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Recycling Reimagined | Science News

March 18, 2021

[Posted by Chuck Almdale]

On January 18, 2021 we posted Plastics and other annoying ‘recyclables’ which drew from a May 2020 Discover Magazine article. Consider this — drawn from a Science News article — a companion piece. Recycling plastics is less efficient, less wonderful, than we think, than we hoped it would be.

Chemists are reimagining recycling to keep plastics out of landfills

Too much of today’s plastic is impossible to recycle | Maria Temming | 27 January 2021

It feels good to recycle. There’s a certain sense of accomplishment that comes from dutifully sorting soda bottles, plastic bags and yogurt cups from the rest of the garbage. The more plastic you put in that blue bin, the more you’re keeping out of landfills and the oceans, right?

Wrong. No matter how meticulous you are in cleaning and separating your plastics, most end up in the trash heap anyway.

Take flexible food packages. Those films contain several layers of different plastics. Because each plastic has to be recycled separately, those films are not recyclable. Grocery bags and shrink wrap are too flimsy, prone to getting tangled up with other materials on a conveyor belt. The polypropylene in yogurt cups and other items doesn’t usually get recycled either; recycling a hodgepodge of polypropylene produces a dark, smelly plastic that few manufacturers will use.

Only two kinds of plastic are commonly recycled in the United States: the kind in plastic soda bottles, polyethylene terephthalate, or PET; and the plastic found in milk jugs and detergent containers — high-density polyethylene, or HDPE. Together, those plastics make up only about a quarter of the world’s plastic trash, researchers reported in 2017 in Science Advances. And when those plastics are recycled, they aren’t good for much. Melting plastic down to recycle changes its consistency, so PET from bottles has to be mixed with brand-new plastic to make a sturdy final product. Recycling a mix of multicolored HDPE pieces creates a dark plastic good only for making products like park benches and waste bins, in which properties like color don’t matter much. More….

From Science News 30 January 2021

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