Plasma-powered plastic breakdown paper ranks among journal’s top 10% most viewed of 2023
Study explores the use of plasma for plastic decomposition and depolymerization.
A research paper coauthored by University of Michigan Nuclear Engineering and Radiological Sciences (NERS) professor John E. Foster and recent NERS PhD graduate Roxanne Z. Walker has earned recognition as one of the most viewed papers in Plasma Processes and Polymers in 2023. The paper, “Evidence of plasma-driven decomposition of common plastics exposed to an atmospheric nonthermal discharge,” presents a promising pathway toward cleaner plastic recycling using plasma rather than toxic chemicals or inefficient thermal processes. Here the goal is to depolymerize the plastic so that the resulting monomers can be used to fabricate higher-quality plastic materials or utilize gaseous species for fuel.
Walker completed her PhD at NERS in August 2024, and the publication is a key component of her doctoral thesis. Additional co-authors included Sophia Gershman of the Princeton Plasma Physics Laboratory and Dorothy E. Doughty of Rutgers University. The work was carried out in part at the Princeton Collaborative Low Temperature Plasma Research Facility (PCRF) which provided advanced diagnostics to assess the performance of the UM plasma reactor.
The team explored the use of pulsed, spark-based nonthermal plasma to decompose common plastics like low-density polyethylene (LDPE), polypropylene (PP), and polyethylene terephthalate (PET). By operating at atmospheric pressure and room temperature, their method avoids the extreme heat and lack of selectivity typically associated with traditional pyrolysis.
The study found that plasma effectively converted plastics into light gaseous hydrocarbons such as methane, acetylene, and ethylene. Introducing hydrogen into the gas mixture significantly boosted gas production, particularly methane, due to a process called hydrogenolysis—where hydrogen atoms assist in breaking the chemical bonds in plastic molecules. Among the plastics tested, LDPE showed the highest decomposition yield, likely because of its lower melting point.
Notably, the plasma process remained stable regardless of the type of plastic or gas mixture used. Surface damage and chemical changes to the plastics were confirmed using infrared spectroscopy. For the short treatment times explored, a small fraction of the plastic was converted—approximately 1 to 2.5 percent over five minutes at very low power. The study gave insight into decomposition mechanisms.
This work contributes to a growing body of research aimed at creating low-energy, scalable recycling solutions. By demonstrating that nonthermal plasma can break down plastics into monomers selectively, the paper lays a foundation for novel recycling technologies that are potentially more sustainable and widely deployable.
“There are a lot of scientists out there working out what to do about our massive plastics problem,” said Walker. “I am grateful to have participated in research at PCRF trying to find solutions using plasma!”
“ There is so much plastic waste in the environment now, it may be possible to recycle what’s out there without the need to generate new plastics,” said Foster. “We can simply depolymerize the existing waste with plasmas to make monomer feedstock to make new plastic from the old. Right now plastic production and subsequent waste is unsustainable–damaging the environment—but the promising plasma method may be an instrument in the toolbox that can change the way we manage this emerging problem of plastic waste.”
The paper was published open access thanks to the Wiley–Big Ten Academic Alliance (BTAA) agreement with the University of Michigan.