The Earth’s vast oceans have become a dumping ground for the plastic waste that humans generate. Every year, anywhere from 4.8 to 12.7 million tons of plastic enter the oceans, according to some estimates.
Replacing traditional plastics with those that degrade in the ocean would reduce harm to marine animals and the environment. And now, scientists at the Wood Hole Oceanographic Institution (WHOI) report a bioplastic that degrades even faster than paper in seawater.
The new material is the foam version of a bioplastic called cellulose diacetate (CDA). It could be a degradable, sustainable replacement for the Styrofoam used in single-use food packaging, the team says.
CDA is made from cellulose, the natural polymer found in plant cell walls, especially in wood pulp, and that is used to make paper. The bioplastic has been around for decades, and is used to make cigarette filters, photography film, and seed coating.
The WHOI researchers speculated whether foam versions of these bioplastics could enhance their use and their biodegradability. CDA foams could, the researchers say, could be a sustainable replacement for polystyrene (PS) foam, commonly known as Styrofoam. The material is used widely in food packaging and insulation but has no good recycling technology so most of it ends up in landfill.
In a new study published in ACS Sustainable Chemistry & Engineering, the researchers evaluated several CDA and conventional PS foams for their marine degradation. The team determined relationships between degradation rate and foam properties.
The researchers added tiny pores to CDA to make several foams of various densities. They placed CDA and PS foams in tanks with continuously flowing seawater. Over a 36-week-long test, the CDA foam lost about 70 percent of its original mass, while the Styrofoam showed zero degradation. “The degradation rates of the CDA foams were about 15 times that of solid CDA and the fastest of any plastic reported in the ocean,” the authors write.
Some of the paper’s co-authors are from Eastman, a bioplastic manufacturing company. The company recently launched a compostable, lightweight food packaging tray made of foamed CDA that could be an alternative to Styrofoam trays.
Source: Bryan D. James et al. Foaming Enables Material-Efficient Bioplastic Products with Minimal Persistence. ACS Sustain. Chem. Eng. 2024.
Image: ©Anthropocene Magazine
