Innovative alternatives to traditional plastic

From agave-based car parts to soy pots, NSF-funded engineers explore bio-based plastics

Credit: Iowa State University, Center for Bioplastics and Biocomposites, Ford Motor Company

Today is Earth Day, and this year’s theme is ending plastic pollution. While plastics have greatly increased our quality of life, setting the stage for advances in medical devices, food packaging, consumer goods and electronics, there are growing reports over a worrisome environmental legacy of plastics.

To address this concern, engineers funded by the National Science Foundation (NSF) are making materials designed to be less harmful for the environment and more sustainable.

The Center for Bioplastics and Biocomposites (CB2) is an NSF-funded Industry–University Cooperative Research Center (IUCRC) that develops novel plastics, coatings and composites from renewable materials.

“We focus on sustainability,” said CB2 Center Director David Grewell. “We want to leave this planet in the hands of our children and grandchildren in a better condition than how we found it.”

CB2 has developed bio-based plastic horticulture pots that can be purchased in stores around the country. The pots are made from a bioplastic created from a mixture of soy meal and corn based plastics, so they also act like fertilizer for the plants inside. This reduces the amount of additional fertilizer needed for the plants, which can run off into the local ecosystems and cause serious environmental impacts. They’re also sturdier than natural fiber-based pots, which can resemble soft tofu in a matter of minutes, once watered.

“It took about 10 years to make the pots, because we needed to identify a material that was water stable,” Grewell said. “Corn protein is water stable, but when we made pots out of corn proteins, they unfortunately killed every plant in them. We found out that’s because they had an herbicidal effect on seedings.”

Credit: Iowa State University, Center for Bioplastics and Biocomposites, Ford Motor Company

Part of the challenge in creating sustainable materials is that they come from biomass that changes from year-to-year and crop-to-crop, according to Grewell. Understanding the chemical processes behind those changes and how to account for them is a fundamental research challenge. The CB2 team had to modify the soy and corn proteins to make the pots hold water — and not kill the plants.

“It’s like frying an egg,” Grewell said. “All you’re doing is changing the structure of the protein — just changing the morphology, the conformation, of that soy protein molecule to make it more water insoluble.”

The soy-based pots now hold water and can degrade in the soil in one to two years once planted, or degrade in compost in only six weeks.

Research on the CB2 horticulture containers show that tomato and pepper plants that were started in these containers and then planted with the container near their roots had twice as much fruit as plants started in the traditional petroleum-based plastic containers.

CB2 researchers are also experimenting with creatively reusing discarded materials to not only cut down on waste, but to boost the U.S. economy.

Credit: Iowa State University, Center for Bioplastics and Biocomposites, Ford Motor Company

Cars of the future could be 15–25 percent lighter thanks to Tequila — repurposing the agave fibers used to make Tequila that are currently wasted, that is.

Agave is used in Tequila production, and the leftover fibers can be turned into bio-based plastics that provide a low-weight alternative to petroleum-based plastics. The automotive industry (Ford Motor Company, for example, is one of 22 CB2 industry partners) is especially interested in this product because it doesn’t break like glass fiber during production and is strong but lightweight.

“While the initial component is small, the weight savings in a car means gas savings and reduction in greenhouse gases,” Grewell said.

According to Alper Kiziltas of Ford Motor Company, the agave fiber-filled composites have a projected weight and cost reduction of 14 percent and 5 percent, respectively. They also require less energy to produce — about 25 percent — because the material flows quickly at relatively low temperatures and pressures, Kiziltas says.