New life for plastic bottles.

From polluting waste to ultra-light super-material: thanks to research, a new step towards the resolution of the global plastic waste emergency.

Researchers of the National University of Singapore (NUS) have recently made a significant contribution to the global theme of plastic waste by developing a technology for converting waste plastic bottles into aerogel for many useful applications.

Plastic bottles are commonly made of polyethylene terephthalate (PET) which is the most recycled plastic in the world. The airgel PETs developed by the research team led by NUS, using plastic waste bottles – the first time in the world – are soft, flexible, durable extremely light and easy to handle. These also demonstrate that they have a higher insulating power and a higher absorption capacity. These properties make them attractive for a wide range of applications such as thermal and acoustic insulation in buildings, in the field of oil leakage cleaning, for light linings of firefighter uniforms and in masks for carbon dioxide absorption that could be used during operations at risk of fire and fire escapes.

The team

This pioneering work was carried out by a research team led by Associate Professor Hai Minh Duong and Professor Nhan Phan-Thien of the Department of Mechanical Engineering at the NUS Engineering Faculty.

The aerogel PET production technology was developed with Dr Xiwen Zhang of the Singapore Institute of Manufacturing Technology (SIMTech), within the Agency for Science, Technology and Research (A * STAR).

Recycling of waste plastic bottles

Plastic waste is toxic and not bio-degradable. Such waste often ends up in oceans and landfills, affecting the marine environment and causing problems, such as contamination of groundwater and land shortages. Globally, the annual consumption of plastic bottles has grown continuously and is expected to exceed half a trillion tons per year by 2021.

“The waste plastic bottle is one of the most common plastic waste and has destructive effects on the environment. Our team has developed a simple, environmentally friendly and cost-effective method of converting the rejection of the aerogel PET plastic bottle for a multitude of uses. A plastic bottle can be used to produce an A4-sized PET-aerogel sheet. Manufacturing technology is also easily scalable for mass production. In this way we can help reduce the environmental damage caused by plastic waste, “said Associate Professor Hai Minh Duong, project leader of the research group.

Versatile PET aerogel

The research team took two years (2016 – 2018) to develop the technology to make PET aerogels. This work was published in the scientific journal Colloids and Surfaces A in August 2018.

“Our PET aerogels are very versatile. We can perform different surface treatments on them to adapt them to different applications. For example, if incorporated into methyl groups, airgel PET can absorb large amounts of oil very quickly. Based on our experiments, these materials have a behavior that is seven times better than commercial absorbent materials and therefore are particularly suitable for cleaning up oil spills, “Prof Nhan added.

Safer and lighter uniforms for firefighters

Another interesting application is to exploit the insulating property of aerogel PET for fire safety applicationsThe existing firemen’s uniforms are massive and are often used with other breathing and safety devices. This can have consequences on firefighters, especially during long operations.

When covered with fire-resistant chemical compounds, light aerogel PETs demonstrate superior thermal stability. They can withstand temperatures up to 620 ° C – This is seven times higher than the resistance of the thermal liner used in firefighting uniforms, but weighs only 10% of the weight of the conventional thermal liner. The soft and flexible nature of the PET aerogel also provides a higher comfort.

Prof. Nhan explained, “By adopting aerogel PETs that are coated with fire-resistant materials like a lining material, firefighter uniforms can be made lighter, safer and cheaper. It is also possible to produce cheap jackets for personal use that are heat resistant

2 in 1 masks that absorb harmful carbon dioxide and dust particles

When coated with an amino group, PET aerogel can quickly absorb carbon dioxide from the environment. Its absorption capacity is comparable to the materials used for gas masks, which are expensive and massive.

In order to illustrate this application, the team incorporated a thin layer of aerogel PET into a commercial mask capable of absorbing fine particles, in order to create a mask that could effectively absorb both dust particles and carbon dioxide.

Prof Nhan said, “In countries with high urban density, such as Singapore, carbon dioxide absorption masks and heat-resistant jackets made using PET aerogels can be placed next to fire extinguishers in tall buildings to provide additional protection. to civilians, in the event of a fire “

“Masks lined with amines reinforced with aerogel PET can also benefit the living population in countries like China where air pollution and carbon dioxide emissions are very important issues.” Such masks can be produced easily and can be also potentially reusable “added Associate Prof. Duong.

NUS researchers are also trying to make small changes to the surfaces of aerogel PETs to absorb toxic gases such as carbon monoxide, which is the deadliest component of smoking.

In their previous work, the research team successfully converted paper waste from the fashion world into cellulose and cotton containing aerogel, respectively. Teamed up with this latest innovation that involves the recycling of plastic in airgel, Team NUS has earned the first place and prize in the Sustainable Technologies category of 2018 Create the Future Design Contest by Tech Briefs.

Next steps

The team presented a patent for the new PET aerogel technology and will continue to improve the performance of aerogel PET and explore new applications. Researchers are also strongly inclined to work with companies to bring the technology to market.

The thermal properties of aerogel PET

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