Researchers from the University of Canterbury, New Zealand, developed a way to recycle biodegradable plastics and turn them into useful foam.

Biodegradable plastics typically cannot be recycled because they are made to quickly degrade and end up in landfills. Even if they could be recycled, the process weakens the plastic and eventually it becomes unusable. Researchers created a way to turn biodegradable plastic cutlery into foam that can be used as insulation or floatation devices that do not require high strength.

The bulkiest foams have the largest air pockets and are good for flotation devices. Source: Heon Park

Recycling biodegradable plastic could alleviate some global pollution problems. Because the biodegradable material eventually breaks down, it is better for the environment if plastics can be repurposed.

With the new method, the plastic cutlery is placed in a chamber filled with carbon dioxide. As the pressure in the chamber increases, the CO₂ dissolves into the plastic. When the pressure is released from the chamber, the gas expands within the plastic and causes the plastic to turn into foam.

Foam is an ideal material because it does not need to be strong in most applications. For example, bulky foams are large and have a lot of air pockets, making them useful as buoys. The team says that lower chamber pressures lead to bulkier foams in a process that could be implemented at a large scale.

A paper on the new method was published in Physics of Fluid.