Researchers have developed a new technology that addresses long-standing challenges in plastic recycling - challenges that have limited most plastics to single-use and fueled growing waste.
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The Problem
At present, less than 20 % of all plastics undergo recycling. To enhance this percentage, it is essential to address multiple challenges, such as the irreversible degradation of properties throughout the recycling process, the restricted capacity to mix different types of plastics, issues of discoloration, and the transfer of harmful chemicals.
Current Approaches
Mechanical recycling, which entails the physical sorting of materials and their subsequent reprocessing into new production materials, faces the challenges previously mentioned. A suggested remedy for these issues is chemical recycling, which uses heat and catalysts to break down plastics into compounds that can be refined into fuels or further processed for petrochemical manufacturing.
The current state of chemical recycling is both energy-consuming and expensive, necessitating the breakdown of plastics as well as the reconstruction of severed chemical bonds.
Aqueous Chemi-Mechanical Recycling
A group of researchers from the Department of Chemical Engineering at WPI and The University of Akron collaborated with the startup Seauciel to investigate a third method introduced by the company, referred to as "aqueous chemi-mechanical recycling."
This technique utilizes the properties of water heated beyond its typical boiling point to transform polymers present in plastics into a state where they can mix at the microscale. Tests conducted on this method indicate that microscale mixing occurs following the chemi-mechanical treatment.
The research findings revealed that the chemi-mechanical treatment achieved a 96 % reduction in volatile organic compounds, which contribute to the "recycled plastic smell," when compared to plastics processed through mechanical recycling.
Chemi-mechanical recycling effectively eliminates pigments from polymers, bringing the recycled material closer to the appearance of virgin plastic. The researchers discovered that by meticulously regulating the duration of exposure to high temperatures during this treatment, they could minimize the loss of molecular weight in the polymers throughout the processing – a significant limitation of mechanical recycling – while consuming considerably less energy than chemical recycling.
The research team also noted that this process can produce recycled plastics at a cost comparable to virgin materials and has a carbon footprint that is similar to mechanical recycling and significantly lower than that of incineration.
The Next Steps
The team's upcoming projects are anticipated to involve the expansion of the technology, alongside additional research aimed at delivering a comprehensive physical comprehension of the essential phenomena.
With continued progress, this new technology could ultimately make single-use plastics a thing of the past. Large quantities of plastics are disposed of in landfills or enter the ocean, causing environmental damage and representing lost potential for material reuse and energy capture.
Michael Timko, Study Author and William B. Smith Professor, Department of Chemical Engineering, WPI
Journal Reference:
Reed, R. M., et al. (2026) Aqueous chemi-mechanical recycling for blending, decolorizing, and purifying mixed polyolefins. Chemical Engineering Journal. DOI: 10.1016/j.cej.2026.173097. https://www.sciencedirect.com/science/article/pii/S1385894726005565?via%3Dihub