In 15 or 20 years, we may be swimming in carbon composite waste. The material is so strong, and so durable, it is also very hard to get rid of.
It’s important because many major new aircraft designs include large amounts of carbon composite because of the success of the Boeing Dreamliner 787. Now breakthroughs are coming in auto design with carbon fiber reinforced plastics (CFRP).
That’s great news for the environment and climate change because planes and cars can go much farther with less fuel. But long term, how do we get rid of the stuff?
Boeing cared enough to lead in the establishment of the Aircraft Fleet Recycling Association to promote use of carbon- fiber reinforced plastic (CFRP) scrap.
The key in retaining value is separation of the carbon fiber from the polymer matrix.
Researchers at the High-Performance Materials Institute at Florida State University reported at the Automotive Composites Conference and Exhibition in Troy, Mich. this month that supercritical fluid solvents are a possible answer.
First researchers made aircraft-type composites (Hexcel 8552/IM7) and then put them in a reactor of supercritical water using potassium hydroxide as a catalyst.
As much 99% of the resin was removed from multiple layer composite samples. In the abstract submitted for the conference, the researchers reported: “The recovered fibers, which retained their original woven architecture, show excellent retention of the properties. Scanning electron microscopy revealed the fiber showed no surface damage after recycling.”
The reclaimed fabrics were then used to fabricate reclaimed-fiber composites by vacuum-assisted resin infusion. The reclaimed degradation product was also combined with fresh resin and cured.
“You can use it right away to manufacture composites,” said Changchun Zeng, assistant professor FAMU/FSU in a presentation at the ACCE. He calculated the cost of the recycled carbon fibers at 77 cents per kg. The research is still in preliminary stages.