Physical Properties And Application Of Yak Nap

Yaks, also known as Tibet cattle and horsetail cattle (tail like ponytail), belong to the mammalian family, ruminant livestock, usually growing at altitudes of 2100~6000m altitudes. Yak hair is thick and thick, and its inner layer is short and thin, that is, yak hair. Its color is mostly black, dark brown or black and white mixed, pure white very few. There are dense hairs on the lower abdomen, shoulders, strands and flanking areas. Yak is strong and strong. It is good at climbing mountains, crossing mountains, wading across rivers, and carrying heavy load. It has been named "plateau boat" since ancient times.

Yak is a unique cattle species in China. Except for Asia, it has no natural distribution in other parts of the world. Yaks are mainly concentrated in the two foothills of the Himalaya mountains and the Kunlun mountains and their extended areas. At present, there are more than 1400 Yaks in the world, and about 13 million in China, accounting for more than 92% of the world. The annual yak yield per year is about 0.75~1.5kg and 0.5kg respectively. The average amount of cashmere in raw yak is 70%, about 30% of coarse hair and short hair. Only nine countries in Asia are produced in the world.

1 yak velvet physical property

1.1 section morphology

　　 Yak hair The structure of yak hair is similar to that of sheep hair. Yak hair is elliptical or nearly round. Fine villi are composed of scales and cortical layers, mostly composed of scales, cortical layers and medullary layers. The two type hair is between the hairs and the coarse hairs, with a discontinuous medullary layer. Yak hair with different fineness is not obvious and its shape is different. The scales of fine velvet are like flowerpots, and one is stacked on the hair shaft, and the scales are smaller. The cortex is more developed, consisting of two cortical cells, positive and negative. The crystalline area of positive cortical cells is small, so the hygroscopicity is high, the hygroscopic expansion rate is large, and the crystalline region of the cortical cells is larger, so the hygroscopicity is small, and the expansion rate after hygroscopic decreases. There is no continuous medullary layer in the fine villi, only 3.69% of the intermittent punctate medulla and 96.31% of the medullary layer. The chemical structure of yak hair is similar to that of sheep hair. It consists of 18 amino acids. The content of various amino acids is different from that of raising condition and age.

1.2 fiber fineness and length

The fineness and length of yak hair vary with the different parts of the growing area and cattle body. The finest fibers of yak hair can be 7.5 m, most of them are between 30~35 and m, with an average fineness of about 18 m. In fineness distribution, the amount of 30~40 and M fibers is large, and the fineness of the fibers is difficult to remove in combing, resulting in a higher rate of coarse hairs. Therefore, in the standard, 35 micron m is defined as the fineness of yak hair and wool, that is, 35 or less m is called velvet, and that of more than 35 m is gross and yak hair can reach 100 micron. There are also differences in the distribution of different fineness on Yak body. In the back of yak, there are more cashmere content and fineness of the cashmere fiber; the plush content of the yak is the second, but the fineness is coarsely, while the abdominal cashmere is less and the fineness is in the middle. In terms of a certain pile fiber, the unevenness of the upper, middle and lower segments is larger, the upper part is the warm season, and the grass is more abundant, and the fineness is slightly thick. The middle section grows well in the warm and cold transition period, and the fineness is finer. The unevenness of the upper, middle and lower segments of the 1 fibers reflects the imbalance of perennial nutrition supply of yaks. The length of yak hair is different from that of the growing area and the different parts of the cattle. On the same yak body, the velvet fibers on the back are the longest, about 60mm, and the femoral part is about 31mm, the abdomen is the shortest, usually only about 26mm, and the average length is 36mm.

1.3 curling

The yak hair has less crimp and irregular curl shape. The crimp number is 6.20 /25mm, the crimp rate is 22.71%, the crimp elasticity is 89.43%, the residual crimp rate is 20.31%, the crimp elastic rate indicates the recovery ability of the crimp after the fiber is stressed, and the crimp rate indicates the durable fastness of the crimp. Because of the higher crimp and crimp elasticity, yak hair has better cohesive force, and its product is plump and soft, and it is comfortable to wear. As a result, the fabric feels better in its handle, elasticity and fullness than Australian wool.

1.4 friction properties

Yak hair is less resistant to wear than cashmere and wool, but better than camel hair and seahorse hair. The friction coefficient of yak hair is higher than that of 70 wool, but it is better than cashmere. It is not easy to tear off with hand, and it is also better to be spherical. {page_break}

1.5 specific resistance

Generally speaking, when the resistance test value is kept below 1 * 108~10 * 108 ohma, the spinnability of the fiber is the best, and when the 10 x 108 ohm is high, it is difficult to carry out the spinning. At this time, some measures must be taken to reduce the specific resistance value so as to increase the spinnability. Yak hair is prone to electrostatic phenomenon, and its specific resistance decreases with the increase of moisture regain. Because the electrostatic phenomenon of yak hair is more serious, it is easy to scatter the fibers, the bars are hairy, and the filament winding parts cause breakage. The average moisture regain of yak hair is 14%. When the moisture regain of yak is higher than 20%, the specific resistance can be reduced to less than 2.5 * 108 ohms.

1.6 mechanical properties

The breaking strength of yak hair fiber is 5.15cN, the elongation at break is 45.86%, and the breaking length is 15.75km. The moisture absorption rule of yak hair is similar to that of wool. When moisture absorption begins, moisture absorbency is faster, then slowly, and reaches equilibrium. The bending fatigue resistance of yak hair is worse than that of wool and other special animal villi. Under repeated bending action, the macromolecules in the fibers are continuously stretched and bent, which will eventually make the structure loose, damaged or even broken. Because of the frequent movement of human arms, the damage to the axilla of yak sweater often occurs. The color of yak hair is mostly black, brown, yellow and gray, and pure white is less. Its gloss is the worst in special animal hair. The warmth retention property of yak hair is the same as that of cashmere, and is better than that of sheep hair. The insulation rate of yak hair is 57%. Inorganic acids (such as sulphuric acid) and organic acids have less damage to yak hair than that of cashmere. This shows that yak hair has certain resistance to acid, but strong acids can still cause damage to them when the concentration is high and the temperature is high. Yak hair is alkaline resistant, which is only better than cashmere. Its resistance to oxidizing agents and reducing agents is slightly better than that of cashmere. Chemical processing should pay attention to processing conditions to reduce the damage of yak hair fiber.

　 2 products of yak and nap purpose

According to the properties and physical indexes of yak hair, wool spinning and worsted spinning systems can be used, and the combed cotton spinning system (the so-called semi combed spinning system) can be used. Yak wool blended with wool can be used for spinning on worsted spinning system for weaving worsted fabrics. Pure spinning or wool mixing can be used for spinning and processing woolen or knitted products on the combed spinning system. The yak fleece spinning or blending with other fibers can be used for spinning and processing woven or needle spinning products on the cotton spinning system.

Yak products can be divided into two categories: knitting and weaving. Knitted products include yak sweater, yak wool underwear, hat, socks, shoulder protector, waist protector, kneecap, scarf, etc. the ingredients can be pure yak hair or yak hair and cotton, wool, silk, Apocynum and far-infrared fiber blended. This kind of product has the characteristics of soft handle, warmth retention, Kizawa Soya, generous style, high grade and elegance, and some products also have health care function. Woven products can also be divided into two types: wool and cotton, and the wool type is divided into worsted and woolen products. Worsted products are blended with yak and cotton or silk or chemical fiber, and are processed into shirts, Western-style clothes and other fabrics. Yak wool and wool, sheep cashmere or wool type chemical fiber can be processed into yak wool blended worsted fabric. There are woollen blended woollen woollen fabrics, yak hair blended fancy cloth, herringbone tweed, yak velvet blended coat, woollen coat, imitation fur coat, short woolen coat, yak hair hunting suit, yak velvet blanket (such as blended tourist blanket, Blended Colored carpet, blended jacquard blanket, snowflake blanket, upright blanket, etc.), yak hair plush, woolen blanket blanket, etc. Yak velvet fabric is soft, slippery and warm, with a rough style, a full plump skin and a dull color. Most of them are camel, yellow, dark red and other colors.

　　 3 Summary

Yak hair is soft, fluffy and warm. It is a valuable textile material for special animal fibers. Due to the short history of development and utilization of yak hair, efforts should be made to develop and apply it so as to make better and more efficient use of this precious textile resource. According to the current actual situation, the development direction of yak products should be high mixing ratio, high-grade and deep processing.