Making Bioplastics More Compostable

A team of researchers at Michigan State University’s School of Packaging has found a way to make bioplastics, a sustainable alternative to traditional petroleum-based plastics, more biodegradable. Led by Rafael Auras, the team has created a bio-based polymer blend that can be composted both at home and in industrial settings.

The Problem with Plastic Waste

In the United States, less than 10% of plastic waste is recycled, and in Australia, the figure is around 13%. Most of the plastic waste ends up as litter, leading to economic, environmental, and health issues. Auras, an MSU professor, emphasized the significant problem with waste, particularly plastic waste.

By creating biodegradable and compostable products, the team believes they can reduce the amount of waste going to landfills. An added advantage is that plastics meant for composting wouldn’t need to be cleaned of food contaminants, a common hindrance in efficient plastic recycling. Auras illustrated this with examples like coffee cups or microwave trays with tomato sauce, which could be composted without rinsing or washing.

Working with Polylactic Acid (PLA)

The researchers worked with polylactic acid (PLA), a material derived from plant sugars instead of petroleum. PLA’s waste byproducts are natural substances like water, carbon dioxide, and lactic acid. While PLA can biodegrade in industrial composters, it doesn’t happen quickly or completely.

In their experiments, the team found that PLA could sit for 20 days before microbes began digesting it in industrial composting conditions. To speed up this process and enable home composting, they integrated a carbohydrate-derived material called thermoplastic starch into PLA. This starch helps microbes break down the PLA more easily.

Postdoctoral researcher Anibal Bher, along with doctoral student Wanwarang Limsukon and others, observed how different PLA-thermoplastic starch blends broke down during composting. They tracked the entire pathway of the process, preserving the strength and clarity of regular PLA films.

A Step Towards Sustainable Packaging

The researchers have shown that fully compostable bio-based plastic packaging is achievable. However, Auras noted that this alone wouldn’t ensure commercial adoption, as challenges are not only technical but also social and behavioural.

There’s a public misunderstanding that biodegradable materials can break down quickly anywhere. These materials need specific conditions to decompose in a timely manner. Auras warned that if people think biodegradable items can be littered, it could worsen the problem. The technology they developed is intended for active waste-management scenarios.

For more information on this research, you can visit MSU’s website.