Researchers transform plastic bottle waste into ultra-lightweight super-materials that can be used in many applications

Plastic bottles are usually polyethylene terephthalate (PET), the most recycled plastic in the world. PET aerogels developed by the NUS-led research team and using plastic bottle waste – a world first – are flexible, flexible, durable, extremely lightweight and easy to handle. They also demonstrate superior thermal insulation and strong absorption capacity. These properties make them attractive for a wide range of applications, such as thermal and sound insulation in buildings, cleaning up oil spills, as well as as a lightweight coating for firefighters' coats and masks. Absorption of carbon dioxide that can be used during rescue and fire fighting operations. escape.

This pioneering work was carried out by a research team led by Associate Professor Hai Minh Duong and Professor Nhan Phan-Thien from the Mechanical Engineering Department of the NUS Faculty of Engineering. The technology to produce PET aerogels was developed in collaboration with Xiwen Zhang of the Singapore Institute of Manufacturing Technology (SIMTech), within the Agency for Science, Technology and Research. (A * STAR).

Recycle waste plastic bottles

Plastic waste is toxic and non-biodegradable. This waste often ends up in oceans and landfills, affecting marine life and causing problems such as groundwater contamination and soil scarcity. Globally, annual consumption of plastic bottles has increased steadily and is expected to exceed half a trillion tons per year by 2021.

"Plastic bottle waste is one of the most common types of plastic waste and has adverse environmental effects. Our team has developed a simple, economical and environmentally friendly method to convert plastic bottle waste into PET aerogels for many exciting uses. Bottle can be recycled to produce an A4 PET airgel sheet. Manufacturing technology is also easily expandable for mass production. We can help reduce the environmental damage caused by plastic waste, "said Professor Assoc Duong.

Multipurpose PET aerogels

The research team took two years (from August 2016 to August 2018) to develop technology for the manufacture of 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 give them different surface treatments to customize them for their applications, for example, when they are incorporated into various methyl groups, PET aerogels can absorb very quickly large quantities of oil, their performance is up to seven times higher than existing commercial sorbents and are perfect for cleaning up oil spills, "added Professor Nhan.

Lighter and safer firefighters

Another innovative application is to exploit the thermal insulation property of PET aerogels for fire safety applications.

Existing firefighter coats are bulky and they are often used with other breathing and safety equipment. This could have detrimental consequences on firefighters, especially during protracted operations.

When coated with flame retardant chemicals, the new lightweight PET aerogel offers superior thermal resistance and stability. It can withstand temperatures of up to 620 degrees Celsius – it's seven times more than the thermal coating used in conventional firefighters, but weighs only about 10% of the weight of thermal coatings classics. The soft and flexible nature of PET airgel also offers greater comfort.

Professor Nhan explained, "By using PET aerogels coated with flame retardants as a coating material, firefighters' coats can be made much lighter, safer and cheaper." It is also possible to produce inexpensive jackets. heat resistant for personal use. "

2 in 1 mask that absorbs carbon dioxide and harmful dust particles

When it is coated with an amine group, the PET airgel can quickly absorb carbon dioxide from the environment. Its absorption capacity is comparable to that of materials used in gas masks, expensive and bulky. To illustrate this application, the team has incorporated a thin layer of PET airgel into a fine particle commercial mask to create a prototype mask capable of effectively absorbing dust particles and carbon dioxide. carbon.

Professor Nhan said: "In highly urbanized countries such as Singapore, carbon dioxide absorption masks and heat-resistant sheaths made with the help of PET aerogels can be placed alongside fire extinguishers in high-rise buildings to enhance the protection of civilians when they leave the fire. "

"The masks coated with amine-reinforced PET aerogels can also benefit the inhabitants of countries such as China, where air pollution and carbon emissions are major concerns. masks can be easily produced and potentially reused, "added Assoc Prof Duong. .

NUS researchers are also studying the possibility of simply changing the surface of PET aerogels to absorb toxic gases such as carbon monoxide, the deadliest component of smoke.

In their previous work, the research team had successfully converted paper and fashion waste into cellulose and cotton aerogels, respectively. Associated with this latest innovation involving the recycling of plastic bottle waste into aerogels, the NUS team has recently been awarded first place in the "Sustainable Technologies" category of the "Create the Future Design" 2018 competition. , organized by Tech Briefs.

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Researchers turn fashion waste into a multifunctional material

More information:
Steven Salomo et al. Manufacture and advanced properties of hybrid aerogels polyethylene tetraphalate fiber – silica from waste plastic bottles, Colloids and A surfaces: Physico-chemical and technical aspects (2018). DOI: 10.1016 / j.colsurfa.2018.08.015