In a field where progress is often slowed by trade-offs between performance, cost, and environmental impact, a new recycling method reported this month suggests a practical way to recover much more value from discarded plastics. Led by Michael Timko, professor and head of chemical engineering at Worcester Polytechnic Institute, the work describes a chemi-mechanical process that removes pigments, reduces contaminants, and preserves key material properties in recycled polyolefins, the most widely used class of plastics.
Reed, M. R., Pathan, A. N., Banerjee, A., Timko, M. T., & Eagan, J. M. (2026). Aqueous chemi-mechanical recycling for blending, decolorizing, and purifying mixed polyolefins. Chemical Engineering Journal, 529, 173097. https://doi.org/10.1016/j.cej.2026.173097
The study, carried out by researchers at Worcester Polytechnic Institute in collaboration with the University of Akron and the startup Seauciel, addresses a persistent limitation of today’s recycling infrastructure. Despite decades of effort, less than one fifth of global plastic waste is recycled. For common packaging materials such as polyethylene and polypropylene, the problem is not simply collection. Repeated mechanical reprocessing degrades polymer chains, darkens color, traps odors, and concentrates additives that restrict where recycled material can be reused. As a result, many plastics are effectively “downcycled” into lower-value products before eventually being discarded.
Michael Timko, professor and head of chemical engineering at Worcester Polytechnic Institute stated,
“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.”
Chemical recycling has been proposed as an alternative because it can, in principle, return plastics to feedstocks similar to those used in virgin production. In practice, however, these routes often require high temperatures, catalysts, and multiple reaction steps to break and rebuild polymer chains. The energy demand and capital cost have limited large-scale deployment, particularly for mixed or contaminated waste streams.
The approach examined by Timko and colleagues sits between these two extremes. The process, referred to as aqueous chemi-mechanical recycling, uses water heated above its normal boiling point under pressure. In this state, water exhibits properties that allow polymer chains to temporarily mobilize without being chemically broken down. When mixed plastics are exposed to these conditions for controlled periods, the polymers soften and interpenetrate at the microscale, allowing different materials to blend more uniformly than in conventional mechanical recycling.
One outcome of this treatment is a marked reduction in visual and chemical contamination. Pigments that normally persist through grinding and remelting are largely removed, bringing the recycled material closer in appearance to uncolored, virgin plastic. The research team reports that volatile organic compounds associated with the characteristic odor of recycled plastics were reduced by approximately 96 percent compared with standard mechanical processing. This is a significant practical result, as odor has been a barrier for recycled plastics in consumer products and food-adjacent applications.
Equally important is what the process avoids. By carefully limiting exposure time at elevated temperature, the researchers minimized molecular weight loss in the polymers, preserving tensile strength and other mechanical properties that typically decline after repeated recycling cycles. Measurements showed that the treated materials retained performance closer to that of virgin plastics than mechanically recycled equivalents.
From an engineering perspective, the energy balance is central. The chemi-mechanical method requires more input than simple remelting but far less than full chemical depolymerization. According to the study, the overall energy use is comparable to mechanical recycling and substantially lower than incineration or current chemical recycling pathways. Economic modeling suggests that, at scale, the cost of material produced could approach that of virgin polyolefins, a threshold often cited as critical for industry adoption.
Independent work in polymer engineering over the past few years has emphasized that improving recycling rates will likely depend on incremental advances that fit within existing industrial frameworks rather than entirely new infrastructures. In that context, the reported process is notable because it can handle mixed polyolefin streams, a common reality in post-consumer waste, without requiring extensive sorting. It also aligns with broader trends toward water-based and solvent-reduced processing in chemical engineering.
The authors are cautious about framing the technology as a complete solution. Scaling remains a challenge, particularly in managing pressure, temperature control, and throughput for large volumes of waste. Further work is also needed to fully understand the transport phenomena and polymer dynamics that enable microscale blending under these conditions. Nonetheless, the results point to a pathway where plastics could be recycled multiple times without the steady loss of quality that currently limits reuse.
For Timko, the motivation is both technical and systemic. Large quantities of plastics still end up in landfills or the environment, representing not only pollution but also lost material and energy potential. If recycled plastics can reliably match the performance and appearance of virgin materials, the incentive structure across manufacturing and consumer markets changes.
The study contributes to a growing body of research suggesting that the future of plastic recycling may not hinge on a single disruptive breakthrough, but on carefully engineered processes that reduce degradation, remove contaminants, and fit within realistic energy and cost constraints. For engineers working at the intersection of materials science and sustainability, aqueous chemi-mechanical recycling offers a concrete example of how rethinking processing conditions can unlock new performance from familiar materials.
Adrian graduated with a Masters Degree (1st Class Honours) in Chemical Engineering from Chester University along with Harris. His master’s research aimed to develop a standardadised clean water oxygenation transfer procedure to test bubble diffusers that are currently used in the wastewater industry commercial market. He has also undergone placments in both US and China primarely focused within the R&D department and is an associate member of the Institute of Chemical Engineers (IChemE).
