What are the raw materials for carbon fiber prepreg?

Carbon fiber prepreg is a composite material primarily composed of carbon fiber and resin, along with other additives. The details are as follows:

Carbon Fiber

PAN-based Carbon Fiber: This is the most commonly used type of carbon fiber in prepregs. It is made from polyacrylonitrile (PAN) precursor through processes like high-temperature carbonization and graphitization. PAN-based carbon fiber offers high strength, high modulus, and good fatigue resistance, making it ideal for applications where lightweight and high-performance materials are required.

Pitch-based Carbon Fiber: Derived from petroleum or coal tar pitch, pitch-based carbon fiber has a high graphitization degree, resulting in excellent thermal and electrical conductivity. It also has good mechanical properties, especially in terms of compressive strength. Although it is more expensive than PAN-based carbon fiber, it is preferred in some high-end applications that demand superior thermal and electrical performance.

Rayon-based Carbon Fiber: Produced from rayon fibers, rayon-based carbon fiber has relatively low strength and modulus compared to PAN-based and pitch-based carbon fibers. However, it has unique properties such as high porosity and good chemical resistance, which make it suitable for specific applications like in the production of activated carbon fibers and certain types of filters.

Resin Matrix

Epoxy Resin: Epoxy resin is one of the most widely used resin matrices in carbon fiber prepregs. It offers excellent adhesion to carbon fibers, high mechanical strength, good chemical resistance, and low shrinkage during curing. These properties ensure a strong bond between the carbon fibers and the resin, resulting in a composite material with high performance and reliability. Epoxy-based prepregs are commonly used in aerospace, automotive, and high-performance sports equipment industries.

Polyester Resin: Polyester resin is another popular choice for carbon fiber prepregs, especially in applications where cost is a significant factor. It has good mechanical properties, relatively low viscosity, and is easy to process. Polyester-based prepregs are often used in the construction of boats, wind turbines, and some general industrial applications.

Vinyl Ester Resin: Vinyl ester resin combines the advantages of epoxy and polyester resins. It has excellent chemical resistance, good mechanical properties, and better impact resistance than polyester resin. Vinyl ester-based prepregs are suitable for applications in corrosive environments, such as in chemical plants, wastewater treatment facilities, and marine applications.

Additives

Curing Agents: Curing agents are added to the resin matrix to initiate and control the curing process. The type and amount of curing agent used depend on the type of resin and the desired curing conditions. For example, in epoxy resins, common curing agents include amines, anhydrides, and latent curing agents. The choice of curing agent affects the curing time, temperature, and final properties of the prepreg.

Accelerators: Accelerators are used to speed up the curing reaction of the resin. They are often used in combination with curing agents to adjust the curing rate according to the specific processing requirements. For example, in some epoxy systems, tertiary amines can be used as accelerators to reduce the curing time at room temperature or lower the curing temperature.

Coupling Agents: Coupling agents are added to improve the adhesion between the carbon fibers and the resin matrix. They chemically bond with both the surface of the carbon fibers and the resin, enhancing the interfacial strength and improving the overall performance of the composite material. Silane coupling agents are commonly used in carbon fiber prepregs to improve the wetting and adhesion of the resin to the carbon fibers.

Fillers: Fillers such as calcium carbonate, silica, and carbon black can be added to the prepreg formulation to modify its properties. Fillers can improve the stiffness, dimensional stability, and fire resistance of the prepreg, as well as reduce the cost. For example, adding calcium carbonate can increase the hardness and reduce the shrinkage of the resin matrix, while carbon black can improve the electrical conductivity of the prepreg.