A method to convert commonly discarded plastics into resin used in 3D-printing could allow better use of plastic waste. Researchers developed a simple and efficient way to convert polylactic acid (PLA), a bio-based plastic such as filament, into a high-quality resin in products such as plastic silverware, and food packaging.
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“We found a way to quickly turn it into something that’s stronger and better,” says Yu-Chung Chang, a postdoctoral researcher in Washington state, and we hope to get people to upcycle it instead of throwing this stuff away. will be encouraged.” University School of Mechanical and Materials Engineering and co-corresponding author of the study, published in green Chemistry, “We made strong material straight from the dustbin. We believe this could be a good opportunity.”
About 300,000 tons of PLA are produced annually, and its use is increasing dramatically. Although it is bio-based, PLA, which is classified as a number seven plastic, does not break down easily. It can float in fresh or salt water for up to a year without spoiling. It is also rarely recycled because, like many plastics, when it is melted and re-formed, it does not perform as well as the original version and becomes less valuable.
“It’s biodegradable and compostable, but once you look at it, it turns out it can take up to 100 years to decompose in landfills,” Chang says. “In fact, it still creates a lot of pollution. We want to make sure that when we start producing PLA on a million-ton scale, we will know how to deal with it. , In the study, lead author Jinwen Zhang, professor in the School of Mechanical and Materials Engineering, and colleagues developed a rapid and catalyst-free method to recycle PLA, breaking down long chains of molecules into simpler monomers—many of the others. Building blocks for plastics. The entire chemical process can be done at mild temperatures in about two days. The chemical they used to break down PLA, aminoethanol, is also cheaper.
“If you want to rebuild a Lego castle into a car, you have to break it down brick by brick,” Chang says. “That’s what we did. Aminoethanol precision-cuts PLA back into a monomer, and once it’s back to a monomer, the sky’s the limit because you can re-polymerize it into something stronger.” .
Once PLA was broken down into its original building blocks, researchers reconstructed the plastic and created a type of photo-curable liquid resin commonly used as “ink” printing for 3D printers. When used in 3D printers and cured into plastic pieces, the product showed similar or better mechanical and thermal properties than commercially available resins.
While the researchers focused on PLA for the study, they hope to apply the work to polyethylene terephthalate (PET), which is more common than PLA, has a similar chemical composition, and presents a major waste problem.
The researchers have filed a provisional patent and are working to further optimize the process. They are also looking at other applications for the upcycling method.
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