Turning vegetable waste into bioplastics

Italian team find new ways of converting vegetable waste into bioplastics.

Italian researchers  from the Italian Institute of Technology (IIT) have found a new way of turning vegetable waste directly into bioplastics that they say is more efficient and environmentally friendly than existing techniques to produce bioplastics.

Current bioplastics are created by processing plant material to create monomers, which link up to create the longer polymer molecules that make up plastics. Although the resulting material is usually biodegradable – making it a greener alternative to regular plastic – the way it is produced has come under criticism. According to Ilker Bayer from IIT, making bioplastics takes multiple steps, requiring more energy, and often uses crops that could otherwise be used for food.

 Ilker Bayer and his team say they have found a better way. They uncovered it while looking at the process for creating cellophane, which involves passing cellulose – the material that makes up plant cell walls – through multiple acid and alkali baths. They discovered that dissolving cellulose from cotton and hemp in trifluoroacetic acid converted it directly from its naturally crystalline form to an amorphous form suitable for molding into plastic without the need for any further processing.

 They replicated the process on vegetable waste products, including rice hulls, cocoa pod and spinach and parsley stems from an Italian company that powders vegetables for use in vegetable drinks and some pastas.

“These are the parts we don’t want to eat,” says Ilker Bayer. “They could all be easily converted into useful bioplastics, with different properties, based on the starting material – rubbery for spinach, but firmer for rice hulls.”

The new materials have a different combination of stiffness and stretchiness compared to both existing bioplastics and traditional plastics. They can also inherit the properties of the original plant, meaning parsley plastic could have antioxidant properties, or cinnamon plastic could be antibacterial.

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