NUS turns composite waste into aerogel in the lab

At the National University of Singapore, the team led by Duong Hai Minh starts with a material that recycling plants usually struggle to handle: carbon fiber locked into epoxy resin. The researchers grind the whole composite together, add a cellulose-based binder, and freeze-dry the mixture. The laboratory result is a light, sponge-like aerogel rather than a separated pile of fiber and discarded resin.

That choice avoids a central problem with thermoset composites. The epoxy component cannot be melted down, while conventional approaches can require high energy, harsh chemicals or high temperatures to recover only the carbon fibers. Wind-turbine blades, aircraft fuselages such as those of the Boeing 787 or Airbus A350, and automotive frames all contribute to a composite waste stream that currently goes to landfills or high-emissions incinerators.

The freeze-drying process leaves microscopic, interconnected pores filled mostly with air, slowing heat transfer. The resulting material has a density of 0.08–0.12 g/cm³, porosity of 91.25–94.51%, and an elastic modulus of up to 418.95 kPa. In laboratory tests, its thermal conductivity reached 0.042–0.049 W/m·K, while its noise reduction coefficient reached up to 0.51.

In practical terms, aerospace, manufacturing and waste-management companies could eventually have another outlet for composite scrap: insulation, acoustic material or oil-spill absorbent. For the latter use, the aerogel receives a silane-based water-repellent coating so it absorbs oil while repelling water; testing recorded nearly 15 g/g oil uptake after that modification. NUS says the team is now seeking industry partnerships.

The boundary is clear. These are laboratory-scale batches, not a demonstrated factory process. The researchers' next hurdle is continuous, large-scale freeze-drying, and the findings published in Waste Management still need to make that transition before the material can handle industrial waste volumes.