One of the major benefits of using carbon fiber parts in planes and cars is that the light weight of carbon fiber makes these vehicles more fuel efficient. The overall lower weight requires less energy to move them, so less fuel is needed to get them to their destination.
While carbon fiber parts are durable and have a high tensile strength, they do eventually wear out and need to be replaced. Additionally, producing carbon fiber parts does produce carbon fiber waste. Since carbon fiber can be costly to produce, can end-of-life parts and production waste be recycled?
Keep reading to learn how we can reuse and recycle carbon fiber waste.
Challenges of Recycling Carbon Fiber
Carbon fiber is extremely durable, but recycling it isn’t as easy as it may seem. Processes that produce carbon fiber waste during part production can leave the fibers damaged. However, an estimated 30% of produced carbon fiber ends up as waste during production, so finding ways to recycle and reuse this waste is important to make carbon fiber more sustainable and affordable.
Additionally, for end-of-life parts, carbon fiber locked inside resin requires a process to remove the resin and extract the fiber. Often, these processes use harsh chemicals to dissolve the resin or high temperatures to melt it away, which require a lot of energy. And while the fiber gets recycled, the removed resin is waste.
Processes for Recycling Carbon Fiber
Developments in recycling carbon fiber revolve around reducing the time and energy spent on the process. Most commonly, carbon fiber is reclaimed from end-of-life parts using one of two processes:
- Pyrolysis, or high heat that burns off cured resin
- Solvolysis, or a solvent is used to dissolve cured resin
Solvolysis is also a method used on uncured prepreg waste, or carbon fiber that is woven with a matrix of a thermoset polymer that requires no additional resin for curing. Solvolysis dissolves the uncured polymer away, and the fiber can be reused.
The troubles with pyrolysis are that the resin is wasted and it requires a lot of energy to perform. Additionally, both pyrolysis and solvolysis started as batch processes, where the process is done after production in small quantities. Recycling in batch processes is better than not recycling at all; however, batch processes are typically more costly than inline processes. This is recycling that can be done within the regular production process, and it’s time saving and cost-effective.
Solvolysis is a prime candidate for inline carbon fiber recycling, and developing resins with recycling capabilities in mind leaves opportunity for recycling the resin as well. Some companies are developing resin meant to be reused, so the monomer solution of the resin can actually dissolve cured resin back into a liquid, recurable state.
What can Recycled Carbon Fiber (rCF) be Used for?
While the integrity of reclaimed carbon fiber isn’t compromised, recycled fibers tend to be fluffy and less dense than virgin fibers, so it’s difficult to “reweave” them into the carbon fiber sheets we’re used to.
Injection Molding & 3D Printing rCF
Recycled fibers can be turned into dense pellets, which are common in injection molding of carbon fiber. Injection molding with carbon fiber pellets is already done with virgin fibers, but using recycled fiber produces the same final product in an environmentally friendly way at a lower cost.
3D printing filaments can also utilize rCF. While not a complete carbon fiber filament, the recycled fibers can be mixed with traditional ABS filaments to reinforce the final product.
Nonwoven rCF Fabric
Woven carbon fiber fabric is sleek and eye-catching, but recycled fibers can’t be rewoven. That doesn’t mean they can’t be used to create carbon fiber fabrics. rCF fabrics aren’t as sleek as woven fiber, but they are still useful for processes currently using virgin woven fibers. The fibers can still be aligned for strength and arranged in different directions to suit the needs of the project.
Repairing Carbon Fiber Consumer Products
Carbon fiber might seem difficult to repair when it breaks. Unlike metal, it can’t just be welded back together. However, carbon fiber is repairable. The aerospace industry repairs carbon fiber parts quite regularly, and cars and trucks with carbon fiber parts can be repaired following an accident, so long as the damage doesn’t deem the vehicle a total loss.
Carbon fiber repairs do require expertise, so it’s not advised to perform a DIY repair on carbon fiber vehicle parts, bike frames, or other consumer products that will need to bare weight. However, repairing a carbon fiber part when possible prolongs the life of the product and is less expensive than replacing it.
Developing processes to recycle and repair carbon fiber are important for the sustainability and reduction of carbon fiber waste. Recycling and reusing carbon fiber correctly doesn’t affect its strength, making it usable in place of virgin fibers in some cases.
Carbon Fiber Casting from PCMI
PCMI Manufacturing is an innovator in carbon fiber casting. Our unique casting process uses a lower cost material and faster cycle times that result in a 20-30% cost savings for our customers. Click the link below to learn more about how we can help you with your next carbon fiber project.