The U.S. Department of Energy recently awarded researchers at University of Wisconsin-Madison $12 million to lead a Multi-University Center on Chemical Recycling of Waste Plastics (CUWP). One of their first projects tackled a previously unrecyclable type of plastic. If you’ve been grocery shopping for a while, you may have noticed a shift in how a lot of food is stored. “If you go to the grocery store today you’ll notice a lot more of your food is packaged in plastic packaging than it was 10, 20, 30 years ago,” said George Huber, a chemical and bioengineering professor at the UW-Madison and leader of the CUWP.
These are commonly multi-layer plastics — layered films made out of different plastic materials to form one package. “None of these films can be recycled today,” Huber said. “All of these films that are produced go to landfill because there’s no technology to recycle them.”
Scientists at UW-Madison have developed a way to recycle these. “What we wanted to do was to design a method to extract each individual component in a very pure form,” said Reid Van Lehn, a Conway Assistant Professor with the University.
Van Lehn developed a method to match solvents to individual films used in multilayer plastics that will dissolve them one at a time leaving the other layers behind without damaging it. The solvents can then be evaporated off, leaving the plastics in the original form. It’s a process called solvent-targeted recovery and precipitation, or STRAP. “Here we’re getting back the original polymers that can then be immediately remade back into the film,” Van Lehn said. “So in principle it’s a very efficient recycling process.”