It might be possible to make greater use of plastic waste if a technique to change a frequently discarded plastic into a resin for 3D printing was developed.
The WSU research team, including postdoctoral researcher Yu-Chung Chang, used PLA plastic waste to create a high-quality resin for 3D printing. Image Credit: Washington State University
To create high-quality resin from polylactic acid (PLA), a bio-based plastic used in items like filament, plastic tableware, and food packaging, a group of researchers at Washington State University devised a quick and easy process.
We found a way to immediately turn this into something stronger and better, and we hope that will provide people the incentive to upcycle this stuff instead of just toss it away. We made stronger materials just straight out of trash. We believe this could be a great opportunity.
Yu-Chung Chang, Study Co-Corresponding Author and Postdoctoral Researcher, School of Mechanical and Materials Engineering, Washington State University
The annual production of PLA is about 300,000 tons, and its utilization is rapidly expanding.
PLA, a #7 plastic that is considered to be bio-based, is difficult to degrade. It will not deteriorate after a year of floating in either fresh or salt water. It is also infrequently recycled since, like many polymers, it loses value and functionality after being melted down and reshaped.
It’s biodegradable and compostable, but once you look into it, it turns out that it can take up to 100 years for it to decompose in a landfill. In reality, it still creates a lot of pollution. We want to make sure that when we do start producing PLA on the million-ton scale, we will know how to deal with it.
Yu-Chung Chang, Study Co-Corresponding Author and Postdoctoral Researcher, School of Mechanical and Materials Engineering, Washington State University
Scientists from the School of Mechanical and Materials Engineering, under the direction of Professor Jinwen Zhang, created a quick and catalyst-free technique to recycle PLA in their investigation, which was published in the journal Green Chemistry.
They did this by disassembling the PLA’s lengthy chain of molecules into basic monomers, which serve as the building blocks for many plastics. At comfortable temperatures, the full chemical process can be completed in two days or less. Aminoethanol, the chemical they employed to degrade the PLA, is likewise reasonably priced.
“If you want to rebuild a Lego castle into a car, you have to break it down brick by brick. That is what we did. The aminoethanol precision cut the PLA back to a monomer, and once it’s back to a monomer, the sky’s the limit because you can re-polymerize it into something stronger,” Chang said.
The researchers disassembled the PLA to its constituent parts, reassembled the plastic, and produced a sort of photo-curable liquid resin that is frequently used as printing “ink” for 3D printers. The material demonstrated comparable or superior mechanical and thermal qualities to commercially available resins when it was employed in a 3D printer and solidified into plastic components.
Even though the study’s focus was on PLA, the scientists intend to apply the findings to polyethylene terephthalate (PET), which is more prevalent than PLA, has a comparable chemical structure, and poses a greater waste problem.
They are attempting to further streamline the procedure and have submitted a provisional patent. The scientists are also investigating further uses for the upcycling technique.
Journal Reference
Shao, L., et al. (2022) A chemical approach for the future of PLA upcycling: from plastic wastes to new 3D printing materials. Green Chemistry. https://pubs.rsc.org/en/content/articlelanding/2022/GC/D2GC01745H