University R&D projects continue to push the limits of what can be done with composites.

If there are three words you never want to tell a composites researcher, they are “no, you can’t.” You can’t take scrap carbon fiber from an airplane and turn it into something else. You can’t make a bomb detector small enough to be portable. In this issue, Composites Manufacturing highlights research projects at six universities that did those things – and more. The forward-thinking researchers inspire innovation by challenging conventional wisdom.

Kayaking with Recycled Materials

Project: Recycled CFRP kayak
School: University of Birmingham
Location: Birmingham, England
Principal Investigator: Gary Leeke

To succeed in England’s 125-mile Devizes to Westminster International Canoe Race – widely considered one of the toughest endurance events in the world – a kayaker needs to be in peak physical condition and have a well-made kayak that almost flies across the water. While Gary Leeke’s kayak from the 2016 race doesn’t literally have wings, it achieves speed thanks to recycled aerospace-grade carbon fiber. This marks the first time a kayak has been made out of recycled FRP, says Leeke, a former researcher at the University of Birmingham now at Cranfield University.

“We’ve used aerospace fibers previously in our plates (canoe panels), but not in a full-scale demonstrator, so we wanted to show people you can take waste from one sector and use it in another,” explains Leeke.

Leeke says the benefit of recycled aerospace carbon fiber is that it makes the kayak very stiff, which is great for racing. A stiff hull causes less ripple in the water, which allows a racer to travel fast. The downside is that aerospace-grade fibers are very heavy compared to what is normally used to make a kayak. Most kayaks are made from materials that weigh 150 grams per square meter. The recycled material that Leeke made weighed 300 grams per square meter.

Leeke and Liam Grover, Leeke’s academic colleague and racing teammate, used a carbon fiber recycling process called solvolysis – which entails splitting chemical bonds with a solvent – to make the material for the kayak. They put the carbon fiber composite that they wanted to recycle in a mixture of water and acetone, then placed it inside a pressure vessel and heated it to 300 C. The acetone and water vaporized and raised the pressure to about 150 bar.

Gary Leeke recycled CFRP kayak

Gary Leeke, front, and Liam Grover hit the water with the world’s first kayak made out of recycled CFRP.
Photo credit: Nick Rawle, Creative Concern