A team of researchers developed a type of plastic that’s infinitely recyclable, according to a paper in the science journal Nature Chemistry.
The plastic, poly(diketoenamine), or PDK, could provide companies with a closed-loop solution, meaning raw materials can be infinitely reused, to the global problem of plastic waste by dramatically improving global recycling rates.
Currently, an estimated 9% of the plastic that’s used around the world gets recycled. That means that the vast majority of the more than 8.3 billion metric tons of plastic created since the 1950s has ended up in landfills.
In recent years, the scale of plastic pollution — and the harm it causes wildlife — has created a backlash against plastic production in general.
But PDK suggests a viable alternative to the many types of junk plastic available.
“Most plastics were never made to be recycled,” said lead author Peter Christensen, a postdoctoral researcher at Berkeley Lab’s Molecular Foundry, in a press release. “But we have discovered a new way to assemble plastics that takes recycling into consideration from a molecular perspective.”
If you’ve ever wondered why there are so many recycling codes on the bottom of plastic containers, it’s because most types of plastic are hard to process and two different types of plastic often require different methods of recycling.
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Even plastic that manages to get recycled is rarely “upcycled” into a higher quality material or recycled into the same quality material. Instead, most plastic that gets recycled turns into something of lower quality, because the recycling process often degrades the original material in some way, whether through contamination or wear-and-tear.
Plastic is made up of carbon-containing molecules called monomers that are combined to form polymers. Monomers are often combined by adding chemical additives that can also give the resulting plastic various characteristics such as toughness and flexibility. The problem, however, is that these additives make it hard to recycle plastic in the future because they stick to the monomers.
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With PDK, the researchers at the Department of Energy’s Lawrence Berkeley National Laboratory developed a recycling technique that fully retrieves the original monomers of a piece of plastic, which can then be repurposed into new types of plastic of the same or higher quality.
Once PDK is ready to be recycled, it’s placed in a vat of acid that dissolves the chemical additives that bind it together, leaving the monomers intact.
The researchers think that this method can significantly reduce the problem of plastic waste around the world.
“We’re interested in the chemistry that redirects plastic lifecycles from linear to circular,” said Brett Helms, a staff scientist in Berkeley Lab’s Molecular Foundry, in the press release. “We see an opportunity to make a difference for where there are no recycling options.
“We’re at a critical point where we need to think about the infrastructure needed to modernize recycling facilities for future waste sorting and processing,” he added. “If these facilities were designed to recycle or upcycle PDK and related plastics, then we would be able to more effectively divert plastic from landfills and the oceans. This is an exciting time to start thinking about how to design both materials and recycling facilities to enable circular plastics.”
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Governments around the world have begun to restrict forms of plastic that are especially hard to recycle, including polystyrene, commonly called styrofoam, and single-use plastics. Companies that depend on plastic packaging are also looking for alternatives to reduce their ecological footprint.
While PDK doesn’t address the problem of single-use plastics, still involves fossil fuels for production, and depends on municipalities to develop infrastructure to effectively recycle it, the new material could provide a bridge to a more sustainable future.