Plenty of us have been haunted by images of washed up trash on the shorelines of the planet’s oceans, our takeout containers mocking us as they sit wholly in-tact after decades.
That’s why scientists at the Wood Hole Oceanographic Institution have been working for years to study the lifespans of plastics in the ocean.
They have studied what types of plastic products, like straws or food wrappers, most commonly contribute to plastic pollution. And as the field evolves to create more biodegradable alternatives to plastic, their work is paramount.
After years of testing, a new version of cellulose diacetate (CDA), a plastic-like polymer derived from wood pulp, has been found to be the fastest-degrading bioplastic material tested in sea water.
WHOI scientists say it is a promising replacement for foam and plastics, like Styrofoam, which can litter the environment indefinitely.
The scientists, who published their discovery in ACS Sustainable Chemistry & Engineering, found that adding small pores — called foaming — to CDA material made it degrade 15 times faster than other CDA-based items, 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 Collin Ward, senior author of 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,” Ward added.
“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 and his colleagues worked with scientists from the bioplastic manufacturing company Eastman, which provided funding and supplies for the study.
The researchers monitored “foamed” and solid CDA in a tank of continuously flowing seawater, which was sourced from Martha’s Vineyard Sound. They also controlled the temperature, light exposure, and other environmental variables to mirror a natural marine environment where these materials would end up.
After 36 weeks of monitoring the materials, the team found that the CDA foams lost 65-70% of their original mass. In other words, they were over halfway through degrading after a little over eight months.
“Using continuous flowing seawater tanks enables us to bring the dynamics of the microbially active ocean into the lab,” lead author Bryan D. James said in a statement.
“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.”
This is not the first time these researchers have used the seawater tank.
In previous work, they found that straws made from their foamed CDA degraded 190% faster than solid CDA materials. With further research, they are now optimistic in the practical use of foamed CDA.
The study’s authors say that replacing the traditional single-use plastics and Styrofoam materials that are still commonly used in takeout containers or cups is their top priority.
Fortunately, they are already entering the market, thanks to Eastman, which has launched a compostable, lightweight tray made from foamed CDA.
“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 at Eastman.
“That is how our collaboration with WHOI works; they significantly broadened our understanding of how our commercial and developmental materials degrade.”
Working with Eastman as an industry partner informed the scientists’ research to ensure their findings could be scalable. By offering a “turn-key replacement for Styrofoam goods,” companies like Eastman can create CDA solutions without investing in new equipment, Ward explained.
Carbeck added that the properties of this bioplastic foam make them well-situated for packaging and insulation applications — without causing harm to ocean environments, should they 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,” Carbeck said.
It’s a sentiment the scientists share.
Ward added, “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.”
Header images courtesy of Ivan Radic (CC BY 2.0) and Rachel Mann, @Woods Hole Oceanographic Institution