Quality Characteristics Of Wool Fibers

wool fiber is the deformation of the skin of sheep, excellent warmth, mostly used in autumn and winter clothing, but easily eaten by insects. Textile wool fibers are mainly sheep's wool, usually called wool, or wool fiber, or wool for short.

Wool is a natural protein fiber, the main component is called keratin protein composition, keratin content accounted for 97%, inorganic 1 ~ 3%, the main elements of wool keratin is C, O, N, H, S.

Wool Fiber
1. the linear density of wool
The linear density of wool fiber has a great relationship with various physical properties. Generally, the finer the wool, its linear density is more uniform, the strength is higher, the curl is more, the scales are dense, the luster is soft, the fat and sweat content is high, but the length is short. Therefore, the linear density is an important indicator of the quality of wool. The small linear density of wool fiber is beneficial to the yarn strength and yarn strand dryness. But too fine wool spinning more prone to defects. The linear density of wool fiber is also closely related to the quality and style of wool fabric.

Commonly used indicators of wool thread density are average diameter, quality count and Tex number. If the distribution of fiber diameter can be obtained, the coefficient of diameter variation can be used to represent the unevenness of the linear density of a batch of wool.

The diameter of wool fibers varies greatly, with fine wool about 7 μm in diameter and coarse wool up to 240 μm in diameter. Even on the same wool, the diameter difference can reach 5 ~ 6μm. The reasons for the difference in wool thread density are very complex, including the breed, age, sex, wool growth site and feeding conditions of sheep.

In the same sheep, with the capillary of the shoulder, the hair of the body side, neck and back is the second, the hair of the front neck, buttocks and abdomen is thicker, and the hair of the throat, lower leg and tail is thicker.

Quality count is an indicator of wool thread density that has been used for a long time in the wool industry. At present, commercial transactions, grading in the wool textile industry, the formulation of the strip process, are based on quality count as an important basis. In the last century, the quality of wool has always been evaluated by sensory methods in commerce. An international conference at the end of the last century, according to the requirements of spinning equipment, spinning technology and wool quality at that time, called the number of English combed wool yarn counts that various linear densities of wool could actually be spun as quality counts, in order to express the quality of wool. With the development of science and technology, the improvement of spinning methods, the continuous improvement of textile quality requirements and the progress of fiber performance research, wool quality count has gradually lost its original meaning. At present, the quality count of wool only represents the fineness index of wool with an average diameter within a certain range.

2. the length of wool fibers
Wool fiber due to the existence of natural crimp, its length can be divided into natural length and straight length. Under the natural curl of the fiber bundle, the straight line distance between the two ends is called the natural length, which is generally used to indicate the length of the hair cluster. The length of the wool fiber after the curl is removed and straightened is called the straightened length. Straightening length is used in wool spinning production.
The length of wool fiber varies greatly with the breed, age, sex, wool growth site, feeding conditions, shearing times and seasons of sheep. Generally, the length of domestic fine wool is in the range of 5.5~9cm, the length of semi-fine wool can reach 7~15cm, and the length of coarse wool is 6~40cm. On the same sheep, the hair on the shoulders, neck and back is longer, and the hair on the head, legs and abdomen is shorter.
When the linear density of wool fiber is the same, the wool with long and neat fiber and less short hair content, yarn strength and strip dry are better. The length of wool is also the basis for determining the spinning special number and selecting process parameters.

the curl of 3. wool
The curl of wool fiber is related to the form of wool quilt, fiber linear density, elasticity, cohesion and felting. Crimp also has a great influence on yarn quality and fabric style.
The curls of wool fibers are deep and shallow. According to the depth of the crimp, that is, the wave height, and the length, that is, the wave width, the crimp shape can be divided into three categories, one is weak crimp. The characteristic of this kind of crimp is that the arc of crimp is less than half of the circumference, and the length direction of the fiber is relatively straight, and the number of crimp is less. Most of the curls of semi-fine hair belong to this type. 2 is often curled. It is characterized by a curled waveform that is approximately semicircular. Most of the curls of fine hair belong to this type. 3 for strong curl. It is characterized by a higher amplitude of the crimp. Curl number more. Abdominal hair of fine wool sheep mostly belong to this type. Often curly wool is used for combed wool spinning, spinning yarns and fabrics with elastic and smooth surfaces. Strong curly wool is suitable for coarse carded wool spinning, spinning surface hair plump, feel good, elastic wool.

The index that indicates how much wool fiber crimp is the crimp number; the index that indicates the depth of crimp is the crimp rate; the index that indicates the crimp elasticity has the crimp recovery rate and the crimp elasticity recovery rate. Their definition, calculation formula and test method will be discussed in the fourth chapter of the chemical fiber crimp test content.

Generally, the curl number of fine wool is 6~9/cm.

4. wool fiber
The moisture absorption of wool fibers is expressed by moisture regain. The moisture absorption of wool is strong in common fibers. Under general atmospheric conditions, the moisture regain is 15% ~ 17%.

5. WOOL FIBERS
The tensile strength of wool fiber is lower than that of common natural fiber, and its breaking length is only 9~18km. Generally, the fineness of wool is fine, and the less the medulla layer, the higher the strength.
The elongation ability of wool fiber after stretching is large in common natural fibers. The elongation at break can reach 25% ~ 35% in dry state and 25% ~ 50% in wet state. After the external force is removed, the elastic recovery ability of elongation is better than that of common natural fibers, so the fabric woven with wool is not easy to produce wrinkles and has good wearability.

6. Wool Fiber
Wool fibers are more acid-resistant than alkali-resistant. The relatively dilute acid and concentrated acid will not damage wool for a short time, so acids are commonly used to remove plant impurities such as grass clippings in raw wool or tweed blanks. Organic acids such as acetic acid and formic acid are important accelerants in wool dyeing. Alkali will make wool yellow and dissolve.

Wool Fiber
(1) the moisture absorption is good, the common moisture regain rate is 15 ~ 17%, the limit moisture absorption rate can reach 40%, and the moisture absorption is better than cotton.
(2) wool felting: wool fiber and its fabric under hot and humid conditions, the mechanical force, so that the wool aggregate gradually shrink tightly, and interspersed with entanglement, cross-felting, this nature is called wool felting.

Falling is one of the important characteristics of wool, wool fabric through felting, can improve the fabric thickness and tightness, produce neat suede, beautiful appearance, feel full, improve warmth. However, some varieties, such as worsted fabrics and woolen sweaters, require clear lines and stable shapes, and must reduce felting. The method of destroying the scale layer or scale covering is usually used.

(3) plasticity: wool puffed under hot and humid conditions, loss of elasticity, under the action of external force, pressed into various shapes and rapid cooling, release the external force, to press into the shape can be for a long time unchanged, this performance is called plasticity. Plasticity can produce two results in processing.

A, tentative: after shaping by higher temperature than heat treatment of steam or water, so that the fiber back to the original shape.
B, Yongding: after the shaping of the fiber in the steam treatment for 1~2 hours, can only make the fiber slightly shrink the basic shape unchanged, this phenomenon is 4 Yongding.
(4) wool fiber elasticity is good, is a natural fiber in the elastic recovery of good fiber.
(5) the proportion of wool is small, between 1.28 and 1.33.
(6) good insulation, is a poor conductor of heat.
(7) The strength of wool is lower than other fibers, 1.5g/D, but the elongation at break can reach 40%. Because wool is thicker than other fibers and has higher elongation at break and excellent elasticity, wool fabrics are stronger than other natural fibers in use. LzJTnypZX

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