Light, sturdy, pliable and cheap, the plastic has thousands of purposes and benefits for the industry and the end consumer. Its disposal is the challenge: from more than 8 billion tons of plastic produced in mankind history, only 9% have been recycled and 70% have become waste.
Although plastic itself is fully recyclable, it’s usually mixed with additives, paints, temperature stabilizers, and so on, to be used commercially. A full recycling in such cases requires energy consumption and economic investment. At least for now.
Researchers at Berkeley Lab, an innovative laboratory of the University of California, in Berkeley, engineered a new type of plastic and a new type of chemical process which make the material entirely and virtually recyclable for good. In an article published in the magazine Nature Chemistry magazine, scientists named the new substance poly-diketoenamine, or PDK.
Plastic works as a Lego piece
The PDK developers explain that the material works as a Lego piece: the pieces (or chemical molecules) may be assembled and disassembled so the plastic may be used as needed, and reused in different shapes, textures and colors, for different purposes, as many times as possible – and without deterioration of quality.
“We have discovered a new way to assemble plastics that takes recycling into consideration from a molecular perspective,” explains Peter Christensen, researcher at Berkeley involved in the project. This works from the deconstruction of polymers (large molecules comprising all types of plastic) into smaller compound units, called monomers.
Conventional plastic, when chemically bound to various types of additives, loses great part of its recycling capacity, especially for the cost required to recover it. Because they have no economic return for the recycling industry, they are disposed as common solid waste. PDK works in a different way, its creators claim.
“With PDKs, the immutable bonds of conventional plastics are replaced with reversible bonds that allow the plastic to be recycled more effectively,” says Brett Helms, one of the scientists involved in the project. The key lies in its chemical process.
When PDK is disposed, it’s immersed into a highly acidic solution that breaks the bonds between monomers, setting them apart from any chemical additives. Also, there’s no deterioration of their original features. In tests performed at Berkeley Lab, such monomers were restored into polymers and formed new plastic materials.
Scientists expect that the new material may be used as input for objects such as stickers, telephone boxes, watch bands, footwear, computer cables and car parts. “We’re interested in the chemistry that redirects plastic lifecycles from linear to circular,” completes Helms.
Content published in June 27, 2019