“Under those conditions, it will break down and dissolve the resin,” explains Leeke. “When you depressurize and lower the temperature, you can recover your fibers quite nicely.” He adds that while 300 C seems scorching, it’s cooler than the common heat-intensive process, pyrolysis. Leeke says that at 500 C, pyrolysis can burn off the resin and lead to some fiber damage.
However, Leeke and Grover hit a number of proverbial bumps in the water while developing their new material. Limited by the size of the reactor available at the university, each solvolysis process cycle only produced about 0.6 square meters of material. As a result, it took six weeks to make enough material – 14.5 square meters – for the kayak.
“In the future, we envision that you could take rolls of prepreg material, strip back the resin and reuse the actual fiber itself,” explains Leeke. “This is what we would’ve liked to have done with our kayak – do it in a one-step process.”
The manufacturer, Kirton Kayaks Ltd., also ran into issues. As Leeke explains, small kayak manufacturers would like to use RTM, but can’t since the technology is too expensive. Hand lay-up wasn’t an option either because the bio-based thermoplastic resin couldn’t flow through the heavy aerospace-grade fibers. Ultimately, Kirton Kayaks opted for vacuum bag infusion.
Despite the obstacles, Leeke says the kayak “performed impeccably” on the water, which he joked is more than he could say for himself and Grover, as they eventually had to drop out of the race after 85 miles due to Grover’s back injury.
However, Leeke says they plan on using the kayak again in next year’s Devizes to Westminster International Canoe Race. Kirton Kayaks would like to make another kayak with a different material, so Leeke is considering processing a lighter grade material that would reduce the weight of the boat and travel a bit faster in the water.
Project: Polymer damage inspection
School: University of Illinois at Urbana-Champaign
Location: Champaign, Ill.
Principal Investigator: Wenle Li
In many industries, it’s common to utilize a color-coded system to identify potential problems or emergencies. No matter the market, code red usually means it’s time to panic. However, thanks to a new polymer damage inspection system developed by researchers at the University of Illinois at Urbana-Champaign, seeing red could help engineers fix problems in structural applications before they get out of hand. That is often difficult with composite structures, as even significant damage is barely visible sometimes.