WHOI Scientists Discover Fastest Degrading Bioplastic in Seawater

Newswise — Woods Hole, Mass.(Oct. 17, 2024)  — Scientists at the Wood Hole Oceanographic Institution (WHOI) have been working for years to find out what types of plastics have the shortest and longest lifespans in the ocean, and what types of plastic products, like straws and food wrappers, most commonly contribute to plastic pollution. With more biodegradable materials being developed, like cellulose diacetate (CDA)—a plastic-like polymer derived from wood pulp—researchers are racing to ensure they can replace traditional plastics without causing harm to ocean environments. 

Now after years of testing, a new version of CDA was found to be the fastest degrading bioplastic material tested in seawater—and it’s a promising replacement for other foam plastic materials, like Styrofoam, which can linger in the environment for many years. In a new paper published in ACS Sustainable Chemistry & Engineering, WHOI scientists Bryan James, Collin Ward, Chris Reddy, Yanchen Sun, and Kali Pate, found that adding small pores—called foaming—to CDA material made it degrade 15 times faster than solid CDA, and even faster than paper.  

“What excites me most about this study is its translational nature. This study is the culmination of years of research focusing on understanding the fundamental controls on CDA biodegradation in the ocean,” said Ward, senior author of the study. He and the WHOI team partnered with scientists from bioplastic manufacturing company Eastman, who provided funding, contributed as coauthors, and supplied materials for the study.

“We translated the foundational knowledge into the design of a new material that simultaneously meets consumer needs and degrades in the ocean faster than any other plastic material we know of, even faster than paper. It’s a great success story in a field that often focuses on the negative aspects of plastic pollution rather than working towards solutions to the problem,” Ward added.

The study involved monitoring both foamed CDA and solid CDA in a tank of continuously flowing seawater from Martha’s Vineyard Sound, at a specially designed lab at WHOI. The researchers also control the temperature, light exposure, and other environmental variables to mimic the natural marine environment. 

“Using continuous flowing seawater tanks enables us to bring the dynamics of the microbially active ocean into the lab. The ocean is continually changing, and it was important that we replicated this environment by replenishing microbes and nutrients, making for a much more environmentally realistic experiment,” lead author James explained. After 36 weeks, the team found that the CDA foams lost 65-70% of their original mass. 

In a previous study using their dynamic seawater tank, the researchers tested straws made of standard plastic, paper, solid CDA, and foamed CDA, and found that the solid CDA and paper straws reduced in mass the quickest. Scientists then compared two straws made from CDA, one made from solid CDA and one from a foam CDA and found that the degradation rate of the foam straw was 190% faster than its solid counterpart, resulting in a shorter projected environmental lifetime than the paper straws.

“As a materials scientist and engineer, it’s been exciting to demonstrate that foams can be materially efficient, meaning they achieve functionality using the least amount of material possible, reducing cost and many environmental impacts,” said James. “In addition, when they are made from biodegradable plastics, they can be one of the least persistent forms of a material.”

Replacing Styrofoam plastic and single-use plastics, such as take-away containers that routinely leak into the ocean and are not biodegradable, are one of the most urgent uses for this material, according to the study authors. Foamed CDA products are already entering the market with Eastman launching a compostable, lightweight tray made of foamed CDA, designed to replace plastic trays used in existing industrial food packaging. 

“Partnerships between industry and academia are essential for accelerating solutions to the most urgent global challenges, where academia can provide unique insights, and industry partners can use those insights to develop solutions at scale,” said Jeff Carbeck, Vice President of Corporate Innovation of Eastman. “That is how our collaboration with WHOI works; they significantly broadened our understanding of how our commercial and developmental materials degrade.”

Carbeck highlighted that this study demonstrates the potential that CDA foam holds in helping address challenges with single-use plastic packaging. “The properties of foams make them ideally suited for many packaging and insulation applications, and this research shows that foams made of biodegradable materials will rapidly degrade in the marine environment, should they accidentally end up there. Embracing biodegradable materials for consumer goods is a critical step towards preserving our environment, reducing plastic pollution, and fostering sustainability for future generations,” he said. 

“One of the advantages of teaming with an industry partner is that we can ensure the new technology is scalable. One of the criteria when designing the new material was that it had to be a drop-in, turn-key replacement for Styrofoam goods, meaning that the companies that convert the raw CDA into the biodegradable foam don’t have to invest in new equipment,” Ward explained. “Advancing new plastics not made from fossil fuels, are compostable, and don’t persist in the environment as pollution, can be a win for consumers and the environment.”

Key Takeaways 

• In collaboration with Eastman, WHOI scientists found that cellulose diacetate foam (CDA) is the fastest degrading bioplastic in an ocean environment.
• This new foam material is demonstrated to be a viable replacement for Styrofoam products and single-use plastics, like food packaging trays, as it achieves all the benefits of plastic but doesn’t contribute to plastic pollution.
• This biodegradable bioplastic foam was evaluated in a flow-through seawater tank. After 36 weeks, the CDA foam lost 65-70% of its mass, and the degradation rate of the CDA foam was 15 times faster than solid CDA.

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Authors:

Bryan D. James,^*,1 Yanchen Sun,¹ Kali Pate,¹ Rahul Shankar,² Mounir Izallalen,² Sharmistha Mazumder,² Steve T. Perri,² Katelyn R. Houston,² Brian Edwards,² Jos de Wit,² Christopher M. Reddy,¹ Collin P. Ward^*,1 

Affiliations: 

1 Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, MA, USA 02543

2 Eastman, Kingsport, TN, USA 37662

About Woods Hole Oceanographic Institution

The Woods Hole Oceanographic Institution (WHOI) is a private, non-profit organization on Cape Cod, Massachusetts, dedicated to marine research, engineering, and higher education. Established in 1930, its primary mission is to understand the ocean and its interaction with the Earth as a whole, and to communicate an understanding of the ocean’s role in the changing global environment. WHOI’s pioneering discoveries stem from an ideal combination of science and engineering—one that has made it one of the most trusted and technically advanced leaders in basic and applied ocean research and exploration anywhere. WHOI is known for its multidisciplinary approach, superior ship operations, and unparalleled deep-sea robotics capabilities. We play a leading role in ocean observation and operate the most extensive suite of data-gathering platforms in the world. Top scientists, engineers, and students collaborate on more than 800 concurrent projects worldwide—both above and below the waves—pushing the boundaries of knowledge and possibility. For more information, please visit www.whoi.edu.