Since the end of last century, carbon fiber rod has become one of the key words in the application of advanced composite materials. With the domestic production technology of carbon fiber rod raw materials gradually breaking through the international technology blockade, the batch production capacity of T300, T700 and other models of carbon fiber rod precursor has been realized.
With the rapid development of thermosetting carbon fiber rod composites, especially the epoxy based carbon fiber rod composites.
In contrast, the application of thermoplastic carbon fiber rod composites is very limited. Why is the development of carbon fiber reinforced thermoplastic composites slow in China? The author believes that there are several reasons.
First of all, the market demand for thermoplastic carbon fiber rod composites is not comprehensive enough, and the advantages of thermoplastic carbon fiber rod composites are not fully valued, which affects the normal growth of market demand.
It is generally believed that thermoplastic polymers are inferior to thermosetting polymers in terms of service temperature, mechanical properties, creep resistance and aging resistance.
In fact, thermosetting carbon fiber rod composites are not without shortcomings. They have a series of weaknesses, such as long molding cycle, poor impact toughness, short storage time of prepreg, can not be reused, and local damage is difficult to repair.
Compared with thermosetting resin based carbon fiber rod composites, thermoplastic carbon fiber rod composites have the advantages of high toughness, high impact resistance and damage tolerance, unlimited prepreg storage period, short molding cycle, high production efficiency and easy repair.
The utilization value of thermoplastic carbon fiber rod composites has not been fully understood and developed, which directly affects the generation of market demand. The extremely limited demand exists in high-end small areas such as aerospace, which hinders the further development and application of thermoplastic carbon fiber rod composites from the source of supply and demand.
Secondly, the manufacturing technology of thermoplastic carbon fiber rod composites has high technical requirements, which limits the entry of some enterprises with insufficient technical level and production capacity to a certain extent.
Most thermoplastic resins have high viscosity at the melting temperature and can not impregnate fiber fabrics well. Therefore, the preparation of prepreg for thermoplastic resin based carbon fiber rod composites is very difficult, which can not solve the problem of infiltration of thermoplastic resin at high viscosity, let alone others.
The commonly used prepreg process for thermoplastic composites is the melting method, and its basic processes include fiber drawing, wire spreading, preheating, impregnation, cooling, winding, etc.
When the prepreg of thermoplastic carbon fiber rod composites is prepared by melting method, the problems of hollow dry spots caused by high resin viscosity and short impregnation time, and the need for good and nondestructive dispersion of fibers should also be solved.
Moreover, the high cost of raw materials has led to the restriction of downstream application demand. The price of carbon fiber rod precursor is not cheap. The price of high-end thermoplastic resin is dozens of times that of ordinary epoxy resin. In addition, the high production technology requirements and the superposition of various factors lead to thermoplastic carbon fiber rod composites.
In particular, the price of carbon fiber rod composites based on peek and PI, which are high-end thermoplastic resins, is daunting. On the other hand, the domestic use of carbon fiber reinforced thermoplastic composites mainly depends on imports.
The supply of high-performance thermoplastic composite prepregs abroad is monopolized by tencate, Cytec, Ticona and other companies. These companies have the ability to supply various series of glass fiber/carbon fiber rod reinforced Pei, PPS and peek thermoplastic prepregs. The price of prepregs after monopolization is naturally high.
The transformation of domestic scientific research achievements on thermoplastic carbon fiber rod composites is not smooth. There is a certain foundation for the preparation and research of prepreg for thermoplastic composites in China, but compared with developed countries.
There is still a big gap, and the continuity of follow-up work is not strong, which leads to the lack of key technologies and equipment related to material preparation and structure forming in China.