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With the in-depth study of polypropylene, the application field of polypropylene high-strength yarn has expanded to industrial use. The strength of polypropylene high-strength silk can reach 7.0 ～ 7.9cN / dtex, and it is widely used: filter cloth, geotextile, sling, conveyor belt, etc.
What influences the strength of polypropylene high-strength yarn?
1. The strength of polypropylene high-strength yarn is affected by the melt index
The melt index of the raw material indicates the level of the molecular weight of the raw material to a certain extent. Under the same process conditions, the molecular weight in the fiber increases and the molecular entanglement degree is large. There is a tendency for slippage between chains, which is manifested in a decrease in fiber strength. In the spinning process of polypropylene high-strength silk, several raw materials with different melt indices are used.
During the trial spinning process, it was found that under the exact same process conditions, the melt index of the raw materials is different, the strength of the finished yarn is different, and there is a certain regularity.
Experiments show that under the conditions of the same spinning temperature, the same draw ratio and the same process parameters, the lower the melt index of polypropylene chips, the higher the strength of polypropylene high-strength yarns.
2. The strength of polypropylene high-strength yarn is affected by the stretching ratio
The drawing process of the primary fiber destroys the original structural form of the primary fiber and generates a new ordered structure. Under the action of tensile stress and thermal effects, the mobility of the macromolecular segment is increased, and various structural units slide the fiber Axial orientation aggregation, rearrangement, adding new binding points, so that more molecular chains of the fiber are in the best stress-bearing state, and regularity of the three-dimensional structure (ie, crystallization); fiber density increases with the increase of the stretching ratio .
As the draw ratio increases, the strength of the fiber increases, and the draw ratio contributes more to the strength of the fiber.
3. The strength of polypropylene high-strength yarn is affected by the drawing speed
In the one-step spinning process of polypropylene high-strength yarn, the drawing speed is approximately equal to the spinning speed. The degree of orientation and crystallinity of the fiber are affected by the drawing speed in addition to the drawing ratio.
In the drawing process of polypropylene primary fibers, two changes must be completed. One is to completely destroy the natural crystallinity, and the other is to rearrange and recrystallize the macromolecules. Due to the long molecular chain of polypropylene, if the drawing speed is high, the development of tensile deformation can not keep up with the change of tensile stress, the hysteresis is serious, and the macromolecules do not have enough time for orientation and crystallization, showing the strength of the fiber decline.
Different drawing speeds, that is, different spinning speeds, have different fiber strengths, and the fiber strengths decrease as the drawing speed increases.
As mentioned above, the main factors affecting the strength of polypropylene high-strength yarns are the melt index of the raw materials, the stretching ratio and the stretching speed. Among them, the draw ratio contributes a lot to the strength of polypropylene high-strength yarn.
Xuzhou Heping Chemical Fiber Co., Ltd. is located in Xuzhou, Jiangsu. Silk can be used in all aspects of our lives. Heping chemical fiber polypropylene high-strength yarn, supplied by manufacturers, with complete categories and high-quality after-sales service, users can buy with confidence. Heping Chemical Fiber also has high-quality polypropylene industrial yarn, polypropylene high-strength yarn, high-strength polypropylene network yarn, high-strength polypropylene yarn and split film industrial yarn.
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