Researchers create plastic alternative that's compostable in home and industrial settings

Researchers at Michigan State University say they've developed a new biodegradable plastic alternative that's easier to compost.

The team created a bio-based polymer blend that’s compostable in both home and industrial settings, the university's School of Packaging announced last week after their work was published in the peer-reviewed ACS Publications journal.

Biodegradable plastics can cut down on waste from single-use plastics like straws and water bottles, said team lead Rafael Auras, who hopes the research can make a dent in the global effort to reduce plastic waste.

“We can reduce the amount that goes into a landfill,” Auras said.

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How researchers hope to break down substances faster

The team worked with polylactic acid, or PLA, which has been used in packaging for over a decade. Instead of petroleum (like typical plastic), it uses plant sugars and breaks down into water, carbon dioxide and lactic acid.

But PLA can only break down in the heat of industrial composters, not home composters. Even in industrial composters, PLA doesn't always break down quickly or completely.

It can take as much as 20 days before PLA starts to be digested by microbes in an industrial compost setting, researchers said.

To accelerate this process, the team incorporated what's called a "thermoplastic starch" into PLA. This carbon-based starch helps the microbes in compost more easily break down the bioplastic.

Adding the thermoplastic starch will not compromise the quality of PLA, such as the strength, clarity and other desirable features, researchers said in the release.

Additionally, the bioplastic can be composted alongside food scraps. That means you wouldn't have to rinse food out of takeaway containers or coffee out of a disposable cup before throwing it out.

The research demonstrates that compostable bio-based plastic packaging is possible, but implementation is a different story.

“In fact, many industrial composters still shy away from accepting bioplastics like PLA,” Auras said in the release.

Other research groups effort more compostable plastics

Last month, a team at the University of Washington announced it had created a bioplastic out of blue-green cyanobacteria cells, otherwise known as spirulina that can degrade on the same timescale as a banana peel in a backyard compost bin.

In 2021, the University of California Berkeley announced researchers had invented a way to make biodegradable plastic break down faster. The researchers embedded polyester-eating enzymes into the bioplastic itself which would help the plastic break down under the heat and water conditions that occur during composting.

Findings don't make littering OK

The team expressed concern about common misconceptions that anything compostable biodegrades under any conditions.

“If people think we develop something biodegradable so it can be littered, that will make the problem worse,” Auras said in the press release. “The technology we develop is meant to be introduced into active waste-management scenarios.”

Nonetheless, the team hopes to raise awareness around waste and change the conversation around plastic.