NSF backs research into plant-based alternative to plastics

Purdue professors Alex Chortos and Mukerrem Cakmak are part of an interdisciplinary research team recently awarded a nearly $3 million NSF award.

The circular economy is the modern vision for industrial production, where companies strive to extend product lifecycles and reduce waste through reuse and recycling in a virtuous circle of sustainability and natural resource conservation. As vital as this is across all production sectors, the importance of plastics has been emphasized by increasing understanding of their negative impacts on health and the environment.

Cakmak head shot
Mukerrem Cakmak, the Reilly Professor of Mechanical and Materials Engineering

A solution to this problem is being investigated by an interdisciplinary team of researchers that include Purdue professors Alex Chortos in mechanical engineering and Mukerrem Cakmak in mechanical and materials engineering. The research is supported by a newly announced NSF award of $2,985,348.

The key innovation is the production of plastic from natural hemp oils, a process that was developed by professor Gregory Sotzing at the University of Connecticut. The award supports the characterization of this new class of plastics from natural agricultural resource hemp to accelerate their adoption in sectors that include electronics manufacturing and medical devices. These hemp-based polymers not only would exhibit strong functional properties but also have multiple paths by which they can be recycled and degraded to lower greenhouse gas emissions.

Hemp is a fast-growing crop that thrives in a wide range of locations and does not compete with food production. It can reduce reliance on legacy petrochemical-derived plastics and their accompanying environmental damage, health concerns and supply chain vulnerabilities.

“Our initial work on medical devices has demonstrated that a polycannabinoid polymer, a new class of bio-based polymers created through the polymerization of oils derived from the hemp plant, has the potential to contribute new functionality to products like point-of-care medical devices and 3D-printed electronics,” Chortos said. “For example, biodegradable and 3D-printed electronics, given the pervasiveness of electronics and the Internet of Things, will reduce problems stemming from the proliferation of electronic waste.”

The project has a workforce development component, engaging with students from middle through high school via hands-on experiences and training in skills like additive manufacturing to interest next-gen workers in STEM and manufacturing.

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Alex Chortos, assistant professor in mechanical engineering

The research dovetails with Purdue’s longstanding commitment to manufacturing, recently expanded with the foundation of its Manufacturing and Materials Research Laboratories. MMRL brings together Purdue faculty from different engineering and manufacturing disciplines — including the schools of Industrial, Materials, Mechanical and Nuclear Engineering — to further manufacturing research, funding and industry collaborations.

MMRL itself has a strong educational and workforce development aspect through manufacturing-related professional master’s degrees, executive education programs and undergraduate minors and certificates. It’s one of the first offshoots of Purdue’s eXcellence in Manufacturing and Operations (XMO) initiative, a collaboration between the College of Engineering and the Mitchell E. Daniels, Jr. School of Business, Purdue Polytechnic Institute, the College of Agriculture and the College of Science.

The research project also aligns with the U.S. government’s priorities for investments in biomanufacturing and its 2022 National Strategy for Advanced Manufacturing.

“The emergence of high-performance biodegradable plastic products has improved our quality of life through new industrial and medical technologies,” said Cakmak, the Reilly Professor of Mechanical and Materials Engineering and co-PI. “But the disposal of petrochemical-derived plastics through incineration and landfills negatively impacts the environment. The ability to grow hemp across many regions of the U.S. also can strengthen the resilience of the supply chain, an issue of paramount importance after the last several years of major supply chain disruptions and dislocations.”

The research also has the potential to strengthen the U.S. economy and its ability to provide sustainable jobs. The U.S. has many plastics manufacturers; hemp-based alternatives can help them maintain their viability as petroleum-based plastics are phased out. An American-made, bio-based polymer with superior properties to legacy plastics will enhance their competitiveness while expanding the availability of circular lifecycle plastics globally.

The Purdue researchers are collaborating with colleagues at the University of Connecticut, which has facilities to synthesize the large amounts of polymer needed for manufacturing tests. Characterizing the polymers through measurements and correlations with stipulated process parameters will be performed jointly through the expertise of the collaborating institutions.

Specifically, the project will investigate two hemp-derived monomers with different properties in combination with dicarboxylic acids. Characterizing the different combinations of starting molecules will provide fundamental knowledge of their structure-property relationships underlying the widely tunable properties.

“Bio-based polymers must be designed to have cost and performance metrics that can compete with incumbent plastics and must be capable of upcycle reclamation and/or biodegradation,” said Richard Gross, professoer and co-PI at the Rensselaer Polytechnic Institute and a leading expert on the chemistry and degradation mechanisms of polymers. “Meeting these goals will help us enable the transition from a linear, waste-ridden production process to a true circular lifecycle for sustainable plastics products.”