Maryam Shakiba, assistant professor in the Charles E. Via, Jr. Department of Civil and Environmental Engineering, has received a National Science Foundation Faculty Early Career Development (CAREER) award. Her resulting project will investigate how macroplastics degrade into microplastics under the highly coupled effects of weathering and mechanical stresses.

According to the National Park Service, plastics account for up to 90 percent of trash found in oceanwaters and along shorelines. This includes unsightly straws and bottles floating in the water that we commonly associate with ocean pollution, but these macroplastics, defined as anything larger than 5 millimeters, only touch the surface of the environmental damage. Large pieces often degrade into microplastics, which can cause even greater ecological harm in our oceans, according to Shakiba.

“Plastic items gradually degrade into smaller pieces through a combination of weathering and mechanical load. This plastic pollution is a global concern,” said Shakiba. “I aim to discover the path that macroplastics take as they degrade into microplastics and how long those particles persist in the ocean.”

Ingesting microplastics can cause harm and death in many species of ocean life. Marine animals ingest plastic pieces, mistaking them for fish eggs, plankton, or other food sources. The National Park Service notes that hundreds of thousands of sea creatures die from complications relating to plastic debris each year. Causes range from a stomach full of plastic that they cannot digest to  becoming fatally entangled in debris.

Shakiba said that due to the slow degradation of plastics, it is difficult for scientists to estimate how much microplastic debris exists or how long it will stick around. “Answering these questions is critical to efficient mitigation and prevention policies for known and suspected adverse effects of plastic pollution,” she said.

Shakiba’s project will focus on polyethylene, polypropylene, and polystyrene as examples to map the pathways of other soft microplastics during creation and help determine the fate of macroplastics. Current models study how polymers degrade due to factors such as mechanical loading, temperature, oxygen, salt water, and UV irradiations. Shakiba wants to establish physics-based equations for degradation in soft polymers based on the polymers’ network statistics, chemistry kinetics, and stored and dissipative energies. She will also develop multi-physics-guided machine-learning algorithms to assist the modeling.

Ultimately, the findings will help Shakiba propose modifications in plastic manufacturing and recycling practices to reduce the generation of microplastics. “These findings would help guide academics, industry, government regulators, and non-governmental organizations,” said Shakiba.

The CAREER award is the National Science Foundation’s most prestigious award for early-career faculty, encouraging them to serve as academic role models in research and education and to lead advances in the mission of their organization. 

To satisfy the award’s requirements, CAREER awardees must find ways to integrate education and research into their projects as well as conduct outreach.

Shakiba will train the next generation of engineers and researchers in the multi-physics and mechanics of soft polymers through lectures and lab tours, primarily aimed at high school students. Furthermore, workshops and meetings for industry professionals will be offered to provide recommendations for recycling processes.

“Educating students and industry members at the intersection of mechanics of materials, polymer sciences, and data-driven modeling is essential for the future workforce within the polymer industry to provide solutions for recycling processes, and mitigate plastic pollutions,” said Shakiba.   

Her prospective findings on polymer properties can provide insights into the aging and degradation of other soft materials. “Overall, I hope my findings can assist ocean environmentalists to estimate existent microplastics in an effort to improve detection procedures and guide manufacturing, processing, and package processes to reduce plastic pollution in our oceans,” said Shakiba.

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