mm                     13.5

Elongation at break CV/%                   16.44

Breaking elongation/%                           5.39

Breaking elongation CV/%                   16.44

The strength and tensile break performance of yarn are important testing projects for the quality of yarn. From the above testing results, we can see that the yarn strength is lower. Therefore, the bamboo carbon fiber is a fiber with low strength and high tensile break performance.

 

1.2 Hairiness

The hairiness testing results of bamboo carbon fiber/cotton 40/60 14.7 tex are showed in Table 1. (The hairiness value H is 9.05, hairiness H X-R is 0.84, CV of hairiness value H is 2.44%)

From Table 1 we can see that, if the hairiness length is longer, its proportion is smaller. If the hairiness length is longer, it will greatly harm the weaving performance of yarn, especially the hairiness length is longer than 2 mm, and it is easier to tangle with each other, so we should control the hairiness.

The flat knitting machine with certain mode is only suitable for weaving the knitting yarn that has certain linear density range. The relationship between the machine mode and yarn linear density is showed as follows:

T_t=K/E²                       £¨1£©

T_m=E²/K¡¯                     £¨2£©

In the formula,

E----Machine model £¨each pin /25.4 mm£©;

Tt ----Yarn linear density£¨tex£©£»

K,K¡¯----The constant that is suitable for processing yarn linear density;

K,K¡¯ is related to physical and mechanical properties of yarn, the tension, flattening degree and knots. According to practice, K£½7,000-11,000. If K value is greater than 11,000 (K>11), it is hard to weave; if K value is smaller than 7,000 (K<7), and the fabric is too thin. According to the formula (1):

When K value is 7,000,

Tt=7000/16²£½27.3 tex

When K value is 11,000,

Tt=11000/16²£½43 tex

Therefore, the line density range is 27.3 tex - 43 tex. The line density of single yarn is 14.7 tex, we can use two yarn feeding to weave.

 

Bamboo carbon fiber has a variety of health-care performance, using 14.7 tex ¡Á 2 bamboo carbon fiber/cotton blended yarn to increase the wear behavior of fabric and it is suitable for wearing next to the skin. According to the knitted fabric¡¯s characteristics, we use the basic weft plain stitch, 1+1 rib construction, full needle rib and Ponte-roma to weave. The samples are showed in Fig.1.

Bamboo carbon fiber/cotton blended yarn has much hairiness, we use the waxing process to improve its cluster performance and soft and smoothness of the yarn, reduce the friction during weaving process, reduce the knitting load, thereby the process of weft-knitted loop formation is easy to produce. After the waxing process, the friction factor reduced 30% - 40% during weaving.

 

We should reasonably adjust the feeding tension and drawing tension when weaving, and adjust the corresponding position relationship between needle and sinker. Because of two plied yarn, we need to adjust the yarn tension and avoid knit faults. Especially for the plain knit fabric, uneven yarn twist easily led to appear the skewing phenomenon. Through the testing, the yarn tension should control in 2 cN - 3 cN.

 

We test the vertical density, horizontal density, thickness and gram heavy of the specimen, the testing results are showed in Table 2.

From a point of the appearance of the fabric view, the fabric has flat appearance, distinct grain, and the basic performance is in line with the quality of knitted fabric.

 

Through testing the organizational design and weaving technology of bamboo fiber knitted products, we can conclude that the weaving elements of bamboo carbon fiber/cotton blended yarn. Selecting bamboo carbon fiber/cotton blended yarn to develop four kinds of knitting fabrics, which are weft plain stitch structure, 1+1 ribbing structure, full-needle rib structure and Ponte-roma structure. When weaving, the yarn tension should be controlled in 2 cN - 3 cN. The appearance of the fabric is smoothness and its basic performance is suitable for quality standard of knitting fabric. Bamboo carbon fiber yarn has better weaving performance, it is suitable for development of bamboo fiber blended knitted fabric, and is in line with the conception of health care and fashion concept, which has broad prospects of development.

 

[1] Zhu Ping. Functional Fibers and Functional Textiles£ÛM£Ý£® China Textile Press£¬ 2006: 2-5.

[2] Hu Weiwei. Concerned about the New Type of Functional Fiber£ÛJ£Ý£® China Fiber Detection£¬2005£¨S1£©: 54-56.

[3] Meng Jiaguang. The Design and Production Process of Sweater£ÛM£Ý£® China Textile Press£¬ 2006: 4-5.

[4] Zhang X.P. Bamboo Fiber Textile in Japan£ÛJ£Ý£® World Forest Dynamics£¬ 2002£¨6£©: 12.

[5] Fu M.Y. Improvement in bamboo research in China and the Utilization of Bamboo Habitats£ÛJ£Ý£® Bamboo Academic Research£¬2002£¨6£©: 56-57.

[6] S. M. M. Hasnin£¬D. Biswas£¬M. W. Sheikh and M. Ali£¬Particleboard Making Characteristics of Three Bamboo Species£ÛJ£Ý£® Bangladesh Journal of Forest Science£¬1999£¬26£¨2£©: 19-22.

Cotton Textile Technology English Version - 2010 / 2

(2010-05-05)