Polyacrylonitrile (PAN)-based carbon fiber is a high-performance material widely used in aerospace, construction, sports, automotive, and medical fields. This article reviews the development history and current status of PAN-based carbon fiber domestically and internationally, its preparation, structure, properties, and applications. It also discusses relevant standards and testing methods and offers a future outlook.

Introduction to PAN-Based Carbon Fiber

Carbon fiber is an advanced material known for its superior mechanical properties. It combines the inherent characteristics of carbon with the flexibility and processability of textile fibers, making it an essential reinforcing fiber. With a specific gravity of less than one-quarter of steel and a tensile strength generally exceeding 3500 MPa, carbon fiber composites offer strength 7-9 times that of steel and an elastic modulus ranging from 23,000 MPa to 43,000 MPa. These properties make carbon fiber a promising material in engineering applications.

PAN-based carbon fibers, derived from polyacrylonitrile, asphalt, or viscose, undergo processes like pre-oxidation, carbonization, and graphitization, resulting in fibers with more than 90% carbon content. These fibers exhibit high strength, high modulus, low density, high-temperature resistance, corrosion resistance, friction resistance, conductivity, and low thermal expansion, among other properties. PAN-based carbon fiber is the most widely used, accounting for over 90% of production due to its simple manufacturing process and excellent comprehensive performance.

1. Development Status of PAN-Based Carbon Fiber

1.1 International Development

The development of PAN-based carbon fiber began in 1959 when Japan's Akio Shindo patented a process for producing high-performance carbon fibers from polyacrylonitrile. Today, the production of PAN-based carbon fiber is dominated by large tow fibers from the USA and small tow fibers from Japan, accounting for about 80% of global supply. Major producers like Toray, Toho, and Mitsubishi in Japan lead the market, with Toray being the largest PAN-based carbon fiber manufacturer globally.

1.2 Domestic Development

China began researching carbon fiber in the 1960s, achieving slow but steady progress. Despite developing products close to Toray's T-300 level, domestic production capacity remains limited. In recent years, companies like Anhui Huawan Carbon Fiber have initiated industrial production, but most of China's carbon fiber demand is met through imports, significantly constraining related industries.

2. Preparation, Structure, and Performance of PAN-Based Carbon Fiber

2.1 Preparation Process

PAN-based carbon fibers are made from polyacrylonitrile fibers, either homopolymer or copolymer, through processes involving polymerization, spinning, pre-oxidation, carbonization, and graphitization. The production involves converting polyacrylonitrile resin into fibers, which are then treated to enhance their performance and stability.

2.2 Structure

Carbon fibers feature a "disordered" structure of stacked graphite microcrystals along the fiber axis, influencing their performance. The spacing between layers and the presence of voids affect the fiber's properties.

2.3 Performance Characteristics

Carbon fibers possess unique properties such as high tensile strength, high modulus, low density, high-temperature resistance, and corrosion resistance. They also exhibit excellent fatigue resistance, low thermal expansion, good conductivity, and biocompatibility.

3. Applications of PAN-Based Carbon Fiber

3.1 Aerospace

Due to their high strength-to-weight ratio and rigidity, PAN-based carbon fiber composites are crucial in aerospace applications, including missiles, rockets, satellites, and aircraft.

3.2 Sports and Medical Equipment

Carbon fiber composites are extensively used in sports equipment like golf clubs, tennis rackets, and bicycles, as well as in medical implants and devices.

3.3 General Industry

In the automotive industry, carbon fibers are used in vehicle frames, pistons, and brake systems. They also play a role in wind energy, electronics, and infrastructure, enhancing the strength and durability of various components.

4. Standards for PAN-Based Carbon Fiber

China has established several standards for carbon fiber performance and its application in composites, such as:

• GB/T 3362-2005: Tensile properties of carbon fiber multifilament yarns.

• GB 3362-1982: Method for testing the number of fibers in carbon fiber multifilament yarns.

• GB 3364-1982: Diameter and equivalent diameter testing methods.

• GB/T 3355-2005: Resin content testing in carbon fiber reinforced plastics.

These standards ensure the quality and consistency of carbon fiber products, facilitating their broader adoption and application.

5. Future Outlook

The carbon fiber industry is crucial for modern material applications, transitioning from the steel era to a new age of composite materials. Carbon fiber's role in advanced technologies and industrial applications will continue to grow, driven by ongoing research and development. To achieve this, China must focus on overcoming technical challenges and improving production processes to reduce reliance on imports and enhance domestic capabilities.