PVC plastics now recyclable after breakthrough by Michigan scientists

Polyvinyl chloride or PVC is now a recyclable type of plastic after scientists at the University of Michigan discovered a way to chemically recycle the widely used material.

PVC is a heavy-duty type of plastic with a zero percent recycling rate in the United States, but that is expected to change after research by university chemists found a way to re-use one of its most noxious components. The material is one of the most produced plastics in the nation and the third highest by volume in the world. The study of chemical recycling of PVC published last month in the journal Nature Chemistry. Former postdoctoral researcher Danielle Fagnani was the first author and U-M Chemistry Professor Anne McNeil was the principal investigator.

“PVC is the kind of plastic that no one wants to deal with because it has its own unique set of problems,” Fagnani said. “PVC usually contains a lot of plasticizers, which contaminate everything in the recycling stream and are usually very toxic. It also releases hydrochloric acid really rapidly with some heat.”

McNeil explained how plastic is typically recycled by melting it down to reform it into lower quality materials, a process called mechanical recycling. But when PVC is heated, one of its primary components, called plasticizers, leach out very easily – as well as hydrochloric acid.

Those toxic plasticizers can then slip into other plastics in the recycling stream, while the hydrochloric acid can corrode recycling equipment and even cause chemical burns to workers. The plasticizers are highly noxious endocrine disruptors, which means they can interfere with hormones in humans and other mammals.

The researchers explored electrochemistry to find a way to recycle PVC plastics without using heat.

They discovered the plasticizer that caused a major challenge to recycle the material through traditional means in contrast improves the efficiency of the electrochemical method. And the hydrochloric acid problem is resolved, too.

“What we found is that it still releases hydrochloric acid, but at a much slower, more controlled rate,” Fagani said.

The acid can subsequently be used by industries as a reagent for other chemical reactions. Additional chemical components of PVC can also be re-used, though researchers continue to look for uses for other leftover materials.

PVC is used in a vast range of plastics, from medical equipment like tubing, blood bags, masks and more, to building materials such as modern plumbing, window frames, housing trim, siding, and flooring. It also coats electric wiring and is found in shower curtains, tents, tarps, and clothing.

The focus of McNeil’s lab at the university has been to find ways to chemically recycle various kinds of plastics. The idea is to break plastics down into component parts that are not degraded and can be re-used by industry.

“It’s a failure of humanity to have created these amazing materials which have improved our lives in many ways, but at the same time to be so shortsighted that we didn’t think about what to do with the waste,” McNeil said.

She said only a few types of plastics are recycled and it leads to progressively lower quality polymers.

“Our beverage bottles never become beverage bottles again. They become a textile or a park bench, which then ends up in a landfill,” McNeil said.