31 Aug, 2020 By Johny 2 Comments

With the continuous expansion of the application fields of carbon fiber composite materials, the recycling of its waste has also attracted certain attention. In the case of increasingly serious pollution and resource waste, attention should be paid to the selection of materials and the cost of recycling from the initial stage of composite material application. This is conducive to reducing recycling costs as a whole and reducing waste in the environment.

The application of carbon fiber reinforced composite parts should consider the resin matrix of the composite material, and use thermoplastic resin as the composite matrix as much as possible under the premise of ensuring the performance, which will facilitate the recovery and recycling of carbon fiber. Carbon fiber reinforced thermoplastic composite materials mainly have three forms: short fiber (0.2-0.4 mm) reinforcement, long fiber (6-10 mm) reinforcement and continuous fiber reinforcement. The recycling method of carbon fiber reinforced thermoplastic composites has a lot to do with the shape and molding method of carbon fiber in the resin.

At present, the main preparation method of carbon fiber reinforced thermoplastic composites is melt molding, including: injection molding, compression molding, lamination molding, winding molding, pultrusion molding, etc. For high melting point thermoplastic resins, such as polyetherimide (PEI) and polyether ether ketone (PEEK), solvent molding can be used.

Because the thermoplastic resin has a linear molecular structure, it is easy to transform from solid to liquid at high temperatures. Therefore, carbon fiber reinforced thermoplastic composites can be recycled by remelting and remolding. Compared with thermosetting resin-based carbon fiber composites, they can be recycled Stronger.

Although thermoplastic resins can be repeatedly shaped many times, for short carbon fiber reinforced thermoplastic composites, the key to its reuse is to maintain the degree of orientation of short fibers in the composite. Regularly arranged short fiber reinforced composites can stretch The strength and tensile modulus are maintained at 80-90%.

Whether it is reinforced by short carbon fiber or continuous carbon fiber, in the process of recycling and reuse, if the performance of recycled carbon fiber reinforced thermoplastic composites can be improved, its recycling value will be further enhanced.

Chip remolding is also a common method for recycling thermoplastic resins. When the degree of fiber orientation is similar, the volume content of carbon fiber is the main factor that affects the mechanical properties of the composite material after recycling. The modulus value of the recycled carbon fiber reinforced composite material mainly depends on the length of the carbon fiber, and the strength value depends on the fiber and resin. The quality of impregnation.

Through industrial optimization, the slice remodeling method can realize the low-cost repeated recycling of carbon fiber composite materials, which can meet the application of carbon fiber composite materials in general civilian fields.

Recently, in addition to the aerospace field, continuous carbon fiber reinforced thermoplastic composite materials are gradually being used in orthopedic surgical medical equipment, electronic appliances, high-end industries and other fields. Whether from the perspective of product performance or recycling, the advantages of thermoplastic carbon fiber composite materials The development prospects are worth looking forward to.