Washington State University: Recycling PLA plastic into high-quality printing resin
A method of converting commonly discarded plastic into resin used in 3D printing could make better use of plastic waste. A Washington State University (WSU) research team has developed a simple and effective method to recycle and convert polylactic acid (PLA), a bio-based plastic used in products such as filament, plastic silverware and food packaging, And converted into high-quality resin.
Yu-Chung Chang, a postdoctoral researcher at Washington State University, said: "We found a way to instantly turn it into something more powerful and better, and we hope this will inspire people to upgrade these things rather than throw them away. ."
According to Washington State University, approximately 300,000 tons of PLA are produced each year, and its use is increasing dramatically. Although it is bio-based, PLA, which is classified as a #7 plastic, does not break down easily. It can float in fresh or salt water for a year without degrading. It's also rarely recycled because, like many plastics, when it's melted and reshaped, it doesn't perform as well as it originally did and becomes less valuable. "
It's biodegradable and compostable, but once you study it, it can take up to 100 years to decompose in a landfill," Yu-Chung Chang said. "Actually, it still causes a lot of pollution. We want to make sure that when we start producing megaton PLA, we'll know what to do with it."
In the study published in the journal Green Chemistry, researchers led by Professor Jinwen Zhang from the School of Mechanical and Materials Engineering have developed a fast and catalyst-free method to recycle PLA, breaking down long-chain molecules into simple monomers . The entire chemical process can be done in about two days at mild temperatures, and the chemical they use to break down PLA, aminoethanol, is also cheap. "
If you want to turn a Lego castle into a car, you have to take it apart brick by brick," says Yu-Chung Chang. "That's what we did. Aminoethanol precisely cuts the PLA back to the monomer, and once it's back to the monomer, you can repolymerize it into something stronger."
Once PLA is broken down into its basic components, the researchers rebuild the plastic and create a light-curing liquid resin commonly used as a printing "ink" for 3D printers. When used in a 3D printer and cured into plastic parts, the product showed mechanical and thermal properties equal to or better than commercially available resins.
While the researchers focused their research on PLA, they hope to apply this work to polyethylene terephthalate (PET), which is more common than PLA, has a similar chemical structure, and exists in a larger waste problem.
