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Pavana Prabhakar
June 6, 2021

Drying out: Prabhakar receives NSF CAREER Award to study moisture’s impact on polymer composites

Written By: Alex Holloway

Fiber-reinforced polymer composites are used in countless facets of everyday life, from the vehicles we travel in to the infrastructure in the world around us.

Pavana Prabhakar is seeking ways to better design these commonplace materials to deal with another ubiquitous substance: water. Whether used in aircraft fuselages, automobile chassis, pipes and even marine structures, polymer composites inevitably come into contact with moisture.

“In all of these applications, these composites are exposed to moisture to different extents,” says Prabhakar, an assistant professor and Charles G. Salmon Fellow of Structural Engineering in the Department of Civil and Environmental Engineering. “For example, in marine decking, there’s constant contact, while for aircraft fuselages, it’s just moisture in the air. Whatever the amount, moisture is detrimental to these structures; we’ve seen weight gain, swelling and premature structural failure when they are exposed to moisture.”

Prabhakar received a prestigious CAREER Award from the National Science Foundation to tackle this issue. The $536,000 grant will fund a five-year research project in which she will use novel experimental and computational research approaches to better understand how moisture can infiltrate the composites.

Fiber-reinforced polymers are strong, yet lightweight, and that has led to their widespread use in structural applications. To create them, manufacturers combine fibers into bundles and place them in resin, which hardens, binds the fibers in place, and forms the composite. However, the same fibers that give composites strength may also control moisture infiltration. Prabhakar says the fibers, which are usually about 10 micrometers in diameter, can be laid in complex patterns. Those patterns can, in turn, lead to complicated moisture diffusion pathways through the composite material.

While the issue of moisture degradation in these materials is known, Prabhakar says there’s not yet been much research into the connection between fiber architecture within the composites and moisture diffusion pathways. With better understanding of these relationships, Prabhakar hopes to both fill a scientific knowledge gap and strengthen the foundation for designing future generations of stronger, more damage-tolerant composites.

“These pathways can affect the extent of material degradation, and further introduce failure mechanisms that are different from what we’ve observed without moisture diffusion happening,” Prabhakar says. “It’s rare that fibers have been studied from this perspective, to see what their role is with these diffusion pathways.”

CAREER Awards include a public outreach component, and Prabhakar hopes to make an impact on the workforce that works with fiber-reinforced polymer composite materials. She says industries in the field face a number of challenges, including an aging workforce, high worker demand and an insufficient pipeline to produce workers who can meet that demand. She says there are also demographic imbalances, with women and minorities underrepresented in the workforce.

“We want to help create this talented and diverse workforce that can then go on to work in these industries,” Prabhakar says. “We’ll be offering a graduate-level blended online course on composite materials that will be designed with working professionals and adult learners in mind. We’re partnering with the College of Engineering’s Engineering Professional Development program to deploy this course and hope that it can reach a wide audience to directly contribute to workforce development.”

The course will form a key pillar of Prabhakar’s outreach, but she’s also looking at other methods of engagement. She will hire undergraduate researchers to assist in the project, with a focus on students from traditionally underrepresented groups.

She also will work with the Wisconsin 4-H Youth Conference to give young students a chance to interact with fibers and polymer composites.

“We’ll have students work with some of these materials with regular fibers like wool to understand how they contribute toward material properties,” she says. “It’s a very cool hands-on workshop, and I’m very excited about this chance to expose younger kids to this kind of research.”