What are the specific effects of temperature on the quality of Polyester DTY?

Temperature has many specific effects on the quality of Polyester DTY (polyester stretch deformation yarn) during its production process. The following is the manifestation in the two key links of spinning and stretch deformation:

Spinning link
Melt fluidity: The spinning temperature is generally controlled at 280-290℃. If the temperature is too high, the viscosity of the polyester melt will decrease due to overheating, and the fluidity will be too strong, making the spun yarns uneven in thickness and even floating, which seriously affects the uniformity of the fiber's linear density. If the temperature is too low, the melt viscosity will increase and the fluidity will deteriorate, which will cause spinning difficulties, hairy yarns, broken ends, and rough fiber surface, affecting the appearance quality.

Molecular weight change: Too high a temperature will accelerate the thermal degradation reaction of the polyester melt, resulting in a decrease in molecular weight, and a decrease in the mechanical properties of the fiber such as strength and wear resistance. On the contrary, if the temperature is too low and the polymerization reaction is incomplete, the molecular weight distribution will also become wider, which will also affect the fiber quality.
Crystallinity: The appropriate spinning temperature helps to control the initial crystallinity of the fiber. If the temperature is too high and the crystallization speed is too fast, larger grains will be formed inside the fiber, making the fiber hard and brittle, and the flexibility will be reduced. If the temperature is too low, the crystallinity is insufficient, and the fiber is prone to dimensional changes in subsequent processing, affecting the processing performance and the quality of the final product.

Stretching deformation link
Thermal setting effect: During the stretching deformation process, the temperature of the first hot box is usually 180-220℃. If the temperature is too high, the fiber will become stiff and feel worse due to excessive heat setting. It may also cause the fiber color to turn yellow, affecting the color. If the temperature is too low, the fiber molecular chain has insufficient mobility and cannot be fully set. The curling stability is poor, and it is easy to disappear and reduce elasticity in subsequent use.

Orientation: The stretching temperature affects the orientation degree of the fiber molecular chain. If the temperature is too high, the molecular chain moves too violently. Although it can be quickly oriented under the action of the stretching force, it is also easy to de-orient, resulting in unstable fiber orientation and reduced strength and modulus. If the temperature is too low, the molecular chain segments are difficult to move, and it is difficult to achieve the ideal orientation effect. The properties of the fiber such as strength and gloss will also be affected.
Dyeing performance: Appropriate stretching temperature helps to form a uniform fiber structure, allowing the dye to evenly enter the fiber, resulting in good dyeing uniformity. Too high or too low temperature will lead to uneven fiber internal structure. For example, too high temperature will increase the fiber crystallinity, making it difficult for the dye to enter the crystalline area, resulting in uneven dyeing; too low temperature will cause the fiber amorphous area to have a loose structure, resulting in too high a dyeing rate and reduced color fastness.

Polyester DTY Silver Series ZE0006-ZE0668 121