Carbon Fiber Composite
Recycling Technology
Innovation Achievement

After enduring market downturns in 2020 and 2021, the carbon fiber composite market rebounded in 2022, with global production increasing by approximately 9% and resulting in a market value of $3.6 billion. Taiwan ranks fourth globally in the total production of carbon fiber composites, covering 2,000 to 3,000 different products, mainly concentrated in sports equipment, PCBs, and yachts.

 

In Taiwan's composite materials industry, it is estimated that approximately 30% of carbon fibers appear as scraps, indicating that these valuable materials ultimately end up in landfills or are incinerated. Therefore, the composite industry is actively seeking through various research collaborations to improve the efficiency of high-quality materials usage, generate new economic momentum, and create resource value with the goal of developing key technologies to address current disposal issues. Overall, carbon fiber composite recycling technologies can be categorized into the following three categories:

 

 (1) Physical mechanical method:

The physical-mechanical recycling process involves breaking down waste composite materials into smaller fragments, typically ranging in size from 50 to 100 mm. Subsequently, using grinding separation technology, which involves blowers and sieves, the waste is classified to separate materials with higher fiber content from those with higher resin content. It is important to note that a limitation of this method is that the carbon fibers undergo damage during the process, thereby rendering valuable long fibers unrecoverable for further processing.

 

 (2) Solvent dissociation method:

In the chemical recycling process, polymers from the waste composite materials are initially dissolved in chemical solutions, which can be acidic, alkaline, or a special solvent. Then, depending on the nature of the polymers, appropriate chemical solvents and catalysts are selected to accelerate the chemical reactions. Before chemical dissolution, the solid materials are mechanically crushed to increase their surface area, thereby enhancing the dissolution efficiency. Once the polymers are dissolved, carbon fibers can be recovered and cleaned to remove any surface residues. The main advantage of this chemical solvent recycling method is the preservation of long fibers with maximum mechanical efficiency, which is beneficial for subsequent traditional plastic processing.

 

 (3) Thermal pyrolysis method:

During the pyrolysis process, waste composite materials are decomposed using thermal energy. This process can be categorized into three main types: combustion/incineration, high-temperature fluidized bed, and pyrolysis. Typically, pyrolysis operates at relatively high temperatures, ranging from 450 to700°C. At such high temperatures, the resins in the composite materials are easily burned off, allowing the high-quality carbon fibers to be preserved. However, the setting of the pyrolysis temperature is crucial as different types of resins require different optimal temperatures. Inappropriate temperatures may result in coke residue on the carbon fiber surface or cause the carbon fibers to shrink in diameter, thereby affecting their strength.

 

Among the three carbon fiber composite recycling technologies, thermal pyrolysis holds a competitive advantage in terms of plastic processing, particularly with the integration of microwave technology, enabling real-time heating during the process. Currently, the processing plants cooperating with PIDC adopt foreign microwave-assisted pyrolysis technology. Through the unique design of the microwave reaction field, they can more effectively manage energy density, shortening the processing time for waste composite materials, and demonstrating energy-saving and mass production characteristics.

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If you would like to further understand the collaboration approach for this technology, please contact PIDC's Planning and Promotion Team.

E-mail: pidcc4@pidc.org.tw

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