A team from the University of Washington has developed a method for using used coffee grounds as a raw material for 3D printing. The material is based on a mixture of coffee grounds, reishi mushroom spores and other natural binders and could serve as a sustainable alternative to polystyrene in packaging or for other applications. The research results were published in the journal 3D Printing and Additive Manufacturing.
The approach uses the properties of mycelium, the root network of fungi, which can form a stable, water-repellent and biodegradable structure. For this purpose, coffee grounds are mixed with reishi mushroom spores, rice flour and xanthan gum and processed into a printable paste. This so-called mycofluid mixture is then processed using a specially developed 3D printing nozzle that can hold up to one liter of the material. The printed objects are then stored in humid conditions for ten days so that the mycelium forms a solid outer layer and bonds separate components together. The pieces are then dried to stop the fungus from growing.
“We’re especially interested in creating systems for people like small businesses owners producing small-batch products — for example, small, delicate glassware that needs resilient packaging to ship,” said Danli Luo, a University of Washington doctoral student in human centered design and engineering. “So we’ve been working on new material recipes that can replace things like Styrofoam with something more sustainable and that can be easily customized for small-scale production.”
The material properties of dried Mycofluid exhibit comparable stability to expanded polystyrene (EPS), which is commonly used in packaging. The material absorbs only a small amount of water and returns to nearly its original weight after drying. Since all components are biodegradable, this material presents a potentially environmentally friendly alternative to conventional plastics.
“We’re interested in expanding this to other bio-derived materials, such as other forms of food waste,” Luo said. “We want to broadly support this kind of flexible development, not just to provide one solution to this major problem of plastic waste.”
In the future, the researchers aim to investigate whether similar bio-pastes can be made from other organic waste materials to broaden potential applications. The project was funded by the National Science Foundation.
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