Researchers have found a new way to repurpose a particular type of plastic in a unique way to create a range of novel electronic and energy-generating applications.

Researchers have found a way to reuse black plastics and repurpose carbon materials from them into carbon nanotubes, which are valuable for a range of energy-related applications. (Image source: Swansea University)

Scientists at Swansea University in the United Kingdom have developed a method to recycle chemicals from black plastics—which typically aren’t recycled–to fabricate carbon nanotubes, a highly valuable material for next-generation electronic applications.

The work is significant because it’s found a new use for plastic waste that today usually bypasses the recycling process and goes directly to the trash, said Alvin Orbaek White, a fellow at the Energy Safety Research Institute (ESRI) at Swansea University, who led the research.

“The big picture here is that black plastic isn’t recycled simply because it can’t been seen by the optical scanners in recycling centers,” he explained to Design News. “So it ends up going through the entire sorting process and is left on the conveyer belt with all the undesirable plastics diverted for recycling. My work is significant because it demonstrates how a plastic, that is typically not recycled, can still have use as a feedstock for making other materials.”

Those materials are CNTs, which “have quite interesting and useful properties compared to the waste that it came from,” he told Design News.

Chemistry is Key

The carbon found in black plastics is what is key to their ability to be repurposed, which the recycling industry does not identify as valuable at this time, White explained.

“Black plastics are just like other plastics, but they are colored black,” he told us. “The black coloring allows them to hide whatever color they were previously, and this gives the opportunity to mix all the plastics together to form ‘black plastic.’ This can mean that they can be made of a blended polymer combination, or they could be made a single type of polymer.”

This is one of the challenges of recycling these materials, he said, because they are classified by color but not their polymer chemistry, which is what he found interesting for his work, White told Design News.

White and his team removed the carbon from black plastics and then constructed nanotube molecules from the bottom up using the carbon atoms, they reported. They then used the nanotubes to transmit electricity to a light bulb to demonstrate their results.

“The carbon from the plastic is reused,” White told Design News. “The plastic is totally reformatted. It is not plastic by the end of the chemical reaction; the carbon has been essentially stripped from the plastic and used as the building blocks of the carbon nanotubes.”

Researchers published a paper on their work in The Journal for Carbon Research.

Boon for Renewable Energy?

CNTs can be used to develop a wide range of new applications, including conductive films for touchscreen displays, flexible electronics fabrics that create energy, and antennas for 5G networks, White said.

One industry that finds CNTs particularly useful is the renewable-energy sector, he told us. This is because the materials offer “long range-electricity transport that will rival the use of traditional copper cables,” White told Design News.

“Traditional cables lose electricity on a continual basis over long distances, so they always have to be in short distances between power source and power use,” he explained. “But many renewable sources, such as solar or wind, may require power stations be positioned in hard-to-reach and sparsely populated areas. These are far away from the people who use the power, so with traditional materials the cables can’t deliver the power because it gets lost in translation.”

The use of CNTs as electrical wires could overcome this problem, which is why one of the uses researchers are eyeing for the materials is as electricity conductors, White told us.

White hopes to use this current work as a basis to set protocols to recycle other types of what he calls “problematic plastics” so they can be repurposed for new uses, he told Design News.

Elizabeth Montalbano is a freelance writer who has written about technology and culture for more than 20 years. She has lived and worked as a professional journalist in Phoenix, San Francisco and New York City. In her free time she enjoys surfing, traveling, music, yoga and cooking. She currently resides in a village on the southwest coast of Portugal.

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