A scientific team at the University of Washington has made a groundbreaking advancement in the fight against plastic waste; the team has created bioplastics that decay at the same rate as a banana peel in a standard compost heap.
Crafted entirely from the blue-green cyanobacteria known as spirulina, the new bioplastics mimic the mechanical properties of traditional, single-use plastics, providing a viable and eco-friendly alternative, the University of Washington (UW) researchers, say.
The team’s research findings were published in the journal Advanced Functional Materials.
According to Eleftheria Roumeli, the study’s senior author and a UW assistant professor of materials science and engineering, the team sought to develop “bioplastics that are both bio-derived and biodegradable in our backyards, while also being processable, scalable and recyclable.”
The spirulina-based bioplastics not only decay at a rate similar to organic waste but are also, on average, ten times more robust and rigid than earlier bioplastics created from spirulina. This makes them a promising option for various industries, including disposable food packaging and everyday household plastics such as bottles and trays. The plastic is also recyclable.
The researchers say spirulina was chosen for several reasons. Not only can it be farmed on a large scale due to its existing usage in food and cosmetics, but spirulina cells also absorb carbon dioxide during growth. This makes the biomass a carbon-neutral or potentially carbon-negative raw material for plastics.
Hareesh Iyer, the lead author and a UW materials science and engineering doctoral student, highlighted another unique feature of spirulina: its inherent fire-resistant properties. “When exposed to fire, it instantly self-extinguishes, unlike many traditional plastics that either combust or melt,” he said. “This fire-resistant characteristic makes spirulina-based plastics advantageous for applications where traditional plastics may not be suitable due to their flammability. One example could be plastic racks in data centers because the systems that are used to keep the servers cool can get very hot.”
The process to produce these bioplastics involves the application of heat and pressure to mold the spirulina powder into various forms, mirroring traditional plastic manufacturing techniques. As Roumeli explained, this eliminates the need to completely overhaul manufacturing processes for industrial-scale production. She noted, “We’ve removed one of the common barriers between the lab and scaling up to meet industrial demand.”
The researchers’ version of spirulina bioplastics stands out from previous iterations due to its enhanced strength and rigidity, which they achieved by fine-tuning processing conditions and studying the resultant material’s structural properties.
However, there are still some obstacles before these bioplastics can be rolled out on an industrial scale. Despite being robust, they are relatively brittle and water-sensitive. Iyer cautions, “You wouldn’t want these materials to get rained on.” The team is committed to overcoming these challenges and continues to investigate the fundamental principles governing these materials’ behavior.
The intention is not merely for these bioplastics to decay naturally. “Our spirulina bioplastics are recyclable through mechanical recycling, which is very accessible,” Roumeli said. “People don’t often recycle plastics, however, so it’s an added bonus that our bioplastics do degrade quickly in the environment.”
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