The future explosion in production capacity of thermoplastic carbon fiber will benefit which industries?
The development of the materials industry has a history spanning over a century, during which new materials characterized by lightweight, high strength, and rigidity have emerged, gaining popularity across various fields and industries. From earlier glass fibers to today's carbon fibers and aramid fibers, these high-performance fibers can be combined with different matrix materials to create composite materials that are more stable in shape, possess enhanced performance, and allow for more efficient processing. This article discusses the currently trending thermoplastic carbon fiber composites. However, as of now, the global production capacity for this type of composite remains scarce. To achieve diverse applications, it is essential to address the challenges of improving technological levels and increasing production capacity limits. Assuming future breakthroughs in technological bottlenecks lead to an explosion in the production capacity of thermoplastic carbon fiber composites, which industries would benefit?
Significance and Limitations of Thermoplastic Carbon Fiber Composites
Thermoplastic carbon fiber composites are often compared with thermosetting carbon fiber composites, glass fiber composites, and aramid fiber composites. Some studies suggest that thermosetting carbon fiber composites exhibit higher stiffness, while aramid fiber composites possess better toughness. However, certain thermoplastic carbon fiber composites, such as continuous carbon fiber reinforced polyether ether ketone (CF/PEEK), demonstrate superior performance compared to their thermosetting counterparts.
In fact, the advantages of thermoplastic carbon fibers extend beyond mechanical properties. They also present benefits in terms of preparation, processing, and recycling.
Due to the rapid processing and recyclability of thermoplastic materials, fiber-reinforced thermoplastic composites are increasingly being used in aerospace, automotive, construction, and chemical industries. The ability to melt thermoplastic materials and their fiber-reinforced composites allows manufactured parts to be reformed into new products, which is a significant advantage over thermosetting polymers and their fiber-reinforced composites.
However, due to the poor interfacial adhesion between carbon fibers and thermoplastic matrices, various surface treatments, such as chemical, plasma, and electrochemical methods, have been applied to introduce surface functional groups and improve interfacial bonding. Carbon fiber reinforced thermoplastic composites have been fabricated into various lightweight components with high impact resistance, reparability, and recyclability through manufacturing processes such as injection molding, compression molding, and extrusion.
While thermoplastic carbon fiber composites and their corresponding components inherently possess advantages, they also face certain limitations. For instance, unidirectional thermoplastic carbon fiber composites exhibit low tensile strain and the presence of residual solvents can negatively affect final performance. To extend the tensile failure strain, hybrid thin layers, angular layers, and corrugated layer sandwich structures have been utilized. Before the technology matures, widespread application of thermoplastic carbon fiber composites will require extensive research and experimentation.
What are the Promising Application Directions for Thermoplastic Carbon Fiber?
Research on thermoplastic carbon fiber composites has been ongoing, but currently, it faces certain bottlenecks. The high-temperature molten state of thermoplastic resins cannot efficiently wet carbon fiber bundles, leading to uneven distribution within the produced thermoplastic carbon fiber prepreg and significantly lowering performance levels. Furthermore, the subsequent processing of thermoplastic carbon fiber prepregs also encounters many challenges. Only by resolving these issues can more industries benefit from these materials.
1.Aerospace: The use of carbon fiber composites in aircraft began with auxiliary structures such as ailerons, elevator trim tabs, and rudders. CFRP (Carbon Fiber Reinforced Polymer) exhibits excellent mechanical properties, including high strength-to-weight ratio and high stiffness-to-weight ratio. With advancements in technology, the performance of fibers and matrices has significantly improved, enhancing the performance of laminates and allowing this material to be applied to major aircraft structures such as fuselages, vertical tails, tailboxes, and wings, replacing traditional lightweight metal alloys. Thermoplastic carbon fiber can replace some thermosetting carbon fiber, providing better performance in these components.
2.Wind Power Generation: According to the Global Wind Energy Council, the total installed capacity of wind power worldwide reached approximately 743 gigawatts in 2020, with an increase of 53% in newly installed capacity, totaling 93 gigawatts. In wind turbine blades, carbon fiber has significant advantages over glass fiber, including higher specific tensile modulus, higher specific tensile strength, and better fatigue resistance. The consumption of carbon fiber in wind turbine structures has increased from about 800 tons in 2004 to more than 30 tons in 2021, and it is expected to exceed 81 tons by 2025. Thermoplastic carbon fiber composites can also be widely applied in the growing wind energy equipment sector.
3.Automotive Manufacturing: Over the past decade, stricter automotive emission standards and the rapid growth of electric vehicles have prompted the industry to reuse carbon fiber to reduce weight. The use of lightweight materials such as CFRP (Carbon Fiber Reinforced Polymer) composites in automotive structures is the most direct method for weight reduction. In 2013, carbon fiber consumption saw significant growth, continuing on an upward trend. In 2021, the demand for carbon fiber reached 9.5 tons and is expected to exceed 12.6 tons by 2024. China is the largest producer and end market for electric vehicles globally, and the application of thermoplastic carbon fiber in automobiles can provide stronger acceleration performance while also offering better safety protection.
4.Pressure Vessels: High-pressure gas storage containers are one of the largest and fastest-growing markets for advanced composites, particularly filament-wound carbon fiber composites. Due to the excellent fatigue performance of carbon fiber composites, the lifespan of Type III and IV CFRP composite pressure vessels can reach up to 30 years. The Type V all-carbon fiber composite liner-free tanks were first manufactured in 2012 for storing argon in satellite components. One application of thermoplastic carbon fiber composites in unidirectional tapes is in the production of pressure vessels, with promising market potential for storing high-pressure hydrogen, argon, and other gases in the future.
5.Sports Equipment: Major products made from carbon fiber include golf clubs, fishing rods, and tennis rackets. Since 2010, the use of carbon fiber in sports and recreational equipment has shown a steady growth trend. In 2021, the amount of carbon fiber used in sports reached an impressive 18.5 tons. Golf clubs and bicycles are the largest consumer areas for carbon fiber, accounting for 27.6% and 25.4% of total consumption, respectively. Sports goods made from thermoplastic carbon fiber composites are expected to elevate competitive sports to new heights. As production capacity increases, the prices of these types of sports goods continue to decrease, making them more accessible in everyday life.
Recycling of Discarded Carbon Fiber Products is Urgent, and Implementation Needs Improvement
The improvement in production capacity for thermoplastic carbon fiber composites can indeed drive rapid development in the carbon fiber industry and advance sectors such as aerospace, wind power generation, automotive manufacturing, and pressure vessels. However, it also raises an urgent question: how to efficiently recycle damaged and discarded thermoplastic carbon fiber products. With the current low production capacity of thermoplastic carbon fiber composites and products, it is estimated that by 2025, the manufacturing process may generate around 20,000 tons of waste and scrapped parts annually. If production capacity increases significantly in the future, the amount of waste will also rise substantially.
Throughout the manufacturing process from raw materials to finished products, a large amount of waste is generated, including dry fibers/fabrics, cured or uncured prepregs, cut-offs, test samples, and unapproved products. The average scrap rate for carbon fiber composite production is approximately 32.4%. Depending on the manufacturing process or application, traditional manufacturing methods such as autoclave production in aerospace and RTM processes have scrap rates exceeding 50%, while hand-produced sports goods have scrap rates of 4-8%. For more modern composite manufacturing processes, molding and composite techniques yield a scrap rate of 30-50%, pultrusion has a rate of 5-10%, and filament winding processes have a rate of 2-3%. As manufacturing processes continue to mature, scrap rates are expected to decrease.
Although the percentage is small, the total volume of carbon fiber reinforced plastic waste is significant, especially as the carbon fiber industry is rapidly expanding; thus, corresponding carbon fiber waste is also increasing. Currently, most waste from thermosetting carbon fiber composites is disposed of through landfilling. In contrast, thermoplastic carbon fiber composites possess better recyclability. If related companies take charge and appropriate laws and regulations are enforced, this can effectively alleviate the current challenges of inefficient carbon fiber waste management. Xinhong Industrial Co., Ltd. believes that carbon fiber and composites provide convenience and value to our lives, and while we benefit from them, it is essential to focus on recycling efforts to protect the environment, which in turn protects the continuity of civilization.
