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  • The Molecular Foundry study's lead researcher says most plastics were never made to be recycled.

    The Molecular Foundry study's lead researcher says most plastics were never made to be recycled. | Photo: Reuters file

Published 9 May 2019

After chemicals are added to the plastic, the monomers bind with the chemicals and make it difficult to be processed at recycling plants, the researchers explained.

A new U.S. research is seeking to make plastic 100% recyclable by altering the chemical composition of the material from the point of the manufacturing process.

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“Most plastics were never made to be recycled,” Peter Christensen, lead author of the study and a postdoctoral researcher at Berkeley Lab’s Molecular Foundry, said in a statement. 

Plastic is made up of molecules known as polymers that are composed of carbon-containing compounds known as monomers. After chemicals are added to the plastic, the monomers bind with the chemicals and make it difficult to be processed at recycling plants, the researchers explained.

“But we have discovered a new way to assemble plastics that takes recycling into consideration from a molecular perspective.”

The group of scientists at Berkeley Lab is working on a method to separate the polymers of the plastic which would allow the manipulation of the chemicals which limit re-purposing.

“We’ve already seen the impact of plastic waste leaking into our aquatic ecosystems, and this trend is likely to be exacerbated by the increasing amounts of plastics being manufactured and the downstream pressure it places on our municipal recycling infrastructure,” Brett Helms, a staff scientist in Berkeley Lab’s Molecular Foundry, added.

The study, which was published in Nature Chemistry, details a new way to assemble plastics and reuse them "into new materials of any color, shape, or form."

Helms highlighted that "we’re interested in the chemistry that redirects plastic life cycles from linear to circular. We see an opportunity to make a difference for where there are no recycling options.”

The scientists have managed to develop a new type of plastic material called poly(diketoenamine) or PDK, which differs from traditional plastics in the way the additives bond to it.

"Poly(diketoenamine)s ‘click’ together from a wide variety of triketones and aromatic or aliphatic amines, yielding only water as a by-product," the study details.

"Recovered monomers can be re-manufactured into the same polymer formulation, without loss of performance, as well as other polymer formulations with differentiated properties. The ease with which poly(diketoenamine)s can be manufactured, used, recycled and reused — without losing value — points to new directions in designing sustainable polymers with minimal environmental impact."

An acid bath, the scientists say, is sufficient to alter the way PDK plastic form bonds with other chemicals making it reversible.

Currently, only one-third of recyclable plastic is re-purposed after the recycling process.

Plastic pollution in the world's oceans is tracking to be a US$2.5-trillion problem that is already causing a negative impact on "almost all marine ecosystem services," including areas such as fisheries, recreation and heritage.

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