South Dakota State University researchers demonstrate switchgrass-based biodegradable film

In South Dakota, new study from researchers at South Dakota State University has demonstrated how a transparent and strong biodegradable film can be derived from switchgrass (Pancium virgatum), a perennial prairie tallgrass native to North America.

In the United States, switchgrass grows abundantly and in a variety of different climates, making it a valuable resource for soil conservation, ornamental grass, heat production and biofuels. Switchgrass is also composed of roughly 58% lignocellulosic material, making it an ideal material for the development of plastic-replacing products.

To make the films, researchers first extracted lignocellulosic material, the most abundant renewable biomass on Earth, from milled switchgrass. Lignocellulosic material, or plant dry matter, is composed of cellulose, hemicellulose and lignin.

After the material was extracted, a filtration, bleaching, washing and drying process resulted in a white residue that was then used to create the films. Once fully dried, the team assessed the film’s qualities.

Results showed the films to be transparent, high in tensile strength and completely biodegradable within 40 days at 30% soil moisture. The last characteristic — biodegradation — is crucial in the development of bioplastics as the primary challenge with petroleum-based plastics is their inability to degrade. For example, a plastic bottle will take more than 700 years to naturally degrade in soil. Bioplastics, ideally, would biodegrade in a fraction of that time, greatly reducing the amount of plastic waste in the environment.