Coconut oil and microwaves can convert hard-to-recycle plastic car parts to strong, lightweight foams, a new study shows. These foams are used for packaging, insulation in buildings, and cushioning and insulation in cars.
Over 11 million tons of plastic are expected to go into cars and trucks in 2018. The good news, at least in the US, is that 95 percent of these vehicles—and more than 84 percent by weight of each vehicle—eventually gets recycled.
But not all the plastics are made the same. While some are easy to recover, polyurethanes and polycarbonates need complex energy-consuming chemical recycling methods that require high temperatures. Chemical recycling converts the plastics into simpler molecules that can then be added to polyurethane foams.
Not too many people have tried to make useful products with these recycled raw materials. The few recycled plastic foams that have been made in the lab are too brittle or dense.
Researchers at the Institute of Macromolecular Chemistry in the Czech Republic and the Cracow University of Technology in Poland have previously found that they could degrade polycarbonates using a reagent that they derived from coconut oil. They have now used that same renewable reagent to recover polyurethane and polycarbonate from waste car plastics. They chop up the waste parts into small pieces, mix it with the coconut oil reagent, and then heat the mixture with microwaves in a reactor for 30 minutes. The method is detailed in the journal ACS Sustainable Chemistry & Engineering.
The result is a brown liquid that can be added to virgin liquid plastics to make foam. Foams made with 50 percent recycled plastic content had the best mechanical properties, they found.