Don’t trash your old clothes, they may be able to save lives

SIAU MING EN Today Online 24 Jan 18;

SINGAPORE – Instead of throwing out that old, worn cotton T-shirt, it can now be turned into a supermaterial to help save lives, and keep drinks cool for a longer time.

In a world first, a team of researchers from the National University of Singapore’s (NUS) Faculty of Engineering has found a “fast, cheap and green” way to convert cotton-based fabric waste from unwanted clothing into cotton aerogels, a highly porous and light material with strong absorption capacity and low thermal conductivity.

First created in the 1930s, commercially-produced aerogels today are usually derived from wood and glass fibre. They are used to absorb water-insoluble liquids such as oil, as well as for heat and sound insulation.

Associate Professor Hai Minh Duong, one of the lead researchers on this project, said their method of producing aerogels is more cost-efficient and quicker as compared to the commercially produced versions, which take three to seven days to produce. In comparison, cotton aerogels can also be produced within eight hours to two days, said the researchers as they unveiled their findings in a media conference on Wednesday (Jan 24). They can also be easily compressed, reducing storage and transportation costs.

Their product is also more eco-friendly, as fabric waste which is usually resold as second-hand clothes or donated to others, can now be turned into aerogels. Assoc Prof Duong also noted that Singapore disposes one tonne of textile waste every five minutes, and 92 per cent of such waste is incinerated as there is no textile recycling plant here.

“This new eco-friendly cotton aerogel is a major improvement from the aerogel that our team had previously developed using paper waste,” said Assoc Prof Duong. He added that they “will continue to explore new functions for this advanced material”.

The NUS team took more than two years to develop and patent their method, which cuts fabric waste into small pieces before blending to form recycled cotton fibres. Water and a solvent is added to the fibres before they are placed in the freezer for 24 hours. The mixture is freeze-dried to remove the water and then cured for three hours before the cotton aerogel is formed.

There are two main uses for their product. At present, haemorrhage control devices comprise a syringe filled with small capsules of cellulose-based sponge. This is inserted into a gunshot or deeply penetrating wound - which can be life-threatening - to release the capsules, which expand and apply pressure on it to stop blood flow. The pellets made from cotton aerogels developed by the NUS researchers can expand to 16 times its size in 4.5 seconds, and absorbs blood three times faster than existing pellets, said Assoc Prof Duong.

The research team also worked with DSO National Laboratories, the largest defence research and development organisation here, to develop a thermal jacket for the military canteens that soldiers use to carry fluids. The jacket, which weighs about 200 grams, comprises cotton aerogel that is sandwiched between neoprene and polyester fabrics.

This allows for the ice slurry of crushed ice and liquid water in military canteens to stay at a temperature of -2°C for four hours. Without a jacket, a canteen can only keep water cold for about 30 minutes.

Its manufacturing cost of about S$8 is also cheaper than a vacuum flask, and the thermal jacket is also lighter and more effective at heat insulation.

Professor Nhan Phan-Thien, who is also a lead researcher on the team, added that the heat insulation properties of the cotton aerogels can also be applied to other consumer product such as cooler bags to keep food items fresh.

“We also foresee tremendous potential for other high value applications, such as pipeline insulation and transportation of liquefied natural gas which needs to be stored at a low temperature,” he said.

The team is currently in talks with two companies from Singapore and the United States to commercialise the technology.


NUS researchers turn unwanted clothing into 'supermaterial'
Channel NewsAsia 24 Jan 18;

SINGAPORE: A research team from the National University of Singapore (NUS) has devised a "fast, cheap and green method" to convert cotton-based fabric waste such as unwanted clothing into a type of aerogel, announced the varsity on Wednesday (Jan 24).

Aerogels can be used to keep military water bottles cold, as well as control of rapid bleeding effectively, among other uses.

They are sometimes called a "supermaterial" because they are among the lightest materials in the world, highly porous with strong absorption capacity and low thermal conductivity. However, when aerogels were first created in the 1930s, they were not widely used by industries due to the high production cost.

Scientists have since found ways to improve the manufacturing process, and the team from NUS has taken it a step further by pioneering the development of aerogels using cotton fibres harvested from textile waste.

"This new eco-friendly cotton aerogel is a major improvement from the aerogel that our team had previously developed using paper waste," said Associate Professor Hai Minh Duong, who led the team with Professor Nhan Phan-Thien.

Both are from the Department of Mechanical Engineering at NUS.

"It is highly compressible, hence storage and transportation costs could be greatly reduced. Furthermore, these cotton aerogels can be fabricated within eight hours - this is nine times faster than our earlier invention and about 20 times faster than current commercial fabrication processes. They are also stronger, making them more suitable for mass production," said Assoc Prof Duong.

The scientists have demonstrated several uses for the cotton-based aerogels including in the making of a lightweight thermal jacket for military canteens, which offers "better heat insulation performances compared to commercial insulated water bottles such as FLOE bottles". The cotton aerogel-insulated flasks are "highly comparable to that of vacuum flasks", said NUS, but are lighter and less costly.

This property of the cotton aerogels can also be applied to other products, such as cooler bags that keep food items fresh and has "tremendous potential for other high value applications such as pipeline insulation and transportation of liquefied natural gas which needs to be stored at a low temperature", said Prof Nhan.

The team also showed how the material can be used to effectively treat excessive and rapid loss of blood, which can be life-threatening. Existing haemorrhage control devices use cellulose-based sponge, which has "relatively slow" expansion and absorption rates.

NUS' cotton aerogel pellets are more effective than the sponge, with each pellet able to "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," said Assoc Prof Duong.

NUS said the team has filed a patent for the novel cotton aerogels and is exploring commercial opportunities.

Source: CNA/hs