Blended yarn refers to two or more different varieties or different characteristics of the fiber blended yarn. Through blending, the excellent properties of different fibers can be brought into play, and the varieties can be increased to improve the wearability of textiles. The nature of the blended yarn, of course, depends on the properties of the fiber components, but also depends on the blending ratio. Each fiber group in the blended yarn will affect the law of fiber internal and external transfer in the twist triangle, resulting in the trend of uneven radial distribution of different fiber components. In terms of the feel, appearance, style and durability of the fabric, the fiber located on the surface of the blended yarn plays a decisive role, for example, when more fine and soft fibers are distributed on the surface, the fabric feel will be soft and delicate; When more coarse and rigid fibers are distributed on the surface, the fabric feels rough and rigid. If more fibers with high strength and good wear resistance are distributed on the surface, the fabric will inevitably be durable.

Factors affecting radial distribution of fibers in blended yarn

In the twisting triangle area, the fiber internal and external transfer must overcome the resistance of the surrounding fiber, and the resistance of the surrounding fiber and the centripetal pressure of the fiber are related to the physical properties of the fiber.

(1) Fiber length

Long fibers tend to be distributed in the inner layer of the yarn, and short fibers tend to be distributed in the outer layer of the yarn. This is because the long fiber is easy to be held at the same time by the front roller and the lower end of the twist triangle area, and under the action of spinning tension, the force is larger, so it is transferred inward. Short fibers are not easy to hold at both ends at the same time, and under the action of spinning tension, the centripetal pressure is small, so it is not easy to transfer inward.

(2) Fiber fineness

The flexural stiffness of the fine fiber is small and easy to bend. Under the action of centripetal pressure, the fine fiber is easy to transfer inward and distribute in the inner layer of the yarn. Coarse fibers, on the other hand, tend to be distributed in the outer layer of the yarn.

(3) Fiber cross-section shape

The bending stiffness of the special-shaped fiber is large, and it is not easy to bend. Under the action of centripetal pressure, it is not easy to transfer inward and distribute in the outer layer of the yarn. Circular fibers, on the other hand, are easily transferred inward and distributed in the inner layer of the yarn.

(4) Initial modulus

The fibers with high initial modulus tend to the inner layer of the yarn, and the fibers with low initial modulus tend to the outer layer of the yarn. Because the initial modulus of the fiber is high, in the case of the same elongation, the spinning tension is large, the centripetal pressure is also large, and it is easy to transfer inward.

(5) fiber crimp and surface state

The crimp and surface state of the fiber will affect the transfer resistance between the fibers, so the fiber with a large friction coefficient is not easy to transfer inward and distribute in the outer layer of the yarn.

The radial distribution of fibers with different properties is an important issue in the structure of blended yarns. If these laws are properly applied, better product properties can be obtained and special yarns can be designed. For example, in polyester/cotton blended yarn, the selection of thick and short polyester can make the polyester more distributed in the outer layer of the yarn, the fabric made of good wear resistance, feel more smooth; In the polyamide blended fabric, the selection of thicker and shorter polyamide than the fiber to be blended can make the polyamide more distributed in the outer layer of the yarn, give full play to the characteristics of excellent wear resistance of polyamide and make the fabric wear resistant; Another example is wool/viscose blended yarn, the choice of viscose fiber is thinner and longer than wool fiber, which is conducive to yarn strength and dry, and because the wool is distributed in the outer layer, it gives the fabric a good wool shape.

Common moisture regain of blended yarn

The common moisture regain of blended yarn can be calculated according to the weighted average of the common moisture regain of each component fiber and the blending ratio.

The formula is as follows:

Where :Wk -- the common moisture regain of the blended yarn;

W1, W2... -- DiYi and the second...... in blended yarn Common moisture regain of fiber:

P1, P2... -- DiYi and second kinds of blended yarn.... · Dry weight blend ratio of fiber.

For example: polyester/cotton (65/35) common moisture regain

Common moisture regain: polyester ~0.4%, cotton ~8.5%, calculated as follows:

The common moisture regain of polyester/cotton (65/35) is 3.2%