Cotton waste converted into eco-friendly aerogel
Scientists from the National University of Singapore have found a new use for unwanted clothing and other cotton-based fabric waste – they've devised a method of converting it into an aerogel. Among other things, the ultralight material could be used to keep water bottles cold, and to control bleeding from deep wounds.
Led by Associate Professor Hai Minh Duong and Professor Nhan Phan-Thien, the team harvested cotton fibers from textile waste, then used them to produce the aerogel via a proprietary "fast, cheap and green" process – perhaps similar to the process by which they previously produced an aerogel from paper waste.
Like other aerogels, theirs is not only very lightweight, but it's also highly porous and absorbent, and exhibits low thermal conductivity. Unlike other aerogels, however, it can be produced inexpensively and quickly – about 20 times faster than it takes to fabricate conventional aerogels.
In one experiment, the scientists created a thermal insulating jacket for military canteens, that consisted of a layer of the cotton aerogel combined with other commonly-used fabrics. When placed on a canteen containing an ice slurry, the jacket was able to maintain the liquid at a temperature of 0.1 to 1.0 ºC (32.18 to 33.8 ºF) for over four hours. While this level of performance is similar to that of existing vacuum flasks, such flasks are considerably heavier and more expensive than the insulated canteen.
The researchers also used the aerogel to create absorbent capsules of the type that are used to stop battlefield wounds from bleeding. Such capsules – which currently take the form of mini cellulose-based sponges – are injected into wounds via a large syringe. Once in the body, they absorb blood and expand, applying pressure to the wound from the inside and stopping blood flow.
"Each cotton aerogel pellet can expand to 16 times its size in 4.5 seconds – larger and more than three times faster than existing cellulose-based sponges – while retaining their structural integrity," says Duong. "The unique morphology of the cotton aerogels allows for a larger absorption capacity, while the compressible nature enables the material to expand faster to exert pressure on the wound."
The university is now looking for partners to commercialize the technology.
Source: National University of Singapore