Turning waste into gold: circular economy research makes plastic more sustainable

October 14, 2021

Plastics have changed our lives since the 1950s. But these amazing materials are mostly made up of fossil hydrocarbons like oil, gas, and coal – and none are biodegradable. The vast majority of the 18 trillion pounds of plastic ever produced is now trash in landfills and oceans.

While plastic recycling efforts began in the U.S. in the 1980s, the total domestic plastic recycling rate is only 8.7% as of 2018.

Arizona State University Professor Timothy Long (right) works with PhD student in Chemistry and Graduate Research Assistant Boer Liu (left) and PhD student in Materials Science and Engineering and Graduate Research Associate Clarissa Westover (center) at the ASU Biodesign Center for Sustainable Macromolecular Materials and Manufacturing, which Long directs. Photo by Andy DeLisle / ASU
Download full picture

“The sustainability of plastics remains a major challenge; it’s an impending national and global crisis, ”said Timothy Long, professor at the Ira A. Fulton Schools of Engineering and the School of Molecular Sciences at Arizona State University. “It comes to the fore now so that people speak to each other. There is now a sense of urgency. ”

One way to reduce the challenge of plastic waste is to introduce circular economy: the notion that everything that is created is fed back into the production system without anything ending up in the landfill.

“It’s the idea that trash turns to gold,” says Long, who also directs the Biodesign Center for Sustainable Macromolecular Materials and Manufacturing. “How do we absorb these plastic waste streams and turn them back into a valuable raw material? This is a really important area of ​​research at the moment, not just for universities, but for all leading plastics-producing industries. “

Developing a viable plan for a circular plastics economy is the focus of the Emerging Frontiers in Research and Innovation project of the National Science Foundation (EFRI), which Long is leading with an interdisciplinary research team. This team includes ASU and Virginia Tech – two early university members of the Ellen MacArthur Foundation, a global center and trailblazer for advances in the circular economy – as well as the National Renewable Energy Laboratory, Oak Ridge National Laboratory, and Adidas.

EFRI projects are selected to drive transformative ideas that can change knowledge and have long-term effects on major challenges or other societal needs.

“The ideas are new, the engineering is demanding and the team is the right team to solve it. I think that’s a big part of our choice, ”says Long. “We are not only approaching science and technology, but also the humanistic elements of technology.”

Long and his research team are working to eliminate discarded plastics as part of their $ 1.89 million EFRI Molecules For Manufacture project to optimize and standardize processes to create a circular economy for at least one type of plastic : Polyurethane foams or PUFs.

PhD students Ren Bean and Jose Sintas discuss the chemical structures of monomers at the ASU Biodesign Center for Sustainable Macromolecular Materials and Manufacturing.

Research associates Ren Bean (left) and Jose Sintas discuss monomers, which are represented as chemical structures, at the ASU Biodesign Center for Sustainable Macromolecular Materials and Manufacturing. Timothy Long and other researchers will study these monomers as part of the National Science Foundation’s Emerging Frontiers in Research and Innovation project. The combination of molecular science and technical expertise is important to synthesize new monomers that will help improve the functionality and performance of polymers used in many plastics. Photo by Andy DeLisle / ASU

Bring foam waste to new life

Long and the other researchers plan to literally walk on mattresses in the fight against plastic waste. The main component of polyurethane in mattress foam is the sixth largest family of polymers in the world; Mattresses can provide easier collection routes than other sources of foam, which include gym shoes, seat cushions, and insulation.

At ASU, Long relies on a team of scientists from the ASU Biodesign Institute and the School of Molecular Sciences as well as engineers from the School for Engineering of Matter, Transport and Energy and the Polytechnic School, two of the seven Fulton Schools.

“The interdisciplinary culture that exists at ASU is really crucial for this project,” he says.

Long’s research group of chemists, materials scientists and engineers goes back to basics and examines how PUFs are made and explores their molecular structure.

As Long and his team advance to the molecular level, Kailong Jin, assistant professor of chemical engineering, and his research group are developing a new solvent-free process that converts PUFs directly into other polymers using enzymatic catalysts.

“If successful, this research will develop a scalable approach to recycling crosslinked polyurethane waste into a library of valuable polymer products,” says Jin.

Meanwhile, Matthew Green, an associate professor of chemical engineering, and his research team are on what he calls “cleanup”.

“Taking apart a polymer doesn’t mean you’ve created a circular economy out of plastic. You have to show that you can get these molecules back in high purity and use them over and over again, ”says Green. “My job is to try to isolate and purify the components of the electricity that leave their breakdown process, and in a very energy-efficient way.”

Kenan Song, an assistant professor of mechanical engineering, examines how advanced manufacturing techniques can be used to process waste foams, from traditional mold making to new additive manufacturing technologies.

“We are developing new manufacturing principles that will renew the porous microstructure of foams for better performance in recycled products,” says Song of his research team at the Advanced Materials Advanced Manufacturing Laboratory. “By using additive manufacturing, we save material and energy consumption compared to conventional subtractive processing.”

The efforts of the ASU teams are backed by two national laboratories that “bring some of the most advanced research tools we have in the country and they bring vital national expertise to the equation,” Long says.

Oak Ridge National Laboratory provides analytical tools to help researchers understand and measure the basic mechanics of degradation and reuse of foams.

The National Renewable Energy Laboratory brings expertise in chemical processes, reactor design, and purification strategies to break down the polymers in PUFs in a process called depolymerization.

The economic and social side of recycling technology

This research goes well beyond the science and technology of polyurethanes. Jennifer Russell, Assistant Professor of Sustainable Biomaterials at Virginia Tech, and her research team ensure that the technologies developed by ASU researchers are actually adopted worldwide. The economic, social and ecological effects of creating a circular system for PUF are taken into account.

Russell’s team will analyze PUF waste from industry, commerce, institutions and homes and confirm whether mattresses pose greater waste management challenges compared to sneakers or any other source and are the best raw materials for recycling.

The environmental impact at each stage of the PUF lifecycle is another important consideration for Russell’s team. You will examine whether the diversion of PUF products and waste and their recycling leads to the desired reductions in environmental impact.

“We don’t want to propose any new technologies or new systems that put us in a worsened environmental situation,” she says.

The techno-economic assessment will help Russell’s team evaluate the economic performance of new technologies developed by ASU researchers, the infrastructure and systems required to divert and recycle PUFs, and the economic benefits that the companies will gain Using recycled PUF materials instead of new materials.

Russell’s team will also make qualitative and quantitative forecasts of future conditions and material requirements with relevant stakeholders from management, manufacturing, government and industry “to ensure that the infrastructure and system solutions developed within the framework of this project are actually viable, appropriate and planned jointly . ”

Adidas, a leading manufacturer of polyurethane-based textiles, including PUFs for use in athletic shoes and other equipment, will be a key industry stakeholder in this EFRI project.

“Adidas offers an external validation of our work with regard to the translation effect,” says Long. “It improves the chances that we will bring what we learn here at ASU to market.”

The company also provides facilities and tests to help evaluate the properties of recycled foams to ensure that they meet the requirements of Adidas and other companies.

Work towards a more sustainable future

The entire EFRI team looks forward to working together and learning from one another on a project with immense potential.

“Polyurethanes make up a huge proportion of the polymers we make and use, and we don’t currently have any viable recycling strategies,” says Green. “If we are able to achieve what we put into the proposal, it will have an immense social impact.”

Russell says she enjoys the opportunity to recognize the need for technological solutions alongside sustainable behavioral and economic advancement and analysis of unintended consequences – and to demonstrate a model for addressing other problematic but important sustainability challenges.

“If we can’t get people to use the innovations we create, even the most perfect technological and innovative breakthroughs will ultimately be useless,” says Russell. “We not only strive for technical solutions for the challenges of the depolymerization of PUFs, but also for a system view that ensures that these solutions are economically viable, scalable and environmentally friendly. To achieve this, we had to consider and incorporate the human dimension of recycling and a circular economy right from the start. ”

Comments are closed.