Scientists at the U.S. Department of Energy’s Ames Laboratory and their partners from Clemson University have discovered a green, low-energy process to break down polystyrene, a type of plastic that is widely used in foam packaging materials, disposable food containers, cutlery, and many other applications.
Polystyrene is part of a much larger global plastic waste problem. Hundreds of millions metric tons of polymers are produced each year, a large majority of which is discarded after use. Due to the chemical stability and durability of industrial polymers, plastic waste does not easily degrade in landfills and is often burned, which produces carbon dioxide and other hazardous gases. In order to stop the growing flood of polymer waste and reduce carbon dioxide emissions, plastics have to be recycled or converted into new value-added products.
Currently, recycling of the vast majority of plastics is not economically feasible; their sorting and separation are time and labor intensive, while chemical processing and remanufacturing requires a significant energy input and toxic solvents. Re-processed polymers often show inferior performance to that of the freshly manufactured “made from scratch” materials.
A team of scientists at Ames Laboratory used processing by ball-milling to deconstruct commercial polystyrene in a single step, at room temperature, in ambient atmosphere in the absence of harmful solvents. Ball-milling is a technique that places materials in a milling vial with metal ball bearings which is then agitated until a desired chemical reaction occurs. Called mechanochemistry, this experimental approach has numerous applications in new materials synthesis, and attractive features where plastics recycling is concerned.
The deconstruction of polystyrene proceeds through a series of chemical events involving mechanical cutting apart of the macromolecules, which generates free radicals detectable in the milled material even after its prolonged exposure to air. The metal bearings used for milling and the ambient oxygen act as co-catalysts that enable extraction of the monomeric styrene from the oligomeric radical-bearing species formed. The experiments showed that the temperature rise in the material during milling is not responsible for the observed phenomenon since the temperature inside the milled powder does not exceed 50oC while the thermal decomposition of polystyrene in air starts at about 325oC. The Clemson’s group confirmed the comprehensive deconstruction of the original polymer into smaller fragments, oligomeric materials, suitable for further processing into new value-added products.
“This method represents an important breakthrough that enables dismantling of a polymer simultaneously with its break-down under ambient conditions, that is, ~300oC below the thermal decomposition temperature of the pristine material” said Ames Laboratory Senior Scientist Viktor Balema. “We think this proof of concept is an exciting possibility for developing new recycling technologies for all kinds of plastics, and that will contribute to establishment of the circular economy.”
His partner from Clemson University, Kentwool Distinguished Professor Igor Luzinov, further commented that “this discovery opens new avenues for low temperature recovery of monomers from multicomponent polymer based systems such as composites and laminates. Also, our technology will allow extracting the monomer from crosslinked materials containing styrene units in their structures.”
Alfred P. Sloan Foundation Research Fellow, Professor Aaron Rossini of Iowa State University, further noted that “electron paramagnetic resonance spectroscopy shows large concentrations of free radical carbon-centered species in polystyrene that was milled in air. This is a startling result because free radicals are normally very reactive. Also, the presence of the radicals gives direct evidence that the milling directly causes scission of the polymer chains. We expect that the reactive sites associated with the free radicals can be used to functionalize the processed polymers to obtain new value-added products.”
Original Article: Polystyrene waste is everywhere, and it’s not biodegradable. Scientists just found a way to break it down
More from: Ames Laboratory | Clemson University
The Latest Updates from Bing News & Google News
Go deeper with Bing News on:
Recycling polystyrene
- Victoria's single-use plastic ban starts today, but experts worry it does not go far enough
Changes include prohibiting the supply and sale of plastic straws, cutlery, plates, drink-stirrers and cotton bud sticks, bringing Victoria into line with most other states.
- Plastic Recycling Market Is Driven By The Increasing Environmental Awareness Among The People Says GIS Analyst
Global plastic recycling market report from Global Insight Services is the single authoritative source of intelligence on Pl ...
- NexKemia acquires assets of polystyrene scrap recycler Eco-Captation
Eco-Captation is Quebec's leading polystyrene recycler, according to NexKemia's parent company, Integreon Global.
- EPS maker NexKemia boosts access to recycled PS with acquisition
Expanded polystyrene maker NexKemia Petrochemicals Inc. is acquiring a PS recycler in a deal that aims to use artificial intelligence to boost the use of recovered materials in new products. Subscribe ...
- NexKemia buys Quebec polystyrene waste recycler Eco-Captation
In a move that increases its footprint as a mechanical recycling hub, Canada-based expandable polystyrene (EPS) manufacturer NexKemia has finalized the purchase of Eco-Captation, a polystyrene waste ...
Go deeper with Google Headlines on:
Recycling polystyrene
[google_news title=”” keyword=”recycling polystyrene” num_posts=”5″ blurb_length=”0″ show_thumb=”left”]
Go deeper with Bing News on:
Polystyrene waste
- Victoria's single-use plastic ban starts today, but experts worry it does not go far enough
Changes include prohibiting the supply and sale of plastic straws, cutlery, plates, drink-stirrers and cotton bud sticks, bringing Victoria into line with most other states.
- ‘Go green during Thaipusam’
Organisations setting up thaneer panthals (refreshment stalls) offering free food and drinks, as well as devotees have been urged to refrain from using polystyrene containers and cups during Thaipusam ...
- Victoria the latest Australian state to ban single-use plastics from today
Victorians will no longer be able to purchase single-use plastics, with the state government’s ban on the items coming into effect today.
- Prevent food wastage during Thaipusam, do away with polystyrene food containers - CAP
With nearly 70 tonnes of food going to waste during the Thaipusam celebration two years back, the Consumers’ Association of Penang (CAP) and the Malaysia Hindu Sangam have urged devotees not to resort ...
- NexKemia acquires assets of polystyrene scrap recycler Eco-Captation
Eco-Captation is Quebec's leading polystyrene recycler, according to NexKemia's parent company, Integreon Global.
Go deeper with Google Headlines on:
Polystyrene waste
[google_news title=”” keyword=”polystyrene waste” num_posts=”5″ blurb_length=”0″ show_thumb=”left”]