Recycling for Honeycomb Carbon Fiber Composites

High-performance thermoset materials cannot be remelted or reshaped. Consequently, recycling carbon-fiber-reinforced composites poses significant challenges.

The aerospace industry relies heavily on carbon-fiber-reinforced bismaleimide (CF/BMI) composites for their exceptional durability and outstanding mechanical properties. However, their thermoset nature and complex structures make recycling difficult, exacerbating environmental concerns related to composite waste disposal. Researchers have introduced an eco-friendly recycling method for honeycomb sandwich CF/BMI composites, addressing these issues and supporting circular material usage.

You can also read: Confronting the Challenges of Carbon Fiber Recycling.

A Mild and Efficient Recycling Process

Researchers designed a mild chemical recycling process to recover carbon fibers from honeycomb sandwich CF/BMI composites efficiently and sustainably. The process involves three distinct steps: cutting the composite waste into smaller pieces, treating the material with dichloromethane (DCM) to separate laminates, and degrading the bismaleimide resin using diethylenetriamine (DETA).

The flow diagram of the degradation experiment of the CF/BMI composite honeycomb
sandwich structures. Courtesy of Green and mild approach for carbon fibers recycling from
honeycomb sandwich thermoset composite wastes.

By breaking down the resin into oligomers, the process preserves the structural integrity of the carbon fibers, ensuring their high-quality recovery. Furthermore, this innovative method achieves nearly 100% recovery of carbon fibers while also generating reusable degradation liquid products (DLPs).

High-Quality Recycled Carbon Fibers

Recovered carbon fibers (rCFs) retain 96.6% of the tensile strength of virgin fibers, demonstrating their excellent mechanical properties and usability in manufacturing. Additionally, the process preserves the fibers’ surface morphology and improves wettability, making them suitable for producing high-performance composite materials.

Moreover, the mild reaction conditions minimize damage to the carbon fibers, providing a significant advantage over conventional recycling methods that often compromise fiber quality. These improvements highlight the value of this approach for industries requiring reliable, high-quality recycled materials.

Reusing Degradation Liquid Products

Another innovative feature of the method is the direct reuse of degradation liquid products (DLPs) as curing agents for epoxy resins. This eliminates the need for additional separation processes, simplifying material reuse and reducing resource wastage.

Epoxy resin materials created using these DLPs demonstrate mechanical properties comparable to commercial alternatives, further enhancing their value. By combining fiber recovery with DLP reuse, the method ensures efficient recycling and supports a sustainable lifecycle for composite materials.

Expanding Applications for Recycled Materials

Recycled carbon fibers have immense potential for manufacturing new composite materials, particularly in aerospace, automotive, and renewable energy sectors. Their superior strength, low weight, and sustainability make them ideal for high-performance engineering applications.

Future research will focus on improving fiber alignment and interfacial bonding, further expanding the usability of these recycled fibers. Consequently, these advancements could establish recycled carbon fibers as a standard material in advanced composite applications.

Environmental Benefits of the Method

This recycling method offers a sustainable and energy-efficient alternative to traditional techniques, aligning with global goals to reduce environmental impact. The mild chemical conditions lower energy consumption, while solvent recovery minimizes waste, ensuring an eco-friendly recycling process.

By addressing the challenges associated with CF/BMI composite recycling, the method reduces landfill waste and promotes a circular economy within high-performance industries.

Paving the Way for Circularity

This study presents an effective and scalable recycling solution for honeycomb sandwich CF/BMI composites. By recovering high-quality carbon fibers and reusing degradation byproducts, the method combines sustainability with material innovation.

As industries increasingly prioritize eco-friendly practices, this approach lays the groundwork for a sustainable future in composite material usage. Furthermore, the findings emphasize the critical need for ongoing research into recycling technologies to meet the growing demand for sustainable solutions.

To read the complete study click here.