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On the brink of a recycling revolution?

2017; National Academy of Sciences; Volume: 114; Issue: 4 Linguagem: Inglês

10.1073/pnas.1620655114

1091-6490

John H. Carey,

biodegradable polymer synthesis and properties

We’re awash in plastics, many of which are hard to recycle. Could innovations, girded by the right incentives, finally whittle down the piles of plastic waste? The waste that arrives at MBA Polymers’ big blue factory in Worksop, in England’s industrial heartland, is a dirty, smelly mess. Fresh from a metals recycler that has extracted hunks of steel from the crushed remains of cars and other trash, it contains many types of plastic jumbled in with carpeting, rubber, glues, bits of metal and glass, and even the occasional dead animal. Inside the cacophonous facility, powerful magnets and other technologies strip out everything but the plastic, which is ground into small 6–8 millimeter particles. Companies are finding better ways to recycle multiple types of plastic, but costs often remain a barrier. Image courtesy of Shutterstock/Warut Chinsai. These flakes are then washed, sorted, melted, filtered, and extruded. The final result: small pellets of pure plastic that can be melted down and then reshaped into anything from printers to vacuum cleaners, thus replacing virgin polymers made from fossil fuel feedstocks. “We take some of the ugliest waste streams and produce high-value products,” says MBA Polymers Inc. director Mike Biddle, who founded the company in his garage in California. Such transformations aren’t confined to MBA Polymers. There’s been a “quiet revolution” in the technology of mechanically sorting waste plastic, says Edward Kosior, managing director of international recycling consultant Nextek. Near-infrared scanners, centrifuges, and other high-tech tools can now sort plastic flakes as small as 2 millimeters from mixed trash. That means recycling companies can produce high-quality plastic not just from the contents of carefully sorted curbside recycle bins, but also from general municipal solid waste. And the advances aren’t limited to sorting. Researchers are using clever chemistry to break apart the polymer molecules in …