College of Engineering News • Iowa State University

Research project aims to make plastic films more biodegradable

A graphic featuring headshot for the five Iowa State University researchers involved on this project.

That plastic film packaged around many consumer products might become easier to recycle thanks to an interdisciplinary team of researchers at Iowa State University and beyond.

The effort is being led by Xianglan Bai, associate professor of mechanical engineering (ME) at Iowa State. The goal of her and her team’s project is to develop a novel recycling technology to convert the waste plastic films (mainly consisting of polyolefins) into biodegradable polymers at a lower cost compared to current methods. The researchers hope their findings might help to lessen the amount of plastic waste that currently accumulates on land and in water.

Bai and her multidisciplinary, interinstitutional research team will develop a novel, hybrid, plasma-based conversion technology to efficiently convert heterogeneous and highly contaminated waste plastic films into environmentally-friendly polymers.

“Our hybrid conversion technology will employ a closed carbon loop approach to convert waste plastics into biodegradable polymers at much improved carbon and energy efficiencies, thereby, promoting both environmental sustainability and circular carbon economy,” Bai said.

Advancing past research

This new project, supported by a $2.5 million grant from the Department of Energy’s (DOE) Office of Energy Efficiency and Renewable Energy, will build upon past research she has done in the realm of plastics. With past funding from DOE, the National Science Foundation, and the Iowa Energy Center, Bai and her team have developed various thermochemical conversion approaches to recycle waste materials and to mitigate the pollutant formation during the recycling process.

Specifically, the researchers plan to advance a process they have developed known as non-thermal plasma-based, chemical conversion technology. Non-thermal plasma, also called cold plasma, is a partially ionized gas with high chemical reactivity, generated by applying a high-voltage electric field to neutral gases. Non-thermal plasma is considered a green low-energy technology due to its ability to use renewable electricity as the power source and its low energy input requirement, according to Bai.

“In our studies, we found that in comparison to conventional thermochemical approaches, applying non-thermal plasma-based approaches to biomass or plastics can greatly improve conversion, increase chemical selectivity of the products and lower energy inputs,” said Bai. “In the last two years, my group has published several papers on Green Chemistry to describe our novel plasma-based approaches to convert biomass into high value chemicals.”

A multidisciplinary, interinstitutional research team

For her portion of the project, Bai will develop a novel non-thermal plasma-based chemical conversion of waste plastics. Other than applying the knowledge about polymer chemistry, the research will also utilize ME principles such as thermodynamics, fluid mechanics and heat transfer.

“These ME concepts and methods will be used for feedstock preparation and conversion, reactor design, flow control and heat transfer analysis, and process optimization,” Bai said.

Fellow collaborators on this project include ME associate professor Mark Mba-Wright, who will provide an economic and environmental analysis of the new technology, while Hui Hu, Martin C. Jischke Professor in aerospace engineering at Iowa State, will contribute his expertise on advanced laser-based diagnostics and thermodynamics for non-thermal plasma characterization as well as plasma reactor design and optimization. Keith Vorst and Greg Curtzwiler from Iowa State’s Department of Food Science and Human Nutrition, will examine waste plastic feedstock preparation and characterization. Bai and her team also plan to recruit four graduate students and one postdoctoral research associate to contribute to this project.

In addition to the Iowa State researchers, the team will also collaborate with colleagues at the University of Missouri and Sandia National Laboratories as well as Quasar Energy. Much of the plastic conversion work will take place on Iowa State’s campus, while the University of Missouri and Quasar Energy will focus on downstream processing of converted plastics. The Iowa State team will also utilize the Low-temperature Plasma Research Facility at Sandia National Laboratories.

Work on this project is expected to begin in May and funding will continue through May 2025.