Ultra-light cars made from recycled carbon fibre are a step closer thanks to a new method of recycling, developed at UNSW Canberra, which leaves the product substantially stronger.
As the world continually takes steps forward in manufacturing and technology, products are built using more advanced materials and become more sophisticated, but also more complicated.
This presents a problem when these products reach the end of their useable life, as they’re either difficult or expensive to recycle, or both.
For example, as the world transitions to electric vehicles, disposing of their used batteries, some made with highly toxic materials, will be a challenge.
As it stands, many advanced products either end up in landfill or incinerated, and that is a waste of valuable resources and harmful to the planet.
One material, that up until now has been difficult to recycle, is carbon fibre.
However, a UNSW Canberra researcher has developed a new method to recycle it in a way that not only means less of the material is wasted, but also uses less energy and leaves more of it intact and able to be turned into more useful new products.
Carbon fibres are thin strands of carbon that are exceptionally strong and lightweight. The fibres are combined with plastic to create a composite which can be used to construct a variety of products.
Carbon fibre is commonly used to build aircraft, wind turbines, and it is the primary material used in Formula 1 cars, which need to be as light as possible to increase performance. You might encounter carbon fibre in high-end bicycles and other sporting equipment like hockey sticks or tennis racquets.
UNSW Canberra researcher Di He said that, until now, recycling carbon fibre had always resulted in the material being heavily degraded.
“This project was a collaboration with our partner in the automotive industry who wants to investigate building cars out of recycled carbon fibre,” explained Dr He.
“But with the previous methods of recycling carbon fibre, the material was heavily compromised.
“The mechanical performance of objects made from the existing recycled fibres is degraded by 80 to 90 per cent, compared to using new fibres.
“Typically, it is only reused to make low-value products like tables or chairs, products that don’t experience heavy forces or loads.
“The existing method of recycling involves shredding the composite, which destroys the carbon fibre, before heating it to remove the plastic. After it has been shredded, the fibres look like individual hairs or cotton wool strands.
“In our method we don’t shred the carbon fibre and we optimised how we heat it in a furnace.
"This leaves the fibres intact, and therefore the new product made from the recycled carbon fibre is much stronger.
“Our method degrades the carbon fibre by less than 30 per cent, which is a 50 per cent improvement on existing methods.”
While the recycled carbon fibre produced using Dr He’s method is not yet able to be used to construct a car, it is significantly closer to that goal than before. The new and improved recycled carbon fibre can potentially be used to construct individual parts of a car, such as a roof.
Car manufacturers are interested in carbon fibre vehicles as the decrease in weight would make the cars significantly more energy efficient. This would help them to meet the fuel efficiency standard announced by the Australian Government earlier this year. As we transition to electric vehicles, this would also help reduce vehicle electricity consumption, thereby increasing vehicle range.
Carbon fibre is a costly product to make, which explains the appeal of recycled carbon fibre, in addition to the environmental benefits. Recycling carbon fibre requires one-tenth of the energy needed to produce it from scratch.
One of the lead researchers from the UNSW Canberra Advanced Manufacturing Research Group, Associate Professor Matthew Doolan, said that as the world progressed with engineering and technological advancements, it needed to think more about reducing waste.
“As we make more advanced products we also make them from significantly more advanced materials, and as a result we are creating problems at the end of the life of that product,” Associate Professor Doolan said.
“The standard practice of just dumping these products, or burning them, is unsustainable and cannot continue forever.
"Exploring other options available to us is one of the key questions we’re hoping to help answer at UNSW Canberra.”
Dr He and Associate Professor Doolan, along with their collaborators, recently published their findings regarding recycling carbon fibre in the journal Composites Part A: Applied Science and Manufacturing.
Read more here: https://doi.org/10.1016/j.compositesa.2023.107749