How plastic bags can now be upcycled

By Alice Clifford via SWNS

Notorious plastic bags can now be upcycled to meet the large demand for high-value plastics.

Polyethylene plastics are used to make plastic bags, milk cartons, bottles and many other everyday objects that are extremely difficult to recycle.

Only 14 percent of all polyethylene plastic products can be recycled and only into low-quality products such as garden furniture.

But this may be all changing thanks to scientists at the University of California, Berkeley and Lawrence Berkeley National Laboratory.

They have found a way to break the sturdy polymers into the three-carbon molecule called propylene.

This high-demand molecule can then be used to make valuable plastics such as polypropylene, used in ropes, twine, tape, carpets, upholstery, clothing and camping equipment.

The discovery will allow them to turn former waste products into major high-demand products, with very minimal fossil fuels, they report in the journal Science.

Polyethylene plastics make up about one-third of the entire plastics market worldwide, with more than 100 million tons produced yearly from fossil fuels.

John Hartwig, UC Berkeley’s Henry Rapoport Chair in Organic Chemistry, said: “To the extent they get recycled, a lot of polyethylene plastics get turned into low-grade materials.

"You can't take a plastic bag and then make another plastic bag with the same properties out of it.

"But if you can take that polymer bag back to its monomers, break it down into small pieces and repolymerise it, then instead of pulling more carbon out of the ground, you use that as your carbon source to make other things — for example, polypropylene.

"We would use less shale gas for that purpose, or for the other uses of propane, and to fill the so-called propylene gap.”

This form of upcycling can produce high-value products, meet the high demand for propylene in the plastics industry, give wasteful products a new purpose and reduce the use of fossil fuels.