Plastic polyethylene terephthalate (PET) bottles are one of the most pervasive plastic rubbish items being dumped in rivers and oceans around the world with annual consumption of plastic bottles set to reach more than half a trillion by the year 2021. In a revolutionary breakthrough, research scientists from National University of Singapore (NUS) have created the world’s first aerogel from recycled PET bottles, which can be used for heat and sound insulation, oil spill cleaning, carbon dioxide absorption and other fire safety applications. This is an important discovery which could greatly reduce the amount of plastic bottles being dumped into oceans.

An aerogel made of PET material. (Photograph from NUS News online)

Led by Assoc Prof Hai Minh Duong and Prof Nhan Phan-Thien from the Department of Mechanical Engineering at the Faculty of Engineering in NUS, the research team set about its aerogel project in a bid to reduce disposable waste in the environment.

“Plastic bottles are one of the most common types of plastic waste and have many detrimental effects on the environment. To combat this, our team has developed a simple cost-effective and green method to convert plastic bottle waste into PET aerogels for many exciting uses,” said Assoc Prof Duong in a press release statement from NUS.

What is an aerogel?

An aerogel is a synthetic, porous, low density, ultralight solid material derived from a gel where the liquid component in the gel has been replaced with a gas. Being made from PET plastic, the aerogel created by the team from NUS Engineering, has the advantage of being flexible, soft and very durable. The aerogels can also be customised for different uses by applying different surface treatments to it.

Versatility is its middle name

In addition to its strong absorption capacity, the aerogel also has great thermal insulation properties which makes it suitable for use as a lightweight lining for firefighter coats. After coating the aerogels with fire retardants, the PET aerogel can withstand temperatures of up with 620 degree Celsius. That’s more than seven times higher than existing firefighter coats and yet they are 90% lighter than conventional thermal lining. Its soft and flexible properties also provide the coat wearer with better comfort. Prof Nhan also emphasised the value of using PET aerogels as a safer, lighter, cheaper and more comfortable alternative to existing firefighter coat lining materials.

When treated with various methyl groups, the aerogel can absorb large amounts of oil quickly and can be used to clean up oil spills as they outperform today’s commercial sorbents by a factor of seven.

When coated with an amine group, the aerogel is found to have carbon dioxide absorption abilities comparable to materials used in existing gas masks today. The aerogel can be pressed into a thin layer in a commercial dust particle mask and be able to capture dust particles as well as carbon dioxide, capabilities that are not available on the market today.

Producing Aerogels

According to Assoc Prof Duong, a single plastic bottle can be recycled into an A4-seized PET aerogel sheet and the fabrication technology used also scales easily for mass production.

The team collaborated with Dr Zhang Xiwen from the Singapore Institute of Manufacturing Technology (SIMTech) under the Agency for Science, Technology and Research (A*STAR) to develop the technology to produce the PET aerogels.

The technology to fabricate the PET aerogels was developed over two years from August 2016 to August 2018 and was published in the scientific journal Colloids and Surfaces A in August 2018.

Looking ahead

The research team is looking to make more modifications to the PET aerogels so they can absorb toxic gases such as carbon monoxide. The team has filed a patent for the PET aerogel technology and are looking to work with companies keen to bring the technology to market.

Read more about plastics and its harmful effect on marine and human life in our November 2018 Issue 3 Volume 151 of Asian Diver magazine by subscribing here or check out all of our publications here.

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