First, let's know about the classification of carbon fiber.

Carbon fibers are classified into 3 categories according to their main raw materials.

• PAN

• PITCH

• RAYON

Only PAN can meet the safety and durability requirements of load-bearing structures.

The K 

The K number is larger than 12, but the carbon fiber which is not more than 24 is still in the range of small tow fiber.

Why use small PAN tow fiber for structural reinforcement?

The tensile strength of the tow is very stable, the dispersion is small, and the coefficient of variation is below 5%. It is easy to control the performance and quality of the tow effectively in the process of production and use. However, the tensile strength of large tows is unstable, the coefficient of variation is as high as 15-18%. The reliability of large tows is poor, and there are more phenomena such as carbon fiber adhesion and broken wires. This will affect the strength and stiffness, reduce the performance, and the performance will be more dispersive, which can not be used as reinforcement materials for load-bearing structures.