Styrofoam lasts a very long time and is thus a large problem for the environment, yet people still like cups so what are we to do? The answer is to make those drink holders out of milk and clay!
The research began with an accidental discovery in the lab. One of Schiraldi’s students freeze-dried clay and got something intriguing enough to warrant a closer look. So, the team started mixing the clay with a variety of materials.
When they added a cow’s milk protein called casein, they ended up with a super-light, fluffy, and foam-like material. With further experimentation, they hit on a recipe that worked well enough for publication in the journal Biomacromolecules.
“The process,” Schiraldi said, “is simplicity itself.”
The researchers start by throwing a scoop of clay and some water into a kitchen blender. Two minutes of mixing produces what Schiraldi’s students call a clay smoothie.
Next, they add some casein powder, a dried version of the most common protein in milk. The final ingredient is a tiny amount of a glycerol-based material, which basically stiffens up the solution’s chemical bonds.
After running the blender one last time, the scientists pour the dirty-looking water into molds and freeze them like ice-cubes. Then, they freeze-dry it get all the water out.
The result, Schiraldi said, is a material that has all the same properties of Styrofoam, but is 98 percent bio-based. At 100 degrees Celsius (212 degrees Fahrenheit), the milk-containing foam lets out a few drops of water. But it stays sturdy up to 200 degrees Celsius (392 degrees Fahrenheit).
In tests conducted by the U.S. Department of Agriculture, close to a third of the new material broke down after about 45 days in industrial compost conditions. That’s a huge environmental leap beyond Styrofoam and other types of Expanded Polystyrene Foam, a category of materials that is often used as disposable packaging for electronics and other products.
“Compared to expanded polystyrene foam, we’re in a different league,” Schiraldi said. “Styrofoam lives forever.”
