The factors affecting the strength and elongation of the yarn are mainly the two aspects of the fiber properties and yarn structure of the yarn. The strength and elongation of the blended yarn are closely related to the difference in the properties of the blended fiber and the blending ratio. Temperature and humidity The external factors such as the strong test conditions have the same effect on the strength and elongation of the yarn as the fiber.


Fiber properties
01

Length of fiber, linear density:

When the fiber length is long and the fiber is fine, the frictional resistance between the fibers in the yarn is large, and it is not easy to slip off, so the yarn strength is high.


When the fiber length is good and the fiber is fine and uniform, the yarn is evenly dried, and the weak ring is less and not significant, which is beneficial to the improvement of the yarn strength.


Fiber strength:

When the strength and elongation of the fiber are large, the strength and elongation of the yarn are also large; the fiber strength and the unevenness of the elongation are small, and the yarn strength is high.


Surface friction properties of the fiber:

When the friction coefficient μ of the fiber surface increases, the sliding resistance between the fibers is large, the slip length lc decreases, the proportion of the number of slip fibers decreases, and the yarn strength increases. Increasing the number of crimps of the fibers increases the sliding resistance between the fibers.


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Yarn structure
02

(1) The influence of the structure of the short fiber yarn on its strength and elongation is mainly reflected in the twist.

When the twist coefficient increases, the frictional resistance between the wood fibers increases, which is not easy to slip off. This is a strong positive side for the strength of the short fiber yarn, but as the twist coefficient increases, the fiber tends to become larger and larger, and the fiber strength increases. The effective component force in the axial direction of the yarn is reduced, and the fiber breakage in the yarn is not uniform at the same time, and the increase in the yarn diameter when the fiber is inclined is an unfavorable factor for the relative strength of the yarn.


(2) The impact of the joint stock

The cooperation of the single yarns makes the plyyarn strips evenly distributed, and the single yarns have contact between them, so that the cohesion between the outer fibers of the single yarns is increased; the strength of the strands is greater than the sum of the strengths of the individual yarns.


(3) Arrangement of fibers in spun yarn

The strength of the rotor yarn is lower than that of the ring yarn: in the rotor yarn, there are more irregularly arranged fibers, such as folding, curling, and ringing, and there are fewer normal transfer fibers, resulting in poor fiber and fiber cohesion, and more slipping fibers during stretching. .


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(4) bulked yarn

The tensile breaking strength of the bulked yarn is smaller than that of the conventional yarn, and the elongation at break is large.

Structural characteristics: heat-shrinking treatment is carried out by mixing two fibers having a large difference in heat shrinkability, so that the highly shrinkable fibers in the sliver are sufficiently retracted, and at the same time, the normal fibers having small heat shrinkage are forced to compress and wrinkle along the axial direction of the yarn. Showing bulk properties.


Stretching and breaking process: The number of fibers that bear the external force when the bulked yarn is stretched is small, and the tension of each fiber is not uniform. When starting to stretch, only a small portion of the fiber bears the external force, and the other fibers are loose and slack. After the current fiber is broken, the latter fiber is stretched and bears the tensile force until it breaks.


(5) textured yarn and elastic yarn

Each of the fibers is in the form of a coil spring or a curled oriented buckling curve by various shaping methods.

In the course of starting a certain stretch, the fiber is actually gradually stretched under the condition that the tensile force is increased little, and it has a high elongation at break.

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